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.

CNC Mill Upgrade -4

I removed the old XY & Z axis servo motors from the mill.  Each one weighs about 15kg (33lb).

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The old servo motors.  The X and Z were working fine.  The Y was faulty, but I do not know whether the fault was in the motor, the encoder, the controller, or the connecting wires.  I will put them on Ebay as 2 working, one for parts.

Then I removed the belt drive pulley off each motor.  There was a grub screw, which would not budge.  Assuming that it had been Loctited, I applied some heat, judiciously.  The grub screw came out, but the pulley would not budge, so a little more heat, and a gear puller.   Two of the gears came off, but one still would not budge.

I asked for advice, and I was loaned a different type of gear puller. (thanks Rudi).  This time, some movement of the gear on the shaft was noted, and eventually the last motor gave up its gear.

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This one worked.

The shaft of the old motors was 16mm diameter.  The new motors had 19mm shafts.  So I spent some time on the lathe boring out the gears to fit the shafts of the new motors.  The keyways of the old motors were 5x5mm, and the new ones were 6x6mm.  So, I borrowed a 6mm broach (thanks Stuart), and enlarged the keyways in the rebored gears to 6mm width.   The new keyways needed a lower profile, so some time on the mill and surface grinder  to reduce the thickness of the keys to 4.5mm.

That was quite a few peasant hours hours on the lathe, mill, and surface grinder, but the end result was good.

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The new servo motors, with the timing belt gears fitted, with keys in place.  I will set each motor in place on the CNC mill, determine the final exact position of the gear on the shaft, then indent the shaft for the grub screw.  Then, when I am sure that all is correct, the gear, grubscrew and shaft will be Loctited.

Another small issue was that the boss on the new motors was 5mm deep compared to 3.5mm deep for the originals.  So the mounting plate for each motor needed the recess to be deepened by about 1.5mm.

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I used a boring head on the mill to deepen the first one, but it did not produce a good finish, so the next 2 (shown) were deepened on the lathe, in a 4 jaw chuck.

Meanwhile, back to the rats nest in the electric control enclosure….

 

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The bare space top left is where the old servo controllers lived.  They were removed.  Then I spent a half day tracing each wire from the controller to the old servo, and removing it.  That produced a carton full of wires.  The rats nest is now a little less tangled.  A lot more of those wires will be removed as the job progresses.

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The new servo controllers bolted into position.  They are fatter than the originals, so a bit of rearranging was required.  The yellow box top right is the main spindle speed control (VSD) which is being retained.

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And on the right hand side, newly bolted into position today, from the top down, are the smooth stepper, the C11 breakout board, and two C10 breakout boards.   Awaiting some expert wiring.  (Stuart, are you reading this?)

 

Upgrading the CNC mill -3. Moving a threaded hole in steel plate.

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this is the new Y axis servo motor, sitting on its mounting plate, after the old servo has been removed

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Unfortunately the existing M8 threaded holes in the mounting plate are just in the wrong position for the new motor’s 8mm mounting holes.

So, do I 1. make a new mounting plate and assembly?   2. machine or file the new motor’s holes to fit the old plate?   Or 3. Fill the old mounting plate hole, then drill and tap new holes in the correct position  ??

  1.  seemed a lot of work   2. would have looked ugly and probably voided the motor’s warranty      3.  Seemed tricky, but I decided to give it a go.   If unsuccessful I could always revert to 1.

Filling the old holes.  Could have used steel thread and silver soldered it into place.  In retrospect, would probably have been the best option.   Could have used steel thread and Loctited it into place…. decided against, in case subsequent machining  softened the Loctite.   Could have filled the old holes with bronze, and drilled and tapped new threaded holes….   well, for better or worse, that’s what I decided to do.

The new holes impinged about 25-33% on the old holes.

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The old holes were bronzed.   I improved my technique as I moved around the holes.

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After cleaning up on the mill, the new holes were center drilled 

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Then drilled to size, and tapped.  revealed that the bronze did not entirely fill the voids. 

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I wondered if the bronze would accept a suitable degree of tightening of the M8 cap screws, but all seemed fine.   Note the jacking bolts, to prevent distortion of the weldment in the milling vice.

The bronze-steel sandwich did cause the tapping drill to wander slightly, but not enough to cause concern.  Next time I will try silver soldering in a steel filler piece.

Meanwhile, I have been removing parts and wires from the electrical enclosure.

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The servo controllers are removed.  Bit of a rats’ nest hey!  About 90% to go…

 

Installing the lathe gear

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I neglected to take a photo of the completed gear.  In this shot it is almost finished.

I intended to reassemble the spindle and its cluster of gears, spacers, and taper roller bearings myself, but after talking to an expert on the topic (Swen Pettig), I realised that sometimes it is better to leave surgery to a surgeon.

I gratefully accepted Swen’s offer to help.  In his working  life Swen had performed this task on many, many occasions.

Firstly Swen reinserted the taper bearing outer races in the headstock.  The lathe spindle is approx 80mm diameter and 800mm long so it is heavy.  After carefully cleaning, it was fed into the headstock, progressively loading the bearings, gears, spacers, clips and nuts, and moving and tapping them down the shaft as it was moved into place.

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Note the photo prints to remind us of the order of reassembly.  Board to protect the lathe bed.  Repaired gear laying flat.  Surgeons’ towels blue rags.

when it was all reassembled and tightened, the retaining disk at the chuck end was loosened, sealed with liquid gasket (Loctite product- cannot remember the name), and retightened.

Then Swen went through a lengthy process of checking the end play, using a dial indicator, tapping each end of the shaft with a copper hammer, and finally settling on 0.01mm of play.

Then we had a short test run at low speed, and he tested the end play again, with no change.

Then we set it running at 200 rpm, and went and had a cup of coffee for 20 minutes.  Came back and checked the bearings temperatures.   All cold, all good.

I reinstalled the external gears, the cover, etc, and took some decent cuts in some cold rolled bar.

All good.  Oil change soon.

 

CNC Mill Upgrade -2

The major components arrived this week, from China and USA.  Switches, and other components which go “ping” will be bought locally as required.  I am hoping that existing pulleys, belts, brackets will be adaptable.

The motors to drive the X, Y and Z axes are 1.2kW AC servo motors which can be connected to single or 3 phase power.  Each one weighs 6.7kg (14.7lb) .  From China, they are nicely finished.   Substantially shorter than the old servos which they are replacing and slightly larger diameter.  I am hoping that the slightly larger diameter will not cause major problems.

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AC servo.  There are 3 of these.  Kitchen knife to open the box and for scale.

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Old Y axis servo on the right, and the new AC servo left.

 

And each servo motor came with a controller and cables and connectors.

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And the electronics came from USA.

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C11 breakout board.

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C10 breakout boards x2

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And the Smooth stepper control board.  It is tiny, but the most expensive electronic component.

All up cost so far is ~$AUD2100, of which shipping is about 25%.

Next step is to swap over the servos.  The old shafts are 16mm and the new ones are 19mm.  I intend to machine the bores of the pulleys.  Hope there is enough meat  Tofu to allow that.

Preparations for gear cutting

Almost ready to cut the lathe gear.  It is 237mm diameter, 25mm thick, with a new rim Loctited and Scotch pinned to the old hub.

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I borrowed the 6-12″ Mitutoyo micrometer from a GSMEE member.  Thanks Rudi.  I had to learn how to read an imperial micrometer.  The rim is glued and pinned to the original hub.

And today I made a tool holder for the new-old gear cutter which I purchased from Russia.  It was meant to have a 27mm bore, but when measured was closer to 27.1mm, so I made an arbor to match.

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The cutter on the new arbor.  It required 2 attempts to get acceptable dimensions. It will be held in the vertical mill with an Er40 collet chuck.  It runs true.   Not bad for an ex gynaecologist hey?   Might need to sharpen the teeth on this old-new cutter.

Meanwhile, on advice from Swen, another GSMEE member, thinking ahead, and setting up to trial fit the new gear after it is cut.   Here is Swen, making some steel temporary bearings to try the new gear on the shaft, after the gear is made.  Tapping out the old taper bearing races.   This is what Swen did for a living when he was in the work force.  I have learned heaps just watching Swen doing his stuff.

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I admit that I would not have been brave enough to do this.  “Piece of cake” says Swen, tapping out the race with a copper drift.

CNC rotary table and preparing a gear blank

Hi readers.   Sorry for the long break.  Since my return from UK I have been severely jet lagged, then very busy, and not much time in the workshop.

The jet lag going westwards to from Oz to UK was minimal, but after the homeward trip it took 2 weeks to start feeling normal again.  It is a 22 hour flight, plus 2 hour stop over in Singapore.   I do not remember ever having such marked jet lag before, and  not much was done during those initial 2 weeks.

When I did venture back into the workshop, I discovered that my CNC mill was malfunctioning.  The Y axis has been a bit unpredictable for quite a while.  I found a broken wire and fixed it, but the problem returned.  After a previous electronic failure in the Z axis, my CNC expert advisor, Stuart,  suggested that I should  replace the electronics in a major upgrade.  The mill is a solid industrial machine, mechanically in sound condition, and is worth spending some time and money on.

It is a 1997 model, and the memory in the CNC motherboard is a whopping 7k!  I was able to get a fair bit done with the 7k, and the situation was improved by linking an external PC, and using V-Carve Pro.  But there was a limitation in that the mill is a 2.5 axis machine.  Not that I want to use 3 or 4 axes very often, but the lure of improving the mill is irresistible.

So I am in the process of ordering 3 new servo motors.  They will be AC single phase servos, rather than 3 phase motors.  I have installed one of these in my small Boxford lathe as a spindle motor, and it has proved to be reliable, compact, powerful and inexpensive (well, fairly inexpensive, comparatively speaking).  They have been ordered from China.  Cost-wise, the three axis motors will be much less expensive than one of the existing 3 phase servos.  On top of that I will need a breakout board, ESS smooth stepper to link to a computer, and various switches, wiring, power supplies etc.

I will document the steps of the rebuild.

But the item that I was getting to, was hooking up my rotary table to CNC.  I had expected to pick up a new gear for my big lathe on my return from the UK, to replace the one with the broken tooth.  I was pretty annoyed to learn that the gear maker had not done the job, and worse still he had not notified me that it had not been done.  Since he never answers the telephone, I drove to the factory, expecting to pick up the new gear, as arranged and promised, to be met with apologies and excuses.  Long story, I have decided to make the gear myself.

It has 77 teeth, an unusual number for a gear, which means that it has to be made, not purchased off the shelf.  I have a dividing plate with 77 teeth, but I could see plenty of potential for making mistakes using that, so I elected to finish the CNC conversion of the rotary table which I had started last year.  The mechanical aspects had been finished.  All that was required were the electronic hookups.   Fortunately for me, I have a friend who is an expert at these.

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In the center is the rotary table, an 8″ Vertex.  The stepper motor is a NEMA 36.   The intervening aluminium block is the coupler.  The controlling program is Mach 3.  Originally I intended to use an Arduino, but it seemed more complicated and less robust than this setup, which involved using the breakout board of the CNC lathe (right), and a new Gecko driver. (see next pictures)

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Looks complicated and messy.  Much better with the doors closed.  The rotary table Geckodrive is the one on the left.  The 2 on the right are for the lathe.  The black white and green wires 8,9,10, are from the breakout board.  The black and red 1 and 2 are from the 48v power supply, and the stepper motor power is from Windings A and B, 3,4,5,6, in the thick white wire.

I confess that I have little understanding of the wiring.  Stuart had it hooked up in under an hour.  A bit longer configuring and tweaking Mach 3, and it was working.  The extra Geckodrive, and some wires were the only extra components required to make the electronic connections.

I shot a video of it working, with giving a commentary.  But it is so bad that I will reshoot it, and add it to this post in a day or 2.   Sorry.  Not done yet.   But I have been busy preparing the blank for cutting a new gear.

I decided to retain the hub of the gear and to add on a new ring which will be machined, and then new teeth cut into it.

Firstly I had some 25mm steel plate water jetted approximately to size.  I chose water jetting in preference to laser cutting or oxy-acetylene cutting to avoid any inadvertent heat hardening.

I also had the original gear water jetted to remove the outer 25mm, including the teeth, because it had originally been heat treated hardened, and I did not fancy machining that on my other lathe and maybe breaking more teeth!

It was not cheap.  But a nice finish, which machined easily.  So the hub and the blank ring were machined with a 0.1mm gap, and glued together with Loctite 620.  Then Scotch pins were inserted.   Since my CNC mill is out of action, I reverted to calculating X and Y co-ordinates, using FS Pro.  See screen shot below.

 

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My CNC mill is out of action, so I reverted to doing some XY calculations on the manual mill with DRO, using FS Pro.   Screen shot above.

 

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And in the above shot, I have drilled and threaded some M6 holes and Loctited in some M6 grub screws.

Then machined it to size,

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The 6mm holes are the Scotch pins.  The 10mm holes are to attach the assembly to the CNC rotary table for cutting the teeth.

So, this post might be a bit ramshackle and disorganised.   A bit like my workshop at present, and possibly my brain.  My GP has started me on blood pressure medication, so I will blame that.

Watch this space for cutting the gear, soon.

 

CNC Mill Upgrade

I was not planning any more major projects for 2019, instead intending to finish the triple expansion engine, the beam engine, the vertical boiler, and the CNC rotary table.

But… my hand has been forced.

The Y axis on my CNC mill has been a bit unpredictable for some months, and on my return from UK, it has totally stopped working.  It seems to be the encoder on the Y axis servo.  I could just repair or replace the encoder, but after discussing the situation with my expert advisor Stuart, I have decided to replace all of the electronics in the mill.  New axis motors, new breakout board, new drivers etc.  It is a 1997 model, and this is the second electronic failure this year.  Plus, it is only a 2.5 axis mill.  It will move in only 2 directions per move….   XY or XZ or YZ,  never XYZ in a single move.   Plus I would like to add a rotary axis, making it a 4 axis machine.

The in built computer in the mill has a 7k memory.  That’s correct, 7000 bits.  I have an external computer linked to it, which makes it a bit more useful, but the Fagor controller is clunky and idiosyncratic, and I would like to switch to Mach 3.

So, I will document the upgrade as it happens.  The mill is a good solid machine, with big ball screws, and 1000mm of x travel, 450mm Z and 450mm Y.  It is worth spending some money on it.  There are a lot of big, old, CNC machines with obsolete electronics out there for sale.  It will be a project which might just be worth watching.

Showing the handwheels for XYZ axis movements, including the broken X axis handwheel

 

Lathe Woes

Removed the gear with the broken tooth from my GBC 400-1000 lathe yesterday, with some help from my brother.    Approached the disassembly a bit nervously.  Did not want to break or damage anything else.

First took some photographs, so I can put things back together eventually, in the correct places and order.

Then removed the chuck, then the back gears, then the large heavy plates at each end of the spindle.  The cap screws came out without any drama, but the end plates required breaking free of the paint, and out of the tightly fitting mounting rebates.

Then loosened the big nuts against the internal gears, the external gears, and one grub screw.

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Tabbed locknut undone, allowing the gear cluster to be slipped and driven towards the left, eventually allowing the spindle to be removed.

Gradually removed the spindle by tapping the gears along the spindle with brass drifts.  Pretty tight.  And retrieved the little bits as they fell into the oil in the headstock.

Was finally able to lift the spindle out through the chuck end of the headstock.  It is heavy.   Took two of us to lift it out without damaging the outer races of the tapered roller bearings.

Then looked at the broken gear, and retrieved the tooth from the headstock oil.

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The broken tooth.  Unfortunately, on closer inspection, and adjacent tooth is also cracked.  And very likely more are on the way.   This is more serious than initially thought.  It is a big heavy gear, 240mm dia, with a 65mm long collar,

Next step was to look closely at the meshing gear.

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With a good light, and getting close I still had trouble checking for cracks.  Only when I looked at this photo did I realise that I had forgotten to change my sunglasses.   Ah, the joys of getting old and forgetful.

Meanwhile, I remembered a tool which might help with the inspection….

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It is a cheap fiberoptic inspection camera.  Worked fairly well here, and I am reasonably happy that the other gear is not cracked.   But it did convince me that I should have bought a better quality fiberoptic camera.  Put it on the wish list.

So, I have a large, hardened steel gear with at least 2 cracked/broken teeth.  Options?….

  1. Buy a new gear.  I will try, but not confident.  The local importer of these particular Chinese lathes went out of business last year.
  2. Get a new gear made.  I will get a quote.
  3. Make a new gear myself.  Or, if all else fails….
  4. Machine off the teeth of the damaged gear, and the adjacent 20-30mm.   Then make a new set of teeth on a ring which will be attached to the old core of the damaged gear.
  5. Use the lathe without that gear.   This option does not appeal.
  6. Install a VSD and use electronic control of spindle speeds.  The main spindle motor is 5HP, so it is possible.

More information required.  Watch this space.

Read the rest of this entry »

Back in the workshop, a Lathe Problem…

I have a problem with my big Chinese lathe.  I was hearing a KNOCK-KNOCK-KNOCK as the main spindle was revolving at low speeds with one setting of the gears.

It is a GBC 1000-400 lathe, meaning that it has a maximum of 1000mm between centres, and it will turn a 400 mm disk.  It weighs 2 tons.  Has been quite useful when turning flywheels, big lumps of metal, large pieces of wood and so on.

So today I removed the cover from the headstock and had a look.   The cause of the knock was quickly obvious.

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The headstock of the GBC 1000-400

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The big gear on the main spindle at bottom.   See the broken tooth?  The meshing gear is intact.

So, what do I do about this?   I need some suggestions, people.

Thoughts so far….

  1. remove the spindle, remove the gear and bronze braze a replacement piece of steel or bronze, then machine a new tooth.
  2. same as 1, except use silver solder.
  3. same as 1 or 2, except do the job insitu (after draining all of the gearbox oil, and screening off the other headstock parts).  Unfortunately the missing tooth is close to the headstock case, so filing or grinding a new tooth would be tricky.
  4. leave it as is, and just avoid using that gear.  I can do that.  It removes 3 of the 9 gear ratios, including the slowest speed (40 rpm), and is not an elegant, or desired solution.

So what do you think?   The gear is most likely made of steel rather than cast iron, from its appearance.  The base of the break is shiny, smooth and not porous.

Here are some pics of the ends of the main spindle.   It does not look too complicated to remove the main spindle, but what would I know.

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The main spindle is the one in the centre.

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And the other end, with a self centering 4 jaw in place.

I imagine that the main spindle bearings will be pre-loaded, tapered, roller bearings.  I certainly do not want to damage them.  And how difficult will it be to reinstall the bearings and main spindle?   I imagine that it will involve some careful and precise work.   Am I taking on a job which is way beyond my abilities?   If anyone has experience of this task I would be delighted to hear your views.   I have no drawings or plans of the headstock to assist.

(In parentheses, when I was a teenager, I remember my father pulling a Toyota Crown automatic gearbox to bits, identifying a fault, and fixing it.  There were bits of the gearbox everywhere.  But he fixed the problem.  He was not a mechanic, but he had a go at things, and usually managed the task, as in that case.  Similarly, I dont mind having a go at this lathe job, but I would prefer not to risk destroying the lathe, so any expert opinions will be welcome.   Option 4 above remains a possibility.)

 

Beware of Greeks Bearing Gifts

Well, this one is OK because it came from a Hollander.

One of my blog readers, Huib, decided that I would be the recipient of some of his workshop items which he says were surplus.  This was as a thank you for johnsmachines.com.

So, a parcel arrived yesterday, and after a quick look inside, I decided to make a video of opening the items, and showing you.   It was great fun for me, and I hope that it will be entertaining for you.  It is the biggest file which I have uploaded, so give it a few minutes to open.

 

(This is the longest video which I have uploaded, and I have now deleted it to make some space at my WordPress storage, which is almost full.)

Oh, any other readers who would like to send me surplus tools or other interesting bits and pieces….  please feel free.  If Haas, or Hardinge would like a review on one of their machines please send it and I would be happy to do a review.

A Long Drill Bit

I have not been looking forward to attaching the Trevithick Dredger Engine to its base.

I needed to drill through the steel plinth and the wooden plinth, and then through the top part of the base.  Trouble was that the boiler and engine were in the way.

And it was not feasible to tip the whole assembly upside down and drill from underneath.

Ahah! what about a long drill?   I measured it.  The drill would need to be 450mm long!  Even a long drill bit, ferociously expensive, comes at a maximum length of 150mm.

So, I made a long drill bit, 5mm diameter, 600mm long

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That is a new 5mm cobalt drill bit, silver soldered into some 8mm drill rod.  Could have been a bit shorter, but it was long enough.

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Using the long drill bit, I was able to drill through the steel support, and through the top wooden layer of the base.   Then bolted the parts together.   And was then able to place the engine and the wooden layer on their ends, and to drill the remaining holes from below, confident (fairly confident anyway), that nothing could go wrong.   As in the above picture.

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Meanwhile, I had added the valve which controls the boiler feed pump output, and connected it to the boiler feed pump.

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Boiler feed pump valve.  This valve was left over from the vertical boiler project.  Just right, when I have repainted it.

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Next I must drill a 5mm hole through all layers of the base.   150mm!  4 holes, one in each corner.   The long drill made today will not do because the 8mm shank is too thick.   I must make another long drill, with a 5mm diameter shank.  Watch this space!

 

 

New Oxy-Propane Torch just watch!

Yesterday I took delivery of a tiny oxy torch.  I guess that most buyers would be jewellers,   but if you watched my post about silver soldering the tiny Trevithick dredger engine firebox door hinges, you will understand my interest in this Ebay offering for $AUD28.

I am experimenting with making videos for this post, so please excuse the amateurish faults in the following videos.

And here I am experimenting with the tiny torch.  Frankly, It is probably not up to the job here, but it was interesting trying it.  I can see that it will be very useful for other small jobs.

Please excuse the awful video technique.  I can see that I need a better camera, tripod, and technique.

This little oxy – propane/acetylene/MAPP gas/hydrogen/ etc is pretty awesome.

And BTW, the leak in the water pre-heater was fixed!

6″ Vertical Boiler. Calibrating the pressure gauge

I bought 2 pressure gauges at a recent Model Engineering Club auction night.  I paid $AUD40 for the pair, although I was really only interested in the smaller one.

It was a bit of a gamble.  Would they work?  Accurate?

Stuart mentioned that he had an instrument for calibrating gauges, and he checked my gauges.

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This gauge was item 51 at the auction.  It is about 4″ diameter and has some style!   Brass of course.   The cream painted instrument with the shiny brass weights is the calibration gauge.  It confirmed that my gauge was spot on at pressures of 50, 100, 150, 200 qnd 250psi.

The smaller gauge, 38mm  1.5″ diameter which I will use on the Trevithick dredger engine, was not quite as accurate, being 2.5psi out, but is adequate for use.  It is also British made, brass, and nice appearance.

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6″ Vertical boiler. 2nd Braze

Today was cold, wet and windy. so the wood heater was started when I arrived at the workshop.

Then a couple of hours using emery paper and steel wool to get shiny copper surfaces ready for silver soldering on the vertical boiler.  Then copious application of flux to the surfaces.  Loose bits held with iron wire.

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A slight re-shaping of my forge to accomodate the shape, and allow access to the top front and sides.

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Not so pretty after applcation of heat from the oxyacetylene torch and the weed flamer at the same time.  Both hands were fully occupied, so no action photos.

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And after the usual sulphuric acid bath and rinse.  A couple of joins need to be redone, and then a test for leaks.

Reader and GSMEE member Ian asked about the cam lock clamps which I used in a recent post.

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They are “KNU-VISE” clamps, used in aircraft manufacture I believe.  I bought a box full of them in Ebay’s early days, when bargains were still to be found and US postage was not prohibitative.  Very useful for powerful clamping up to about 50mm.

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Another Use for Magnets

I purchased some bronze disks for use in the model Trevithick dredger engine.  The disks 204mm diameter had been bandsawn off rod.  I had specified minimum thicknesses of 7mm and 12mm.  One disk was 9.2-9.7mm thick and the other was 12-15mm thick.

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The bandsawn blanks of LG2 bronze.

In preparing the disks for machining I filed off a few protrusions, and using a straight edge, identified the valleys and ridges.

The thicker disk was held in the 3 jaw chuck and both faces were turned flat with no problems except avoiding the needles which were thrown off in a wide arc around my lathe.  Final thickness 12.5mm.  A persisting divot should be able to be avoided in the final part.

The thinner disk needed to be packed out from the jaws of the chuck by 4-5mm in order that the lathe tool  cleared the jaws during machining.  In the past I have used machined packing pieces, but it is always a fiddle to hold the workpiece, the 3 packing pieces and the chuck key in only 2 hands.  Today I had a brainwave.

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I used rare earth magnets!

I tried to measure the thickness of the magnets, but they are so powerful that I was not confident that I was getting accurate readings.  So I just used them and measured the thickness of the finished workpiece.

I am sure that this idea is not original.  But it is to me.

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Here is the thin workpiece held in the 3 jaw, and packed away from the chuck by rare earth magnets.  Of course the magnets are attracted only to the jaws, and not the bronze workpiece, which helps, but I will try this on steel later.  Should work for magnetic metals also.

After machining both faces I took various measurments of the workpiece thickness.  The measurements in mm were 8.73, 8.68, 8.69, 8.72, 8.70, 8.72.   Not perfect, but not too bad at all.   I wonder if I might have improved the measurements by surface grinding the magnets.  I wonder if the chuck and its jaws are contributing to the variation.  It was certainly an easy method.

If the workpiece had been thinner I could have increased the thickness of the packing by doubling up the magnets.

For those who are following the Trevithick Dedger Engine build, the bronze was not cheap.  The 12-15mm disk was $AUD90 and the 9mm disk was about $AUD80.  From George White P/L, Melbourne.  I will be nervously trying to not muck up the machining.

A New (to me) Tool

One aspect of our weekly GSMEE meetings (Geelong Society of Model and Experimental Engineers) is that I learn something new at every meeeting.  The exposure to new information is not too surprising considering that our group has members who are or were a machinery designer, mechanical engineer, CNC operator, marine engineer, aircraft mechanic, a quarry operator, gun enthusiasts, a fireman and various other areas of expertise.  Even a bee keeper.  And even a retired gynaecologist.

Recently Neil brought in a boiler which was assembled but not yet soldered.  And it was held together with spring loaded clamps the like of which I had never before seen.  Some other members were also very interested in the clamps, which are, apparently, extensively used in aircraft panel assembly and repair, and also in car body work repairs.

boiler clecos

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Neil’s boiler end plates, clamped together.

The clamps are called CLEKOS or CLECOS.  They are easily applied and removed and are reusable.  They are used for temporary joining of materials to facilitate marking, drilling, riveting, soldering, welding or gluing.  Exciting to me because I can see many applications in model engineering and wooden toy making.

The Clecos come in a variety of sizes and configurations.

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This Cleco requires a 1/8″ hole, and will join materials up to 1/2″ total thickness.  This type joins 2 or more pieces of material which have a hole drilled as small as 2.5mm up to 5mm.  The range of hole sizes may be larger than I am aware.   Only one face of the materials needs to be accessible, so the Cleco can be used to fasten material to a closed container such as a boiler.   It is spring loaded and requires a tool to apply and remove it.  Application and removal is very quick.  Any materials which will accept a drilled hole can be used-  metal, wood, cardboard.  It would not work with easily compressed material such as foam rubber.  The application pliers are available on Ebay and are inexpensive.

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This spring loaded Cleco looks particularly interesting.  The clamps are small, have clamping thickness of 20mm and a reach of 1/2″ to 1″.  Again, they are not expensive ($AUD7-11), and very quick to apply and remove.  Surprisingly powerful grip would be quite adequate for gluing or riveting or soldering.

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Some Clecos do not require the application pliers but use a wing nut.

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And others use a hex nut.  Anyone know why there is a copper surface coating?

The Clecos are surpisingly inexpensive.  On Ebay I have seen the spring loaded fasteners as cheap as $AUD1 each, and the pliers at $AUD15.    I bought a kit comprising pliers and 20 fasteners for $AUD49.  Ebay UK has the best selection and many have free postage.  The range on US sites is good, but postage costs assigned by Ebay are astronomical.

(A reader has commented……

The Clecos and other skin pins are colour coded, silver 3/32, copper colour 1/8; Black 5/32′ gold 3/16 brown 1/4…..     thankyou “someone”.)

 

 

Small Tube Bender

 

I have recently been busy installing a steam powered water injector on the 3″ Fowler traction engine.  Involved quite a few bends in 1/4″ copper pipe.

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Some of the new pipework on the traction engine.  Since this photo, I have also made the winch functional.  (pics of that in future post)

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Hand pipe benders.

I was not totally satisfied with the regularity in the bends, or the straightness of the runs in the pipe.  That provoked some discussion at our model engineering group, and one member (Stuart T) showed us the pipe bender which he had made some years ago.

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Pipe bender designed and made by Stuart Tankard.

 

As you can see it has a  heavy duty frame,  shoulder bolts holding the rolls with machined slots for various sized pipe, and a 19mm hex connector for the driving battery drill.  A demonstration of pipe bending on this machine convinced me of its superiority to the hand held benders

Fortunately for me Stuart still had the plans which he had drawn up, so I made my own bender.  I made a couple of changes to Stuart’s design.  I made a 1/4″ hex on the driving screw, to accept the commonly used connector for battery drills.  And I did not have any suitable bronze for the main bush, so I made a brass bush, which incororated  a thrust ball bearing which engages during the bending procedure.  Probably unecessary but it was there in my junk drawer so I used it.

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The radius of the bend in the tube is determined by the radius of the roll.  1″, 3/4″ and 1.5″.  Each radius has grooves for 1/8″ 3/16″ 1/4″ 5/16″ 3/8″ and 1/2″ tube.  Since then I have also made 2″ rolls.

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Aluminium rod for the rolls.  

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Using a bearing to centralise the tailstock end before center drilling.

Groovetools

The lathe tools used to make the grooves.

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3 rolls turned from each length, with an allowance for parting.  Then drilled and reamed, and parted in a lathe big enough for the 2″ bar to be securely held.

 

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Completed bender.  The wooden box keeps the components organised.  Not a tribute to the craft of wood working but it will do.   The vacant pegs are for 2″ rolls which are yet to be made.

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The raw materials for the tool.  1″ X 3″ and 1″ square mild steel, and 1/2″ silver steel.

The bender is held in a bench vice.  The bending process is quick and controllable using a variable speed battery drill.

The symmetry of the rolls (as opposed to the asymmetry of the hand held tools) means that the centre and the mid point of the bend is totally predictable.

Since then, I have made some further changes in the design of the pipe bender.

  1. I have added some feet so it sits squarely on the bench and does not require a vice for support, although it can be held in a vice if preferred.  The tool is quite heavy, so small jobs can be managed without a vise.
  2. I drilled and threaded some extra holes, to accept 2 rows of 3 rolls.  See the photo below.  That pipe bender has now become a pipe straightener.  I made some extra rolls, so now there are 6 rolls of the 2″ size.  As long as the 3 rolls in each row are identical, the rolls in the 2 rows can be different for the straightening process, but ideally there should be 6 rolls for each pipe diameter.  Straightening copper pipe is easy, as long as there are no kinks or very sharp bends, and the copper must be annealed.  The pipe should be approximately hand straightened, cut to length plus about 2″, then pulled through the rolls which have been adjusted so the rows  are almost touching.  3 or 4 passes, with some rotation of the pipe each time results in a near perfect straight pipe.   Any slight residual bend can be eliminated by rolling the pipe on a flat surface.
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Some extra threaded holes added pipe straightening to the tools functionality.

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Two rows of rolls are needed to straighten bent pipe.  So I made 3 extra wheels in 1/4″ and 3/16″ sizes.  Later I realised that the extra three rolls do not have to be identical diameter to the first three, as long as each triple are identical.  The tool straightened this bend quite nicely, although with some experience, I would now probably hand straighten it a bit before putting in the tool. 

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After 2 or 3 passages.

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And some rotation with each pull through

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The copper does have to be annealed to get a good result.

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And to put a bend in that nice straight tube…  some shuffling of the roll positions….attach the drill (slow speed setting)

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And a quick and easy bend. 

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Pretty good

 

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The underside.  Substituted cap screws for grubscrews, so the tool sits flat on the benchtop.  quite adequate for light bending jobs, but straightening needs a vise.

 

BAND SAW WELDER

Some posts ago I described my method of making band saw blades by silver soldering the join.

My band saw does have a German brand welder attached, but I have never been especially succesful with the results, so I have continued to silver solder, and very satisfied with those results.

But a friend asked to use the welder because that was the method which he was used to, so I watched.

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Colin, examining the welder, after clamping the blade ends.

In the meantime, I had used fine emery paper to clean the electrical contacts, and Colin had cut the bandsaw blade ends square, then used emery to clean up the blade ends for a distance of 25mm.   Then the ends were clamped into position.

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The appropriate current was selected and the button was pushed.  The current lasted only a second or so.

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Then the weld was annealed.  Heated red hot and slowly cooled.  Repeated several times.  The annealing makes the weld less brittle, and softer, easier to file or grind flat.

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The join before grinding flat.

Colin made 2 blades, then I made 4-5.  Very quick.  Much quicker than silver soldering.  Time will tell whether the joins last longer.

 

INSTALLING LATHE LEAD SCREW COVERS

I decided to install lead screw covers on my Colchester Master 2500 lathe.  The lathe is about 50 years old, so you might say that it is a bit late in its life to install covers now, but I really like my Colchester, and the lead screw appears to be in good condition, like the rest of the lathe.   And lately I have been turning some cast iron, which is quite abrasive.  And I occasionally use a tool post grinder.  So, protect the lead screw I bought some covers from DY-Global in South Korea.

To give DY-Global a free plug, the covers arrived at my home in Australia, from Korea, 48 hours after I paid for them.   With a hand written thank you note.  Fantastic service.

Anyway, back to the installation.  I had installed covers on another lathe a few years ago, and I was not looking forward to repeating the experience.   If past experience is anything to go on, the installer is lucky if afterwards he (or she) does not require skin grafts and a blood transfusion.

Handling the covers is like handling an oiled snake, which bites.

So this time, I thought about the job in advance.

And I made mental notes, which I am now setting down, for your benefit.  And mine, if I ever have to repeat the task.  I might add that the covers do not come with any installation instructions.  Nor could I find anything on the web which helped.  So this is how I managed.

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The unprotected leadscrew

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With the carriage moved to the tailstock end

Firstly, clean and oil the leadscrew.  This can be done after the cover installation, but it is a lot easier if done beforehand.

Also, tke note of the dimensions of the lathe hardware where the covers will sit, to make sure that the covers will fit, and not obstruct the leadscrew nut or anything else.

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There are 2 covers for each leadscrew.  Take note of the outside and inside diameters, and the compressed length of the cover.

Then, wearing eye protection and gloves, compress the cover with one hand, while removing the metal clip with the other hand.  Then very carefully, allow the cover to expand to its full length.  WARNING:  the cover is under considerable tension (correction…  Should read “compression”).  Do not allow it to explosively expand.  How do I know this?   Do not ask.

The alternative method is to disassemble the lead screw, half nuts, leadscrew bearing mounts and most of the carriage.  It might be easier to do this, but I did not,  so I will press on with my chosen method.

The expanded cover will be about 1 meter long, depending on specifications.  It will be oily and slippery, and attract whatever dust and crap you have lying around your lathe.  I suggest that you wipe the exterior surfaces clean, to make subsequent handling a bit more like handling a dry snake than an oily one.   Re-oil it after installation.

Lay the cover near the leadscrew, in its intended position.  The carriage should be at one extreme end of the lathe.   You will note a big diameter end and a small diameter end.  In my case I decided that the small diameter should be at the carriage end.

The next instruction is the pearl in the description.  Read it carefully.

Using fingers, prise open the big diameter end of the cover and slip it over the lead screw about half way long the exposed length.  It will resist you, but be forcefull.

Then twist the cover to screw on the rest of it.   Simple!

I found that 95% of the cover went on in a few seconds, but the final 3 or 4 turns of the cover would not go on by twisting.  To get those last turns on, I used small flat screw drivers to lever them on.   Even better, I realised later, would have been to use bicycle tyre levers.

The cover then snaps into place, in a most satisfying manner.

 

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The big diameter end of the cover slipped over the leadscrew.

 

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Screwing the cover on.   Make sure to keep the small diameter coils inside the big diameter ones.

 

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One of the covers in place.  The one on the other side of the carriage is mirror reversed of course.

 

 

 

The compressed cover occupies about 50mm, so the carriage movement is slightly reduced.

The first time I installed these covers took me several hours.  And skin grafts and a blood transfusion.   Now that I have this technique it takes me about 5 minutes.

 

 

Heat in the workshop. Heaven!

Today I fired up the pipe heater which I have welded up over the past few days.

Fantastic!!

I was so keen to get warm on this 10 degree celcius day, that I deferred water proofing the flue.

And of course it rained!

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I forgot to bring some newspaper or kindling, so I used a propane torch to get the wood burning.

Within 5 minutes the temperature of the burner was over 200c, and in an hour it was 350 degrees celcius/ 660 fahrenheit.  Heaven.

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The shape of the furnace accepts wood up to 1400mm long.   The handle at the bottom is the ash tray.  The hefty looking handle above is for the furnace door.   The bit of RHS on the floor is so I can open the door when it is hot.

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This is the external sheath of the flue.  The strip of corrugated iron is to separate the hot internal flue from the cooler external layer.

And then it rained!   And I had not installed the waterproofing fitting to the roof.   So water poured down onto the heater, and filled my workshop with steam.!!

Despite today being only 10 deg celcius, I happily machined away until 6pm.  2 hours later than I usually stop due to the cold.

Then I had to go home to cook dinner.   SWMBO was getting hungry.

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