identifying chuck jaws

[paul 1950Participant @paul1950]

[paul 1950Participant @paul1950]

is there a way of identifying chuck jaws or do i bin them the threads match my pratt burnerd 5" but the slot in the side is not as wide and they are shorter

[Brian WoodParticipant @brianwood45127]

Hello Paul,

Chuck jaws are made in matched sets to suit the chuck they are supplied with. Those look like an inside and outside set for a three jaw self centreing chuck, but they may not even be of Pratt manufacture. The only exception would be for soft jaws without the outer steps, but they will still have to match the scroll pitch and at 1/3 a revolution difference across the set to grip work correctly. Being stepped these are not soft jaws.

If the slot is too narrow there is no way they will even enter you five inch chuck and being shorter too I suspect they originally belonged to a four inch or even three inch chuck.

Sadly I don't think you can use them but rather than bin them offer them on ebay [ suit 3 J chuck, make and size not known] and see what they fetch. You might be surprised

Brian.

[BazyleParticipant @bazyle]

……….being sure to give detailed dimensions for the slot etc, It is amazing how some people give no details at all or just slap a wooden ruler in the general vicinity and think that is good enough.

[paul 1950Participant @paul1950]

I was thinking of putting them on eBay as they are no use to me but knowing what they might fit would help, being shorter makes me also think they are off a smaller chuck. i have bought lots of old lathes in the last few years and forgot which one they were with.

[Brian WoodParticipant @brianwood45127]

Paul,

If you cast about you might even find the chuck they belong to if things have become scattered as you say!.

I echo what Bazyle has added of course, dimensions are all important. Good pictures help too, the stuff I have seen offered with a fuzzy greyish blue picture are legion and frankly of no help at all. Most potential buyers pass quickly on.

Brian

[paul 1950Participant @paul1950]

better photo 2" long 19/32 wide 17/32 slot 1/8 grooves

[Brian WoodParticipant @brianwood45127]

Hello Paul,

The chuck would have had the same numbers stamped on it to match up with the jaw set. Turn that one over and you should find a jaw number 1, 2 or 3 stamped on the other side in the channel. If these all came from the same chuck then the number 247 will be on all six jaws.

That would have fitted a chuck with 1/8 inch pitch scroll. It looks nice and clean too without damage and visually very much like Pratt Bernard origin.

It's a shame they got separated.

Brian

[paul 1950Participant @paul1950]

the external ones are numbered 1 to 3 and are a set with 247 on the others have a no 1 with 57 2 and 3 have 249 on them. i bought a few lathes over a period of time from the same person and all the bits were mixed up the boxford lathe had southbend chucks there were myfords drummonds and a sensca falls star lathe the same one in the photo on http://www.lathes.co.uk/senecafalls/

[Brian WoodParticipant @brianwood45127]

Paul,

I recall your early posting on the subject of chuck fitting between these lathes with the same nominal pitch but cut as UNC on Southbend and BSW on Boxford. They almost fit for a few turns until the mismatch in thread pitch angle locks up.

Something of a problem for you there and always a risk you take in buying from someone who heaves everything into a box without regard.

I hope you were able to get over that satisfactorily. As for these jaws, sell them on with the best description and good pictures you can muster. At least the outside set is a matched trio, the others certainly aren't

Brian

[Mike PooleParticipant @mikepoole82104]

follow this link for some info on common jaw sizes.

Mike

[Swarf, Mostly!Participant @swarfmostly]

Hi there, Paul,

If you're going to sell these jaws on eBay or elsewhere, I suggest that you do the following:

Press the threaded side of one of the jaws onto one of the old-fashioned ink pads or anoint it using a free-flowing felt-tip pen or even using engineers' blue and then press it on to a sheet of plain white paper. Add a few principal dimensions using pencil and ruler and then scan or photograph the result. Include the scan or photo with whatever other description/depiction you list.

This will complement the dimensions of the jaw thickness and groove width & depth and will give any prospective buyers a better idea whether your jaws will match their chuck or not.

Best regards,

Swarf, Mostly!

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