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DIN 55027 / ISO 702/III / BS4442 bayonet lathe spingle question

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Rainbows27/07/2016 01:31:32
641 forum posts
182 photos

Anyone have a lathe with the fitting described here or here?

I am trying to work out how the standard works out in terms of the driving stud.

There is the 4 piece bolt circle for the studs and common sense would say the driving stud is in the middle of two of the studs. However the pdf graphics makes it appear like the stud is closer to one stud than the other.

Just thought I would check if anyone here knew to confirm it.

Perko727/07/2016 04:25:25
344 forum posts
24 photos

That looks a bit like the chuck mounting on my Sieg C6. It has three driving studs which are attached to the chuck backplate and are inserted through holes in the mounting flange on the spindle. There is a rotating plate behind that with bayonet-style holes which engage with the driving studs, and then held in place by nuts on the threaded end of the studs. Sounds more complicated than it is, harder to describe too. Mine is a 5" chuck and only has three drive studs, but i imagine the larger sizes would have more. The drive studs and the bolts holding the flange to the spindle all seem to be evenly spaced.

Don't know if that helps at all.

Geoff P

Thor27/07/2016 06:13:10
1259 forum posts
39 photos

Yes Rainbows, it looks like it is closer to one stud than the other. I have not noticed that before, most larger lathes I have been in contact with uses a Camlock spindle nose. As Geoff says, Sieg C6 has a bayonet fixing with 3 driving studs, but unfortunately the spigot is cylindrical and not tapered as the DIN 55027.


JasonB27/07/2016 07:34:13
18609 forum posts
2047 photos
1 articles

I had an Emco 8.6 that used a modified version of the Din mounting. Just the short taper and 3 threaded studs in the chuck, no drive stud needed. Fix with three loose nuts and washers from the back which for out ME size machines is adequate.

Its a very tight tolerance on the taper as you want it to be fully seated as the back of the chuck touches the rear flange, too little and it won't self ctr on the taper, too much and it will get stuck.

David Jupp27/07/2016 07:52:24
737 forum posts
17 photos

Does this help?


For full details - join a major library so you can view the vast majority of BS online collection for free.

John McNamara27/07/2016 09:37:27
1313 forum posts
113 photos

Hi Rainbows

My Heidenreich and Harbeck lathe has a Din 55027 size 6 spindle nose.

The taper and face dimensions are the same as a similar size Camlock spindle nose, the difference is there are no cams the chuck is bolted to the face. Note the dark (knurled) ring on the back face, it can be rotated a few degrees, this presents holes and slots that are milled in the ring, "keyholes" that allow the chuck fitted with posts that have a smaller diameter threaded section with a nut pass through the ring. the ring is then rotated capturing the nut. The nuts can then be tightened with a spanner.

The process is a little slower than rotating keylock cams, on the other hand it is extremely stiff. My lathe does not and never did have the driving stud, the 4 M12 studs are more than enough to hold the chuck fast on the taper and face. Far more securely than a Camlock.

For a 6 inch chuck surely 3 firmly tightened bolts would be fine.

A few images below that include measurements.



John Stevenson27/07/2016 09:54:00
5068 forum posts
3 photos

Two of my lathes have what is usually referred to as the 'A Series '


Yes the driving dowel is offset but as it's also held by 4 studs it's a bit overkill.

As John says in the post above the full sized versions have the same taper as the 'D Series ' but fixed studs into the chuck on the back.

They also have the 'keyhole' plate which allows you to offer the chuck up with nuts on the studs, rotate the keyhole plate and nip the nuts up.

Many don't realise you can fit them with the nuts on and then just nip up.


Personally I think they are quick, I can swap chucks on my machines faster than the camlocks.

Another advantage is it's positive, tight is tight and no looking at lining up arrows or going round a second time.

They cannot come undone under severe interrupted cuts like camlocks can and often do

Edited By John Stevenson on 27/07/2016 09:54:57

Rainbows27/07/2016 12:39:47
641 forum posts
182 photos

Who is good at russian?

Also what are those little studs eqaully spaced between the stud holes? I could see them on other images and they looked like cap head bolts

Based off the russian standards I need to make the keyholes longer but otherswise I mostly got the idea of it I think.

Bodger Brian27/07/2016 13:41:01
177 forum posts
40 photos
Posted by Rainbows on 27/07/2016 12:39:47:


Who is good at russian?

I have a Lithuanian colleague here at work who should be able to translate, although I think it would be a bit much to ask him to translate the whole document. Any particular bit you're interested in?


Edited By Bodger Brian on 27/07/2016 13:41:22

David Jupp27/07/2016 13:56:33
737 forum posts
17 photos

The 2 'little studs' are shown in the standard as counterbored holes (presumably to take cap head screws with a little clearance - I guess these would go through the obround slots in the bayonet ring to allow it to be held in place behind the spindle nose).  [edit - or maybe they limit rotation of bayonet disc].

Edited By David Jupp on 27/07/2016 14:04:33

John McNamara27/07/2016 14:07:54
1313 forum posts
113 photos

Hi Rainbows

I just opened the Russian document, right clicked in Google chrome and translated it to English, the translation was rather good.

The level of detail and tolerance specifications are excellent.

I kept a translated printout.


Rainbows27/07/2016 15:40:49
641 forum posts
182 photos

Ok I originally found it on mobile. Opened it on my laptop and got it all. Originally I thought it might have been saved all as an image so it would have been an ache trying to copy it into text to put into a translator.

Thanks for the lithunian offer though.

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