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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: CNC MILL

Turkish Bombard. The Barrel Script

Well, I bought a pair of NSK bearings for the Z axis of my CNC mill, and removed the old ones and inserted the new ones.  Cost $AUD 200.  Plus 2 or 3 half  days of  dirty heavy work.    And the problem persisted!!@!@

OK.  Time to get an expert opinion.  Here comes the cavalry.  Thank goodness for my expert friend Stuart T.

Very puzzling.  Even for Stuart.  There was some unwanted movement in the Z axis (about 2mm), despite being apparently properly installed.  Not a problem with the ballscrew or ballnut.  Even Stuart was puzzled.

“have you got any left over bits and pieces?  Is it all installed the way it was before?”

To cut the story short, we installed a thicker washer below the locknuts, and it seemed the problem was fixed.  Or was it?

Today I did another test run of the bombard mouth Arabic script.  Worked fine.  OK.  Time to finish the bombard.

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Here is the finished result, ready for painting.  I have used a 20 degree engraving carbide bit with a 0.2mm flat end.  There is some loss of fine detail but it is I think, adequate.  When it is painted, the filling putty above the pin screws (the white circles) will be invisible.  The engraving took a total of about 60 minutes, at 500mm/minute, 15,000 rpm.

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The setup.   A large angle plate clamped to the table.  The work clamped to the angle plate.

The translation of the Arabic script is “Help O God the Sultan Mehmet Khan son of Murad. The work of Munir Ali in the month of Rejeb. In the year 868.”

Modelling a Turkish Bombard -4 Decoration

The decoration around the barrel is formed by a repeating pattern, which when milled, very cleverly forms 2 identical patterns.  One is excavated and one is the original barrel surface.  You will see what I mean if you look at the pictures in the earlier blog, and the video below.

It took me an evening of experimenting on the computer to work out the system and draw it.

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Then I measured the diameters of the 2 gun components, calculated the circumference, (OK it is not rocket science.   3.142 times diameter), then working out the number of identical shapes which would fit around the 2 different diameters, at the same size and spacing.   Amazingly, it took 18 shapes to fit almost exactly around the barrel, and 16 of identical size almost exactly around the breech.  the angular spacing was 20 degrees and 22.5 degrees.

Then the shape was imported into V-Carve Pro, and G codes were generated.

My CNC mill does not have a 4th axis, so I used a dividing head to move the workpiece at the precise angles.  See the setup in the video.  That meant that the pattern was engraved into 16 and 18 flat surfaces, rather than a continuous cylinder as on the original.

It worked very well.  There were minor compromises due to the shapes being milled with a fine end mill but when you look at the pics I hope that you will agree that it is effective.

I calculated that the milling had to be at a maximum depth of 2mm in order to cope with the curvature, but if I do it again,  I would reduce the depth by 25%.

The first part of the video is a shot of CNC drilling.  Then the CNC routing of the repeating patterns.  Each angular setting of the pattern took 4 minutes to complete.  136 minutes altogether.  In reality, it took a whole day, most of which was spent doing the setups.

 

 

Steam Engine Oilers

Knowing that I have an interest in CNC machining, Tom, from the Vintage Machinery Club in Geelong asked me to make a pair of oilers for a very old Wedlake and Dendy steam engine.  The engine is a large (to me anyway) stationary engine, which is run on steam several times each year.  The oilers for the cross slides were missing.

We searched the Internet for pictures of W&D steam engines, but could find no pictures or diagrams of the oilers.  So Tom sketched a design, and I drew a CAD diagram.  The dimensions were finally determined by the materials which I had available…  some 1.5″ brass rod and some 1.5″ copper tube.

This is the almost finished product.

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Just needs 1/4″ BSPT fittings and and oil wick tube so they can be fitted to the engine.

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The copper tube silver soldered to the brass cylinders (top), the brass blanks for the lids (bottom) and the mandrel to hold the assembly (bottom centre) during CNC turning and drilling.

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The mandrel to hold the body (left) and the mandrel for the lid (right).  The cap screw head and hole in the mandrel have a 2 degree taper.  The slits were cut with a 1mm thick friction blade.

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Rough turning the base.

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Turning the lid.  The mandrel is held in an ER32 collet chuck

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Engraving the lid.  Using a mister for cooling and lubrication.  16000rpm, 200mm/min, 90 degree TC engraving cutter.

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The oilers work by wicking the oil from the reservoir into a tube which drains through the base onto the engine slide.  When the wick tubes are fitted the oilers can be fitted to the engine.

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The 1865 Wedlake and Dendy

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My lathe is a Boxford TCL125, using Mach3.  The G code is generated using Ezilathe.

Below is a link to an oil cup from “USS Monitor”, of American civil war fame.   One of the first ironclads, powered only by steam.

http://www.marinersmuseum.org/blog/2010/04/one-oil-cup-down/

(ps. The  lathe which I was converting to CNC was the subject of previous posts and is now working, but needs some guards fitted and a bit of fine tuning.)

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.

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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.

Problem with Balls (Incarcerated ball bearing)

The X axis on my NC mill was always noisy in operation from the time I purchased the machine a year ago, and the seller told me that he thought the end bearing was the source of the noise.

In comparison, the Y and Z axes were almost silent in operation, swishing to their allocated positions.

But the machine worked well and accurately, so I did not fuss about the noise.

But a couple of weeks ago, the X axis low pitched rumble changed to a louder, more graunchy sound, which I did not like at all. However the accuracy was still not affected.  And the noise occurred only with rapid feeds.  On machining feeds, it was not noticeable.

So, with some trepidation, and only a vague notion of the construction of the machine, I disassembled the suspect bearing.  That involved unscrewing covers, unbolting the heavy servo motor and lifting it to the floor (not wise.  my back still aches.  next time I will use a supporting jack or platform), then trying to figure how to remove the toothed pulley.  A phone call and text message including photo to my expert friend (thanks Stuart) gave me the necessary information how to remove the tapered bush and pulley.  I made a simple gear puller which screwed into 2 threaded holes in the end of the tapered bush, and the whole lot magically came apart.

The bearing housing, toothed gear and tapered bush.

The bearing housing, toothed pulley and tapered bush.

Removed the toothed belt.

The bearing housing was next, secured by 5 large cap screws.  But it would not budge, despite removal of the screws.  The 2 locating pins were tightly ensconced, and persuasion was required with a series of slim wedges, hammered into the gap.

I took the cleaned up housing containing the bearing to Bob Hamilton’s Bearings and the expert there explained that there were actually 2 bearings pressed into the housing.  These were angular bearings, facing each other.   I thought that he would be able to tell me if they needed to be replaced, by the feel of them.  Unfortunately, he explained, the only way of knowing for sure, is to actually replace them, and see if the problem is fixed.

The replacement bearings would have to be ordered at a cost of $au100, but should be delivered within 24 hours.   Since my machine was out of action and of course I was in the middle of a job, I decided to insert the new bearings.

Sure enough, they arrived the next day.

A bit nervously, I pushed out the old bearings.  I made up a brass pusher to the size of the opening, and the bearings slid out fairly easily.  So far so good….

The reader should be mindful that a retired gynaecologist does not have a vast experience of changing machine bearings.

I carefully noted how the bearings were asymmetric, cleaned the cylindrical cavity and my hands, set up the press, and pushed the first bearing home.

No problem.

Except that the bearing was back to front!

Despite my careful noting of the configuration, I had managed to get it wrong.  Stupid stupid stupid.

And there was now no access to the outer race of the bearing to push it out!

What to do?

I have heard of using frozen carbon dioxide to shrink bearings and make removal easier.  But I have no idea how to access CO2.

The bearing slid in easily enough, so would it matter that much if I pushed on the inner race to get it out?

Oh well.   WTF.   If worse comes to worst I will fork out on another bearing.  But maybe with a separate supplier.  Just to save  much embarrassment.

So I pushed on the inner race.  It took more pressure than getting it inserted.   Then bang!

The inner race, the ball cage, and the balls, popped out.   I retrieved them all.  Fortunately the balls were sizeable and easily found.

But the outer race was still stuck in the housing, and what was worse, there was no edge to push it out.  Nor was there a gap at the housing base.  The race was still pushed firmly home.

F**k,  f**k, f**k.!!

CO2 option??   Same problem.  No idea how access it.

Drill some holes through the housing to allow access for a pin punch?   Ugly idea but might work.  Keep that one in reserve.  I really did not want to risk weakening the housing.  The machine is 18 years old and I am certain that such spare parts would not be available.

Maybe I could somehow lever the race to create a gap at the base and get it started.   But no access, and did not want to risk damaging the housing.

So, to cut this story short, I turned a steel disk about 5 mm thick, with a 25mm central hole,  and outside diameter just to fit into the housing through the race.  The disk had a knife edge.  I cut the disk, to enable it to be expanded.   Inserted it into the point of contact between the race and the housing, then expanded it using a pipe expander.  I could have used a tapered bolt, but the pipe expander worked.  As it expanded, it pushed into the slight groove between the race and the housing, then I felt the race move a little.  Some further expansion, and it moved some more.  Then, hallelujah, the race popped out. (I will insert some pics tomorrow).

The Pics.  (added 16 Sep 2015)

The pipe expander.

The tube expander.  Usually used for joining copper pipe.

The knife edge, split ring, used to dislodge the bearing race. (seen here in its expanded state.)

The knife edge, split ring, used to dislodge the bearing race. (seen here in its expanded state.)

Another view of the knife edge split ring, in its expanded state.

Another view of the knife edge split ring, in its expanded state.

On inspecting the angle contact bearing, I could see no marks or indentations on the bearing surfaces, or the balls.  So I cleaned the bits, reassembled the balls in the cage with clean grease, and pressed the assembly together in the press.  It all went together with a satisfying “click”.  It seemed to rotate smoothly, so I pushed the bearing back into the housing, then its partner, correctly this time.

After reassembly, I tested the machine.

It worked smoothly, and the X axis is now as silent as the other axes.

I feel stupid that I got the assembly wrong first time, but happy that it worked out in the end.  And a bit chuffed that the expanding, knife edged disk idea worked!  Probably reinventing the wheel.  Not happy about breaking apart then pressing together the bearing.  However if it becomes noisy again I will be more confident about replacing it.

I suspect that the original bearings were not actually worn, but just needed the securing nuts to be tightened.  If I had tightened the securing – compressing nuts, I might have solved the problem.  Oh well, live and learn.  I will keep the old bearings as spares.

24000 RPM spindle for CNC Mill 2

Yesterday the spindle was wired to the Variable Speed Drive – single to 3 phase converter, and to power. It span smoothly and quietly, and very fast.  Much quieter than a woodworking router of similar power and RPM.

Today I hooked up the coolant, after testing the pump.  But when I ran the coolant through the spindle, there was no movement of the coolant.  So I reversed the fluid connections in case it was direction specific, but still no action.

The pump and lines were OK, so there was a blockage in the spindle.

I removed the coolant connectors on the spindle, and I could see something white and foreign deep in the works.  A bit of poking around revealed that it was probably a bit of packaging foam.  I dug out some, then blasted the rest out with compressed air.  Testing with the compressed air showed that the way was now clear, so I reinserted the supplied fittings.

And one of them snapped level with the surface of the spindle cover.  Bugger bugger.

I managed to get the broken buried thread out of the spindle using an “Easy Out”.

The broken fitting looked complex.  I certainly did not want to wait for one from China, and I was very doubtful that it would be available locally.  I could have made one, but it looked like a half day job.

So I silver soldered it!

The top of the spindle.  The fittings, with the broken one on the left.

The top of the spindle. The fittings, with the broken one on the left.

The coolant fitting and its broken thread, fluxed and ready for silver soldering.

The fitting in position for silver soldering. Resting on a nail held in a vice.

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The fitting after silver soldering. The threads needed to be cleaned up by running a die down them

This is the setup during the first engraving job.

This is the setup during the first engraving job. The green fluid is the coolant.

Engraving a small brass plate, at 20000 rpm.

Engraving a small brass plate, at 20000 rpm.

24000 RPM spindle for CNC Mill

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The mill quill and spindle is on the right hand side, with a 1 inch cutter insitu. The high speed spindle and its VSD controller is on the left hand side. Of course the cutter on the rhs will be removed when an engraving cutter is installed in the high speed spindle. The wiring hook ups, and coolant pump and lines are yet to be installed It does not look much but it took me a whole day.  The setup is quite rigid.

Today I spent a few more hours setting up the high speed spindle on my CNC mill.

I will post a video when i am doing some label engraving.

Make Your Own LONG SERIES TAP

My current project is a diversion from the triple expansion steam engine, which is about 33% completed.

I wanted to do some engraving on my CNC milling machine.  It is accurate enough in XYZ movements, but the spindle has a maximum RPM of approximately only 3000.  Engraving with a cutter with a tip of diameter 0.1 to 1 mm diameter really requires 10-20 thousand RPM.

I also have in mind making some wooden things using router bits, and they usually rotate at 12-26 thousand RPM.

I wondered about a manufacturers attachment for my mill but could find nothing.

So I decided to make my own.

I briefly considered attaching an electric  router to the mill, but since many projects require constant spindle work for several hours at a stretch, I decided that the spindle should have an inbuilt cooling system.

What I bought was a 2.2kW spindle, 3 phase, with a variable speed controller, giving an RPM range up to 24,000.  It is designed for liquid cooling, and can be used for long periods without overheating.

The spindle has an 80mm diameter, and I will attach it to the 110mm diameter quill on my milling machine.

So, I cut some holes in 16mm aluminium plate.

 

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The aluminium plate attaches to the milling machine quill, like this.

 

To clamp the plates to the quill, and to the spindle, I cut some slits into the holes in the plate, and drilled and tapped some 6mm holes. (done after the above photo was taken).

My problem was that my 6mm taps were all much too short for the job.
I went to my usual industrial tool supplier to buy some long series taps, only to be informed that long series taps are not kept in stock, and would take several days to arrive on special, and very expensive order. Long series taps apparently cost at least 3 times as much as conventional length taps.

Having had success at silver soldering band saw blades, I wondered whether I could add some length to a conventional tap by silver soldering some steel rod, end to end, to the tap.  It was also quite succesful.

Here is the setup for the soldering. (Sorry Americans, what you call soddering the rest of the English speaking world calls soldering).
IMG_2714The angle iron is held in a vice. The tap to be lengthened rests in the angle (after thorough cleaning and application of flux), and the rod likewise (in this case, a cap screw of the same diameter as the tap). The join is silver soldered in the usual manner.

This is what the lengthened taps look like.

I wondered whether the silver soldered join would be adequately strong for the tapping.  the tap was totally buried in the workpiece, and would have been irretrievable if the join had broken, and ruined the workpiece. So I was very cautious when doing the tapping.  Used a tapping oil, and backed the tap out of the workpiece every few turns for cleaning.

I wondered whether the silver soldered join would be adequately strong for the tapping. the tap was totally buried in the workpiece, and would have been irretrievable if the join had broken, and ruined the workpiece.
So I was very cautious when doing the tapping. Used a tapping oil, and backed the tap out of the workpiece every few turns for cleaning.  It worked fine.  It was a demonstration that silver solder is really very strong.

One advantage of using a cap screw for the lengthening rod was that the hex head proved ideal as an attachment for a tapping handle. The tapping handle being an Allen key.

I will post more pics of the engraving-routing spindle when it is finished.

ps. my expert friend Stuart T tells me that silver solder has a similar tensile strength to mild steel!

EXPERIMENTING WITH CNC MILL TAPPING

After manually threading the 56 cylinder head holes, (having CNC drilled the holes), I thought that I should attempt to do some CNC tapping.

The tapping built-in canned cycles in my mill allow only for single pass tapping, and a single backing out of the tap.  No backing off every turn or two to break the chips, as we would all do with manual tapping.  And my only method for holding the tap was in an ordinary drilling chuck;  not ideal, and I wondered what would happen if there should be any slippage of the tap in the chuck.  I was to find out all too soon.

So, first I tried M3 tapping in 3mm brass plate.  Seemed to work fine.  Very fast.  M3 has a pitch of 0.5mm, so it was not difficult to calculate the RPM’s and feed rate.  RPM’s twice the feed rate…   eg 400RPM, feed rate 200mm/minute.

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16 M3 holes threaded in what seemed like a minute or two.

Next I tried a 6mm tapped hole through a solid chunk of brass.  This time, I did not lock the quill.  The reason?  On tapping the 3mm plate, at the end of the tapping stroke, as the chuck decelerated and stopped, I noticed that it slightly pulled the workpiece upwards.  As the tap was backed out (automatically, after 1 second dwell), the upward pulling ceased.  I do not know the reason for this phenomenon but I suspect that the CNC does not perfectly match the RPM’s and the feed rate during the deceleration as the tapping stroke is finishing.  I will read my CNC books on tapping tonight to see whether there is a known explanation for this observation.

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No problems at all with this one.

Then I tried tapping 12mm thick steel bar with a 3/8″ x 16tpi tap.  I used plenty of tapping lubricant.  The calculation for spindle RPM’S and feed rate was more complicated, and I am not totally sure that I got the rates correct.  Because it was a total failure.   The  tap screeched, the mill stopped and gave an error message.  I am sure that the tap slipped in the chuck, totally rendering the calculations to be out.  Anyway, that rather shook my confidence, so until I have worked this process out, I will not be tapping thick steel automatically in my mill.  But brass, no problems.

I have used a Tapmatic attachment in the mill, using the CNC for auto positioning, and that worked fine.  But it does take a few minutes to set up.  At least the Tapmatic allows for some reversing every few turns.

Cylinder Bases. Lathe or milling machine?

I read an expert treatise on making a double expansion steam engine, and I imagine that the comments applies to triples also.  One aspect emphasised the importance of accuracy in making the cylinder bases.  The parallelism of the surfaces, the concentricity of the piston rod hole and the other circular elements, and the thickness. The usual method for making these items is to turn them in a lathe with a 4 jaw chuck, then to reverse the item in the 4 jaw to turn the other face.  It is possible, but very fiddly and time consuming, and relies on expertise, patience, good eyesight, and a good lathe.   All of which are in short supply around here. A triple expansion steam engine requires 3 of these base plates, and while there are some common dimensions, the cylinder bores are all different.  Many of the screw holes are common to the 3 plates.  The thicknesses are all the same. To shorten this rather boring epistle, I decided to have a go at making the base plates on the CNC mill.  Given my previous muck ups, broken bits, crashes, this was a courageous decision, as evidenced by having to bin the first effort.  But the next 3 all seemed to work OK. First I studied the plans and noted the common elements, then I made a jig, with holes drilled at the common positions.

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The underside of the jig, showing the 5mm centre hole and the counterbored holes at the attachment points.

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The topside of the jig, after the first and second baseplates were drilled, thicknessed and shaped. The jig needed to be made very accurately, to retain position of the workpiece after it was reversed, so both faces could be milled. I am told that CNCers build up a collection of jigs over time. They are rarely used again.

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CNC milling the central boss. 20.48mm diameter, and accurate. Note the red positioning device, enabling the workpiece to be removed to check measurements, then replaced exactly in the same position.

To see a video of the CNC mill cutting the external profile click on the link below http://youtu.be/m0d5yuX96Uc

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The cylinder baseplates screwed to the columns. Some trimming of the column tops is required. The baseplates are centered accurately, as far as I can measure. Note that the central jig separating the columns has been removed, and the baseplates are now holding the column tops in position. The columns appear to be lining up correctly.

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The next example of using the CNC mill to perform a task which is normally done on the lathe. The mill cutter is travelling in diminishing circles, producing a central boss, and a flat surface.

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The boss finished to size (10mm dia) and flat surface.

BTW.  In a previous post I mentioned a 1 mm inaccuracy in a CNC milled part.  It happened again when I milled the first base plate, which ended up exactly 2mm smaller than programmed, and had to be re-made.  This time I discovered the cause of the inaccuracy….   I had used an 8mm milling cutter, but had forgotten to tell the CNC computer that I had changed from using the 6mm cutter.  The CNC machine did not notice the change, and cut the part exactly as instructed, very accurately, 2mm smaller than intended.  CNC machines are incredibly clever, but very very dumb.  They do exactly as instructed, even if the instruction is wrong.

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.

108 Accurate holes. CNC again.

The triple expansion engine legs will be bolted to the base, with 9 bolts each.  That is 54 holes which needed to be precisely drilled so the columns are accurately positioned.  Each one of those holes needs to have a mating hole made in the base.  The base hole will be threaded to accept a stud.

Normally one gets accurately mated holes by drilling through both objects simultaneously, but that was not possible in this situation due to obstruction from the columns themselves.

So the solution??   CNC of course!

The hole positions were known from the CAD drawings, and were entered into the CAM program.  The resulting file was too big for my old CNC mill (1997 model), so I attempted to drip feed the information as the machining operation was taking place, but without success.  Several phone calls to my expert friend Stuart did not resolve the problem, so Stuart kindly came to suss it out.    A couple of hours later he had the drip feeding working as a result of a serendipitous error.

We knew that the largish file needed to be drip fed into the CNC mill, but it eventuated that we had to try to enter it directly, and produce an error message first, before drip feeding it.  A bizarre system, originating from the land of Manuel of Faulty Towers.

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A test run in scrap wood.

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Heart in mouth, center drilling in progress

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And  2.5mm through  drilling

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And the mirror image holes in the base. 2.05mm diameter, ready for BA7 threading. See how the holes line up exactly with the marking lines.  Now to make 54 BA7 studs.

A JIG for Machining the columns of the triple expansion marine engine

At last!

A day on the steam engine.  SWMBO went to Melbourne to choose marble so I was free!!

After discussing my problems with machining the triple  expansion engine columns with the senior members of the GSMEE (Geelong Society of Model and Experimental Engineers),  I have machined a JIG to assist with this issue.

The JIG thickness is precisely the width between the columns (30.05mm).  It is made in 2 halves so I can bolt the columns from their critical surfaces which are the con rod slides.

I will use the CNC mill to drill the holes in the jig, and the matching columns, then finish milling the columns which are attached to the JIG.

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The jig for machining the columns. Not yet finished.

 

 

Bottom left is X=0, Y=0.  The photo shows the 4 countersunk M4 screws.

The holes will be centre drilled then through drilled 4mm. The columns will be drilled 3.3mm then m4 tapped.
Hopefully that will happen tomorrow if the workshop is not too hot.

You will see what I am intending with the next post.

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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CNC Mill 10

I am coming to grips with the controls on the Extron-Fagor mill.  Despite multiple readings of the manuals, and doing dry runs without cutters, I have managed to break several cutters in live runs.

However, I am making progress, and it is very exciting to see what this machine can do.

 

CNC MILL 9

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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.

CNC MILL 8

Another day, another problem solved….
I am sure that these ramblings are incredibly boring to everyone, so understand that I am recording them for my own benefit, as a diary, as much as for the interest of anyone else who might be thinking of leaping into buying an older CNC mill.
So today I looked at the lubrication pump.
The manual says that it operates automatically on machine startup, then every 30 minutes, as long as the oil pressure is not too high. But the pump showed absolutely no sign of functioning at any time. And the ways and ball screws were totally dry until I lubricated them with an oil can.
Today I spent hours tracing wires and looking at relays, until my friend Jason S, who is a machine designer, came and had a look for me. He put a multi meter on the wires, and everything seemed intact. Then he identified the appropriate contactor (which I gather is really a big relay), and held it in, and lo and behold the pump worked. So the problem was with the pump controlling mechanism. Then Jason surmised that if he had designed the mill, he would have had the lubrication pump working only if the ball screws and ways were actually in use, not just if the machine was switched on. So next test was to watch the pump with the ball screws activated. Lo and behold the pump worked! So what was the problem? Why was the oil not coming through?
We disconnected some oil lines, and they were dry. So we manually pumped the lubrication pump until the lines filled, (i.e. primed them) and tried the lubrication system again, with the axes working, and it worked!

So the bloody manual was misleading. The lubrication system does not work when the machine is switched on. It only works when the ball screws are operating. And the machine has been out of action for so long that the oil lines had dried out.

Another gripe with the manual, was when I tried to get a canned cycle working (dry run, with no work piece or cutter). I followed the instruction steps exactly, and nothing happened. I retried, with the same result. I tried another canned cycle… same result. Then Jason arrived, and followed the steps.. same result. Then he said “what is that DATA button for? I had no idea. It is not mentioned in the manual. So we tried pushing it, and halelujah, the canned cycle worked.
So why was it not mentioned in the manual ?????
Do people who write manuals, ever test their own instructions? Or try them with an end user???
So bloody frustrating and such a waste of time.

(note added a few days later… I found the DATA key described in a different section of the manual. My mistake, it was there all of the time. If I had read the manual from start to finish entirely, and remembered the entire 150 pages – or whatever – I would not have had the problem. Silly me. )

Anyway, another step towards making some chips.

So now for the final test, the hookup with a computer using a serial port. Fortunately I have an old computer with a serial port, and I will hook it up soon.

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.                                                                                                                                                                                                                                                                                                                                                                               

                                                                                                                                                                                                             

 

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.  

 

CNC MILL 5 with some more pics

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

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.

IMG_2040

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.

IMG_2037

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.