Working With Machines - Lathes, Mills, etc.

[murrayec]

On my workbench thread @Galteemore asked about turning buffer housings and smokebox doors- I had thought about a thread on here about using machines for model building and about the machines themselves for anyone looking for info. So here we go;-

First up Galteemore's request, there will be more about machines later as we go.

Smokebox Door;-

There is a few ways to do this, the two main ones are to spin a sheet of metal to form the door that way, or to turn it from a solid bar. Spinning a sheet of metal requires a former to be made out of hardwood first, which has the inside profile of the door, the former is mounted in the lathe chuck with the sheet of metal pressed up against it with the tailstock, its then 'spun' and a burnished tool is applied to the metal to push it into shape!

This discussion will deal with the solid bar option. This option is simpler than spinning but is a more advanced lathe operation than most because of the curves to the door- 2 curves are generally required, a small radius curve at the outside edge with a larger curve across the door, some doors have compound curves. This is done by hand turning which requires additional tools.

The round bar stock is mounted in the chuck with the minimum amount protruding for the part and a bit of safety from the chuck jaws, if the bar is the same size as the door a four jaw chuck is used and the bar has to be clocked to centre, if the bar diameter is larger than the door a three jaw chuck can be used as the bar will be turned down to size, then the part will be concentric. A four jaw chuck will hold the bar stock far better than the three jaw, very handy because we don't want the tailstock to be used as it will get in the way. Take light cuts and all should be OK.

1. Rough cut. The rough shape is cut to approx size, the cut to the rear of the door should allow for a flange to fit into the smokebox face plate, a parting tool is used to do this cut, just to the depth of the flange initially, allowing for the flange and the final parting cut.

2. Step Cuts to Curves. The front face is step cut to just over size of the final curves on the door to prepare for hand finishing. A flange is also cut on centre to a width n depth for the door handle detail. The centre hole is drilled to size- always use a centre drill to start a hole.

3. Hand Tool Curves. Hand turning is done with a Garver Tool held over a bar tool rest, the rest should be adjustable so that one can angle the tool to form the desired curve. Hand turning takes a bit of practice but once mastered any shape can be created, as long as its round! The other option is to use files to do the curves, ensure there is a handle on all files one uses on the lathe. The door handle flange could be ignored and a washer could be soldered or stuck on when the part is finished.

4. Parting Off. Use grades of emery paper or Scotchbright pads to finish the surface taking care not to loose the edges on the detail and then part off with a parting tool, ensure all slides and the saddle are locked when parting off, and if its a deep cut don't forget to allow for this in the initial setting up. Also don't forget to leave the flange on the back of the door! This is where the tailstock should be used but the centre hole is quite small, an adapter can be used to fit in the hole of the door and apply pressure on the handle flange with a revolving centre in the tailstock.

Using a Garver Tool. Some chaps use a bar mounted in the toolpost as a rest, I have done this it works but I reckon the proper stand is better.

Play with some aluminium bar stock to practice forming curves

Hole setting out can be done before the part is parted off, a punch mounted in the tool post set on centre height can be employed to do this, the chuck is rotated by hand and the cross slide is used to locate where the centre pops are required. A handy device is a printed paper 360deg scale to fit around the chuck and a pointer mounted to indicate the deg of rotation. Tables are available in booklet form or on line to workout rotation.

A long Hilti nail close fit in a block of mild steel makes a grand punch, just need to ensure one can get it on centre height.

Garver tools, my paper 360deg strip and indicator. I do have an indexing tool but the paper strip is far quicker to set up and accurate enough for this kind of work.

No workshop should be without this little booklet- threads, drill sizes, tolerance fit tables, PCD radial hole charts and log tables!

Next well do the buffer housings.......

Eoin

[Galteemore]

Thanks Eoin - just been playing with mine this week to get the hang of it! This is really useful - much appreciated for you taking so much time. We can often get away with UK loco parts in 7mm ( LMS 4F buffers match the SLNC pattern and so on) but some parts are special. Recently I had to add a brass capuchon to an NER chimney to get the Irish look - hopefully I can now turn up whole thing in the lathe..... 

If I ever get the Sligo Tank done, the next scratch build is likely to be a GSWR type so will be lots of interesting bits to turn....

Edited February 18, 2021 by Galteemore

[murrayec]

Lathe Turning Gauge G Wheels for an Alco RS-3

This is a job turning 4 replacement wheels for the loco, it was decided to change the traction tyre wheels for plain ones as the layout is relatively level and the tyres disintegrate over time.

A 41mm dia EN8 mild steel bar was sourced for its relative hardness and ease of machining, the wheels are fixed on a 6mm taper axle with a screw to lock in place. This adds to the complexity having to turn a small taper bore from 4.8mm to 6mm, needing a rather small boring tool which had to be made. Also required to turn the taper was a 'taper gauge' - this is for testing the fit of the taper in the wheels while turning it and to hold the wheel blanks in the chuck as the face truing is being done, again this had to be made first.

Boring tool being ground from a broken 3.75mm dia cnc tungsten carbide bit, using a green stone on the bench grinder to do this, grey stone does not cut carbide very well and generally just falls apart and over heats the tool which is not good- the tool looses it's hardness.

An existing wheel was removed to use as a pattern, 10mm thick wheel blanks were cut from the 41mm bar on the bandsaw the final thickness of the wheel is 8mm so a bit to play with! the taper gauge/mandrel was turned from 16mm dia EN8 ms bar to replicate an axle end from the loco, it has a M4 bolt and washer to hold the wheels when being used as the mandrill, and the boring tool was setup.

The wheel blanks were mounted in the 4 jaw chuck and dialled in to run on centre as the blanks were the exact diameter of the wheels including the flange so no waste to spare. The blank was faced off first as this is the back of the wheel and now is the time to do it. A 4mm dia hole was drilled through using a centre drill first 4mm gives just enough space to get the boring tool in. The boring was done by setting the top slide to the taper angle, the saddle and cross slide were locked and the cutting was carried out using the angled top slide only to create the taper. This is where the bore gauge comes in for checking the fit when doing the final cuts.

When setting up a taper gauge to check fit in this kind of job one sets the top slide to the angle, cuts the gauge and then cuts the bore in the item being made- without resetting the top slide or the cutting tool so that the taper angles will be spot on!

I have no photos of that work but this is one of the completed tapers and faced off wheel backface.

The blanks were then turned around in the 4 jaw chuck and a counter bore was cut for the bolt recess when fitted to the loco and also to be used for holding the blank on the taper mandrill while processing the front of the wheel. The counter bore was done with the little boring bar.

Now the taper gauge/mandrill is mounter in a collet chuck, this kind of chunk is very handy for round bar as it always tightens up on centre, even if one removes the bar and re chucks it- it will be on centre. This chuck is an ER25 type for the mini lathe and can hold bar from 1mm up to 16mm by changing the appropriate collet in the chuck- the 16mm collet is being used here.

The wheel blank has been mounted on the mandrill with the M4 cap screw, the head of the screw and washer needs to be turned down to fit into the counter bore of the wheel blank, an extra washer is installed for packing to allow the outer washer to be turned down to size.

After the screw and washer are turned down and re-fitted the full face of the wheel blank can be faced off and brought to the finished size of 8mm thick. A dial gauge is been used here off the saddle to measure the cut so that when the other 3 blanks are set up to be faced they will all end up at the same thickness.

With all the blanks set to the same size the front of wheel recess detail is part done- the top slide is set to an 8deg angle as the recess is at an 8deg angle, it get deeper out near the tyre. The saddle has a dial gauge set up to watch the depth of the cut and only the top slide is used to traverse the tool.

Inside done to 1mm deep but then the tool binds.

The tool is changed to do part of the outside of the recess but cannot be completed yet until the wheel thread is cut to set the distance, so the detail will match the existing loco wheels.

Outside being done but have to step the tool out near the tyre as it also starts to bind.

Two dial gauges are used her, one to measure off the saddle for the depth of recess and the other off the top slide to stop at a point adjacent the location of the tyre.

Recesses part complete which will be completed with a boring bar after the tyres are cut.

Tyres and flanges are rough cut square first.

All done square.

Now the top slide is set over at 20deg to cut the flange faces.

The tool is set in the post to have a 4deg angle to cut the tyre face when the top slide is wound in to the full flange depth. The saddle and cross slide are locked and only the cross slide is used clocked with a dial gauge to measure the depth and get all the wheels the same.

Now that the tyres are finished the rim dimension can be set. The final cut being done on the front face using a boring bar tool to finish the outside of the recess.

Dial gauges again being used to measure the depth of cut and distance out to the edge of the recess.

Cleaning up the edges with a file.

Blackening being done with blowtorch and WD40.

Blackened.

Complete, the one on the left is an original.

Fitting and going for a test run........

Eoin.

 

 

 

 

 

 

 

 

[David Holman]

Oh my...

Certainly won't be doing that on my tiny lathe, but inspirational all the same.

[Noel]

I've said it before Eoin doesn't look his best in this photo but his engineering work is simply out of this world. Excellence. Hat's off.

[Georgeconna]

3 hours ago, Noel said:

I've said it before Eoin doesn't look his best in this photo but his engineering work is simply out of this world. Excellence. Hat's off.

Could of polished his shoes too!

[murrayec]

Mini Sandblasting Cabinet Upgrades;-

This cabinet was made a few years ago. It's made from a perspex medical display box, Woodies gloves, plumbing bits, and an Expo Tools airbrush sandblast gun. The gun, although it gives an excellent fine finish for painting, is a pain to use. The sand container lasts for about 20 seconds and then it has to be filled again- this works fine, but becomes a pain after about 6 goes. Also the cabinet is not tall enough internally and makes the work tight and uncomfortable.

So some upgrades are needed, as I have a bunch of 6 wheelers, a J10 chassis, and more coming along to paint. These models have a few delicate parts so I prefer to use this setup rather than my larger sandblaster which has a more aggressive grit which is prone to bend/warp delicate parts. Also this blaster has a very light cut, so light that paint can be cut back without going all the way through to the metal or plastic, it can also be used for weathering a model.

The work involved;- raising the lid, designing a sand hopper to feed the airbrush, and lights.

An MDF lid riser was constructed and all the parts needed made from brass and aluminium bar, aluminium sheet and angle, 4mm plastic tube, and a bit of ply wood.

The airbrush sand hopper lid was modified by drilling and tapping an M4 hole and threading a tube through with lock nut to hold, the bore of the brass tube is 2.5mm dia. On the right in the photo is the sand outlet for the new hopper turned up in brass with a brass knurled nut.

These are the bits to hold the new hopper.

The new hopper is made from a Lidl hand-wash container.

Floor underlay foam was used to make a seal for the lid.

New hopper mounted.

This shows how the lid of the hand-wash bottle is modified to take the brass outlet.

Ready for testing.

Well things did not go well- the sand would not flow easily in the 4mm tube, and when the sand was used up in the tube the air would squirt up the tube and fire sand all over the place! So I decided two mods would be tried- a sealed hopper with a small air hole only and a larger diameter tube- 6mm.

6mm diameter silicone tube was acquired and a few new brass fittings were turned up- a 6mm bore hopper out let (that's the old one on the right) and a brass fitting to connect the tube to the top of the airbrush.

The new fitting screws onto the brass M4 threaded tube on the lid and locks onto the nut.

New sealed hopper bottle and LED strip lights (Lidl's best) installed.

The lid on and ready for a test. I still have to find a piano hinge for the lid!

The 6mm dia tube sorted the sand flow problem and I was able to blast the above 6 wheeler bogie part to a lovely silky finish in about 2 minutes. Blowback up the sand tube happens every so often, but pausing the blasting allows the sand to flow down again. Best thing is I could blast this part without having to refill the airbrush hopper every 20 seconds, I reckon a full bottle of sand should last for about 1.5 hours of blasting.

Some more tweaks will be done as I process more parts.......

Eoin

 

Edited March 2, 2022 by murrayec

[Broithe]

Nice - well worth doing - and, if it hadn't worked, you could have kept gerbils in it.

[murrayec]

7 minutes ago, Broithe said:

Nice - well worth doing - and, if it hadn't worked, you could have kept gerbils in it.

I am prepared......

 

[jhb171achill]

10 minutes ago, Broithe said:

Nice - well worth doing - and, if it hadn't worked, you could have kept gerbils in it.

Gerbil smoothies, anyone? 

[David Holman]

Only if sprinkled with Chinchilla dust!

Fantastic work Eoin - thanks for sharing.

[murrayec]

Proxxon MBS 240/E coolant upgrade;-

I bought one of these last year, mainly to cut metal, including steel. When buying it I found the coolant tank & tray optional extras are not available any-more! When cutting steel a coolant system is required if one wants the blade to last a reasonable amount of time.

So I had to make my own;-

An oven tray of suitable size was found in Woodies, the tray was drilled mounted on a timber base with threaded inserts in the base.

Drilled the tray and soldered in a brass pipe for the coolant drain.

Two sheets of 10mm thick Tufnol were cut to form a riser under the saw and then the machine was bolted down. The tray outlet pipe just hangs over the edge of the timber base where a container will be hung to catch the coolant.

2 no. aluminium pipe connectors were turned up, threaded, and screwed into the table outlets.

Drain pipes installed.

These are the parts for the coolant jar (an old Swarfega Tub), the plan is to be able to remove the jar easily, if not in use and for storing the machine away.

The jar sits in the bracket like this (upside down for the photo)

The bracket has a hanger strip on the back to hook onto a bracket fixed to the saw body.

The bracket on the body.

Hung!

The jar on, which will be glued to the bracket after painting.

The outlet is a brass fitting turned up and fitted to the jar using rubber washers to form a water seal.

Tap and 90 deg outlet fitted, the tap is an aquarium air pump tap!

I'm going to wait until I paint the plywood jar bracket before I test the setup, I shall post up a few photo when I do.........

Eoin

 

Edited March 6, 2022 by murrayec

[Adrian]

Wow! This is not something I need to do, or would ever attempt, but that's some serious machinery and equipment you have there and it's obvious you know how to use it. Thanks for sharing all that

[murrayec]

Sand Blaster Hopper Upgrade;-

The hopper I made for the blaster (see above), had a problem with supplying a constant stream of sand. This was due to the hopper outlet being done through the bottle lid which caused a backup of sand on the flat ledge of the lid and allied with the small bore of the outlet the sand stopped flowing!

So a hopper with a better outlet was required......

A €10.00 water bottle, a small kitchen funnel, a cnc'd  ply mounting bracket and a few fittings. This bottle has a lid on top which is better also than the last idea- easier to replenish with sand!

The base of the bottle is cut out, the ply bracket is sized to take the funnel and the bottle on the routed ledge, which are both epoxied in to make a seal. A hose clip is used to fix the outlet fitting into the bottom of the funnel with the aid of a short length of 12mm dia hose shoved onto the funnel outlet.

Up and running and it works far better, there is still a restriction where the feed pipe goes through the cabinet side! But when one lowers the gun inside the cabinet the sand does flow through.

I may make another mod by running the pipe down through the lid, but this requires a mod to the lid and there is not enough time in the day......

These parts took about 30 mins to blast at 60psi, it does take time as the gun is only air brush size, the large blaster would damage stuff like the brake gear and anything delicate on the chassis- note the axle bearings are sealed off so the sand does not get in there.

Eoin.

[Broithe]

Might it be worth rigging up a small motor with an eccentric weight on the support column?

Just a little vibration can be very helpful to 'granular' flows under gravity.

[murrayec]

7 minutes ago, Broithe said:

Might it be worth rigging up a small motor with an eccentric weight on the support column?

Just a little vibration can be very helpful to 'granular' flows under gravity.

Yes, that's a good idea, I have one of those motors and will give it a try the next blasting session

Eoin.

[Broithe]

30 minutes ago, murrayec said:

Yes, that's a good idea, I have one of those motors and will give it a try the next blasting session

Eoin.

Or just tape your mobile to it and ring it from the landline...  

[murrayec]

Turning a cast iron flywheel for a Stuart 10V steam engine.

This is a live steam working model.

This is the kit of unmachined parts, all the materials are supplied to build the complete engine, drawings come with the kit but no machining instructions. I also got the reverser kit, oil lubricator and a few other bobs! These kits can be purchased ready to be assembled but that takes the fun out of it........

A 64 page booklet can be purchased from Stuart Models or TEE Publishing describing the machining process, it is fairly comprehensive but does miss out on a few things. 

The flywheel;-

The casting spru was cut off on the bandsaw, and all casting flash n bumps were removed with hand files. Stuart Models have an excellent reputation for their metal casting.

This is the lathe faceplate holding setup, its easier to do this on the bench and then transfer to the lathe. After assessing the position of the flywheel spokes 3 holes were drilled and tapped M6 in the faceplate to take M6 studs and clamping plates. The rim of the flywheel is supported in 3 places off the flywheel by 2mm thick aluminium shims. Packing is installed under the spokes so when the clamp nuts are tightened up one does not break the casting!

This photo shows the 2mm shims which hold the flywheel off the faceplate so that the lathe tool can cut the outer face without bumping into the faceplate. The rim on the flywheel is quite deep, so this allows for the shims to be recessed in from the flywheel outer face, leaving this face free to be machined in one setting.

The faceplate is now mounted on the lathe and I'm using a scribing block to through up the inner edge of the flywheel rim. With the clamping loose the flywheel can be bumped with a plastic hammer to get this edge to run concentric. The hub of the flywheel ran fairly concentric after this was done so I was happy to go with this and tightened up the clamps.

Flywheel outer face, the rim face, and the hub face were machined using a general purpose carbide insert lathe tool. Then a 7mm dia hole was drilled through the hub for reaming out to 9/32'' (7.1mm) The model is in imperial units!

Before reaming, the hole was countersunk.

Reamed 9/32'' to take the crankshaft.

The flywheel was then rotated to machine the other side, the 2mm aluminium shims can now be seen because I'm not machining the outer face in this setting.

An arbour is now machined up in the collet chuck so that the flywheel can be fitted for machining the hub sides and the inner edge of the flywheel outer rim. The arbour spigot is machined to 9/32'' and just short of the width of the hub so that the M4 cap screw will pull the flywheel up against the arbour shoulder and run concentrically.

Flywheel on and running concentric.

Hub face machined with the general purpose tool and now I'm using a boring tool to cut the inner edge of the rim. All arises were chamfered 45 deg in this setting, the hub arise had to be done with a hand file as the clamping washer was in the way.

 

The flywheel has a 5BA grub screw to fix it to the crankshaft. This is my setup for drilling and tapping the 5BA hole. The flywheel is clamped on a home spun T-Slot plate mounted at 30 deg in the mill vice.

Another look at this arrangement.

5BA grub screw fitted.

Flywheel complete.

This process can be done using a 3 or 4 jaw chuck, but on the mini lathe with the flywheel at 76mm diameter one is just at the limit of these little chucks so the face plate is a far better option.

I might scoot this over to a thread dedicated to this project....

Eoin.

[Georgeconna]

Very Education Eoin. Nice little kit too. 

[murrayec]

20 minutes ago, Georgeconna said:

Very Education Eoin. Nice little kit too. 

Yes, Stuart Models have a lovely range of kits. I also have their beam engine kit which I'll keep for another rainy day!......

https://www.stuartmodels.com/products/set-of-castings/

Eoin.

 

[murrayec]

Milling, drilling & tapping the cast iron Boxbed & Soulplate parts for a Stuart 10V steam engine.

The parts from the kit.

The casting gates were cut off and the faces hand filed for mounting in the mill vice.

Base of boxbed milled level. Hard cardboard is used between the casting and the vice jaws, this helps to increase the hold on the sandcast surface of the part.

Boxbed turned over with top face milled level, drilled and tapped 7BA to take studs to mount the soleplate. The 2 base fixings are drilled out 3mm clear and the top face of the holes are spot faced 6mm dia to give a land for the mounting screw heads.

Soulplate with bottom and top faces milled, the mounting holes are drilled clear for 7BA studs with a 6mm dia spot face to the holes.

Clocking the main bearing journals to get the casting on centre with the mill spindle. The two journals are going to be milled out to size with an 11mm dia ball end milling tool.

Journals milled, the brass piece is the extruded stock from the kit, for making the two crankshaft bearings that fit into the soulplate journals.

Bearing stock being test fitted in the soulplate journals, it fits- after a few side 'dusting' cuts with the ball end cutter! The cutter is 11mm dia but the bearing extrusion measured 11.1mm (7/16'').

That's these parts finished for now, the soulplate will need more tapped holes for the standard and main bearings, this will be done when the parts are ready so that drilling can be spotted from the parts.

Eoin.

 

 

 

 

 

[Gabhal Luimnigh]

Beautiful work, fair dues lad.

[murrayec]

Modifying the Clarke Mini Lathe Tailstock;-

The standard Mini Lathe tailstock comes with a basic system to clamp it down to the lathe bed- a nut n bolt requiring a spanner to operate! There are options when purchasing the lathe, one is a lever-cam tailstock clamp, but Clarke do not have this option. Others do, also kits to convert are available on-line.

The use of a spanner every time to clamp & unclamp is a pain- lever action would be much better.

I found a chap on Youtube who did the conversion with;- M10 threaded bar, M10 bolt, M10 coupler nut, M6 capscrew, 4mm MS plate, and a length of 8mm dia MS bar for the lever handle.

The existing tailstock clamp setup.

Drilling the 10mm dia hole for the cam bolt to pass through to the rear of the stock where the lever will be fixed.

All the bits, the cam bolt has the M6 capscrew threaded in its head 3mm off centre to create the cam, the coupler nut holds the cam bolt in the stock body which is cross drilled and tapped M8 to take the operating handle.....

........like this. The clamp plate and the M10 modified threaded pull bar needs a weld on the underside. This pull bar is cut to size so that the cam rotates anticlockwise from 4 o'clock up to 1 o'clock where the mechanism locks, thus locking the tailstock to the lathe bed. The washers are used to pack the clamp bolt in the stock to line up with the pull bar.

The cam arrangement with the M6 capscrew and washers fitted.

A M6 grub screw was drilled and tapped into the stock body to hold the handle in easy reach when the tailstock is unclamped. Flats were milled on the lever handle for a 7mm spanner to tighten it up.

Up and running, it works beautifully, holding the tailstock rock solid.

I wont need that spanner any more.

Eoin