I have a "made for myford" Bernard 130M Griptru chuck that I would like to use. It was screwed loosely together (a sign of something) but appears to be in excellent condition. However, I'm not convinced the pinions fitted are the correct ones as they are not retained. With everything screwed together the pinions could fall/fly out. As is, it is therefore not usable. Or an I being thick somehow? I have no intention of buying original spare pinions if such a thing exists.
- Thread starter 6ply
- Start date
That's what I assumed at first (bearing in mind no pinion retaining screws) but to answer your question, not that I can see.
Agroshield
Member
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That one is a mystery. As Brad says, they are normally retained by a threaded pin intersecting the relieved part surrounding the square key hole.
See:
www.model-engineer.co.uk
However, if you download this:
on page 6 it does not show any pinion retainers in the exploded diagram or the parts list.
In your initial post, you say the pinions 'could' fall out. I agree with your assessment, but with respect, that is somewhat different to them actually flying out.
Is it possible to reassemble, tighten everything up properly and try to pull a pinion out? Whittle down a stick to fit the key hole and superglue it in so you have something to tug on.
See:
Dismantling and Servicing a Grip-Tru Chuck | Model Engineer & Workshop Magazine
The chuck I am dealing with is a 4inch Pratt Burnerd three-jaw, specially made for a Myford ML7 lathe. It is approximately 40 years old so you may find diff ...
www.model-engineer.co.uk
However, if you download this:
on page 6 it does not show any pinion retainers in the exploded diagram or the parts list.
In your initial post, you say the pinions 'could' fall out. I agree with your assessment, but with respect, that is somewhat different to them actually flying out.
Is it possible to reassemble, tighten everything up properly and try to pull a pinion out? Whittle down a stick to fit the key hole and superglue it in so you have something to tug on.
Thanks for the links and suggestions. I already had a look at the Pratt Bernard pdf but the model engineer article was new to me, and seemed to show retaining screws that do not feature on my chuck. I'm going to have another look at it with everything done up tight. I might also try your suggestion on trying to pull one of the pinions out. I'm still not convinced they are the right ones but we'll see.That one is a mystery. As Brad says, they are normally retained by a threaded pin intersecting the relieved part surrounding the square key hole.
See:
Dismantling and Servicing a Grip-Tru Chuck | Model Engineer & Workshop Magazine
The chuck I am dealing with is a 4inch Pratt Burnerd three-jaw, specially made for a Myford ML7 lathe. It is approximately 40 years old so you may find diff ...
However, if you download this:
on page 6 it does not show any pinion retainers in the exploded diagram or the parts list.
In your initial post, you say the pinions 'could' fall out. I agree with your assessment, but with respect, that is somewhat different to them actually flying out.
Is it possible to reassemble, tighten everything up properly and try to pull a pinion out? Whittle down a stick to fit the key hole and superglue it in so you have something to tug on.
Your chuck number also has a pinion retainer listed in the part numbers. Are the parts / jaws stamped with serial numbers?
I think the M after the chuck means it should have a Myford mounting as this:
Burnerd Griptru Chuck 3 Jaw Internal and External Jaws | eBay
<p dir="ltr" style="margin-top:0; margin-bottom:0;">Burnerd Griptru Chuck 3 Jaw Internal and External Jaws. Backplate I think is 8 tpi x 1 1/4". No key. Please check the photos as they are part of the description. </p>
www.ebay.co.uk
Do any marks on the chuck body go over the backplate joint, ie is it the correct backplate
Pete.
Member
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- 14,732
- Location
- Kent, UK
Pull the jaws out and peek inside the bore they go into. see if there is any cross-drilled hole that lines up with the ring mark left by the pinion groove. If not, they simply missed a step in production. Just drill and fit your own.
Page 6 has item 5 pinion pin
Page 6 has item 5 pinion pin
It's a 100mm/4" chuck just in case I haven't mentioned that already.View attachment 385946
Your chuck number also has a pinion retainer listed in the part numbers. Are the parts / jaws stamped with serial numbers?
I think the M after the chuck means it should have a Myford mounting as this:
Burnerd Griptru Chuck 3 Jaw Internal and External Jaws | eBay
<p dir="ltr" style="margin-top:0; margin-bottom:0;">Burnerd Griptru Chuck 3 Jaw Internal and External Jaws. Backplate I think is 8 tpi x 1 1/4". No key. Please check the photos as they are part of the description. </p>www.ebay.co.uk
Do any marks on the chuck body go over the backplate joint, ie is it the correct backplate
The 3 jaws are stamped 117835.
The chuck body is stamped 10232 inside one of the slots and 377 to the rear.
The chuck back is stamped 27332 and 58 on the inside.
The backplate looks correct to me. The pinions less so.
Pete, definitely no cross drilled holes, but I have certainly considered adding some. They take no load, just stop the pinions falling out.
Big box of carefully disorganised junk
