Looking to get a 6-jaw for my PM1236

[coolidge]

Would just removing 3 jaws from the 6 jaw Bison Set Tru give you the best of both a 3 jaw and 6 jaw in a single chuck? Also does anyone know the smallest diameter stock a 6" and 8" diameter Bison 6 jaw will hold?

 

[darkzero]

Would just removing 3 jaws from the 6 jaw Bison Set Tru give you the best of both a 3 jaw and 6 jaw in a single chuck? Also does anyone know the smallest diameter stock a 6" and 8" diameter Bison 6 jaw will hold?

Yes & more likely no. The jaws are much narrower than a 3-jaw chuck. Occasional use with 3-jaws may be fine but I never do this. Overtime you may get uneven wear vs the used & unused jaws.

IIRC .312" is listed as the min range on both the 6" & 8". When I need to work on diameters smaller & don't want to swap out chucks, I use collets in the chuck (if I can).

 

[coolidge]

As much as I wanted to buy a really cool chuck all attempts at defying darkzero's logic have failed. After this last round of Bison research here are a few points in favor of the various things darkzero has said.

1. The 6 jaw is out of the running, I have several alternatives that would give me the same features. I can't see buying a 6 jaw unless I was doing a large production run of something I really need a 6 jaw for to save time.

2. I took another look at the 4 jaw combination chuck, great 'idea' but I can find no information on how accurate it repeats plus Bison doesn't even have a technical sheet on their site for it and appears to have abandoned the forged steel version altogether.

3. 8 inch vs 6 inch. Well reality set in quickly (Coolidge is about to get an attitude and buy a big ass used Mori) the G4003G swing over the cross slide is only 7.5 inches, 7.6 if you push it. That's not even enough to clear the 6 inch 3 jaw set tru Bison, its max swing is 8 inches and the 8 inch chuck max swing is 9.65 inches. For safety alone I would opt for the 6 inch Bison even then I will have to be mindful of putting the cross slide into the chuck.

Darkzero do you have the OD of the 6 inch six jaw? Bison only lists the max swing I'm guessing with the jaws adjusted all the way out but what's the OD of the chuck body if the jaws are inside of that OD.

 

[coolidge]

MSC is having an up to 40% off metal working sale right now...I selected the Bison Set Tru 6 inch chuck and D1-5 back plate, plugged in the code and got 35% off, the MSC price is $113 less than Enco with a 20% off sale and $115 less than NEBT. :thinking: MSC sales tax will eat up about $70 of that savings though.

 

[darkzero]

As much as I wanted to buy a really cool chuck all attempts at defying darkzero's logic have failed. After this last round of Bison research here are a few points in favor of the various things darkzero has said.

1. The 6 jaw is out of the running, I have several alternatives that would give me the same features. I can't see buying a 6 jaw unless I was doing a large production run of something I really need a 6 jaw for to save time.

2. I took another look at the 4 jaw combination chuck, great 'idea' but I can find no information on how accurate it repeats plus Bison doesn't even have a technical sheet on their site for it and appears to have abandoned the forged steel version altogether.

3. 8 inch vs 6 inch. Well reality set in quickly (Coolidge is about to get an attitude and buy a big ass used Mori) the G4003G swing over the cross slide is only 7.5 inches, 7.6 if you push it. That's not even enough to clear the 6 inch 3 jaw set tru Bison, its max swing is 8 inches and the 8 inch chuck max swing is 9.65 inches. For safety alone I would opt for the 6 inch Bison even then I will have to be mindful of putting the cross slide into the chuck.

Darkzero do you have the OD of the 6 inch six jaw? Bison only lists the max swing I'm guessing with the jaws adjusted all the way out but what's the OD of the chuck body if the jaws are inside of that OD.

When I got my PM1236 & was chuck shopping, I was very close to buying an 8" Pratt Burnerd 6-Jaw Setrite chuck for a great deal. IMO Pratt Burnerd chucks are nicer than Bison chucks but they cost much more. I had a hard time finding the back plate for it & it was expensive as hell. Probably even more expensive now.

If you look at JayBob's pic above, it's showing the stock 3-jaw, look how close the jaw is to the chuck shield. I had a good feeling an 8" scroll chuck (3-jaw or 6-jaw) would hit that. Irrelavent now as I took that dreaded shield off. It really annoyed me.

I think an 8" scroll chuck would clear the ways with the jaws fully extended, if it was a true 8" chuck (see below). Did you mean clear the ways or clear the cross slide? Ways is most important, clearing cross slide doesn't bother me much. The body of 6.25" chuck will clear the cross slide but an 8" won't. Doesn't matter to me cause there's rare a need for the cross slide to fit under the chuck, the compound slide would get in the way first during machining.

------------

Lots of variances on chuck sizes between manufacturers, especially in the 6-8" range, so you have to look closely. To answer you question, Bison lists Set-Tru 6" chucks as 6-1/4". But they're actually 160mm (body OD), which is more like 6.3" (made in Poland...metric system). Bison's 8" Set-Tru chucks are 200mm, which is 7.87".

The 6" 3-jaw that came with my lathe is 160mm (5.9"). Now my 6" super spacer came with a 165mm chuck, that's like 6.5". No where can I find that states the 6" super spacer came with a 6.5" chuck, it's the same SS as the PhaseII.

Now we turn to Fuerda (Gator chucks). Bison Set-Tru chucks only come in forged (full steel boidies). Gator adjustable chucks come in both semi-steel & full steel. So their less expensive semi-steel chucks (EA seires), their 6" is a 6.0" chuck (my guess is 160mm). Their 8" chuck is 8.25" (probably 210mm). Now their more expensive PA series (Tech-Tru, full steel) their 6-1/4" is 6.3" & their 8" is 7.87", just like Bison.

So when you see 6" & 8", pay close attention to see if it's actually 5.9", 6.3", 7.87" or 8.25". Sorry for the long post, just wanted to point that out cause if you got an actual 8.25" when you were expecting to get an 8" may cause you grief.

 

[darkzero]

Last post was way too long already, on to the 4-jaw scroll chuck, aka combo chuck. Doesn't seem to be that popular but when I was looking at them back when I was chuck shopping, it seems those who do have them like them a a lot. Still not a replacement for an independent 4-jaw as it can't hold irregular work or rectangles. Like the 6-jaw, the 4-jaw scroll is another specialty chuck. If you work with square stock a lot, then it's very convenient & still grips round stock fine.

I'm assuming you are looking at the Set-Tru version. For any adjustable chuck (whatever each manufacturer calls their own, Set-Tru, Adjust-Tru, Set-Rite, Tech-Tru, etc.), low TIR is guaranteed around 1/2 to 2 tenths of a thou. They do repeat very well & is one of the reasons why I don't need to use collets much (I only use collets when I need the safety of now chuck jaws). But if you dial in the chuck for low TIR using a 1" test bar, then it's really only good for working on that diameter. So if you dial in at 1", you may not get the same low run out holding 2" stock. Make sense? Well run out would still be pretty low though.

I have Thomson linear shafting that I use for indicating runout in 1" & 1.5" diameters. So if & when it matters, I'll dial in my chuck at 1" when I know I will be doing a lot of work at 1" or at 1.5" using the 1.5" bar, yada yada. I'm just a home shop hobby dude, so it really doesn't matter but it doesn't hurt to practice being more precise, or at least trying to. I dialed it in with 1" & it been like for the past 6 months.

 

[tmarks11]

....the G4003G swing over the cross slide is only 7.5 inches, 7.6 if you push it. That's not even enough to clear the 6 inch 3 jaw set tru Bison, its max swing is 8 inches and the 8 inch chuck max swing is 9.65 inches. For safety alone I would opt for the 6 inch Bison even then I will have to be mindful of putting the cross slide into the chuck.

With the normal positioning of my compound slide (either 90 degrees to the cross slide, or 30 degrees to the cross slide) and my QCTP, the chuck WILL hit the QCTP and/or compound before it hits the cross slide. I would have no safety concerns about an 8" chuck impacting the cross slide (I do however worry about the compound with every cut...)

Your G4003G came with an 8" 4 jaw chuck, as does almost every 12x36 lathe.

 

[darkzero]

MSC is having an up to 40% off metal working sale right now...I selected the Bison Set Tru 6 inch chuck and D1-5 back plate, plugged in the code and got 35% off, the MSC price is $113 less than Enco with a 20% off sale and $115 less than NEBT. :thinking: MSC sales tax will eat up about $70 of that savings though.

Check with Ajax tools. They're on ebay & he usually lists them with the combo deal for the chuck & your choice of back plate. I got both my Bison & Gator chuck from them. They'll be dropped shipped directly from the distributor. Prices have gone up since but he still has great prices

Matt at QMT also carries Bison now. Last I looked his prices on ebay were even cheaper than Ajax. Same thing, listings for chuck & backplate together.

I don't know what's up with Enco, their Bison prices seem way higher than others. Wasn't like that before.

 

[gspen60676@aol.com]

I have a 6 jaw Bison and that's all I have used. If there is a problem with them I'm nevercome across that or any other problem. I like having 6 jaw rather then 3 for holdingmaterial. Patrick

 

[darkzero]

MSC is having an up to 40% off metal working sale right now...I selected the Bison Set Tru 6 inch chuck and D1-5 back plate, plugged in the code and got 35% off, the MSC price is $113 less than Enco with a 20% off sale and $115 less than NEBT. :thinking: MSC sales tax will eat up about $70 of that savings though.

Sooooo, did you buy it yet? ondering: