Lathes & M/C tools

[bertiedog]

I am told that the Harris axles have a plain end, so the machining should be easy, just mount accurately in chuck or collet and machine way enough for the adjustment. The Peatol will manage it straight away.

 

Stephen.

[bertiedog]

Further to my earlier reply about fitting bushes in Bachmann wheels I had a query about Perspex etc, and it is easy to source on EBay, in 5mm and 8mm, 1 metre long at around a fiver including postage.

 

Acrylic rod, Lucite, and Perspex are the same item. Super glue works fine with it as it is basically liquid perspex in chemical structure. Perspex will also take epoxy glue very well indeed. Most paints will work, as long as the polished surface is abraded with fine emery, wire wool, or machining. The high polish on rods and sheet may reject paint if this is not done.

 

Lucite is absolutely identical with Perspex, just trademarks for the US and UK, however Lucite (brand) is made in optical high purity grades.

 

Tufnol is also sold on Ebay 16mm diameter bar, or bigger sizes, it is far more expensive than Perspex, but is extremely tough. It is a resin, reinforced with compressed cloth.

 

Acetal rod, or Delrin could be used in glass filled grades, but they do not glue well, so force fits would be needed for the bush and the axle fit.

 

All round the Perspex is best unless you use Tufnol, or it's close cousin Bakelite plastic.

All plastics should be cut in the lathe with razor sharp tools at lower speeds to prevent melting.

 

Water is a good lubricant/coolant, add a dash of detergent. Do not use any oil, these plastics are slightly porous and it may interfere with painting/glueing later on.

[gordon s]

Thanks for the recommendations Stephen. Found this supplier of Tufnol Rod and a lot of other stuff that may be of interest...

 

Ordered this morning, sent this afternoon, so service looks pretty good as well...

 

http://www.directplasticsonline.co.uk/TufnolRod/

[ozzyo]

Hello all,

 

not really to do with mills or lathes, but what the heck. When your in Tesco, Asda, etc. keep a look out in the kitchen section for granite chopping boards, about 10" x 12" and 5/8" thick for about £10. Ideal for a surface plate for marking out, checking that that chassis is true etc.. IIRC you can get them in two sizes. I haven't bought one as I have a steel surface plate from long ago, if I didn't have it I would have bought one. If you have a look at one of the tool suppliers sites you will see that its a good price.

 

OzzyO.

 

PS. just had a quick look at a couple of tool suppliers similar size but 50mm thick about £50.

[gordon s]

Hi Guys, been playing around with my new toy today and have turned down some Tufnol and Acetal rod to make new bushes for my Bachmann wheels.

 

Just for the hell of it, I've drilled them out to 4mm and am using 3mm stainless steel to produce some new axles. I've also spun a few wheels and skimmed the back surface until they are true.

 

All in all, it's gone well. Just waiting for some tube to make a collet suitable for 21mm drivers.

 

I've been looking at materials though Stephen and Acrylic rod appears to be available in two types, cast and extruded. Cast is more expensive but they have commented that the extruded one cannot be machined.

 

Any comment on that as it seems to contradict earlier information? I don't want to order some and then find I can't use it.

 

Grateful for your view.

 

Extruded Acrylic Rod | Clear

2mm to 40mm diameter

 

On this page you can buy clear extruded acrylic rod in full lengths in the following diameters:

2mm, 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 12mm, 13mm, 15mm, 16mm, 18mm, 20mm, 22mm, 25mm, 30mm, 32mm, 35mm, 40mm

 

Product availability:

- normally from stock

 

Additional notes:

- Extruded acrylic rod is not suitable for machining

- For larger diameters click cast acrylic rod

[bertiedog]

I am afraid the supplier has told half a story, all Perspex,(Lucite), Acrylic plastic, machines, but cast acrylic is preferable for complex shapes etc., or where heat stress later on is expected.

 

 

The extruded forms including sheet and rod may suffer from relaxation with heat after machining, slight dimensional alterations or warping. The extruded plastic has internal stress in it, and this may be released by machining and heat.

 

The cast Lucite, especially the optically clear type, has no internal stresses at all in it and will retain all machined shapes.

 

But for the purposes of models the effect can be dismissed, the extruded acrylic should machine up fine.

 

Stephen.

[gordon s]

Had some fun today turning up a collett to take 21mm Bachmann wheels as per your suggestion Stephen. Works like a dream, so thats got over the first hurdle.

 

Plastics and aluminium tubing has been no problem but I have struggled with Stainless Steel. Do I need a special cutting tool? What speed should I be running at? I've got from 100-300 rpm to choose from. Should I be using a cooling fluid?

 

I must have taken the edge off the tool I was using, so I've resharpened it and all is fine again, but would appreciate some tips as how to turn Stainless. I've got some 3mm diameter I want to use for axles and found a piece of 25mm stainless pipe that I thought I could use. Difficulty in cutting and facing meant I used aluminium instead and that was fine.

[bertiedog]

Stainless steel can be a pig to machine, but if the bar stock is from a model engineering supplier then it will be OK. There are two main types magnetic and non magnetic, and most machinable bar stock is the non-magnetic type. Magnetic is used where heat or vacuum hardening will be done later on after machining.

 

There are dozens of grades and surplus or scrap must be assessed and tested by machining. In sheet form, magnetic grades are more easily machined.

 

There are also free machining grades with graphite, molybdenum, sulphur, or lead added.

 

Unknown source Stainless Steel is a mares nest, God help you if you ever get Inconel grade alloy, it is used for turbine blades, and heat resisting parts in jets, and is only machinable with diamond tooling. The moral is to buy from a supplier that deals with model engineers and is able to give the grade and/or assurance it is machinable.(Reeves, Maidstone models, Chronos, etc.,)

 

Now if the stainless is in tube form it may be very difficult to machine without carbide tools, lower speeds, and lubricant to cool the tip.

 

The reason is the extruded/ formed nature of some tube may work harden the metal. making it difficult. This is one reason that stainless steel wheel tyres are not made from tube, but from bar stock.

 

The tool shapes are normal for tipped carbide, if using HSS steel tools, then have less top rake. HSS will work with free machining stainless steel. If the material has a hard crust due to work hardening, then the tool rake angle must be increased to get the point under the crust as the work turns.

 

Aluminium is often dismissed as too soft, but is fine for tooling, jigs, and parts that will not be stressed as much as steel. It can be use to make parts for lathes like tool holders, and tailstock adaptors.

 

Stephen.

[gordon s]

Thanks Stephen. Both the Stainless 25mm tube and 3mm rod are 316 Stainless and absolutely rock hard. I guessed you were going to say something along those lines, so have used 25mm aluminium for the collett and I'll use 3mm mild steel for the axles.

 

Really pleased with the Bachmann wheels I was playing with today. Just a few thou of the backs and it gave a beautiful mirrored surface, much better than the standard finish.

 

....Now you'll tell me it will corrode....

[bertiedog]

Yes, it may corrode, but with luck not!! you can rub over with WD40 occasionally, it does help. If the mazak does not have mazak rot it will be all right, there is no predicting it.

316 should machine with carbide tips, and 3mm bar should be quite easy, it's the tube that is worst.

Stephen.

[bertiedog]

316 is used in medical parts and food grade, and is harder than 304, (303 is free machining 304). This explains why it is harder to machine, I had to check the numbers.

Stephen.

[halfwit]

I used to machine 316 occasionally and can confirm that is a pig! Tipped tools are a must, as is plenty of coolant. Cast stainless was worse though...

[bertiedog]

I bought a live steamer 5 inch gauge 062 many years ago, and found a leaking regulator.It had come from Kennions in Hertford, and when stripped from the boiler found the regulator was a Stroudley pattern with a floating plate over the pipes ends in a block of steel, not gunmetal, the floating plate seemed to be solid carbide!

 

 

The block would need grinding flat to work, so I removed it and tried to reface in the lathe first, but discovered that it was Inconel, and harder than carbide.

 

To get it to work I replace the whole thing, and all was well for the boiler test.

 

I wondered why Inconel was used and having a theory, I asked Kennions were the model came from, and it turned out to be right, it was near BAE's factory, the old De Havilland plant, and the builder worked in the jet engine dept!!...made from old turbine engine blades......

 

Stephen.

[gordon s]

A question re tailstock alignment.

 

I've made up a 21mm collett which holds the driving wheels perfectly and I'm awaiting a tailstock chuck which will arrive tomorrow.

 

How do I check the tailstock alignment as I want to drill the wheel out dead centre? I've checked the Proxxon manual but it doesn't mention it. There is one large screw at the front which is for locking the sleeve and two smaller allen screws which can be seen along the centre line of the tailstock. Do I assume the tailstock is set dead centre at the factory or does it need setting up?

 

I guess I can turn up another point and set it inside a collett to check the alignment by bringing the two points together, but then I don't know how to adjust it if it's wrong...

 

Questions, questions, questions.....

 

[bertiedog]

At a glance there is no adjustment on the Proxxon, the screws at the back merely retain the machined sleeve unit for the tailstock screw.

If there was an adjustment it would be in the base, a split, that would have two screws, fore and aft, able to move the whole tailstock backwards and forwards, with a locking screw.

Without any screw means it is expected to be in alignment, but does impose a limitation of not being able to turn tapers by the setting the tailstock over method.

However a special tailstock morse mounted centre would overcome that easily, the device can be home made, a disk in the mounting that can be re-set.

 

Basically they have left it so that the tailstock is always aligned, so the tailstock chuck should line up first time.

 

A simple test is to place a metal scrap point in the chuck, turn to accurate point, and gently clamp a disk of brass between the point and the tailstock centre point, and then rotate the headstock mandrill by hand, the disk should not wobble, if it does it is out of line. (Try two or three times to ensure no false readings).

 

Stephen.

[richard carr]

Hi Stephen

 

Can I please have your expert advice on the following?

 

I have a fantastic set of Allan Harris Scale 7 wheels (split axle) for an L&Y Aspinall 4-4-2 Highflyer, already turned and finished. The problem is that I model in 'normal' 32 mm finescale. I want to use the wheels (I build my turnouts to 31.5mm and do not envisage any problems with the S7 profiles on my trackwork), but I do not have the first idea how to go about reducing the back-to-back, or more properly I suppose, how to hold the piece safely so I can do what I want to in my lathe (Peatol/Taig).

 

The 2 drivers and the trailing axle are the usual Harris telescopic axle and taper pin, while the bogie wheels are glued in one end and screwed in the other. I also have to consider retaining the quartering, but that is another issue.

 

Thank you

 

Richard Lambert

 

 

 

Richard

 

The first thing to say is have you got any soft jaws for your lathe, if you haven't you need to get some, soft jaws are just jaws made of mild steel that are easily machinable. If you have some ( or when you get some) you can use a boring bar (an HSS one with a good sharp point is the best choice) to machine a shoulder in the centre of the jaws to a depth of about 1mm ( you don't need to be precise)big enough to hold the wheel by the tyre. You can now grip the tyre of the wheel very firmly in the jaws and as you machined the jaws on the lathe the wheel will turn true. If Alan made the wheels then you can be assured that when you grip the tyre in the soft jaws the end of the axle will still be running pretty true. If he didn't make them then it might not be that true as getting the wheel to run true on the axle is the most difficult part of making wheels. If it is running true then use a fixed steady to support the end of the axle and you should be able to machine off the 1mm (or so) required to get the correct B to B that you need, you can then screw on the other wheel and machine off the excess screw that you will now have.

 

If the axle isn't running that true the best thing to do is to bin it and start again, they can be easily drilled out. If that isn't an easy solution then it may be possible to punch the axle a little further through the wheel at the glued end, be careful though as its easy to damage the axle it self and if you go mad to break the wheel !

 

For the drivers your best bet is to reduce the length of the thicker axle by the amount required to get the right B to B. To do this hold it by the tyre in the soft jaws, you will probably need to machine a wider shoulder to grip the larger wheel. You can then used the fixed steady to support the end of the axle and remove the necessary material. The down side to this is that you will lose the quartering as the holes through each axle will no longer line up. Quartering is relatively easy if you have a jig, I use the one by Metal smiths its reasonably cheap and very easy to use in pillar drill. I tend to use a 1.2mm drill for the hole, first I file a small flat then very gently bring down the drill just to get it to bite then it will pass through both axles quickly. You will then need a taper pin reamer a 1:48 imperial one you can get one from MSC J&L Industrial supply. If you need more taper pins let me know and I can post some to you.

 

If the axle doesn't run true then let me know as things get a lot more complicated and stating from scratch with new axles might be abetter option.

 

Richard Carr

[halfwit]

When using soft jaws you'll need to find a piece of round stock smaller than the wheel dia. for the jaws to grip before trying to bore the jaws out. Run the lathe at a slower speed than you normally would as you'll be taking intermittent cuts, and beware of taking the edge off the tool. Make sure the tool is secure in the holder and that the overhang is at a minimum, which is always good practice anyway. I always tightened the chuck using the same position/pinion. When I worked as a turner I had about half a dozen sets of soft jaws to choose from, I rarely used hard jaws.

[bertiedog]

When using soft jaws, don't forget that gripping a wheel by its tyre may still not be secure, the tyre may be tapered, and the three point contact may be able to distort the rim on some wheels, unlikely on spoked cast iron, but quite possible on a brass, steel or nickel rim.

 

Wheels should be held in a collet, a single split collet will do fine, or a bell, or step collet chuck, this evens the grip, and places it more securely on the shallow taper.

 

Soft jaws can also be made by bolting dural bar to each mild steel jaw, the dural bar is more than strong enough.

 

Another method is three slices of hex aluminium bar bolted to the face of the jaws, and close on a spacer, with the shape machined into the face. The resultant special three jawed collet will be the best possible grip on round objects and accurately repeatable. The hex shape can have the flats turned to face each other, or the points meet at the centre, and you can re-machine them many, many, times.

 

Three round bars slices can be bolted to the jaws to provide a generous blank are to machine recessed groves to take wheels gripped by the flange to face outward for finishing the front.

 

All of this demands spare jaws that are drill-able and tap-able , most makers can supply soft mild steel. If not then get a spare set of hardened and get an engineering shop to cut away the faces, and weld on mild steel strip, it can then be machined in the lathe to give basic jaws, that will take further soft dural jaws.

 

For most amateur work a home made split collet, made from scrap, is easiest to make, and offers the best grip for most round work, and completely compensates for worn, or out of true 3 jaw chucks, ANY chuck will do.

[dikitriki]

Richard

 

The first thing to say is have you got any soft jaws for your lathe, if you haven't you need to get some, soft jaws are just jaws made of mild steel that are easily machinable. If you have some ( or when you get some) you can use a boring bar (an HSS one with a good sharp point is the best choice) to machine a shoulder in the centre of the jaws to a depth of about 1mm ( you don't need to be precise)big enough to hold the wheel by the tyre. You can now grip the tyre of the wheel very firmly in the jaws and as you machined the jaws on the lathe the wheel will turn true. If Alan made the wheels then you can be assured that when you grip the tyre in the soft jaws the end of the axle will still be running pretty true. If he didn't make them then it might not be that true as getting the wheel to run true on the axle is the most difficult part of making wheels. If it is running true then use a fixed steady to support the end of the axle and you should be able to machine off the 1mm (or so) required to get the correct B to B that you need, you can then screw on the other wheel and machine off the excess screw that you will now have.

 

If the axle isn't running that true the best thing to do is to bin it and start again, they can be easily drilled out. If that isn't an easy solution then it may be possible to punch the axle a little further through the wheel at the glued end, be careful though as its easy to damage the axle it self and if you go mad to break the wheel !

 

For the drivers your best bet is to reduce the length of the thicker axle by the amount required to get the right B to B. To do this hold it by the tyre in the soft jaws, you will probably need to machine a wider shoulder to grip the larger wheel. You can then used the fixed steady to support the end of the axle and remove the necessary material. The down side to this is that you will lose the quartering as the holes through each axle will no longer line up. Quartering is relatively easy if you have a jig, I use the one by Metal smiths its reasonably cheap and very easy to use in pillar drill. I tend to use a 1.2mm drill for the hole, first I file a small flat then very gently bring down the drill just to get it to bite then it will pass through both axles quickly. You will then need a taper pin reamer a 1:48 imperial one you can get one from MSC J&L Industrial supply. If you need more taper pins let me know and I can post some to you.

 

If the axle doesn't run true then let me know as things get a lot more complicated and stating from scratch with new axles might be abetter option.

 

Richard Carr

 

 

Richard

 

Thank you very much for your reply - and Stephen for his comments. I have been on holiday, and only just seen the reply, hence the delay in response. Your reply deals with exactly what I needed, and I have all the requisite equipment to at least set it up in the lathe to find out how true the axles are. I don't have the taper pin reamer or quartering jig, but I percieve this as the least of my problems. I don't think I'm minded to start tapping axles out, I'd rather start again, or concede that it is beyond my current skill set to do a good enough job. The wheels are so nice that I don't want to run the risk of a botched job!

 

Regards

 

Richard

[gordon s]

Searched high and low for a set of soft jaws or a new chuck that will fit the Proxxon without success. Any pointers?

 

It fixes to the faceplate with three socket screws on a 15mm (approximately) radius from the centre. The chuck itself is around 72mm diameter.

 

Pleased to say I've been having fun for the last 10 days or so playing with some old Bachmann wheels and eventually managed to get them running round and true. It's a whole new world...

[bertiedog]

On all lathes all chucks fit, within the size range, but each lathe will take them in a different way, the chuck is bolted to a back plate that is designed to fit the lathe nose accurately.

 

The Lathe makers offer the backplate as a blank and it is fitted to the lathe and finish machined on the lathe, to match the back of the chuck, which will have a true round surface and hole in the middle. The bolts only retain it to the back pate, the removal is via whatever system the makers have fitted.

 

 

I do not know what the Proxxon has, but it needs a back plate to suit the lathe, and then a chuck of the right diameter, to fit the lathe.

 

Chronos and other suppliers do small diameter chucks, it does not have to be an expensive one if conversion to soft jaws is involved. Small chucks with soft jaws are rare, but you can get the hard jaws modified by having mild steel faces welded on and drilled and tapped to take aluminium faces.

 

There are expensive 4 and 3 jaws of watchmakers size from Cowells, that would fit via the backplate, and Burnerd do make new, at a high price in any fit and jaw type.

 

Stephen.

[richard carr]

Richard

 

Thank you very much for your reply - and Stephen for his comments. I have been on holiday, and only just seen the reply, hence the delay in response. Your reply deals with exactly what I needed, and I have all the requisite equipment to at least set it up in the lathe to find out how true the axles are. I don't have the taper pin reamer or quartering jig, but I percieve this as the least of my problems. I don't think I'm minded to start tapping axles out, I'd rather start again, or concede that it is beyond my current skill set to do a good enough job. The wheels are so nice that I don't want to run the risk of a botched job!

 

Regards

 

Richard

 

 

 

Richard

 

I well understand what you mean, there would nothing worse than ruining a good set of wheels and if this is your first try at doing something like this perhaps its not he best thing to do. Why not practice on some wagon wheels that you do not need anymore ?

 

Let us know how you get on

 

Richard.

[ozzyo]

Hello all, not a lathe but still a M/C tool. From Thursday 19/8/10 Lidl have on sale a bench pillar drill spec as follows. 9 speed 385-2500, 16mm keyed chuck and vice, £49.99.

Also on sale the same day a 100mm capacity M/C vice with a bench clamp £6.99. I dont know what the quality will be like but it maybe worth a look.

 

OzzyO.

[gordon s]

Been having fun playing with my lathe/milling attachment and a Bachmann Ivatt 4 chassis. I'm going to fit a High Level Gearbox and a Mashima 1626 motor and have modded the Bachmann wheels to take 1/8" axles. These will run in brass bearings with an outside dia of 3.6mm. Any suggestions how to generate a hole or slot to suit the brass bearing? I have some end mills of 2,3 & 4mm, so is it just a case of milling out wider slots in the bottom of the chassis?

 

Edit: Just found Chronos offer a 3.6mm reamer, so that may be the answer.

[bertiedog]

As a general rule do not attempt to ream a slot with cutter of the right diameter, any out of true holding of the cutter will produce a wider slot than expected, and a bigger amount of material is removed in one go. On light milling machines, or lathes, it may also push the work aside a bit as it cuts, taking up play etc., and result in a slot not quite on the centre line that you intended.

 

• Best practice would be to run a smaller diameter slot cutter or mill through the work, not quite to full depth as well, on the nominal centre line. The fact that the slot will be off centre etc., no longer matters, and the second cut should widen the slot towards one wall, with a final cut at the correct position for one side face, then go back and widen in the other direction. For the second and subsequent cuts lower the slot cutter or mill down to the final depth as well.

I know this sounds a lot for a 3.5 mm slot! but it's the way to do any slot in milling work, and with 3.5 using the 3 would suffice with just three cuts at full depth. The first could be one side, but why risk it? Work form the centre out, it allows for corrections. Go too far and it will have to be packed out and glued, that's all in this case.

 

• If you have the rods already then mill the slots wide anyway, put the bearings into place with axle with extensions through the rods in place, and then bed each bearing in epoxy, when set the bearings will automatically be in the perfect position first time.

This works best with full width bearings, not top hat bearings at each side, and may not be possible with the driven axle due to the small space

• With cast mazak, to get a good finish and not get grab on the mill, use a spot of lubrication, oil and paraffin mix etc., or water at minimum.

Hope this helps,

Stephen.