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.

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.

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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.

Oz is hot. Right? Bloody Cold just now.

It is the depths of winter here in southern Oz.  I know that is difficult for you northern hemisphere types to realise, but here at present we have frosts when we get up, and the workshop is just too cold to do anything productive after about 4pm.

And the tooling surfaces rust up in front of my eyes.

So I decided to make a wood burning heater for my workshop.

The workshop is 7m x 13m.  Not lined or insulated.  Just a tin shed.

Electricity supply is dodgy and expensive.  And I dont want to suck power away from my CNC machines.  Bottled gas is very expensive… about $AUD20-25 per day.

But I have plenty of trees dropping dead branches.

So I decided to make a wood burning heater.

Parameters…..

Not occupying much floor space.  No wall space available.

Able to be removed in warm-hot months (it gets up to 110 fahrenheit  / 45celcius in summer.

So this is what I have come up with.  I had some 220mm dia pipes left over from a building job.  That would be the body of the heater.

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The footprint is 300x400mm.  It is 1600mm high.  There is an ash pan under the grate.  The air intake (hidden) and flue are placed to encourage swirling in the pipe, and maximise heat transfer to the body of the heater.  The top is closed with a heavy plate.  I plan to add a proximity rail.

The heater is now finished, and I will do a test burn tomorrow.  If it works as hoped, I will post a video.

And totally unexpectedly, I have bought a model traction engine.  It feels a bit strange to buy rather than build, but here it is.

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1500mm long.  Deceased estate, never run on steam.  Beautifully made.   based on a steam engine which was used to power a sawmill.  ? 3″ scale.  Needs boiler re-certified. 

I will make a ride on driver’s trailer, and a kids ride on trailer.   I really have caught the steam disease.

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Most of the bits and pieces have arrived for this project, so I made a start on the machining today.  I used 80mm dia aluminium rod to make the stepper motor support piece.

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Stepper motor (right), flexible 8-12mm shaft coupler, and the rotary table shaft (left)

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I cut a 92mm cylinder of aluminium, squared the ends, centre drilled a face, drilled it out to 25.4mm, shown in this photo.  Note the 4 ribbons of swarf coming off the work.  The drill bit is an industrial stepped bit, with 4 cutting lips. Then the hole was bored to 28.80mm.

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An upside down photo of the stepper motor (left), motor support which is hiding the flexible shaft coupler, and rotary table (right).  Next to drill and tap for the bolts, and provide access holes for the coupling screws.

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And some more milling to convert the cylinder to a rounded square section, then drilling and tapping for the grub screws and bolts for the stepper motor.  (tapping with the Mogens Kilde tapping head in the picture).

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The finished support block

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Mechanicals finished.  Now for the electronics.

Cutting a thread up to a shoulder

A problem with some thread dies is that they have such a large “lead in” that they are unable to cut a thread up to a shoulder.

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A 3/8″ x 32tpi die.  Note the large lead in taper.

This results in the thread stopping a long way from the shoulder… undesireable in some situations.

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This is a thread made with the die in the previous photo.  I wanted it to go right up to the shoulder, but this is as close as it gets.  About 2mm gap.

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The screw in this upsidedown photo does not allow the shoulder to seat properly.

The solution?  Modify the tool.

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Here is the tapping die, held onto a magnetic chuck, within a machined steel disc to increase the magnetic attachment force.

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So I ground off the top 1-2mm of the die.  My surface grinder is out of action, so I used the tool and cutter grinder.   A bit rough but it worked.

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This is the die after grinding the surface.  Note that there is no lead in.  I ground the unlabelled face so I did not lose the specs of the die.

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And the screw after using the modified die.  The thread  now goes right up to the shoulder.  Incidentally, this is a zoomed photo using an iphone.  Not bad?

So that does the job.

The downside is that in future the thread must be started with the unmodified side of the die, and finished with the modified side.  Adds some time.  And the die is thinner and a bit weaker.

A pity that the dies are not manufactured with one “no lead in” face.

The particular set of ME dies will now all be modified in the same way.

 

A Turntable for the Triple Expansion Engine.

I have not weighed the Bolton 9 triple expansion steam engine, but I would guess that it is 20-25lb.  (weighed it.  25.5lb)

Access to the various bolt on bits and pieces has become increasingly difficult and tricky, and involves frequent repositioning of the engine.

I removed the bolt on base and that has improved the situation a bit.

Then I had a brainwave, thought bubble, inspiration  whatever, and I tried a ball bearing turntable….   you know….. one of those Chinese restaurant middle of the table gadjets.

It is incredibly useful!

Here are some pics and a video showing it in place;  just a demo of the engine at its current (unfinished) stage.  I think that the turntable might  become a frequently used tool for heavier models.

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The Bolton 9 on the turntable

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And the latest additional bits…   non return valves on the water pumps.

Project in the Wings.

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

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

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Dec 2016 MEW article

So I have commenced accumulating the bits and pieces…

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

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

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

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

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

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

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

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

magnifiers

A magnifier soldering station, and head light and magnifier

multimeter

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

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

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

 

 

 

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.

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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.

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

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

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