Some help needed with lathe

This topic has 30 replies, 11 voices, and was last updated 2 November 2013 at 19:03 by Victor francis.

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1 November 2013 at 01:42 #134296
Victor francis
Participant
@victorfrancis52958
Hello Everyone,

This is my first post so aplogies if it's in the wrong section.

I have recently bought a tiny lathe which looks to be homemade, but fairly well.

The lathe came with a dead centre but no drilling attachment in the tailstock, it takes 8mm collets. so, I bought an 8mm arbor with JTO taper and a small chuck, but the arbor will not screw in my drawbar,

The arbor has a M7 thread, my dead centre thread is 4/16, even the top taper appears to be wider. I did ask the seller whether it would fit my lathe, but there you go.

I would really appreciate the help, finding out what arbor I actually need has been near impossibe as none of the collets decribed online seems to have a 4/16 thread,

By the way, the lathe looks to be made in the 1950s in the UK, with backgears and screwcutting ability.

Thank you in advance.

Regards,

Victor,
Advert

1 November 2013 at 01:42 #6940
Victor francis
Participant
@victorfrancis52958
1 November 2013 at 07:43 #134298
Michael Gilligan
Participant
@michaelgilligan61133
Welcome, Victor,

It would be very helpful if you could post some pictures of the lathe.

… Perhaps someone will recognise it.

MichaelG.
1 November 2013 at 07:49 #134299
JC Uknz 1
Participant
@jcuknz1
Where are you?

4/16 sounds vaguely American to me

A good photo of the lathe could help people give you answers..
1 November 2013 at 09:37 #134305
Lambton
Participant
@lambton
Victor,

The threads on the ends of 8mm collets are many and variable. Have a look at pages 3.5 &3.6 in Tubal Cain's Model Engineers Handbook or do an online search for data on 8mm collets.

I can find no reference to any screw thread designated 4/16.

I suggest you find out what 8mm collets are most commonly available and make a new draw bar to suit. I do not think you will have any luck finding collets to suit your non standard draw bar.

Eric
1 November 2013 at 11:00 #134311
roy entwistle
Participant
@royentwistle24699
Victor It sounds as if it could be a watchmakers lathe 8mm collets usually have a 0.268 inch diameter x 40 tip or sometimes 0,625mm pitch You may pick some up if you have a clock fair near you anytime Cowells have supplied me with dawbars in the past A photo would help or more information ie doe's it have a compound slide or a hand turning rest

Best of luck

Roy
1 November 2013 at 11:26 #134317
Ian S C
Participant
@iansc
I think by 4/16, he actually means 1/4", Made in the UK, in the 1950s, it's probably either BSF, or Whitworth, so either 26 tpi, or 20 tpi, I would say it would be unlikely to be 0 BA, but then again it might be. Ian S C
1 November 2013 at 17:25 #134349
Victor francis
Participant
@victorfrancis52958
Hello,

Thank you to all for the suggestions, and for you welcome. My apologies for the newby questions, I am an artist and have worked with metal all my life but I beat it into shape, rather than use machines.

I have taken some photos of the lathe, but it seems to be a homemade job so this is the main problem!

Nevertheless, it is a beautiful little machine, I honestly feel it is worth the effort, even just out of respect for the chap who put so much work into making it. It was in an awful state when it came to me having being neglected by its new owner for many years.

The headstock spindle is threaded but can also take collets, bearings are phosphor bronze conicals, The machine itself is made from fabricated steel..

The reason for buying something so small is lack of space, The bed measures 12.5".

The width of the top of the collet is also different than what RDG sales a standard, Mine is wider and appears to be different .

Yes, I am pretty sure the theaded part on my dead centre is 4/16, the RDG is M7, just spoke to someone from RDG who tells me they only stock that thread for 8mm lathes.

I did think that making a new drawbar would be the solution,problem is that the RDG arbor's top is slimmer than mine so it has a fair bit of play.

By the way, I was told that the lathe is able to screw cut, but it has no reverse so again I am a bit lost.

Could someone advse me on how to post photos here? Thanks again for all your advice, it is much appreciated.

Kind regards,

Victor.
1 November 2013 at 17:37 #134350
Les Jones 1
Participant
@lesjones1
Hi Victor,
Have a look at these two threads.

Posting pictures.
Posting pictures 2

Les.

Edited By Les Jones 1 on 01/11/2013 17:37:50

Edited By Les Jones 1 on 01/11/2013 17:38:45
1 November 2013 at 17:44 #134353
Victor francis
Participant
@victorfrancis52958
Hello Les,

Thank you fro the links, I shall have a look at them.

I have managed to upload some photos, it was very easy and user friendly. Very impressed.
1 November 2013 at 18:09 #134356
Michael Gilligan
Participant
@michaelgilligan61133
That's a nice looking little lathe, Victor

Do you have any collets or other fittings apart from that rather unusual-looking centre?

If yes … please measure them as carefully as you can, and let us know.

If no … put the centre in a box and forget about it … then start buying collets [all the same type if at all possible] from ebay, or wherever.

When you are comfortable using the lathe; modify the taper if you need to, and make a new drawbar to suit what you have bought.

It looks well-worth the effort !!

MichaelG.

.

Edit: This is the sort of advert you want to see.

Edited By Michael Gilligan on 01/11/2013 18:10:24

Edited By Michael Gilligan on 01/11/2013 18:14:45
1 November 2013 at 18:51 #134362
Victor francis
Participant
@victorfrancis52958
Thank you, Michael.

Yes, I also think that it's worth the effort. Just need a suitable arbor for the tailstock and it will do for the wee jobs I have in mind.

Buying collets from the bay and making a new drawbar is probably the only solution. Thing is that the headstock spindle also accepts the same collets as the tailstock, so I really wanted to try finding out exactly what type of collets I need before modifyng the tailstock.

The top of the RDG collet measures 12mm, my dead centre 4/8. The RDG arbor feels as it may have too much play, even if I made a drawbar for it. Bummer, I waited three months for the arbor and chuck to become available on ebayuk.

I know nothing about the lathe's history, it was bought in the UK but this does not guarantee it was made here.

Regards,

Victor.
1 November 2013 at 20:09 #134365
Michael Gilligan
Participant
@michaelgilligan61133
Posted by Victor francis on 01/11/2013 18:51:46:

The top of the RDG collet measures 12mm, my dead centre 4/8. The RDG arbor feels as it may have too much play, even if I made a drawbar for it.

.

Victor,

I don't think there is any need to worry about the major diameter … it's the angle of the cone that really matters.

But, could you please measure the shank diameter of both the arbor and the dead centre.

Something close to 8mm would be useful.

MichaelG.
1 November 2013 at 20:19 #134366
Victor francis
Participant
@victorfrancis52958
Hello Michael.

The diameters of the dead centre's shank and the RDG arbor are both exactly 8mm. The angle of the cone is greater as it is the same length as the RDG's but wider on top. This is why it will not sit tightly in my headstock collet holder.

Kind regards,

Victor.

Edited By Victor francis on 01/11/2013 20:21:58
1 November 2013 at 21:30 #134367
Michael Gilligan
Participant
@michaelgilligan61133
Posted by Victor francis on 01/11/2013 20:19:32:

Hello Michael.

The diameters of the dead centre's shank and the RDG arbor are both exactly 8mm. The angle of the cone is greater as it is the same length as the RDG's but wider on top. This is why it will not sit tightly in my headstock collet holder.

Kind regards,

Victor.

Edited By Victor francis on 01/11/2013 20:21:58

.

My apologies, Victor; I mis-understood

If it's the Angle that differs, then you will almost certainly need to re-machine to fit commonly available collets.

Almost all have 40° angle; but you might find this table interesting, as it includes a few oddities.

Best of luck

MichaelG.

.

Note: The table shows "Half Angle"

Edited By Michael Gilligan on 01/11/2013 21:31:36

Edited By Michael Gilligan on 01/11/2013 21:33:40
1 November 2013 at 22:30 #134371
JohnF
Participant
@johnf59703
Hello Victor, It would be nice to know where you live ? However it is indeed a nice looking lathe and obviously made by someone with considerable skill.

Personally I would guard against altering the spindle, it may be hardened, have you tested for this? I would only consider alteration as a last resort. Its most likely that the maker will have used a standard taper and thread -might now be obsolete but check first.

First I would ascertain the specification of the taper and thread on your centre which I assume is an original part? To do this access to either a shadow graph or toolmakers microscope would be helpful — maybe a local engineering shop would help you with this.

The 4/16 thread is of course a 1/4" [0.250"] as Ian has already pointed out, do you have a thread pitch gauge or can you compare it to other threaded items you have of known pitch — taps, screws etc the diameter of which does not matter, you are only interested in the pitch of the thread. If you can get access to to microscope or shadow graph then you will be able to check the thread angle as well.

Another possibility is a USB digital microscope, I have no experience with these units but I'm sure other members have and will advise.

Screwcutting – another subject but but you don't need reverse to cut threads but you would need a complete set of change gears. There does not appear to be a chasing dial but one could be fitted. More information on the machine will be needed to advise on this subject.

Regards John.
1 November 2013 at 22:36 #134372
Victor francis
Participant
@victorfrancis52958
Thanks,Michael, I shall have a look at the sheet. Meanwhile, if anyone has any further advice it will be greatly appreciated.

If most of the collets have a 40 degree agle, then I will definitely have issues getting something ready made .

My best option would be to get something made. My skills are still not good enough to make something myself but I do have family in Scotland who run an engineering plant, ex Rolls Royce engineers, so they should be able to sort something out.

Time to buy a good quality caliper and measure my dead centre properly.

Regards,

Victor.
1 November 2013 at 22:58 #134373
Victor francis
Participant
@victorfrancis52958
Hello John,

I reside in London UK. Yes, the headstock spindle is hardened, the tailstock spindle appears to be softer.

Most of my tools consist of hammers,will have to get a thread gauge and a good quality caliper. I sometimes do work for a studio that employes a skilled engineer,will have to get him to check the thread and exact angle of the cone. I assume that the chap who initially made the lathe used a a ready made headstock spindle and bearings and tailstock collet holder. However, I am not sure, he may have made every single part himself.

By the way, there is no keyway in the dead centre.

You are right, there is no thread indicator and the only gears I have are those you see in the photograph. There are also no calibration marks on any of the parts,except on the crosslide where some engraved lines are present.

I have tried chucking the dead centre in and copying its angle , with a bit of practice I should be able to eventually get the taper right.

It's a nice little machine but most certainly built by someone experienced enough to not need calibration marks.

I have already stripped and cleaned everything, so I am fairly confident in taking it apart. When it came to me it was in a very neglected state.

Regards,

Victor.
2 November 2013 at 10:17 #134390
Sub Mandrel
Participant
@submandrel
A very nice machine, Victor.

Worth persevering with. Whoever made it would have been quite capable of making their own collets, so you may not find commercial ones that fit. Check your personal messages as can send you some information on collet sizes.

Neil
2 November 2013 at 10:46 #134393
Bazyle
Participant
@bazyle
I think your lathe was built by a machinist using his work lathe and 'spare' material from work hence the big round feet and many design aspects copied from larger lathes that a pure amateur would have not bothered with in needing to get a working lathe as easily as possible.
You may have enough gears to turn at least the common threads. There are free computer programs that calculate the setup for whatever gears you happen to have. On this aspect in case you want extra gears you need to know the 'diametrical pitch' of the gears. That is the number of teeth on a gear divided by the diameter in inches – expect a roughly round figure like 18 or 20.

There are so many Model engineering clubs in London you can probably find one in walking distance. You wouldn't have to join to go along to a meeting and get some one to one discussion about any problems we can't sort out here.
2 November 2013 at 11:38 #134404
roy entwistle
Participant
@royentwistle24699
I think we're back to standard watchmakers collets ie 0.268 dia x 40 tpi judging by the photo

Roy
2 November 2013 at 11:48 #134406
Victor francis
Participant
@victorfrancis52958
Hello Neil, thank you for your kind offer, you have a PM.

Bazyle, yes, I have seen the programs you speak of. I intend familiarizing myself with them and eventually to be able to cut some threads! One of the strangest things about the lathe are the feet, they appear to be the only item on the machine which has been cast. They are made from an alloy.

At some point I intend getting the bed reground, there are a couple of dings and the carriage is a bit stiff towards the middle of the bed. At this moment I am stilll learning.

I initially thought that the chap who made the lathe had used a "off the shelf" headstock bearings and spindle and tailstock collet holder and merely built a machine around them. Now I suspect he may have in fact made everything from scratch, very impressive.

I am assuming he made a wider angle on the collets in order to improve precision. The four jaw chuck you see on the machine is an Adept but looks as if he might have modified the thread to fit the lathe's spindle.

My intention is to keep the lathe and get some tooling made for it. The carriage had a lot of tooling marks made by the milling bit. So, although the machine is nicely made, it looks as if it was very much made as a functional item rather than just a study piece. I have been slowly scraping the marks in order to bring out the metal's sheen.

Thanks again to everyone who has kindly offered advice. Next on the list is understanding how to cut a thread on a machine with no reverse.

Kind regards,

Victor.
2 November 2013 at 12:01 #134408
Victor francis
Participant
@victorfrancis52958
Hello Roy, are you referring to the diameter of the threaded part? I am not sure abot the thread but its diameter is1/4.

I will take the dead centre to be properly measured on Monday, hoping that this will be enough for my uncle to understand via email and make me a suitable arbor. Unfortunately, the caliper I have here leaves a lot to be desired.

Kind regards,

Victor.
2 November 2013 at 12:06 #134410
Steve Withnell
Participant
@stevewithnell34426
I'm with Bazyle, I think this was made in the toolroom as "lunchtime" job. So wouldn't assume anything about anything thread wise. Lovely piece of kit by the way.

Steve
2 November 2013 at 12:17 #134413
Victor francis
Participant
@victorfrancis52958
Thanks, Steve. You are probably both right, made by a machinist in his spare time. That would explain why he didn't spend too much time on details like removing the tooling marks from the carriage.

Kind regards,

Victor.
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