johnsmachines

machines which I have made, am making, or intend to make, and some other stuff. If you find this site interesting, please leave a comment.

Category: Tools.

NEW SPINDLE MOTOR for CNC LATHE?

Now that I have replaced the stepper motors in the Boxford CNC lathe, (see “New steppers for an old CNC lathe”)  I am considering whether I might replace the spindle motor for the same reason…  that it has become less powerful due to the age of its permanent magnets.   Sometimes I am aware that it struggles to keep up the revs while cutting.

Watch the YouTube video about the next generation servo motors.  They use modern rare earth magnets.  They are powerful, compact and precise.  And not cheap.  Stuart T, who has the same Boxford CNC lathe as me, has suggested that these Clearpath motors would be suitable replacements for the ageing Boxford spindle motors .

 

 

 

Harold Hall Grinder Rest – modification; and triple expansion update.

Harold Hall has written many articles and several very useful books about metalworking, using a lathe, using a mill, and much more.

Recently he has been posting videos on YouTube.

He is a very knowlegable, dignified, elderly gentleman.  His books are precisely, beautifully written, and the plans and projects are excellent.  I have made quite a few of the project pieces in my quest to learn as much as I can about machining metal.

I came across his Youtube videos quite recently, and have been enjoying them.  One of them was about his grinding rest.

I made 2 of the HH grinding rests from plans in his book, and they have proved to be useful, reliable, and compact.  Here is a photo of one of them.

IMG_4883.JPG

The original HH plans specify that the footprint of the base is much smaller than I made it.  This one is 200 x 100mm.   The larger footprint adds some extra stability (IMO), and the slots permit the grinder to rest distance being easily adjusted.  It is a bit grimy because it is used frequently.  Polishes up quite nicely.

In HH’s video he mounts the rest on a metal plate, joined with a couple of switchable magnet bases.  Here is a link to HH’s Youtube video.

And in case you are wondering what has happened to the triple expansion engine, I have been working on the reversing mechanism.  The intermediate cylinder reversing curved slide would not fit into the available space, so I removed it, silver soldered in a new end, and ground it several millimeters shorter.  Then reinstalled it.   It is still a mm or so too long but I think that it will do.

IMG_4878.JPG

The high pressure reversing mechanism on the right, and the intermediate hiding behind, on the left of the pic.

IMG_4880.JPG

The intermediate cylinder valve rods and eccentrics.   Rather difficult access.

The Robert the Bruce approach to turning problems.

Robert the Bruce was watching a spider making a web in the cave they were sharing, so the story goes.  The spider tried 6 times to make a difficult connection, and on the 7th attempt, it succeeded.  Robert, who had tried many times to become king of the Scots, was inspired to try yet again, and he did indeed become King Robert 1 of Scotland, eventually.

I thought of Robert more than once recently, when I was making an ER40 collet chuck for my CNC lathe.  The particular  collet chuck involved making a 2.25″ x 8tpi internal thread, a 50mm x 1.5mm external thread, and cutting an 8 degree internal taper.   Not too complicated you say.  I agree, but for the chuck to be useful, each step had to be extremely accurate.

I made 4 successive collet chucks until one was adequately accurate.

CNC lathe - 3.jpg

CHUCK 1, 2 and 3

Chuck 1 actually went very well.   Nice tight spindle thread, taper good, and external thread just right.  But the chuck did not quite seat firmly.  Could it be that the spindle thread (the internal one) was not quite long enough?   So I cut a deep distal groove.    Wound out the carriage.   Oh shit!   Forgot to clear the spindle thread.   Totally destroyed it.   The chuck actually fitted the spindle quite nicely, but with only 10% of the thread remaining, it was useless.

Chuck 2 was made in 2 pieces, on suggestion from Stuart T.  The idea being that if there was any inaccuracy in the lateral runout, the piece with the taper could be adjusted.  OK.   Sounded sensible.  Again all went well, but the spindle thread was not correct.  For some reason the thread cutter seemed to make a new path about half way through making the thread.   So the spindle thread was thinned  excessively.   But still tight.   So I made the tapered half, and joined it all together.  Fitted it to the lathe and measured the runout and taper.  All good.  Less than 0.01mm runout and perfectly parallel to 100mm from the chuck face.   But.   The next day I removed the chuck, replaced it, and did the runout measurements again.  I did not need a gauge.  I could see the wobble.  Chucked the chuck  into the rubbish bin.  That thinnned out spindle thread was hopeless.   But what caused the problem?  The thread was CNC cut, and it should have been perfect.

So chuck 3.   One piece again.    All seemed to go well, but again the big spindle thread was wrong.    Again there seemed to be 2 thread paths.

Then the penny dropped.   The spider made the web connection.   Robert got the throne and John saw the light.

The tool post had moved slightly during the threading!  It had twisted a little, as a result of the T piece in the carriage slipping.  F**K    F**K  F**K!!!

I replaced the T piece grub screws with more solid cap screws, and really tightened them.  Then made another chuck.    I must point out that each chuck was about 6-8 hours of machining, normally a very pleasant time.  But by this time, I felt like that  bloody spider in the cave.

cnc-lathe-5

ER40 Chuck Number 4.

One advantage of making 4 chucks is that each one was made faster, and with more confidence.   This one was made in about 5-6 hours, including painting with selenium oxide to give it a black appearance.

It has a runout at the chuck face of 0 – 0.01mm (which might have been due to inaccuracy in the rod which was being measured), and a taper of 0.02mm at 50mm from the chuck face.  It feels nice and tight when being screwed on.   OK,  Success.   Eventually.

Next job, the throne of Scotland.

But obviously that slipping top slide on the CNC lathe has to follow chucks 1,2 and 3 into the rubbish bin.   It will be replaced by a fixed, immoveable tool post.

Swap Meet Bargains

Yesterday I travelled to Ballarat, (Victoria, Australia) to a swap meet which was held on 22 acres at the airfield.

Most of the stuff in the thousands of sites, was junk from shed and farm cleanouts.  However, despite rapidly walking up and down the rows, I did not quite cover all of the sites.  My Apple watch indicated that I had walked 18km (11.2 miles) and much of that was carrying a backpack full of bought items, so it was no wonder that my ankles were aching at the end of it.

I was really only interested in the few sites which had tools from factory closures.  But my eye was drawn to the very old Caterpillar crawler tractor, a 2 tonner, not too derelict except for a broken exhaust manifold and some rusted growsers.  $AUD9500, so I kept on walking.   Lots of elderly, old and antique cars, motor bikes, and vehicular bits and pieces.

The following photos show most of the stuff which I bought, and some prices (except for the ones which SWMBO must never discover).

ballarat-swap-meet-2

A Japanese woodworker’s chisel.  9 mm wide.  Razer sharp, oak handle.  I buy one of these at each Ballarat swap meet from the same seller, a lovely Japanese woodworker who lives and works in Victoria.  These chisels are a pleasure to use.  $AUD25

Ballarat Swap Meet - 4.jpg

This was a bargain.  A set of good quality English BA open ender spanners, probably unused, for $AUD8

ballarat-swap-meet-3

I dont know what this is called, but it has an INT40 taper, and bolts to the workbench or mill for inserting and removing cutters from the toolholholder, and avoiding the cutter dropping down and being damaged.  Is it a tool setter?  Anyway, $AUD40

Ballarat Swap Meet - 5.jpg

Used but sharp, quality brands.  Carbide ball nose end mill, countersink bit, T slot cutter, and 1/4″ BSP spiral tap. $AUD30

ballarat-swap-meet-6

A new, interesting woodworking cutter, carbide, with left and right hand spirals to avoid surface furring.  $AUD10

Ballarat Swap Meet - 7.jpg

3 Mitutoyo telescoping gauges.  $AUD10

I mulled over a Mitutoyo 1000mm vernier caliper in perfect condition for $AUD300, but decided that it was a wanted rather than needed item, and walked on.

ballarat-swap-meet-12

A box of 12 brand new quality Wiltshire triangular files. $AUD12

ballarat-swap-meet-13

2 very nice Moore and Wright thread gauges, which have BA and Acme threads as well as metric and Imperial angles.  $AUD6

Ballarat Swap Meet - 14.jpg

A box of metric counterbores.  Not cheap, but good price considering the German quality, and condition.  $AUD55

Ballarat Swap Meet - 15.jpg

Small die holder, Sidchrome 10mm spanner, tiny Dowidatadjuster and new box of inserts.  All useful.  About $AUD45

ballarat-swap-meet-11

Chesterman vernier height gauge.  Unusual triangular column. Beautiful condition, complete range of accessories, in a lined box.  Metric and Imperial.  Price not to be dislosed to SWMBO.

ballarat-swap-meet-1

These are brass wick type oilers which I will give to the local Vintage Machinery Society.  No markings.

ballarat-swap-meet-8

My brother was a navigator in the Australian Air Force many years ago, before the age of satellite navigation.  He would sight the stars using a sextant something like this to calculate the plane’s position, while standing in a glass dome in the roof of the aircraft.  (I think that I got that description approximately correct).   He once told me that he would like to have a sextant again, so when I spotted this at the swap meet, and the price was OK, I decided to get it for him.  Maybe it will make up for all of those forgotten birthdays.  So little brother, leave some room in your suitcase when you next visit.  I will leave the clean up and renovation to you.

ballarat-swap-meet-9

Elliott Bros London.

ballarat-swap-meet-10

It looks fairly complete and intact.  Of course I have no idea how it works.

A Full Size Weighshaft

The crowds were down at this year’s Truck Show at the Geelong Showgrounds.  Maybe the  38c weather prediction had something to do with that.

But those hardy souls who did turn up were treated to a feast of steam engines working on steam, and other antique engines popping away, as well as the magnificent trucks, tactors, and military vehicles.  There was a superb display of radio controlled trucks and excavators, and unbelievable machinery created with Meccano.

My interest was mainly focussed, for some reason, on the full sized triple expansion steam engine, which is the prize display in the vintage machinery shed.  it once powered a tug boat, and later a dredge on Port Phillip Bay.   And the following photos and video, if it will upload, show the bits which were of particular interest.

triple-expansion-engine-1-37

The red control handle top right is the main steam control valve.  The one on the left is the reversing control handle.  Note the big steam piston centre bottom.  It is a steam powered reversing control piston.   This engine was made in 1951, so is just about the last gasp in triple expansion steam engine development.

triple-expansion-engine-2-8

and the rod at top is about 5″ diameter.  It is the weighshaft, which carries the reversing levers for each cylinder.  On my model it is 5mm diameter.

triple-expansion-engine-3-6

Another view of the weighshaft and the levers.   Massive.

triple-expansion-engine-4-5

And note the drag links in the adjustable block.   That would have been set at intitial installation, and probably never altered since then.

Video of the big triple expansion engine working.  Maybe not.

For those following my triple expansion steam model engine build, I have put it aside again.  It is at the final assembly stage now.

Meanwhile, I am making some extra tool holders for the CNC lathe, and another ER40 chuck for the CNC lathe.

The ER40 chuck which I am currently using has an M5 shaft which is held with a drawbar, so I cannot feed work through the lathe spindle.  Plus it sticks out of the headstock a bit excessively.  So I have drawn up plans for a new chuck which I will fit to the lathe spindle and use the CNC to make the ER40 taper and threads.  Pics will follow.

And I really need some extra tool holders for the CNC lathe.  I have 5, but have material to make another 10.   The material is high quality cast iron off a scrapped T&C grinder.  I bought the grinder table cheaply (($AUD20 from memory) and have been gradually canibalising it over the last couple of years.   I have cut up the remains into rectangular 30x80x40mm chunks and will make the tool holders in the next couple of days, SWMBO and weather permitting.  Unfortunately there was insufficient material to make a long section, machine it, then cut it up, so each tool holder will have to be made separately.

SS Valve Rods

Making the new valve rods, as predicted, took me an entire day.  They required a high degree of precision, and being in stainless steel, not an easy material to machine, and quite thin and delicate, multiple stages in the machining.

But before I started on the valve rods I made myself a new spanner for the collet chuck on the CNC lathe.  I had been using an adjusting spanner, which was continually  going out of adjustment and causing angst.  The tool merchants did not have anything suitable (46mm opening, and thin profile), so I made my own.

triple expansion engine - 1 (34).jpg

The 46mm spanner being cut from 6mm steel plate.

triple expansion engine - 9.jpg

It is a bit prettier after this photo and being painted.  The rounded jaws facilitate easy application to the collet chuck.

triple expansion engine - 8 (1).jpg

Tightening the ER40 collet chuck with the new spanner.  It works very well.

So then I got on with the new valve rods.  Some end of day photos follow.

triple expansion engine - 2 (6).jpg

The valve rod is the silver coloured rod.  Actually stainless steel.  This photo shows the high pressure cylinder valve and valve chest.  There are 2 other valves, one for each cylinder.  All different sizes.

triple expansion engine - 4 (4).jpg

The high pressure valve chest and valve, the valve rod and guide.  On the right is the Stevenson’s link, yokes and eccentrics which control forward and reverse.  This setup is repeated for each of the 3 cylinders.  This is hooked upto the worm and gear which was shown a blog or two ago.  There are 22 components for each, not counting fasteners.

triple expansion engine - 7 (1).jpg

The low pressure setup.

And thank you to those readers who responded to my whinge about likes and comments.  I will continue this blog until the triple expansion steam engine is finished, and hopefully running.  Not sure after that.

CNC Lathe Conversion- final

Before I am hung, drawn and quartered, for operating a lathe without guards, here is the proof that I have been sensible.

IMG_4292.JPG

Guard over the X axis pulleys.  I like to watch the wheels going round and round, hence the transparent top.   Also note the cover over the exposed ball screw.

IMG_4293.JPG

Cover over the Z axis pulleys and belt, again transparent.  If I wore a watch it would be transparent.

IMG_4295.JPG

I also installed an ER40 collet chuck.   I will be using this for all work with diameters under 26mm.

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.

OK, so guess the purpose

IMG_7699IMG_7704

A pair of sheet metal pliers, to which I welded a steel tab.   Why?

For the answer click on the link.

For some reason the auto link is not working.  You will have to type the link manually.

Later update…   I dont get this.  Even the manually typed link to the explanation does not appear.

OK.   The explanation is that these sheet metal pliers have been converted into canvas stretching pliers for my daughter who likes to make her own canvases for oil painting.  Youtube sucks sometimes.

Try searching “Thomas Baker’s canvas stretching tutorial” to see how the pliers are used.

 

 

 

 

 

 

MORE ANCIENT GREEK TECHNOLOGY, THE ANTIKYTHERA MECHANISM

This mechanism was discovered in 1901, in a Roman era shipwreck, off the Greek island of Antikythera, which is a bit north of Crete.

It has been dated to between 100BCE and 205BCE, with the older date considered the best estimate.  ie, about 2200 years old.  Experts believe that its makers were Greek.

It is currently housed in the Greek National Archeological Museum in Athens.

IMG_4180.JPG

Not much at first glance, but when it was examined with modern scanning and X ray techniques…

Look it up on Wikipedia..

https://en.wikipedia.org/wiki/Antikythera_mechanism

According to the Wikipedia entry the gear teeth are too irregular to have been machine cut,

but watch the computer reconstruction.   Could you make this machine without a lathe and gear cutters?

How much more technology did the ancients have that has not survived the ravages of time?   A lathe for example.

CNC Lathe conversion -16

The wiring of the lathe is complete.  (Except for limit switches.  They can be added at any time).

Mach 3 is configured.  The wireless hand control is installed and working.  Ezilathe installed and waiting for input.

Some covers to be made.

IMG_4154

Hook ups in progress.  That’s the faulty VSD on top of the electronics enclosure.  The CNC engineer lost his hair trying to figure out the problem.

Still some testing and fine tuning required.

But nothing much will happen in the workshop for the next  3 weeks.

 

 

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.

cnc lathe - 2.jpg

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.

cnc lathe - 3.jpg

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.

 

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.

cnc lathe - 1.jpg

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).

cnc lathe - 4.jpg

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

cnc lathe - 3

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) .

CNC Lathe conversion -13

IMG_4125

Adjusting the lead screw.

The 48 tooth HTD pulley has been installed using a taper lock.

Then some time was spent adjusting the parallelism of the lead screw.  That requires quite a few movements of the carriage along the 600mm thread.  Each 360 degree turn of the lead screw advances the carriage 6mm, so you can understand that I became a bit impatient with all of the repetitive hand actions to move the carriage from one end to the other.

So this was a solution to that issue.  That HTD belt is the one that was too long, so I was happy to find a use for it.    The variable speed battery drill shot the carriage end to end in a couple of seconds.

All is now adjusted parallel.

A few more little installation issues, then for the wiring.

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.)

IMG_4117.JPG

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.

IMG_4118.JPG

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

IMG_4120.JPG

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

IMG_4119.JPG

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

 

NOT MUCH GOING ON TODAY

IMG_4092

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.

IMG_4095

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.

IMG_4087

Before (milled surface).

IMG_4093

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!

Workshop Tidy

I sometimes feel a bit ashamed when I have visitors at my workshop.

The reason is that when I am in the middle of a project, I really concentrate my energy on the decisions, the machining, working out how to fix the mistakes…

…. and tidying up as I go, is near the end of the list of must do’s.

Consequently, tools tend to be put aside at the spot where I have been using them.  And off cuts of steel or brass or wood or whatever, lay where they fall.

And as mentioned in a previous post, I have a policy of leaving swarf on the floor, to discourage wildlife from slithering into my workspace.  (see the old post about the tiger snake between the lathe and the milling machine).   And if you are not Australian, look up tiger snakes.   They are just about the most dangerous reptile on the planet.

So my workshop is not the tidy, organised sort of workspace which you might expect from a retired gynaecological surgeon.

But occasionally, the mess becomes so extreme, that I cannot find tools, I trip over stuff on the floor, everything is really dirty, and it is dangerous and embarrassing when visitors call in.  And some of those visitors have workshops where you could eat off the floor.

So yesterday I spent a whole day tidying, sorting, putting away tools, throwing out rubbish, and sweeping the floors.

What about the tiger snakes I sense you asking.

Well, here in the antipodes, we are in the depths of winter, and it is bloody cold.  And all sensible cold blooded reptiles are asleep in their homes. So for a few months it should be safe to sweep up the swarf.   Here’s hoping anyway.

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.

IMG_4089.JPG

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)

IMG_4087.JPG

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.

IMG_4086.JPG

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

IMG_4085.JPG

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.

IMG_4084.JPG

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.

IMG_4088.JPG

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

IMG_4075.JPG

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

IMG_4083.JPG

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.

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.

IMG_4054.JPG

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

IMG_4055.JPG

And gradually drilling the hole to 49mm!

IMG_4059.JPG

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.

IMG_4063.JPG

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

IMG_4064.JPG

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.

CNC lathe conversion-6. EBay problem

My first hitch occurred today.

I was very excited to receive the nut for the cross slide ball screw.  If you have been following these posts you might recall that the ground ball screw for the cross slide came from Taiwan, and arrived in 3 days.  But I had to order the nut from a seller in USA.  The nut was advertised as new old stock, but with no packaging.  That was OK, but the postage cost for such a tiny item was ferocious.

It was the last item to arrive from overseas.   However when I looked at it, it was obviously NOT new.

IMG_4043.JPG

The cap screws holding the ball recirculating tube were different from each other, and the washers underneath were too big for the screws.  Obviously not the way that TNK made it.  Somebody has had the nut apart.  And the ball retaining tube was very scratched  and loose.  Again, not TNK standard.

But no biggie.  If it works — fine.

So I turned up a retaining tube to remove the previous nut from the ballscrew, and it came off without any drama.

cnc lathe - 1

But when I tried to fit the “new” nut, it just would not go on.  Tried reversing the direction.  No go.  Bugger bugger.

Somebody has altered or changed the “new” nut.  Maybe installed balls which are too big, or maybe damaged the entry thread.  I do not know.

What to do.  I have been waiting 2 weeks for this to arrive.

First, Ebay email to the seller.  See what the response is.  Ask for a refund.  The postage was almost as expensive as the nut. If unsatisfactory response, they will get the worst Ebay feedback ever.

There is one other seller of these nuts on Ebay, also in USA, and 50% more expensive, and the postage is also 50% more expensive. (how DOES ebay come up with the postage charges.  It seems more related to the cost of the item rather than the weight-size etc.)  But the nuts are in original packaging.  And I want to get going with this, so fuck it.  Pay up and get it.

I will report in a later post.  (if the bad language in this post seems to reflect my state of mind, well, yes it does.)

 

PS.  Next day.  After sending photos of the issue, the seller accepted responsibility, and I am getting a full refund.  That restores my faith in Ebay/Paypal.   I hope that the next one is in better condition, and comes a bit more quickly.  Sorry for the bad language.