Pratt Burnerd 6 jaw self centering 3 1/4″ Chuck

[Adam HarrisParticipant @adamharris13683]

I have one of these which is not a grip-tru version like the ones Pratt Burnerd currently sell and I wonder how rare or desirable or valuable they are compared to the usual 3 jaw self centering chucks. Since I have never seen another like it I imagine they were not particularly popular or useful. The face of each jaw is rather narrow and it looks somewhat like a claw out of an Alien film – very peculiar! Any comments? A photo is in my library.

[Adam HarrisParticipant @adamharris13683]

[Adam HarrisParticipant @adamharris13683]

3 1/4" diameter (not 3 1/3&quot

[Michael GilliganParticipant @michaelgilligan61133]

Adam,

It looks interesting, but the [grinding] marks on the sloping surface of those jaws don't look up to Burnerd's traditional quality; so I am more than a little puzzled.

Your photo doesn't fully show what I presme to be he model number … do please tell.

MichaelG.

[Adam HarrisParticipant @adamharris13683]

BP79/2803

[Adam HarrisParticipant @adamharris13683]

I suppose 6 jaws would give a better grip than 3 but these jaw faces are almost like knives so i wonder what one would choose to grip with them….

[Adam HarrisParticipant @adamharris13683]

The grinding marks are identical on each jaw and each groove line has a slight curve to it so I can only presume they are original – certainly could not be accidental

[Adam HarrisParticipant @adamharris13683]

Looking more closely I would say these "grinding" marks are more like an engraved pattern possibly to offer finger grip?

[Max ToleranceParticipant @maxtolerance69251]

Probably been used on a drill grinding machine the Brierly company type. I have two of these chucks both made by Pratt Burnerd one is on my brierly and the other is threaded for the J&S 310 T&C grinder.

[Adam HarrisParticipant @adamharris13683]

Hi Max. thanks for that – I see on google the chucks holding the drill bit for grinding on the Brierly type machines do indeed look very similar!

[Michael GilliganParticipant @michaelgilligan61133]

Nice one Max !!

… I had just found this Bison one for comparison.

MichaelG.

.

P.S. Drill Grinding 

That might explain those marks on the Jaws.

Edited By Michael Gilligan on 28/08/2014 21:33:50

[Chris TriceParticipant @christrice43267]

I’ve got a Japanese Hama 4″ version which I use for small bore brass tube. My one is spot on for cocentricity. The down side is no reverse/reversible jaws. I can’t help feeling there is a market for a proper 4″ six jaw chuck. There is one made by an Indian company but I’m not convinced that the quality is there enough for me to pull out the cash.

[MuzzerParticipant @muzzer]

Here's a page from the local tool emporium (in Canada) which shows 2 models. The bottom one has reversible jaws. They are generally for thin wall pipes etc and seem to be more popular in North Merca.

These own brand chucks are generally Chinese or Indian. I was quite temped to get a 6-jaw or possibly a 4-jaw self-centring chuck at one point but a different kind of sense prevailed in the end.

Murray

[Adam HarrisParticipant @adamharris13683]

Michael, I am certain the grooved/engraving marks on the sloping surfaces are there for grip when you reassemble after cleaning – one needs to push all six in when engaging the scroll. I have just done this and can see how it helps. Adam

[Chris TriceParticipant @christrice43267]

This was the conventional 4" six jaw I found.

http://littlemachineshop.com/products/product_view.php?ProductID=2276

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