Tips and tricks in machine tool practice

Jeremy Suter
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Re: Turning a chimney

Postby Jeremy Suter » Sat Nov 20, 2021 10:30 pm

Making an Arbour to re-turn Heljan shunter wheels to P4 standard

The Society has now had delivery of the Form Tools for converting proprietary wheels to P4 standards.

The tool needs to fit over the rim. So the wheel must be held perfectly central and perpendicular to that centre. As I cannot hold the rim, it must be held through the axle hole and gripped on the front and back face of the tyre. What I don't want to happen is the wheel slips on the axle or the tyre slips on the plastic spokes.

These Heljan wheels have a 2mm axle so I will start with an old Gibson pinpoint axle and turn a 0.5 degree taper on one end about 12mm long to allow the wheel to be pushed on without any damage to the boss.
IMG_6723.JPG

I have also run a Dial Indicator on the axle to double check that the collet is not damaged and the axle runs centrally.
IMG_6736.JPG

Now the end of the axle has been turned down to 1.8mm about 4mm plus the point and threaded 10ba. You should just be able to see the taper in this photo.
This was an earlier version which I decided to scrap as it was too small.
IMG_6724 (3).JPG

Now I need a backing plate to fit the wheel against so I first face off a 1/2 inch bar ready to be drilled to fit over the 2mm axle.
IMG_6725.JPG

Once faced off a centre drill is used to start a hole in the centre and then drilled out with a 5/64 inch or 1.98mm then reamed 2mm.
IMG_6727.JPG

I need two of these drilled faced and polished.
The first one needs to be wide enough to catch the tyre, with a small recess to go around the boss on the back of the wheel. It needs to have enough width so that it gives stability on the axle. A wire down the centre to catch it as it parts off.
IMG_6731.JPG

The second one needs a larger recess to go over the crank which is proud of the wheel rim.
IMG_6732.JPG

Putting the two pieces back in the lathe and facing off the other side I used a brass parallel to level it in the chuck.
IMG_6734.JPG

Taking the first backing plate I have drilled a 1.5mm hole all the way through am tapped it with an M2 tap to fit grub screws in each side.
IMG_6737.JPG

I am now drilling a 1mm hole in the back plate in line with the crank pin throw.
IMG_6741.JPG

Slotting onto the axle in the chuck and tighten the grub screws.
IMG_6739.JPG

Once tight I run the dial indicator to check it runs perpendicular to the axle.
IMG_6740.JPG

Slot the wheel on the axle with a 1mm nickel rod through the crankpin hole and the hole in the back plate.
IMG_6742.JPG

Slotting the front plate over and then using the nut to tighten everything and push the wheel onto the axle smoothly and without any distortion.
IMG_6743.JPG

The nut I made from 6mm hexagon Colphos as the 10ba nuts are a bit small for this job.
IMG_6744.JPG

I will double check all is square before cutting any metal off.
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Terry Bendall
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Re: Turning a chimney

Postby Terry Bendall » Sun Nov 21, 2021 9:42 am

Lots of very helpful ideas from Jeremy. I liked the idea of making up the large "washer" to help hold the wheel and the home made nut. Both of these would make gripping the wheel whilst it is re-profiled much easier. The nut does not need to be made from hexagonal material - it could be made from a round bar and two flats filed opposite each other for a spanner and could be made of mild steel.

The same idea could be used for wheels with a larger axle hole. For those without collets, the spindle on which the wheel is mounted, and the backing plate could be turned from solid bar held in the chuck. The spindle does however have to be concentric which it will be when first turned but if it is removed from the chuck and then put back, may not run concentric. That is where a four jaw independent chuck is essential as is a dial test indicator.

Terry Bendall

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Winander
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Re: Turning a chimney

Postby Winander » Sun Nov 21, 2021 10:09 am

Terry Bendall wrote:For those without collets, the spindle on which the wheel is mounted, and the backing plate could be turned from solid bar held in the chuck. The spindle does however have to be concentric which it will be when first turned but if it is removed from the chuck and then put back, may not run concentric.

Terry,
If I was using a three jaw and marked the spindle with the number of an adjacent chuck jaw, and positioned it back in the chuck exactly where it came out, would that be good enough?
Richard Hodgson
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Terry Bendall
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Re: Turning a chimney

Postby Terry Bendall » Mon Nov 22, 2021 4:40 pm

Winander wrote:If I was using a three jaw and marked the spindle with the number of an adjacent chuck jaw, and positioned it back in the chuck exactly where it came out, would that be good enough?


Is certainly a useful technique which I have used occasionally. Ideally two small centre punch (or dot punch) marks each side of the jaw surface the touches the work. Remember we want things to be a accurate as possible, within say 0.03 mm or better if you can.

Terry Bendall

John Palmer
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Re: Turning a chimney

Postby John Palmer » Mon Nov 22, 2021 4:47 pm

For me this thread has been Pure Gold regardless of the discursions into such matters as lamp tops, smokebox doors and the back toolpost it spurred me into making. It's quite convenient from my viewpoint to see it all within the one thread, so may I suggest the possible alternative of a change of title - perhaps to something like 'Tips and tricks in machine tool practice'?

Incidentally, with regard to arbours for wheel turning, I am wondering whether, for those without suitable collet attachments, the arrangements might be adapted into the form of a mandrel running between centres and actuated by a driving dog? Turning between centres was very much the starting point of my lathe education, and I've long thought that it merits more attention than it receives as a method for setting up a turning operation.

Jeremy Suter
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Re: Tips and tricks in machine tool practice

Postby Jeremy Suter » Sat Dec 18, 2021 9:30 am

Returning the flange on a Heljan RTR wheel
I have been given a set of 6 Heljan wheels for the O3 shunter which have a 2mm axle hole. It has a plastic centre with blackened metal tyre and turns out to be Nickel.
So as I have now made the arbour for holding them I am now turning the tyre down to the correct size. The wheels are 3.06mm thick and need to be reduced to 2mms.
DO NOT place the form tool straight over the wheel. It will not last very long and probably damage the wheel.
IMG_6811.JPG

IMG_6796.JPG

Mounting the 2mm collet in the lathe with the arbour in. The wheel is pushed on through the axle hole with a pin through the crankpin so that when any force is placed on the wheel it will not spin on the axle. Slot on the clamping wheel and tighten using the nut to keep the wheel straight so the the rim is gripped rather than the plastic spokes to prevent the tyre spinning on the plastic centre.
IMG_6799.JPG

IMG_6800.JPG

IMG_6801.JPG

The first job is to reduce the height and the width of the flange This is done with light cuts and a plain tool
IMG_6802.JPG

IMG_6804.JPG

I am taking off less than needs to be removed making a note of where I am cutting too on the indexing handle of the lathe so I can repeat on the next wheel . I then clean up any burs on the tyre with a diamond file
IMG_6806.JPG

Now I have a tall thin flange.
IMG_6805.JPG

I have taken the clamp off to show a better picture of what I have done so far.
IMG_6808.JPG

Now I have changed the tool for the profile tool . The meeting point of the tyre and the flange is the only thing on the wheel which is correct. It has to line up with the same position on the form tool. pushing the form tool over the wheel and flange it just cuts a little off the back and the top of the flange.
When the tool meets the tyre stop and make a note where it finishes so you can repeat on the next wheel.
With the six wheels done the back needs to be removed and this will bring the thickness to 2.36mm
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Winander
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Re: Tips and tricks in machine tool practice

Postby Winander » Sat Dec 18, 2021 11:19 am

Jeremy,
Jeremy Suter wrote:so the the rim is gripped rather than the plastic spokes to prevent the tyre spinning on the plastic centre

I assume you measure the tyre to turn the clamp to a suitable diameter to provide an adequate hold but leave sufficient of the rim proud to be able to maximise the cut to the profile. What measurement have you found is effective for the clamp to act on?

When the tool meets the tyre stop and make a note where it finishes

If the coning 1:20 of the tyre is not correct on the original wheel, do you allow the form tool to cut to correct it?

Thanks for clearly documenting the process, and I look forward to what comes next.
Richard Hodgson
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Jeremy Suter
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Re: Tips and tricks in machine tool practice

Postby Jeremy Suter » Sat Dec 18, 2021 1:14 pm

Winander wrote:Jeremy,
Jeremy Suter wrote:so the the rim is gripped rather than the plastic spokes to prevent the tyre spinning on the plastic centre

I assume you measure the tyre to turn the clamp to a suitable diameter to provide an adequate hold but leave sufficient of the rim proud to be able to maximise the cut to the profile. What measurement have you found is effective for the clamp to act on?

When the tool meets the tyre stop and make a note where it finishes

If the coning 1:20 of the tyre is not correct on the original wheel, do you allow the form tool to cut to correct it?

Thanks for clearly documenting the process, and I look forward to what comes next.


Hi Richard. Good questions .
Yes!
Actually the whole arbour was made to suit the wheel. I could recut to do smaller wheels or another crankpin hole, or more to suit another crank throws. I could even take the base off and turn it around and just cut for a different size wheel on that side. The clamp could be recut on one side as well or just make a new one to suit another wheel size.

As for wheels with the wrong coning on. I would correct it although I hope they are not too much out. It will decrease the size of the wheel by a fraction .
This I would do as a first cut before I attacked the flange, by setting up the correct angle on the cross slide taking light cuts with a point shaped cutter, not pin point like this one but with a rounded tip. The tool is ground to a sharp point on the grinder and honed on a stone to take the point off which will give me a smoother cut and last longer.
IMG_6813[1].JPG
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John Palmer
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Re: Tips and tricks in machine tool practice

Postby John Palmer » Sun Dec 19, 2021 2:14 am

Jeremy Suter wrote:With the six wheels done the back needs to be removed and this will bring the thickness to 2.36mm

Jeremy, please could you expand a bit on this aspect of the operation. Looking at the photographs, it seems that after you have generated the flange profile with the form tool you are left with a step in the rim that, in the case of these particular wheels, appears to be between .3 and .5mm wide. Ideally you'd want to be able to remove that step with a facing cut, but that's not possible whilst the rim is being clamped on the arbour as shown in your pictures. Since reduction of the wheel's thickness by removal of this step is apparently the final operation, do you transfer it to a stepped collet for this purpose? Presumably you may also be removing some material from the back of the wheel inboard of the rim, depending on the degree to which the rim stands proud of the spokes' rear face - I imagine that can vary quite a bit from one manufacturer's wheel to another.

Philip Hall
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Re: Tips and tricks in machine tool practice

Postby Philip Hall » Sun Dec 19, 2021 12:52 pm

I have taken a shade off the back of wheels by holding the tyre (protected with a strip of paper) in the three jaw chuck. I have generally ignored the ‘step’ since it’s not noticeable from the front. Possibly not quite the correct way…

Philip

Jeremy Suter
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Re: Tips and tricks in machine tool practice

Postby Jeremy Suter » Sun Dec 19, 2021 10:54 pm

Now with the flange done the back needs to come off.
John you are right.

The easiest way to do that is with the bell collet or step collet as everybody else refers to it as.
So taking the arbour and 2mm collet out and replacing with the No 2 bell collet. I have mounted the wheel.
IMG_6814.JPG

With the wheel mounted in the collet I have set the facing cutter to the boss and will push in and take a cut from the centre to the rim a small light cut to see what happens.
IMG_6815.JPG

Then from the rim to the boss and the boss to the rim and so on. Removing about .2mm at a time.
Being plastic I was a bit worried about how the lathe cutter would affect it. It might have torn rather than cut, or got hot. or just covered the tool with charged plastic. It cut cleanly only leaving a scraping as the cutter left the spoke.
IMG_6817.JPG
IMG_6818.JPG

I have left the boss on. Its .87mm deep and might have to be removed later if the wheel sets will not fit on the chassis

For those without a set of collets

I also tried to do it on the Arbour by replacing the large clamp with a smaller on.
IMG_6819.JPG

I removed the last part of the tyre first. Then working down the spokes to the crankpin hole before removing the pin, I could have carried on and cut the end of the pin at the same time but didn't know if the plastic boss would hold it
IMG_6823.JPG

Now the crankpin plug is removed I carried on to the clamp.
IMG_6822.JPG

Although this way does work I got a cleaner finish in the collet. The plastic spokes give a little movement when the cutter cut the remaining flange and has marked the back of the flange. This may work fine with an all metal wheel.
IMG_6823 (2).JPG


I also tried putting the wheel in the 3 and 4 Jaw Chuck

Beginners DO NOT DO IT.
IMG_6825.JPG

IMG_6826.JPG


Getting it centred correctly is not important on this stage, but getting it to run true and parallel to the cutter will be. The tyre is tapered, even such a shallow taper is not good if not gripped correctly. If you over tighten the jaws it will distort the tyre.
I didn't even try to correct it once I saw it spinning although it could be done using parallel blocks
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David Knight
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Re: Tips and tricks in machine tool practice

Postby David Knight » Sun Dec 19, 2021 11:36 pm

Very helpful Jeremy, a lot of good points and food for thought. Just out of curiosity, if all you had was the Myford what changes would you have made?

Cheers,

David

DougN
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Re: Tips and tricks in machine tool practice

Postby DougN » Mon Dec 20, 2021 12:29 am

Not sure, if this is the right place to ask this question. I have become the owner of a lathe (some might say what took you so long!) It is a Unimat SL.

It was screwed to a work bench but that can't happen at my place. Can any one suggest the best way to mount it and what is the best out come. I have some off cut of 25mm Acacia benchtop which is a solid hardwood. Which I can cut practically any size out of (the off cut is about 600x 800) . I have thought of installing a draw under the top to fit all the associate attachments and be a way to increase the weight so it is well and truly stable when in use. Then a smaller cover to protect it while not in use. Is this a good idea?

Merry Christmas to all

Doug
Doug
Still not doing enough modelling

Philip Hall
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Re: Tips and tricks in machine tool practice

Postby Philip Hall » Mon Dec 20, 2021 12:32 am

Thanks for the tips, Jeremy. So far, I have only taken a few cuts off the backs of flanges, reasoning that as I can’t really see the back of the wheel, there’s no point in going all the way down to the centre.

Mostly this has been done to reduce the thickness of the flange, and thereby increasing the b-b dimension, on Markits EM wheels. The supplied EM axle seems to give a b-b of 16.45 mm which won’t work on my customers’ track! So a light cut off the back of each wheel brings it out to 16.6mm. Here though I often mount the wheel back to front on an axle as I am not touching the tyre surface, so no need to hold the axle dead true.

One possibility that the form tool opens up might be to turn down Markits wheels to P4 standards. Here the axle could be held in a collet as the square ended axle ensures the wheel won’t slip. I think P4 axles are still available. I’ll have to try it sometime.

Philip

Philip Hall
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Re: Tips and tricks in machine tool practice

Postby Philip Hall » Mon Dec 20, 2021 12:34 am

Hello Doug,

When I go down to the workshop tomorrow I’ll take a couple of snaps of the base my SL is screwed to. Too late tonight!

Philip

John Palmer
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Re: Tips and tricks in machine tool practice

Postby John Palmer » Mon Dec 20, 2021 11:09 am

Jeremy, many thanks for that comprehensive answer to my question. On reflection, I completely understand the distortion risk inherent in trying to grip a wheel by its tread – in effect it involves the application of a point load at the three or four points at which the chuck jaws are in contact with the tread.

My desire for a drawbar collet holder capable of mounting those bell collets is all the greater in the light of recent posts featuring this method of work holding, but acquisition of such a capability has gone on the 'round tuit' pile because, in the absence of a suitable commercial offering for the Unimat 3, it involves my making one for myself.

As an alternative I offer the possibility of using the ring chucks that featured in a Chris Pendlenton article in MRJ on wheel fettling some years ago. The advantages of such a chuck are that it grips the wheel tread around its entire circumference (so no point loads applied) and can be of a depth that promotes correct alignment of the wheel along the spindle axis. A disadvantage is that separate ring chucks must be custom made for each diameter of wheel to be turned, and in addition use of an independent four jaw chuck and DTI is desirable if not obligatory.

Regarding Doug's question about a mounting for his SL, I am attaching a shot that shows the base and framework on which my disreputable Unimat 3 is mounted, and that may offer ideas for the mounting of an SL which must be of broadly comparable size. Originally I had my machine permanently mounted on a bench I had constructed for the purpose, but the bench, though it survives, could not be conveniently accommodated in my workspace following a house move, so I came up with this more portable solution. It's constructed around a butcher's meat tray which can be slid out of the framework for convenient disposal of accumulated swarf. The Unimat itself is attached to a well-seasoned piece of board, with pads of rubber interposed between board and bed of the machine.
Portable Unimat 3.jpg
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davebradwell
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Re: Tips and tricks in machine tool practice

Postby davebradwell » Mon Dec 20, 2021 11:45 am

Surely no need to put a ring chuck in a 4 jaw, John. The whole point of such a thing is to hold work truly in a 3jaw that may be past its best as it is machined in situ. By marking it adjacent to jaw #1 it should go back again reasonably well, although obviously wise to check.

Don't your books get spattered with oil from your Unimat?

DaveB

Jeremy Suter
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Re: Tips and tricks in machine tool practice

Postby Jeremy Suter » Mon Dec 20, 2021 10:12 pm

DougN wrote:Not sure, if this is the right place to ask this question. I have become the owner of a lathe (some might say what took you so long!) It is a Unimat SL.

It was screwed to a work bench but that can't happen at my place. Can any one suggest the best way to mount it and what is the best out come. I have some off cut of 25mm Acacia benchtop which is a solid hardwood. Which I can cut practically any size out of (the off cut is about 600x 800) . I have thought of installing a draw under the top to fit all the associate attachments and be a way to increase the weight so it is well and truly stable when in use. Then a smaller cover to protect it while not in use. Is this a good idea?

Merry Christmas to all

Doug

Hi Doug
Its a Useful question to ask anyway.

My feelings are that any small lightweight lathe will need to be held down either screwed to the bench which I am not in favour of. As you might want to twist it round and view from the other side. Or mounted to a board which could be clamped down to give a firm hold when twisting the handles on the lead screw or cross slide.
My small 6mm lathe is kept in the garage and brought into the workshop when needed its already mounted on a box and usually placed on a board which covers the sink to give me extra work space when needed. I don't clamp it as the heavy lamp base is enough to hold it down.
IMG_6848[1].JPG


Philip asked me.

How to cut ball to go on the end of a rod?

Using quite a simple tool simple tool called a radius cutter ideal for doing the tops of domes as well
IMG_6851.JPG

IMG_6850.JPG


Set the cutter in the frame to the correct diameter then line the frame up with the centre line from above and the side of the bar to be cut offer the cutter to the bar and gently twist the cutter round move forward and go again until you have a perfect dome
Obviously the job needs to be done in two halves. Mounting the first half on a rod before doing the second half.

There is another way of doing it with hand tools.
To make a 8mm diameter ball end take a piece of silver steel and drill a 4mm hole in the end face it off square and harden.
To do brass you probably don't need to harden but will want refacing after a short time.
Turn your rod by eye to start with then use the hardened tool pushed against the bar and it will cut the bar to the correct diameter. (I have shown this picture before of a 6mm one I used for cutting an O gauge dome.)
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Jeremy Suter
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Re: Tips and tricks in machine tool practice

Postby Jeremy Suter » Mon Dec 20, 2021 11:10 pm

David Knight wrote:Very helpful Jeremy, a lot of good points and food for thought. Just out of curiosity, if all you had was the Myford what changes would you have made?

Cheers,

David

To do the job in the Myford or any other lathe I would use exactly the same method.
As the flanges are all done I have just posed this picture of the arbour mounted in the Myford Collet
IMG_6827.JPG


As I have not got a collet big enough to hold the tyre to face off the back

Making a ring collet to hold the wheel.
Taking an old piece of steel. It already had a hole in so I have bored out the hole to take the wheel and flange 15.7 mm to a depth of about an inch. And another half inch to 14mm
IMG_6828.JPG

IMG_6830.JPG

IMG_6831.JPG

The hole is now the right size. I need to thin the wall to about 1mm thickness. The hole in the top was already in the bar when I picked it up but will be useful.
IMG_6832.JPG

The next job is to put a slit in it with a .8mm slitting disc in the milling machine.
IMG_6838.JPG

IMG_6839.JPG

Putting it back in the lathe to part off using a pointed cutter to give a tapered end its about a 1.25 inches. giving me a working area of about .25 inch
I will finish the slot with a saw.
IMG_6840.JPG

Putting the new tube back in the lathe the other way round from the way it was originally cut and slotting a piece of 28thou nickel silver sheet in the gap. That's where the hole came in useful to hold the shim with tweezers in the right place.
IMG_6842.JPG

I am going to run the lathe in reverse using this cutter cutting on the on the inside at the rear of the tube until I can slot the wheel in with the flange protruding.
IMG_6834.JPG

I ran a cutter across the rim as well to make sure its square before slotting in the wheel. It's not tight but doesn't fall out.
IMG_6843.JPG

Now taking the nickel spacer out the new tube collet can grip the tyre squarely.
IMG_6844.JPG

Always check and yes it does run square.
IMG_6845.JPG

As with the watch makers version I started in the middle and worked out and in again taking small cuts at a time until the back was level with the flange.
IMG_6846.JPG

IMG_6847.JPG

Last but not least mark which way round it goes I always use the no3 and no1 jaw as the fixed point and scribe a mark on the collet to go between them so it can be used again later.
IMG_6853.JPG

IMG_6855.JPG
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David Knight
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Re: Tips and tricks in machine tool practice

Postby David Knight » Tue Dec 21, 2021 12:22 am

Once again, Thank you Jeremy. Funnily enough I've used a similar technique to make 1 off collets for smaller stock but never thought to apply the same principles to larger bits.

Cheers,

David

Philip Hall
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Re: Tips and tricks in machine tool practice

Postby Philip Hall » Tue Dec 21, 2021 1:13 am

Thanks Jeremy. I looked up your radius cutter on eBay but they were a little more than I wanted to pay for just the one job. Also the shanks of them seemed to be 10mm approx and that is larger than the Unimat SL toolpost will accept. However, your suggested hand turning tool will be just the job, especially as I will be turning acrylic or plastic.

Doug, here are the pictures of my SL on its base:

IMG_1394.JPG


IMG_1397.JPG


It's bolted through the base - a piece of kitchen worktop -which is itself mounted on 'stilts' to raise it up to a comfortable standing height. I've just recently added a bit of extra height. There are strips of thin cork sheet between the lathe and the base, and on the bottom of the 'stilts' to try and cut the noise down a fraction. I'm now in the process of refitting the 70W motor after it came back from repair by an electrical repair company in Maidenhead.

The flat piece of board at the back of the lathe with all the holes in it is used to take all the various lathe tools, centre drills and odd tools I use the most. Other things live in the drawer beneath, which I found in an art shop and is intended for brushes, I think. The lower picture shows a thin plywood cover for the pulleys and belts which I made up by bending, pinning and Gorilla gluing. It just clips in place with a couple of locating pins.

When I finally brought the lathe into use (after owning it for 20 years!) Vincent Worthington kindly did most of the work in setting it up for me. He knows more about lathes than I ever will, and cleaned and serviced it, wired in a new on-off switch (the existing in-line cord switch and cloth lead was frightening!), fitted a new lead screw and made the mounting board and tool board. He also fitted a new Sherline chuck as the Unimat one was well past its best, and I later fitted a new Rohm drill chuck.

It's very heavy, being one of the early ones with the cast iron solid base, so it stays put and doesn't tramp about the bench when it's turned on. The very early ones had a 40W motor, I believe, and I reckon this one is about as old as I am (69) as it has 'Selecta' on the headstock. It does most things I need it to but it would be nice to have something a little more rigid and more powerful maybe, but I can't really justify the expense, and I'm not sure I'd get the full value out of a more modern machine. It is a bit noisy (quieter now the motor has been serviced) but I tend to keep the revs down as if you wind it up it's a bit like having the space shuttle taking off in the back garden.

Philip
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DougN
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Re: Tips and tricks in machine tool practice

Postby DougN » Tue Dec 21, 2021 3:07 am

Thanks to all who have replied to my request on how to mount the lathe, All have merits.

Going through in no particular order:-
The base must be thick and heavy to avoid the machine taking off. Resilient feet and possibly resilient mount to the lathe itself.
Clean up, must be considered. So fitted to a flat surface which a clean able top.
Additional tools - allowance for regularly used tools easily accessible
Storage of additional tools (milling attachment etc.)
Lift the lathe up for ease of use.
Space for a light (up and over) to clip or fit.
Be light enough to move around, maybe handles on the sides so it can be lifted comfortably.

I will keep thinking about this and maybe tinker whilst on holidays.
Doug
Still not doing enough modelling

Terry Bendall
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Re: Tips and tricks in machine tool practice

Postby Terry Bendall » Tue Dec 21, 2021 2:25 pm

DougN wrote:It's very heavy, being one of the early ones with the cast iron solid base, so it stays put and doesn't tramp about the bench when it's turned on


My Cowells lathe is also heavy and I have not found a need to bilt it down. As Jeremy says, sometimes it is useful to be able to move the machine around on the work surface.

If a decision is made to bolt the lathe to a bench or even to a piece of board, it is important to make sure that the surface is flat and not twisted. If the surface does have a twist in it it is possible to dstort the bed of the lathe which will leasd to all sorts of problems and this has ben know to happen to machines of the size of the Myford lathe that Jeremy has. My thought is that if you ned to fix the lather in place bolt it to a piece of good quality plywood or other similar nmaterials that is around 18 - 20mm thick. The board can then be clamped to a work surface if needed.

I have seen Philip's set up and it is very nice. I prefer to use my lathe sitting down which works for me but a couple of years ago I made a drawer to fit under the bench top which stores most of the lathe accessories and this was a useful developement. Fpr larger machines, such as the Myford, using the machine standing up is better.

Some sort of adjustable light is very useful.

Terry Bendall

Enigma
Posts: 533
Joined: Tue Aug 13, 2013 2:49 pm

Re: Tips and tricks in machine tool practice

Postby Enigma » Tue Dec 21, 2021 4:17 pm

I purchased my Cowells around 1980 and it came complete with a sheet steel stand as the photo. It accomodates the motor and switch, is very stable and, when sited on my bench, is at a good height for operating. It is also very useful for 'storing' my most often used tools, drills, bits of brass etc. I have it standing on a heavy bench on a piece of rubber based conveyor belting given to me by a clubmate. The bench also dates back around 40 years and was made from some heavy duty pallet timber (liberated from the 'discard' pile in the company's yard) and a 25mm thick melamine laminate faced desk top (likewise). Heavy and well able to stand the vibrations etc. Not long after this model was on the market Cowells changed to a cast metal base which was 'thinner' but 'I'm glad I got this style as, to me anyway, it is more useful. I have a vintage anglepoise lamp standing behind it for illumination when machining. These days I find I need it more than ever!

Cowells Lathe Dec21.jpg


Sorry about the odd angle of the photo. It was the only way I coul'd get it all in!
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Stephan.wintner
Posts: 109
Joined: Sun Mar 15, 2020 11:04 pm

Re: Tips and tricks in machine tool practice

Postby Stephan.wintner » Thu Dec 23, 2021 11:24 pm

Jeremy, I was thinking about the turning technique below - using a steel rod with a hole to produce a radius. You state that a 4mm diameter hole will produce an 8mm diameter ball end, or 4mm radius.

I'm thinking the resulting surface is actually an elliptical shape, and the chord of the surface would be 4mm. Which works out to approximating a 2.8 mm radius (4 * sin45) - is there something I've overlooked? I assume you hold the steel tool such that the circular edge of the hole contacts the work all around.

Stephan


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