CNC | johnsmachines

Tag: CNC

October 1, 2019

Next Tool Project…A CNC Laser Cutter

The Southworth steam powered boiler feed pump has many gaskets. I have not counted them, but there must be 15-20. All with many 2mm and 4mm holes.

And in the process of making the machine, I have broken quite a few of them with the multiple assemblies and tear downs.

But, fortunately, 2 of the members of my model engineering club have laser CNC cutters, so extra sets of gaskets has not been an impossible ask. (Thank you Brendan and Stuart!)

So, some time ago I asked Stuart, if it would be possible to attach a laser cutter to the CNC mill. His initial answer was NO. But recently, he changed his tune. He attached a laser head to his 3D printed CNC mill and started producing gaskets on request! So, as is a recent pattern, I am walking in Stuart’s footsteps, and I have purchased a 15 watt laser head on Ebay. Chinese of course.

Laser kit 15w

This is the kit. Cost $AuD146.

Laser head

And this is the 15w laser head. Now I have to work out how to attach it to my mill. Shouldn’t be too difficult, as long as I don’t turn on the spindle while it is attached.

My CNC mill, during the electronics upgrade. Most recent photo. Soon to have a laser head.

Stuart assures me that Mach3 can be configured to operate the laser…. turn it on and off, move the axes at an appropriate speed, etc. I think that some trickery is involved.

And future gaskets will be as simple as ….

So watch this space .

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June 15, 2018

6″ Vertical Boiler- the Firehole

The firehole is the opening where coal is shovelled into the firebox. It is oval shaped, and is exposed to the boiler pressure. It is made from thick copper tube. Oval holes must be formed through the boiler wrapper and the firebox wrapper.

The elliptical hole in the boiler wrapper, and the firehole tube.

The first task is to shape copper tube which is circular, into oval shaped tube. I decided to make an oval shaped split wooden form and to compress the annealed copper tube with the form.

The wooden slab is cut into 2 pieces which are then cramped together, and the oval hole is CNC machined.

A 1″ 25mm length of 3.2mm thick walled tube is cut off, then annealed. Note that I have upgraded my forge. I bought some aerated concrete blocks (Hebel), and enlarged and encased the forge. The white Hebel blocks reflect the heat and the forge temperature rises quickly. the outside of the forge remains quite cool, testimony to Hebel’s insulating properties. Hebel is quite inexpensive. A 600 x 200 x 100mm blocks costs $AUD4.60. Heating time is 60 seconds, vs 90 seconds with the previous setup.

The wooden form and the unshaped thick walled copper tube.

After squeezing the annealed coper pipe in the form, using a 6″ vice. Nice elliptical shape. Note the pencil witness mark.

Then the elliptical hole is cut into the boiler wrapper. The vice jaws were replaced by temporary aluminium jaws 4″ high, adequate to hold the 6″ diameter tube. Cutting the elliptical hole on the CNC mill. There are wooden plugs in the boiler tube to prevent the boiler tube from distorting

The finished boiler hole and the elliptical insert. This was tense machining.

The fit is a bit too tight. I will take off another 0.1mm so it is an easy sliding fit, suitable for silver soldering. Then to cut the same elliptical hole in the firebox wrapper, but while the main cylinder is set up in this position I can cut openings for the ashpan and safety valve bush.

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April 3, 2017

Project in the Wings.

While finishing the triple expansion steam engine, I have decided on my next project. Actually, based on my past history of procrastination with the triple, I might even put aside the triple to start on this one.

Reading this article in “Model Engineers’ Workshop” gave me the inspiration to convert a rotary table to electronic control.

Dec 2016 MEW article

So I have commenced accumulating the bits and pieces…

An 8″ Vertex rotary table. I have had this for years, but unused since acquiring a universal dividing head. Should be ideal for this project.

A Nema 24 Stepper motor, shafts at each end, so I can use the table manually as well as electronically. The Microstep driver was supplied packaged with the motor as a kit. $90AUD inc postage.

From the same supplier, a 48volt power supply. $38AUD

The brain of the system. A programable microcontroller “Arduino Uno”. I bought 5 of these for $20AUD post included.

And an easily attachable display. To attach the Arduino. $19AUD

And since I knew nothing about Arduinos, a “Getting Started” book. Excellent. On loan from a friend (thanks Stuart)

And to practice some circuits and get some idea about the Arduino programming, a starter kit of bits and pieces. $75AUD, but has been very instructive and loads of fun. The program to run the Arduino is downloadable free from the Internet, so this kit might be a bit superfluous.

And some items of kit. Each under $20AUD.

A magnifier soldering station, and head light and magnifier

A very cheap multimeter. Previous purchase. Works fine. $10AUD

I have disassembled the rotary table, and ordered a 12/8mm coupler. I am waiting for the coupler before I start designing and cutting the main part to be fabricated which is the piece which joins the stepper and the table.

Also ordered a box to contain the electronics and switches. Havn’t yet thought about cables, joiners etc.

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September 19, 2016

Bombard Model-3 turning the barrel

Another session or two, and this project is complete.

Now how do I make a cannon ball 62-63 mm diameter? In wood will be ok? Does not have to be granite. I could make a mould and cast it in aluminium or lead, but stone would be authentic….. thinking.

ps. Re cannon balls. I will cast them, in cement! Now, how to make a mould.

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September 4, 2016

CNC Lathe Conversion – 17

First Test Run

After some test runs without tool or material, I performed some measurements.

500mm movements along the Z axis were reproduced multiple times with a deviation of 0.00mm! (the Z axis has a ground ball screw)

100mm movements along the X axis deviated 0.02mm. (the X axis has a rolled ball screw).

I was delighted to note that the lathe is extremely quiet and smooth. The only noise is some belt slap from the very old belts, and from the stepper motors.

The video below was taken from my iphone, while I was operating the lathe controls, so please excuse the erratic movements.

The steel is 27mm diameter. 750rpm, 50mm/min feeds.

And the guards will be made next step, without fail.

The G code was generated using Mach3 for these very simple shapes. For more complex items I use Ezilathe.

The lathe is 600mm between centres. 38mm spindle bore. Swing about 300mm.

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July 17, 2016

CNC lathe conversion -15

Another couple of advances in the conversion. Today I installed the lead screw cover and the cable protector to the cross slide stepper motor.

The cable protector was easy and straightforward. It flexes in one direction only, and is fixed at the ends after the cable is threaded through it. The length is adjusted by adding or removing links. It was placed so that coolant liquid will drain out of it, and to minimise the accumulation of swarf. The cables themselves have a thick covering and are well protected. The link protector will not kink, further protecting the cable.

It was cheap. About $AUD20 for 2 meters, posted from China. I used about 1.1m.

Showing the stepper motor cable protector, and the lead screw protector (one half of it. The other half is on the other side of the carriage.)

The lead screw protector was another story. It is a spring steel coil, about 50mm wide, and as it is compressed the coils fit inside each other. I made a big mistake in allowing it to spring open before I had installed it (there were no instructions). It immediately opened to a length of over a meter, in coils about 50-60mm diameter. No big deal, I thought. I will just compress it back to its original configuration. Big mistake.

It was what I imagine coiling a live, oily, biting, boa constrictor would be like. (OK, boas constrict rather than bite. How about an anaconda, or a big eel.)

I fought it for about an hour. And eventually succeeded. Minus a few bits of my skin.

So I did not allow the protectors to expand again until after I had them on the lead screw.

This is what they look like. Pretty cool IMO. They just expanded into position when I removed the restraining clips.

The lead screw stepper motor and protector. The Estop box above will get some ends to exclude swarf.

It was not cheap. The best price that I could find was from South Korea. $AUD200 inc postage. But it is excellent Japanese quality.

The wiring is happening, but the variable speed drive seems to be dead. It has been sitting unused on a shelf for 2 years, so no point asking about warranty. Took it apart to check for broken wires, fuses, burnt out components etc, but nothing visible. Will order another one. About $AUD200. An unexpected expense.

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July 11, 2016

CNC lathe conversion -14

These lathe CNC conversion posts are probably becoming a bit tiresome, but just in case there is someone out there who is interested, I will continue until the job is finished.

The latest was to make and install a spindle speed (and position – thanks David M) sensor. It consists of a disk with a slot cut in the periphery, attached to the main spindle. And an opto-electronic sensor which is connected to its own electronic board, thence to the breakout board and VSD.

The disc with the slot at 8:30 and the sensor at 9:00. I must have chosen the wrong cutter or turning speed for that disc aluminium… looks a bit rough. (note added 13/7 Stuart T says that I should have used coolant-lubricant).

View from above. Any clearer? That gear is now superfluous except as a spacer.

So there is one electronic impulse per spindle revolution. That is enough to measure the RPM’s. Essential for cutting threads.

The beauty of this system is that there is no gear selection or changing, and ANY thread pitch can be selected… metric, imperial, BA etc… any odd ball thread that your heart desires.

cnc lathe - 2

The HTD (high torque drive, I am informed by many readers) pulleys and belts and taper lock fittings. Unfortunately I could not find a taper lock to fit the small pulleys, so when it is all finally, definitely, absolutely, correctly, positioned, I will Loctite them in position. Protective covers yet to be made. I quite like to see the mechanicals in action, so I am intending to make the covers from clear polycarbonate.(Lexan) .

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July 7, 2016

CNC Lathe conversion -12

Today I fitted the lead screw.

No big deal, I sense that you are thinking. After all, the ends are machined, the bearings fitted, and all waits in readiness.

True, but there is a strict sequence of events. And since it has been 3 or more weeks since it has been together, I had to rediscover the sequence, by trial and error. And each bit of the fitting is very heavy, very delicate, very tricky. So it took me several hours to get to the final photo in this blog.

But first a view of the inside of the newly machined apron.

The lead screw fitted. The cross slide screw is also fitted. Note the red E Stop panic button fitted to the left. Next job is to fit a support bearing at the right hand end of the screw. Then to check and adjust parallelism of the screws. A rough check showed that they are within 0.25mm

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July 6, 2016

CNC Lathe conversion -11. Ball screw machining.

Hooray!

Today I collected the lead screw after the ends were machined by Statewide Linear Bearings.

I decided to drive the 100km each way to pick it up, in preference to using a courier. I wanted to ensure that all of the small bits were there, and also just to make sure it was handled properly. Mostly freeway, listening to Dan Carlin on the Persian-Greek wars, so it was a pleasant way to have 3-4 hours to myself. (If you do not know about Dan Carlin, Google him and download an episode. If history at school had been like this, we would all be history addicts.)

This is the lead screw, ends machined, and support bearings fitted. 1100mm long. 28mm dia

All good, except that the nut was back to front. That nut is pre-tensioned, which means that the 2 halves are separated by a precisely machined washer. I was nervous about removing it and replacing it the correct way around. However I had previously asked the ball screw expert about that aspect, so armed with the technique I made up a sleeve of the correct size, removed the nut and replaced it. No balls fell out. So all good! The above picture shows the nut in its correct position.

The nut. Looks expensive? Is expensive. And beautiful.

The machined driven end. $AUD250 machining there. But it is perfectly done.

And with the support bearing installed. A pulley for the HTD belt goes on the distal bit of shaft.

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June 26, 2016

NOT MUCH GOING ON TODAY

This is my workbench after I had almost finished tidying it. Really.

Then I thought about machining the ends of the cross slide ball screw.

So I mounted the collet chuck and checked the runout. 0 to o.01mm. Then I did a test cut in the ball screw. Hard hard hard. But it did cut. Then I chickened out and decided to finish it another day.

So, looking around the workshop for something else to do, I decided to pretty up the new CNC lathe apron.

Before (milled surface).

During

And I forgot to take a photo of the after, but it did look nice and smooth and shiny (look at the mirror finish behind the wheel).

Being retired is great!

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June 24, 2016

CNC Lathe Conversion – 8

Continuing the installation of the ball screws, and stepper motors.

I have completely removed the digital read out module and glass slides, and they will not be reinstalled. Not sure what I will do with them. They are only a year or two old, and in good condition. I will probably put them on Ebay. Same with the old gearbox, carriage apron, and electric controls.

Here are some pics of the plates and blocks which support the ball screws and steppers.

This is the steel plate at the headstock end, bolted to the bed. And the block with the holes is cast iron 42mm thick, to support the leadscrew and leadscrew stepper motor. It was machined out of an old piece of machinery, hence some unintended holes. Being cast iron it was fairly easy to machine, but incredibly dirty. Turned everything in the workshop black, including me. (whoops. Unintended not PC)

This is the block which replaces the gears and controls of the apron under the carriage. The thick block is cast iron, and the stepper motor support is 20mm thick steel. Very heavy.

This plate is hidden under the carriage. It secures the lead screw nut.

The slot in the carriage had to be widened and deepened a bit, in order to accomodate the slightly fatter and taller cross slide nut. See the next photo to see the setup for milling the hole through the carriage.

A rather confusing photo. The carriage is clamped to a large angle plate on the mill, and I am enlarging the hole which accommodates the cross slide ball screw. It was at the limit of what my mill could manage. An intermittent cut, with a lot of tool stick out. Not the best way of doing the job, but it worked OK.

Plastic covers attached to the stepper motors, and toothed belt pulleys fitted.

Checking the centres between the pulleys, using 2 wooden wedges to push the pulleys apart.

The underside of the carriage. The hole and channel at the left side of the picture was machined to accept the larger cross slide screw

So you can see that I have been busy since the last post.

At present the lead screw is at Linear Bearings in Melbourne, having the ends machined to accept the driving pulley, and support bearings. I did consider doing this machining myself, but decided to leave it to the professionals because of the high cost of the item and the hardness of the material.

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June 12, 2016

CNC Lathe conversion-7

I am still waiting for the replacement ball nut for the lathe cross slide to arrive.

Meanwhile, I have been busy machining the supports for the lead screw.

Drilling the holes for the support bolts for the lead screw nut

And gradually drilling the hole to 49mm!

That is a 49mm drill! First time that I have used it! Thank goodness for the FS Wizard app, to give me some idea about feeds and speeds. Following this I used a boring head to enlarge the hole to 55mm.

Gradually enlarged the hole in 20mm steel to 55mm diameter. and here is the lead ball screw, sitting roughly in its proper position.

So this is where I am at. The lead ball screw is sitting approximately in its correct position. Considerable adjustment required. And I am yet to turn the ball screw ends to their correct dimensions.

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June 5, 2016

CNC Lathe conversion -5

This is a list of the components which I have accumulated to convert a manual lathe to a CNC lathe. It is not quite complete, but close.

Lead ball screw and cross slide ball screw. Both with nuts and end bearings. (no pic yet)
The electronic components.

The electronic components, not including computer and parallel cable and manual pulse generator.

Two stepper motors. Nema 34, 1200 inch – oz. With rear covers.

A Gecko microstep drive for each stepper motor

Cable and connectors for the stepper motors

A transformer-power supply (48 volt)

Another transformer-power supply (5 volt).

3 phase 1.5kw motor (top) to replace the single phase motor (bottom)

Timing belt gears 24 and 48 tooth, 5M. Order belts when size is definitely established.

FK20 lead screw bearing and Ball screw covers

The electronic heart of the system- the breakout board. A C11R9

The index pulse board and sensor. A C3.

Manual pulse generator, wireless.

Variable speed drive, identical to this one on the mill

An electrical enclosure, to hold the various components. This stainless steel box was originally an item of medical kit. Here I am checking out one possible location. Not yet definitely decided to use this.

Finally in the electronics section, I will need a computer, loaded with Mach3 and Ezilathe. Surprisingly, it does not need to be a particularly powerful PC. And there are advantages in using an older operating system such as XPpro. I think there are a couple of those in the attic. If not, I should be able to pick one up for under $100.

3. Various structural items. Most of these will be 20mm thick x 200mm wide steel, cut to size and shaped and drilled. I will take pics of these as I make them. I was planning to have them water jet cut, but the shapes a fairly simple so I will cut and machine them myself as I go.

So, that is most of the items for the job. I have spent about $AUD1100 on the ball screws and nuts, about $AUD1500 on the electronics and electrics, and maybe another $AUD500 on pulleys, belts, steel, taper locks, fasteners etc. I will add it all up accurately at the completion. The lathe was cheap, bought sight unseen a few years ago. So all up, I should have a CNC lathe for under $AUD4000. And many pleasant hours of design and machining. And a great learning exercise. Stay tuned!

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June 4, 2016

CNC Lathe conversion -4

I am in the process of collecting all of the components for the conversion. Parcels are arriving from South Korea, Taiwan, China, USA and Australia. Next post I will take a photo of the bits, before I commence assembly. I have spent a lot of hours on the computer drawing up the positioning of the new components, deciding which components to get, then communicating with the sellers and making the purchases. Not to mention hanging around home when parcels are due. If I duck out for 10 minutes, that’s when the delivery van arrives. And of course he leaves his little card “sorry we missed you”.

This post I will show you some of the drawings of the proposed conversion. Of course the first step is to strip the lathe of all of the old manual controls, gears, motor, Digital read out, carriage apron, lead and cross slide screw, electric control box and contents. (taking photos of every component insitu in case of a change of mind, and restoration required later).

Then measuring the bed and carriage in minute and accurate detail, and drawing it in CAD.

This is the lathe side on and end views, showing the new lead ball screw in red and green. The cross slide ball screw is also there, but not well seen at this scale. The 4 ball screws at top left are the possible combinations for eventual installation. The second red one is the position eventually decided. The green ones are with the nut re-installed in reverse direction. I really did not want to remove and re-install the nut, because it is pre-loaded, and I do not want to risk disturbing the setup.

Many drawing versions are required, and as the components arrive, I find myself making changes. This is definitely not the final version. The two carriages show the carriage in its extreme positions on the lathe bed.

This was an early sketch of how I thought I would arrange the cross slide motor and lead screw nut.

This is a fairly accurate drawing of a cross section through the cross slide. Black is existing. Red is the new nut and ball screw. You can see that removal of some of the cross slide bed iron will be required. After looking at this I decided to move the nut and screw up a couple of millimeters.

The Internet has been very useful in showing what fittings are available. These are a few of the catalogues and tables which I have downloaded. Some sites even provide CAD drawings so their components can be inserted into my CAD drawing to see if they will work together.

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May 24, 2016

COMPRESSED AIR ON THE CNC MILL

Compressed air is very, very useful on the milling machine. The tool changer uses air for fast tightening and release. And I often use air to clear the field of swarf, and shavings (yes, I use my mill for wood too).

Recently, at the suggestion of Stuart L of stusshed.com fame, I installed 2 semipermanent nozzles on the mill, with adjustable direction and pressure adjustments. It has been a quantum leap improvement.

carronade - 1.jpg

The pic shows the jets aimed during CNC end milling of wood. The wood shavings are blown away which makes it easier to see how the milling is progressing; blows them away from me which is safer and cleaner; and stops the chips being machined into the work, which leads to a cleaner cut. It also improves any video or photo of the progress. It must also cool the cutter, although not as effectively as a liquid coolant. I have not tried using the misting attachment, which would improve the cooling, but at the cost of dampening the area and the work.

I particularly like the improvement experienced when machining brass or steel. The swarf is removed from the advancing cutter, preventing it being re-machined and squashed into the workpiece. I am noticing better surface finishes. I also adjust the air direction to keep the swarf away from me; particularly valuable when brass needles otherwise would be flying at me.

When cutting pockets, the air keeps the pocket free of swarf, and when using tiny endmills at high speeds I am experiencing fewer tool breakages.

This gadget was inexpensive ($AUD12) from China. It does not work the compressor too hard when the volume is turned back as far as possible, but still adequate. Although there are 2 jets, I find that only one at a time is adequate.

Recommended.

As an afterthought. I rarely use coolant on my lathes, but an air stream on the cutter and workpiece would probably have similar advantages to those listed above. I particularly wonder if it would assist during deep parting… always a tense procedure. I suspect that the cutter becomes hotter and expands more than the workpiece parting slot if there is no coolant. I will mention the result of air cooling and chip clearing on the lathe in a later blog.

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May 20, 2016

Lathe Conversion to CNC -2 and Wall Smashers

After removing most of the lathe gear which will not be required after the CNC conversion, the lathe is looking a bit naked.

The carriage apron, the lead screw, the back gears, the drive rod and control rods have all been removed. Also the cross slide screw and handle. The cross slide itself is temporarily removed, but available for measuring for fitting a ball screw.

I have now made accurate measurements and drawings of the lathe bed and carriage, in order to choose ball screws and nuts for the lead screw and cross slide.

The lead ball screw is easy. There is plenty of room and machined surfaces for attachment. I see no particular problems there. Just time, careful machining and expense. Chinese or Euro-American? As usual, there is a big price difference and maybe not such a big quality difference as previously. Looking at 25 or 32mm diameter, with 550-600mm of thread.

The cross slide ball screw is another matter. The current cross slide square thread screw is 14mm diameter, and I would like to use a ball screw about the same size. The problem is that a ball screw nut is considerably bulkier than the existing square thread nut, so some machining of the cross slide will be required to make space. The cross slide dimensions are already fairly tight, to maximise the swing over the carriage. I do not want to weaken the cross slide too much. So it is all a bit tricky. Time to consider options. And to get another opinion.

No lathe pics, so here are some of Turkish wall smashers.

This one was given to Queen Victoria by the Turkish sultan. It was made about a decade after the fall of Constantinople. It was cast in 2 halves. There is a giant thread connecting the halves. I imagine that the strange square holes are to allow levers to be inserted for the screwing by many strong men. No double entendre intended.

Turkish wall smasher

This one could have been used to make the breach in the wall at the fall of Constantinople 1453. That stone ball is 600mm diameter. With no trunnions or other supporting mechanism the barrel was probably dug into the ground for support. That would allow repeated shots at exactly the same point in the walls. 8-11 shots per day. It was made for the invading Turks by Orban, a christian who had previously offered his services to the defending Byzantines. The Byzantines whose empire by this time had been reduced to a tiny fraction plus the city itself, could not afford his services. The rest is history.

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February 29, 2016

Turning a cannon barrel

Today the exterior surface of the model 1779 naval cannon barrel was turned.

The piece of brass material weighed 5.1kg, was 300mm long and 50.8mm diameter.

I had used Loctite to glue a spigott in the bore, to provide a center and a driving diameter which the small CNC lathe would accept.

Although the lathe was nominally 300m between centres, the toolpost would move only about 200mm. So the turning had to be accomplished by turning the cannon mouth end first, and then reversing the workpiece to turn the breech end.

The CNC lathe, owned by Bob Julian, is about 30 years old, and it came out of a school. In the course of this job, it seemed to progressively free up, making us suspect that this is possibly the first time it has ever been seriously used.

The lathe electronics had been replaced by Stuart Tankard to use Mach3. The G codes were generated by Stuart’s program “Ezilathe”, which is available as a free download on “CNC Zone”. It is an excellent CNC lathe program, and I thoroughly recommend it.

I will eventually post some videos of the turning progress, but my Oz internet connection is so slow, that for the moment I will post photos only.

I started by turning a piece of rubbishy pine as a test.

That’s me, watching carefully. Later we installed the swarf cover.

The metal turning lathe does not miss a beat chomping through wood. These are the roughing cuts. F300mm/min, S800/min.

The Mach3 picture of progress.

The finished distal half of the cannon barrel in pine. If I stuff up the brass version at least I can have a wooden barrel.

Roughing the barrel in brass. 1mm cuts, feed 100mm/min. It took almost 50 minutes for this section, and about 15 minutes for the breech section.

The barrel mouth. No gouging resulting from the 22 degree HSS cutter.

Finish was quite good. Will require minimal polishing with ScotchBrite.

The workpiece was reversed in the lathe, the Z zero carefully set, the X unchanged, and the breech end turned.

The starting weight was 5.1kg. The end weight, including the spigott was 2.9kg. So at least 2kg of brass swarf, most of which I swept up and saved for possible future use.

Next to machine the trunions and some silver soldering.

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January 19, 2016

Homemade lathe with ONE MICRON accuracy.

Watch the video. It is inspirational.

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December 4, 2015

BOXFORD CNC LATHE (4)

Some videos and pics of some stuff made on the Boxford.

CNC is great for multiples. These are oil cups with ME threads.

Steam engine link

Ball end handle for a small lathe

The finish on the distal end was suboptimal.

First step in making Watts parallel motion links for the beam engine.

Base for a Jan Ridders Stirling engine

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The steam control cock and butterfly valve. The body of the top valve and both handles were CNC’d.

If you have found this little series of blogs about the lathe CNC conversion interesting, and would like to see a similar blog about how I got an ancient CNC mill working, let me know. Leave some feedback.

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December 4, 2015

BOXFORD CNC LATHE (3)

Some more photos of the Boxford, after the conversion. Sounds like the Damascus Road doesn’t it. Going CNC is almost an epiphany.

This is the wireless MPG controller. The lathe can be controlled from across the room, using the MPG and the wireless mouse and keyboard. The MPG even has an Estop kill button, along with the one on the lathe.

The new setup. Normally the keyboard and mouse sit under the screen to avoid swarf. Note the multitude of LED and halogen lights. I need those these days.

The old Dell sits underneath, along with other bits and pieces. The trolley has been very useful, as the lathe is progressively expelled from different rooms by SWMBO.

One drawer of tool holders, collets, inserts etc. The other drawer is not so tidy.

The Dickson toolpost, and Diamond tangential tool.

The ER32 collet chuck. Much more accurate than the Burnerd 3 jaw chuck. The mounting plate and backing plate were made by me to a design by Stuart Tankard.

If this conversion is of interest to you, look out for a technical description of the process in an article by Stuart Tankard to be published next year in Australian Model Engineer.

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September 27, 2015

Koffiekop Engine

I have been busy for the past week or so making a Stirling cycle engine. It is the Coffee Cup engine designed by Jan Ridders. It is powered by the heat from a coffee cup of hot fluid. Or an ice cube sitting on the top plate!

Page one of five of Jan Ridders’ excellent plans.

Most of the components of the coffee cup engine.

100mm flywheel.

Possible alternative flywheel, roughed out, I will see how it appears with a bit more finishing. Looks interesting?

An experiment with engine turning on an aluminium surface, using a “Brownells Engine Turning Kit”, kindly loaned to me by Stuart. The pattern is made with the spring loaded wire brush seen in the picture. I used this on the upper plate of the displacement cylinder.

Lots of tiny fiddly bits.

The piston is made from graphite. An interesting material to turn. Surprisingly tough, accepting a 3mm internal thread. And presumably self lubricating. Machining it produces black, pervasive dust. SWMBO is not impressed, since my CNC lathe sits in our living room. I might get marching orders for the lathe as a result of this one.

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September 9, 2015

Lathe Spider

What! More dangerous wildlife in my workshop? (see the previous post about the tiger snake).

No. Not this time. Thank goodness. No more highly venomous snakes wriggling between the lathe and the milling machine. Mind you, we have red back spiders and white tail spiders in abundance here. (both very nasty, to explain to the non Australian readers).

But in this case, a lathe spider is a tool. Used to repair worn lathe chuck jaws.

I wondered why my beautiful Colchester lathe would not part off thin brass rod. Should have been a doddle. Closer examination revealed that the jaws in the Colchester 3 jaw chuck, were “bell mouthed”. That is, worn in their outer extremities. That is where lathe chuck jaws wear initially.

Solutions? Buy new jaws…. none available,. anywhere that I could find. Buy a new chuck…. a new quality chuck of this size (200mm diameter) costs between $500 and $2000. A second hand chuck might have the same problem.

Another solution, which I have used successfully previously, is to regrind the jaws with a tool post grinder. I have a tool post grinder, not used with this lathe, but should be suitable.

So, I spent a half day fitting the tool post grinder to the Colchester lathe. No big deal, but it needed 2 complex bush-washers and a new tool post bolt. It also needed the internal grinding spindle to be fitted to the grinder, a first for this grinder.

I had made a lathe spider a few years ago, for a different lathe and chuck, and it fitted the Colchester!

The 200mm Colchester lathe chuck, and the spider, made years ago, which fitted!

I spent another few hours fitting the spider, grinding the jaws, and the measuring the run out of the chuck. The spider permits the jaws to be tightened inwards, against pressure, then the jaws can be reground using the tool post grinder.

Using the tool post grinder to resurface the jaws.

A very frustrating few hours!!!

Despite multiple runs, grinds and measurements, I could not get the runout to acceptable levels. The best was 0.1mm which is totally not acceptable.

I wondered whether the spider was just not accurate enough.

I also noted that the runout was better (0.05mm) if the jaws were not tightened heavily in the measuring phase. I wondered if the chuck scroll was badly worn, which would mean a new chuck!

So, I searched the net. And found a picture of another style of lathe spider, and I determined to give it a try.

Today, I used the CNC mill to make the new spider. Actually, 3 parts which are fitted individually to the chuck, to give the same effect.

CNC Milling the lathe chuck spider components.

The new version lathe spider bits, clamped to the lathe chuck. This spider is made from 6mm thick aluminium. This photo was taken after the jaws were reground, as you can see.

I ran the grinder in and out a few times, re-measured the runout. Zero, zilch, nada, niente. No movement of the dial indicator. So the indicator must not be touching the test piece, or pushed in so hard that it cannot move.

So I checked the positioning of the indicator, and ran the test again.

Again, NO MOVEMENT AT ALL!

So the runout, at least at this diameter, is zero!

So I tried a smaller test piece. Same result.

So I tried really tightening the jaws hard. Again no movement.

I must point out that when I tighten the jaws for measuring, I always tighten the jaw which is nominated by Colchester. I tried tightening the other two jaws, and found 0.1mm runout. So, the nominated jaw tightening really works. It is not bull shit!

And this lathe chuck spider method really works! It just needs to be made really accurately! (did I say before that I really love CNC).

Next step. Totally disassemble the chuck, and carefully and fastidiously clean every component, then reassemble it with new grease. To rid it of every trace of grinding wheel dust, which could destroy it in no time at all.

I was delighted to see that the internals of the chuck looked perfect! No signs of wear at all. Very happy.

The disassembled lathe chuck

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June 14, 2015

Triple Expansion Steam Engine Update, and some toy making

Some pictures following.

I have made the steam chest valves, the valve buckles, and the valve rods have been commenced.

The three steam chests, with valves and valve rods

The low pressure valve and buckle. Steam chest behind. The machining on the buckle did not quite remove all of the casting roughness.

And on a different subject, regarding last week’s post about making toys, this is the setup on my milling machine for CNC cutting of MDF. I am using the new high speed head running at 20,000 rpm with a 2mm cutter. There is a sheet of sacrificial MDF attached to the mill bed, and the material is attached to the sacrificial bed with double sided tape. I hand held a vacuum cleaner nozzle to suck up most of the MDF dust, rather than breathing it, or having it settle on my machines and causing rust.

CNC’ing MDF on an industrial scale machine.

The MDF after 20 minutes of CNCing. This turned into a raptor.

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March 8, 2015

TRIPLE BORING CYLINDERS

Today I bored the cylinders on the triple expansion engine.

Most model engineers would perform this task on a lathe, bolting the work to a faceplate or possibly using a large 4 independent jaw chuck.

The most accurate machine in my workshop is my CNC mill, so I decided to use the mill.

The setup is as depicted in the photo below.

The cylinder boring setup.

Cylinder boring complete. The setup took a couple of hours. The boring process also took 1-2 hours.

Of course, the high pressure cylinder needed to be center drilled, then drilled to 6, then 12, then 15mm, then bored to size 22.23mm.
Doing the job on the mill, I can be confident that the bores are all on the center line, all parallel, and the centers all correctly located. The intermediate cylinder finish was not acceptable, due to some chatter on the final cut, so I bored it out an extra millimeter to rectify the problem. The extra size will not matter. The piston (and rings?) will be made to fit the bore.

At the end of the session, I have left the setup intact, so I can check whether further processes can be performed using the same setup.

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February 13, 2015

SHORT VIDEO OF CNC CENTRE DRILLING

To see the YouTube video, click on the link below. Sorry about the shaky image. I was holding my iphone in my right hand, while hovering my left hand over the emergency stop button, just in case. But it all went perfectly.

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January 6, 2015

CNC Mill 11

CNC. That is what started this post. Today, I fired up the CNC mill, and made a simple fitting for my Bolton 7, which involved some accurate deep drilling in aluminium. I LOVE CNC!! Drilling 3mm diameter holes through 16mm material, automatically, centre drilling, then deep drilling 1mm peck at a time and automatically clearing the chips, with positional accuracy of 0.001mm. Fantastic! Cannot wait to get more into this.

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December 18, 2014

CNC lathe tool holders.

I needed some extra toolholders for my Boxford CNC lathe, and the following photos show some of the steps in making them on a vertical mill with a horizontal attachment.

The toolpost holder is a Dickson, beautifully made, precise. And it came with 6 tool holders. 6 should be adequate you think? Not so. You really need one holder for every tool that you might use, because with CNC, you want to do the CNC settings in the computer only once. And the Dickson holders are expensive, so I made the extras.

The material for the tool holders is cast iron bar from a house wreckers yard. The bar was 3 foot lengths of iron window counterweights from very old double hung windows. Very cheap $5 each. A bit porous in places, but enough good stuff to get useable 300mm lengths.
Roughly cut to length in foreground, machined square behind, original holder bottom right.

The holders had been dimensioned and drawn up by my expert friend Stuart Tankard.

This is the original horizontal machining set up. I made each holder separately.

For the next batch, I got smarter, and milled 300mm lengths of the bar, and cut them up later. You might also note that I painted the horizontal milling attachment, using Por 15 paint. For the actual milling I also used copious lubricant fluid.

Using a drop bandsaw to cut off the milled blocks. Less than 1mm clearance.

I made about 30 altogether. Some for centre drills, ER collets, various left right and centre insert bit cutters, and quite a few spares for the future.
You might say a cornucopia of toolholders.

The height setting knobs were turned on the Boxford 125 TCL CNC lathe, again designed and G coded by Stuart Tankard. The knurls were cut by Stuart on his 4 axis CNC mill.

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September 13, 2014

CNC MILL 9

Yesterday I cut some metal on the CNC mill for the first time.
I used one of the canned cycles built into the CNC controller, and faced and squared off a lump of brass which will be used for a hot air engine (The Ridder “bobber”).
Despite multiple readings of the manual, I got confused about which units required minus signs, and which ones the machine automatically assumed were positive and negative, and consequently, despite resting my hand on the emergency stop button in case such a contingency occurred, the head crashed straight into the milling vice, breaking 4 carbide tips and leaving a permanent love bite on the vice as a reminder of my incompetence.
After some expletives deleted, I re-entered the numbers, and next time, the machine went through its motions gracefully, purposefully, and quietly, leaving me with a nicely shiny and squared lump of brass.
It was so impressive, that I repeated the exercise, just for fun.
I had checked the squareness of the mill head to the table, and it was all within 0.01mm in 100mm, so nothing was altered.
I had bought a Z axis probe from CTC Tools in Hong Kong, and that was easy to use and accurate, for $a100.
Next step, to hook up a computer and try to download G code programs. Watch this space.

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August 30, 2014

CNC MILL 7

Z axis problem fixed!

My friend Stuart T methodically checked the wires and connections, and diagnosed a problem involving the Z axis encoder. He resorted to removing the encoder, to look at it more closely, and said ” that came off a bit too easily. I wonder if the shaft is connecting properly”. Sure enough, the shaft was loose, which explains the bizarre Z movements followed by a total loss of position information. Someone has joined the 6mm shaft to a 1/4″ socket, and it had probably worked loose during the transport from Echuca to Geelong.

So we quickly made a sleeve to join the 6mm shaft to the 6.35mm socket, tightened it all up, soldered a few wires which broke during the inspection, and hooray it all worked perfectly. Hallelujah.

Oh, and that $20 Chinese hand wheel. It was 10 mm thicker than the originals, and looked out of place, so I chucked in the the lathe, and turned it down to the same 18mm thickness as the originals. It was made of hard plastic-bakelite material which smelled really offensive while I was machining it, and was very abrasive. Tool steel lathe bits were just worn away, but a carbide insert tool coped OK. The reshaped hand wheel looks and feels much better.

Just the oil lubrication pump to fix, then I can start making chips.

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August 29, 2014

CNC MILL 6

Help!

I need a wiring diagram for the Extron mill.

It is a Hafco badged machine, but Hafco (Hare & Forbes) do not have wiring info. The Extron factory in Taiwan has not replied to my emails. Hare & Forbes apparently contacted the factory, and also drew a blank about wiring info.

That is pretty unimpressive. The machine is only 17 years old. In built obsolescence? Just not worth while supporting older machines? If it was a US or European machine there would be no problem getting info. It seems that this Asian factory has a different idea about what constitutes support.

Fortunately I have an expert friend who will, I am confident, be able to work it out.

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August 25, 2014

CNC MILL 5 with some more pics

The broken X axis hand wheel. replacement from China for $a20, including postage….

The replacement folding handle hand wheels arrived from Hong Kong today. I was slightly disappointed in the quality, but then, for $a20 each, including postage, I am not complaining. They are close in appearance to the originals.

The new hand wheel fitted. On the table is a spare new hand wheel, and the broken one. I am considering machining the new one, to be closer in dimensions to the old one.

This is the pneumatic draw bar motor and spring loaded engagement gear. It is now functioning!! I rebuilt a badly corroded valve, and remade a gasket, and hooray, it works perfectly. Still to replace the cover which keeps the dust out of the device. That saves $a700+ for a replacement, and gives me confidence to work on these precision items in the future. The motor behind the draw bar motor is the main spindle motor, a 6hp 3 phase motor with a very noisy fan which is another job for down the track. One thing at a time. We are getting there. I have contacted Extron Corp in Taiwan, in the hope of getting a wiring diagram, so I can look at the oil distribution pump and controller and locate the relay, which I suspect will be the culprit. It does feel good to have fixed 2 of the 5 or 6 problems with this machine.

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August 24, 2014

CNC Mill 4 (with some pics)

Now that I have a couple of days cleaning off the carelessly applied paint, I am prepared to show some photos.
The trouble with a 17 year old machine, even if it has done little work, is that repairs are required before it can be used.
1. New hand wheel
2. Z axis acting strangely. ? encoder faulty, or broken wires.
3. Pneumatic drawbar not working ? needs replacing.
4. Auto lubrication system not functioning. ? relay faulty, other problem.
5. Operator needs considerable training.

The only available space in my workshop was in front of the door

Showing the table, with the tool rests removed, the hand wheels including the broken X axis hand wheel, the turret and the electrical box

The broken X axis hand wheel. replacement from China for $a20, including postage….

Showing the X axis ball screw, the hand wheel gearing, and the coated way (? Teflon)

The control box for the pneumatic power drawbar (not working), and the automatic lubrication pump and reservoir (also not working).

The CNC input control panel. I am still learning how to use this.

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August 22, 2014

CNC MILL 3

Pneumatic draw bar. The draw bar was not functioning at all. One of the valves was completely corroded, so I rebuilt it, making a new rim from brass and attaching it with Locktite. The draw bar now functions, but it leaks air badly. A gasket needs replacing, and I will renew that. But if it is still unusable, I will buy a new air draw bar.

I turned on the mill for the first time today.
It booted up, and self tested OK. The servo motors and spindle work fine, and smoothly. The axes move up to 4000mm per minute. The spindle runs quietly up to 4000rpm. (not immediately. I ran it for 10 minutes at a low speed as per the instructions). There seems to be some limits to the travel on the X and Z axes, not related to the hard limits. There must be some soft limits set incorrectly.

All of the ways were dry. There is an automatic oiler, with plenty of oil in the reservoir. I used an oil can to lube all of the ways and the ball screws, because I am not sure if the auto oiler is functioning. It is meant to operate on startup, and then every 30 minutes. Another item to check.

This mill is an Extron, with 1000mm travel on the X axis, and approx 500mm on the Y and Z axes. It is big (for me) heavy and smooth. I expected that it would need some attention because it has not been used in years. So far the revealed problems have been with the peripheral items and cosmetics, and not the major components or the electronics. So far so good. I will post some pics soon.

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August 18, 2014

CNC Mill 2

I was on call over the weekend, so I had today off, and spent it in the workshop. It was cold. Jumper plus oilskin cold.
I crow-barred the space for the new mill, levelled the mill with a machinists level. One foot was missing so I turned up a new one… 75mm dia, 16mm thick, with a 20mm dia recess to accept the levelling bolt.
Then I started to tidy up the awful paint job, scraping paint off the machined parts, and using my Dremel to wire brush it off plastic parts. Starting to look more respectable.
Then I found a hand wheel control lever stop made from a rolled tube which had broken off at surface level. It was hardened, as I discovered when I tried to drill it out… changed the drill bit to mush. So I used the Dremel with a carbide bit to grind it out. That worked, but it took a lot of time, and I ended up with an irregular hole which I then drilled out to 5mm and tapped 6mm. I have inserted a temporary 6mm cap screw as the stop, and it works but looks a bit gross. Needs a tidy up.
The 3 phase lead does not reach my converter, so I have to replace it with a longer one. The plug is new, so I will re-use that. I have some 20 amp 4 wire lead, so I will use that. Maybe next weekend I will get to fire it up. Saturday is out though. Geelong – Hawthorn AFL game takes precendence.
I need to make some T nuts to suit the 18mm T slots. They are bigger than any machine I have previously owned. I will tap them to accept 12mm studs, rather than the recommended 16mm studs. I already have the 12mm studs, and I cannot see that I will need the bigger ones. If i was to use the table capacity of 900kg the big ones would be useful.

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July 19, 2014

Collet chuck for CNC lathe

I made this ER32 collet chuck for my Boxford CNC lathe. Actually I made 2 chucks, but the first one had 0.03mm runout, so I made this second one more carefully, and it has no measureable runout at all, at the chuck or 50mm out from the face.
The material is stainless steel, so it was difficult to drill the holes and tap the threads, and I used a few tungsten carbide inserts. I am very happy with the end result.
Thanks to Stuart T for the design.

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Tag: CNC