# 8" Bison 4 Jaw Combination Chuck



## Alan H.

I just bought an 8” Bison 4 Jaw Combination chuck for use on my PM1340GT.  

I know there are members here that own and use this chuck.   

While this chuck has been discussed in a few snippets here and there in other threads, I don’t believe there is a thread focused on it.  So I wanted to start one to hopefully collect insights in one spot for folks who may find it helpful.  _(I believe there are four other members here who just ordered this chuck and will be receiving them in the next few days.)_

So to get us started:

*1.      What are the pros and cons of this chuck?  *

*2.      Can you offer any advice for a new user for this specific chuck?* 

Here are some photos of my chuck out of the box, cleaned up and ready to go:


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## 4GSR

Nice!

Sent from my SAMSUNG-SM-G920A using Tapatalk


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## ddickey

Nice, D1-4 mount?


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## Firestopper

Hi Alan,
Great chuck! Mark (mksj) turned me on to an extra one (NIB) he had. I machined my own mounting plate and its dead on. You'll want to make two mini T-handles with magnets for quick work in dialing in pieces. Mark gifted me his originals and I love them. Once you play with it some, you'll be able to dial in in under three-four minutes. I always register my chucks to my spindle with a small center punch mark prior to removing the turned mounting plate. The repeatability on these chucks are phenomenal.  The only cons I have is swarf fouling during boring operation and the added weight but thats the nature of the beast.

Registering the back plate


Running true.


Between this chuck and the 5C system, I have not used the three jaw since.

The two low profile T-handles allow for complete rotation while the small inset magnets hold them in place. 


Its an amazing chuck that brings machining  tolerances fast and easy when removing/reinstalling your work piece for second operations. 

It holds the work well without over torquing.


I'm sure Mark will chime in on the details of the mini T's and magnets.

Money well spent in time saving  and end results.
I hope this helps


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## Alan H.

ddickey said:


> Nice, D1-4 mount?


Yes - fits the PM1340G lathe.  The adapter plate is a model 7-878-084F which is a newer model number.


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## ddickey

Alan H said:


> Yes - fits the PM1340G lathe.  The adapter plate is a model 7-878-084F which is a newer model number.


Okay, I was thinking maybe it was a direct mount.


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## Alan H.

I checked the runout of the face of the Bison adapter plate on the lathe.   I used a B&S Valueline that I keep handy - no runout.  Swapped to a Starrett .0001" indicator - not really anything detectable other than some surface finish vibes.   I am quite pleased.   

I must say that I am also pleased with the PM1340GT spindle!


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## Bamban

I have one coming, it must have been the last one in their inventory at that sale price Mark alerted me on.

When I get mine all checked out I will verify its merit on barrel work and let you guys know. I have an 8 inch 6J Bison set thru I can compare it with. If it proves to be better than the set thru chuck, the set thru will be up for sale. If not this combo chuck will be up for sale.


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## Bamban

Mark,

I am definitely interested in seeing details of the mini wrenches. When I needed to use the 4J on the Jet 1024, I took the lazy route and bought T handled Allen wrenches from eBay and cut them to fit. I dont think I will use the same Bubba solution on this nice combination chuck.


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## mksj

Chuck keys for independent jaws are made from 3/4" drill rod and are 1.85" in overall length. The T bar is 7" and held in with a set screw, the back is drilled to make them lighter. The key tip has a small Neodymium magnet that holds it in the chuck so you can rotate the chuck and not have the keys fall out.




Like firestopper/Paco, the Bison combo chucks is only second to my 5C as far as use on the lathe. I have a nice 3J Set-Tru 6" PBA, but rarely use it. I prefer the 4J combo for most work, and usually it is very quick to dial in a part, the scroll portion will repeat as well as most chucks (usually better than 0.002"). Since you can tweak the pressure on all 4 jaws, I find it holds stock very well.


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## ddickey

What's MKSJ?


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## Dave Paine

ddickey said:


> What's MKSJ?



Not a "what", rather a "who", forum member name is MKSJ.


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## Alan H.

ddickey said:


> What's MKSJ?


That would be Mark, the builder of many of the variable speed control systems on the PM1340GT lathes, mine included.  He is a an electrical controls wizard plus he knows a lot about this hobby of ours!

EDIT: should have said that he's also built controls for lots of other lathes, mills, and machine tools in addition to the PM1340's.


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## Alan H.

Mark and Paco, how do you gents handle this little chuck?  It is a bit heavy isn't it?   Did you build a sled to help mount it or do you simply mule it on there?


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## mksj

Most of the time, two hands, preferably dry, not too old yet that I can't pick it up and get it in place. I have a padded insert block that locks  in position on top of the ways,  I use it whenever I am changing chucks. Just for safety, as the chucks can slip. I mark my chucks so they always go in in the same position, I have the key in the top cam-lock, so I hold the chuck in place with one hand and lock one pin with the other. David Best made a very nice chuck holding sled that fits on his ways, probably a better way to go.


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## Alan H.

mksj said:


> Chuck keys for independent jaws are made from 3/4" drill rod and are 1.85" in overall length. The T bar is 7" and held in with a set screw, the back is drilled to make them lighter. The key tip has a small Neodymium magnet that holds it in the chuck so you can rotate the chuck and not have the keys fall out.
> View attachment 241779
> View attachment 241780
> 
> 
> . . . . . . . . . . . .


Mark, what diameter is the T bar - 1/4"?


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## Firestopper

I do the same as Mark. I took a piece of 3/4" plywood, cut it to cover the ways and brad nailed to rail strips that index snugly to the inside portion of the bed ways. It also can double as a platform for tooling when used behind the tail stock. The Bison is hefty, but not that bad for me yet. I like what David Best shared sometime back for his solution as well.  I should do the same before long.
I also index all my chucks to the spindle (center punch).
David Best's solution is the "best"


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## mksj

Alan H said:


> Mark, what diameter is the T bar - 1/4"?


Yes, 1/4" drill rod. Balance of weight and strength on the T bar. David's chuck carriers are the slickest, but I am already space limited, and I would need a place for the chuck carriers.


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## wildo

Alan H said:


> I just bought an 8” Bison 4 Jaw *Combination* chuck for use on my PM1340GT.



OK- am I being dense here?? What is a "combination" chuck when it relates to a 4 jaw? I have a Bison 3 jaw 6" adjust true chuck, which is what I think of when I think of a combo chuck. The "adjust true" part of it is basically a built in 4 jaw for centering the 3 jaw. But on a 4 jaw chuck... what is the combination? Sorry if that's an obvious question...


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## Alan H.

I have been using a board to protect the ways when changing chucks.  I can "mule" this new one on there but it weighs enough that I decided I did want a sled to make it easier.  Made one last night out of maple, sealed it with spar varnish, and it works fine, although it is not to David's standards!


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## Alan H.

wildo said:


> OK- am I being dense here?? What is a "combination" chuck when it relates to a 4 jaw? I have a Bison 3 jaw 6" adjust true chuck, which is what I think of when I think of a combo chuck. The "adjust true" part of it is basically a built in 4 jaw for centering the 3 jaw. But on a 4 jaw chuck... what is the combination? Sorry if that's an obvious question...


Willy, 
Good question - it's a 4 jaw scroll chuck with independently adjusting jaws.  So you get a scroll and an independent 4 jaw chuck built into one. (i.e. Combination)


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## bss1

I guess I'm joining the club also. Mine is scheduled to arrive tomorrow! Thanks for starting this thread Alan. 

Mark, those are some nice looking wrenches. Quick question, When you mill the square key on the end, do you place the collet block in your vise vertically or horizontally. The last wrench I made I held the block horizontally but in the end I was wondering if it would have been simpler to have held it in a vertical position.


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## Firestopper

Not to answer for Mark, but I would hold it horizontal utilizing mostly the end of the cutter. For me, less chance of mucking it up but really can be done both ways so long as you use a stop to index to every time you rotate the collet block.
bss1, your gonna love your new chuck!


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## mksj

As Paco indicated. I turn the square key portion down on the lathe to the outer diameter of the square corners, then I put it in a square collet block and mill the flats in the horizontal position.  I uses a stop that indexes the block (actually the tip of the key) to the same horizontal position so when you rotate it to cut the flats it remains in the same position relative to the end mill. When you cut the flats, I go slightly oversized first, check the fitment, and slowly creep up on the final dimensions with skim cuts. I also break the edges with a fine file and the edges on the key nose. Some some fine fitment with a file gives a nice fit, without very much play. There is a slight taper toward the nose. I thought of heat treating  them, but I would rather have the key wear as opposed to the pinion socket.
Mark


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## wildo

Alan H said:


> Willy,
> Good question - it's a 4 jaw scroll chuck with independently adjusting jaws.  So you get a scroll and an independent 4 jaw chuck built into one. (i.e. Combination)


Thanks- super interesting! I'm guessing then that the scroll action is ultimately just to get the chuck jaws close to position quickly?


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## Silverbullet

wildo said:


> Thanks- super interesting! I'm guessing then that the scroll action is ultimately just to get the chuck jaws close to position quickly?


Mostly to keep concetricity for doing more then one operation or multiple parts  , like turning 25 square parts and drilling and tapping them.


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## darkzero

I'm not in the market for one but I have always been curious about these combo chucks. Are the jaws fully independent of the scroll? For example, can you use just the jaws independently or do you have to set the jaws first, then tighten up on the work piece with the scroll? I use my 4 jaw when I really need to bite down on something hard. 

I was just wondering cause I see some of you guys using 2 small keys which looks like just for adjustment rather than torquing down with a full size a chuck key.


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## mikey

This is a very cool chuck! So, if I understand this correctly, you would use this primarily for doing multiples of parts with the same OD? Dial one in with the 4 jaws and then just use the scroll to quickly chuck up all subsequent parts, right? If so, it would be interesting to see how repeatable it is. I would think it would be pretty good when using TGP stock.

So, instead of adjusting the chuck body's concentricity like an adjust-tru chuck does, this chuck does the same thing with the jaws, correct?


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## mksj

Mikey is correct, just like a Set-Tru chuck but adjusting each jaw on a scroll mechanism instead of the chuck relative to the backing plate. Also a lot quicker then a Set-Tru to adjust. Still, a Set-Tru repeats very well, but there can be some variation depending on the size of the piece and also if the jaws are reversed, it usually requires readjusting the chuck TIR. In my experience, the sequence of tightening the Set-Tru bolts and chuck to the back plate is more critical to setting up the chuck. The combo is a piece of cake, relative to a Set-Tru, but a Set-Tru once set has better repeatability of the scroll.

So with a combination chuck each independent jaw moves on a scroll mechanism carrier which it is attached to a screw mechanism that then adjusts the jaw. Each jaw can be adjusted independently, the scroll moves all 4 jaws simultaneous in whatever position they are set. It makes it easy to remove your work quickly and then reinserting and maintaining the same concentricity. So I usually will use the scroll and tighten down on stock, and then tweak the independent jaws to 0 the TIR. I usually can do this in under a minute, since you are using two keys you can torque bot down, and then turn the chuck 90 degrees and do the other two. Once set, you can just use the scroll and maintain better than 0.002" TIR on repeat parts, but if I need to be spot on I will tweak one of the independent jaws as needed. One aspect that I do like about the 4J with twin keys, is you can get a good feel on the torque/tension that is applied to the jaws. The twin keys have plenty of torque for their size, remember that when using the scroll it is setting the pressure for all four jaws.


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## darkzero

mksj said:


> Once set, you can just use the scroll and maintain better than 0.002" TIR on repeat



I assumed it would repeat better than that being a quality chuck. I mean I can get my Set-Tru chucks to repeat under .001". Is it because of the movement  independent scrolls for each jaws, like when the pressure is released from them when swapping out the workpiece?

I really wanted one these back when I was looking for a chuck. But at the time a 6-jaw was more useful to me. I really hope I don't "need" one of these too.


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## mksj

Darkzero, the combo has  several factors that can influence the clamping error. You have the cumulative error/movement of both a scroll and the independent jaws (with a separate  screw mechanism in the each jaw carrier).  There is also the method of torquing each jaw, that it is hard to be symmetrical between the jaws without a torque wrench. I would say that most of the time once set, I can repeat to around 0.001", but you can essentially get this down to nil very quickly. The other aspect that surprises me on this chuck, is that at least mine, has the least angular skew of any of my chucks. It holds stock much better than my 3J scroll.


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## ptrotter

I received my Bison chuck and back plate today.Looks really great.  I bought the back plate from MSC.  They have a 30% off promo going on that made the price very competitive and it shipped immediately.  All in all a real good deal.  I am still working on getting the lather set up so I can't try it just yet.

Paul


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## Firestopper

I took a couple of shots of the piece of plywood that protects the ways when changing chucks. Its a simple design that holds securely and still slides easily  back and forth.  As I mentioned earlier, It also doubles as a platform for tooling etc.



The bottom is simple wood strips that ride on the inside of the ways with no play.
No fancy sealer, just a soaking with WD-40 and wiped dry.


Jeez, the lathe is dirty...


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## mikey

Paco, that sled is the least complicated and most ordinary thing I've seen you make. Looks like mine, actually.  

Sometimes simple is best, I think.


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## mikey

mksj said:


> Mikey is correct, just like a Set-Tru chuck but adjusting each jaw on a scroll mechanism instead of the chuck relative to the backing plate. Also a lot quicker then a Set-Tru to adjust. Still, a Set-Tru repeats very well, but there can be some variation depending on the size of the piece and also if the jaws are reversed, it usually requires readjusting the chuck TIR. In my experience, the sequence of tightening the Set-Tru bolts and chuck to the back plate is more critical to setting up the chuck. The combo is a piece of cake, relative to a Set-Tru, but a Set-Tru once set has better repeatability of the scroll.
> 
> So with a combination chuck each independent jaw moves on a scroll mechanism carrier which it is attached to a screw mechanism that then adjusts the jaw. Each jaw can be adjusted independently, the scroll moves all 4 jaws simultaneous in whatever position they are set. It makes it easy to remove your work quickly and then reinserting and maintaining the same concentricity. So I usually will use the scroll and tighten down on stock, and then tweak the independent jaws to 0 the TIR. I usually can do this in under a minute, since you are using two keys you can torque bot down, and then turn the chuck 90 degrees and do the other two. Once set, you can just use the scroll and maintain better than 0.002" TIR on repeat parts, but if I need to be spot on I will tweak one of the independent jaws as needed. One aspect that I do like about the 4J with twin keys, is you can get a good feel on the torque/tension that is applied to the jaws. The twin keys have plenty of torque for their size, remember that when using the scroll it is setting the pressure for all four jaws.



Thanks for confirming that, Mark. You guys have some cool toys, that's for sure. I don't do multiple like parts often enough to justify having one of these things but I can see how it can be handy. I'll make do with my 4 jaw chucks and my adjust-tru for now. Christ, I already have seven lathe chucks; have to draw a line somewhere.


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## Silverbullet

Darkzero THIS IS MIND CONTROL YOU NEED THIS CHUCK AND A SECOND ONE FOR A GIFT TO A POOR GUY IN A WHEELCHAIR this is a recording . You know it's a great one to have for that square stock job coming up. If I had any odd shaped lathe jobs it would be on its way. Never know what kind of things will come up in a job shop.


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## Alan H.

Mark and Paco, what is the rule of thumb for scroll plate engagement with the jaw carriers?  You can roll the chuck jaws out using the scroll key until you are seeing the scroll plate  grooves.  Is there some rule of thumb on how many grooves one should expose?   Of course you can also move the independent jaws out on their carries and the same question also applies to how many threads of the carrier operating screws one should expose .  

The manual that came with the chuck is a tiny little booklet and it does show clamping ranges.  Perhaps that is what one should focus on vs. fussing over the scroll plate groove engagement on the jaws.


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## mksj

Hi Alan,
There are several factors to consider, but my understanding is that the load capacity is based on all the scroll teeth being engaged, and this would also apply to the independent jaw on the scroll carrier. You can see the scroll plate when it becomes exposed and no longer engages the jaw carrier. Yo might try to scroll the chuck to get a good feel of the range, and also that of the independent jaw (I would want at least 4 turns of engagement). I have seen the jaw teeth break when too few teeth have been engaged, so something like 4 teeth is what is what you would want. These chucks also specify working diameters and loads as follows:


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## bss1

I received mine last week. First impression was wow, this thing is big and heavy.  Hoisting it up for the first time left me wishing I was wearing some steel toe boots!

The chuck has a very nice finish and looks very well machined. I also bought the back plate from MSC. I mounted it bare on the spindle and it seemed to have no detectable run-out.  I then installed the plate on the chuck. The fit seemed perfect, again very well machined. 

I used the chuck to make the keys that Mark and Paco have. 




I quickly found that they are a necessity to work with this chuck. The stock key is a PITA to adjust the chuck, at least on a 1340GT.  There is just not much room to spare with the length of the key.  The design of Marks keys was excellent and greatly enhanced the dialing in process. 

My take on this chuck is that it gives you the accuracy of a standard 4-jaw, but much easier to dial in and re-tru if you have to remove the work piece.  While I rarely use my regular 4-jaw because of the time it takes to dial in, I would be more inclined to use this one due to the ease of adjustment. 

My only issue is the size and weight. I tend to use my collet chuck and a 5” 3-jaw the most as it is so easy to handle them and switch out when necessary. For me, this chuck is so substantial, it leaves me less inclined to switch it out for one of the other chucks that could work better for the application at hand.  With that said the size issue is subjective and more reflective of the personal preferences of the user. I think a 6” version of this chuck (if they make one) would be a little better suited for me and the PM1340.   Maybe I just need to go to the gym some more.  It is a very nice chuck, and for the bargain price paid, I am happy to have it as part of the growing inventory of attachments.


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## Reeltor

I gather that this chuck was on-sale and that sale has ended.  With that said, would someone please post what they paid for one of these combo chucks?
I am not really in the market because the pricing that I see is about 3/4ths the price that I paid for the entire lathe but would like to have a price to compare future offerings too.

thanks

Mike


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## Alan H.

Brad, thanks for the feedback.  Yes, that chuck is a chunk of steel to say the least.  I am glad that I built the wooden sled for it so it is easier to handle and to make it a bit easier to heft it around. 

For me the chuck giving me the ability to take pieces out of it and get them back in with ease and some accuracy is outstanding.   The finish on the chuck is outstanding and the scroll is smooth as glass as well as each individual jaw carrier.   I am sure that I am going to be using it often now.

As you pointed out, Mark's chuck key design is quite helpful and a big plus to have to go along with the chuck.  Here's my build of his concept.  I really liked Mark's idea for the magnet embedded in the end to help hold it on there and replicated that as well.  I made mine out of 1144 Extra Strength which was a bit of mistake for knurling.  The 1144 ES is a bit too hard to get a good knurl and I also discovered that my knurling charts were off due to not considering the transverse pitch on 30 degree diagonal knurls.   Meanwhile they are okay as is and quite functional and good to go. 

Thanks to Mark for always being willing to share and help others.  Paco is from the same cloth as well.  Folks like these two plus all the others makes this forum a great place.


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## Alan H.

Reeltor said:


> I gather that this chuck was on-sale and that sale has ended.  With that said, would someone please post what they paid for one of these combo chucks?
> I am not really in the market because the pricing that I see is about 3/4ths the price that I paid for the entire lathe but would like to have a price to compare future offerings too.
> 
> thanks
> 
> Mike


PM sent


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## Reeltor

Alan H said:


> PM sent




I have my answer, thanks


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## bss1

Nice work on the wrenches. The drawing looks excellent as well. I wish I had those skills and patience. I usually scratch down a few measurements and wing it. I must be lucky. I have yet to use the tables for knurling and for the most part come out ok.


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## Alan H.

Nice job on the knurls!   What material is that?

Thanks for the compliment on the drawing but it ain't much.  I am hoping to renew my skills with some 3D cad and eliminate all these sketches.  They take too much time.


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## bss1

Thanks Alan, It’s just some O1 drill rod that I used for the chuck keys.  I had a 3’ section I was working with so I used the spider to support it and did most of the lathe work and knurling before pulling it and taking it over to the Ellis to part off.  I did both wrenches like that, then put them in the collet block to mill the end square. After that I removed the monster Bison 4-jaw and used the collet chuck to finish and counter bore the backside.  I found the collet doesn’t seem to smash the finished knurling as bad as a regular chuck jaw. I’m sure there is a more efficient job sequence. I usually won’t do the knurling step with the collet chuck as it doesn’t get a good enough grip on the stock for the amount of tension I use to cinch down on the knurling Tool. 

I seem to get the same results with brass,  bronze , or aluminum. I have even done some smaller 1/4” 316 SS. I’m sure I just jinxed myself and will never get my knurler to work again...


Sent from my iPad using Tapatalk


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## Firestopper

bss1 said:


> I received mine last week. First impression was wow, this thing is big and heavy.  Hoisting it up for the first time left me wishing I was wearing some steel toe boots!
> 
> The chuck has a very nice finish and looks very well machined. I also bought the back plate from MSC. I mounted it bare on the spindle and it seemed to have no detectable run-out.  I then installed the plate on the chuck. The fit seemed perfect, again very well machined.
> 
> I used the chuck to make the keys that Mark and Paco have.
> 
> View attachment 242554
> 
> 
> I quickly found that they are a necessity to work with this chuck. The stock key is a PITA to adjust the chuck, at least on a 1340GT.  There is just not much room to spare with the length of the key.  The design of Marks keys was excellent and greatly enhanced the dialing in process.
> 
> My take on this chuck is that it gives you the accuracy of a standard 4-jaw, but much easier to dial in and re-tru if you have to remove the work piece.  While I rarely use my regular 4-jaw because of the time it takes to dial in, I would be more inclined to use this one due to the ease of adjustment.
> 
> My only issue is the size and weight. I tend to use my collet chuck and a 5” 3-jaw the most as it is so easy to handle them and switch out when necessary. For me, this chuck is so substantial, it leaves me less inclined to switch it out for one of the other chucks that could work better for the application at hand.  With that said the size issue is subjective and more reflective of the personal preferences of the user. I think a 6” version of this chuck (if they make one) would be a little better suited for me and the PM1340.   Maybe I just need to go to the gym some more.  It is a very nice chuck, and for the bargain price paid, I am happy to have it as part of the growing inventory of attachments.





Alan H said:


> Brad, thanks for the feedback.  Yes, that chuck is a chunk of steel to say the least.  I am glad that I built the wooden sled for it so it is easier to handle and to make it a bit easier to heft it around.
> 
> For me the chuck giving me the ability to take pieces out of it and get them back in with ease and some accuracy is outstanding.   The finish on the chuck is outstanding and the scroll is smooth as glass as well as each individual jaw carrier.   I am sure that I am going to be using it often now.
> 
> As you pointed out, Mark's chuck key design is quite helpful and a big plus to have to go along with the chuck.  Here's my build of his concept.  I really liked Mark's idea for the magnet embedded in the end to help hold it on there and replicated that as well.  I made mine out of 1144 Extra Strength which was a bit of mistake for knurling.  The 1144 ES is a bit too hard to get a good knurl and I also discovered that my knurling charts were off due to not considering the transverse pitch on 30 degree diagonal knurls.   Meanwhile they are okay as is and quite functional and good to go.
> 
> Thanks to Mark for always being willing to share and help others.  Paco is from the same cloth as well.  Folks like these two plus all the others makes this forum a great place.
> 
> View attachment 242571
> View attachment 242572



Those mini "T" turned out fantastic guys!
It'll make things quicker to dial in. Don't forget to pull them off (back side out of sight, out of mind) immediately after dialing in. So cool to see results following discussion. Too many times we talk about things and never "get er done", not here at HM!
Again, nice work fellas.
Turn and Burn!
Paco


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## Alan H.

I have been using this chuck now for the past few days and I can imagine that I will never use my older 4 jaw again plus my three jaw may get very little use as well.  I am thinking this and my 5C collet chuck will be my "go to's" here forward.

This chuck is outstanding.  It let me flip a piece and it was close enough to turn it within a half.   You cannot see the line on this piece of 2.5" chrome moly.   Another positive is that it has finally stopped throwing grease!


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## rzbill

Alan H said:


> Mark and Paco, how do you gents handle this little chuck?  It is a bit heavy isn't it?   Did you build a sled to help mount it or do you simply mule it on there?


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## Firestopper

I used my Bison comb chuck today as well on some delrin. Had to flip it for second counterboring operation. The reamed through hole remained absolutely dead nuts X2. Gotta love them chucks


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## Bamban

Nice reports guys. Mine is still in the box. I am still stuck on using the 6J set thru for barrel work when not using the front spider.


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## ptrotter

I finally cleaned up the Bison 4 jaw combination chuck I purchased awhile ago and mounted it to the back plate.  Beautiful piece of equipment.  I just got my PM1340GT set up and it is time to see if I can dial in the chuck.  I need to get a couple of small keys for the jaws like others have made.  Does anybody know if one can buy these anywhere?  Without a mill it is hard to make something like this, or perhaps somebody on here would be interested in making a set, for a fair price of course.  I'm pretty new to machining, so it is going to be interesting learning all these new things.

Paul


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## ronboult

These chucks seem very nice but are prohibitively expensive in Au. Ray C recently reported on a range of 6 jaw chucks made by a company CME and labelled San do. His review was very favorable. On doing a search this company also makes a range of 4 jaw plain back scroll chucks with two piece jaws at a price I can afford. 
My plan is to make a D1-4 back plate and convert the chuck body to a set true design. If I align the four set tru adjusting screws with the 4 jaws can any body see any reason why this arrangement would not be comparable with the combination style chuck ( within the scroll accuracy of the cheaper chuck)?
Ron


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## 6061T6

Sorry about necroposting. I've been researching this chuck and came across this thread.
Can someone tell me what is the best place to buy this chuck? I'm hoping to save some money but not buy from shady fly-by-night operator.


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## mksj

Any of these vendors would be recommended, I have purchased chucks from all three over the past 10 years:


			Bison Scroll Chuck - 8" Plain Mount, 4-Jaw 7-848-0800
		









						Bison 8" 4 Jaw Combination Manual Chuck Plain Back 7-848-0800
					

Bison 8" 4 Jaw Combination Manual Chuck Plain Back 7-848-0800




					www.smalltools.com
				











						8" 4-Jaw Plain Back Independent Chuck at Grizzly.com
					

The jaws on this chuck move independently, so you can use them for holding odd shaped pieces or where zero tolerance is required. Forged steel body with a large thru-hole, this chuck has heavy-duty reversible jaws, (hard top jaws and hard master jaws), and a set of mounting bolts and eye bolt...




					www.grizzly.com
				




Bison D1-4 Backplate I believe is the 7-878-084F. Gator also has one which is the FLD 200mm series, but price difference is nominal, so I would recommend the Bison. Price on these chucks have gone up quite a bit, but still comparable to a Bison 6J scroll. I would go with the semi-steel as opposed to the more expensive forged steel.








						Bison Finished D1-4 Adapter Plate 7-878-084F for 8" Chucks
					

Bison Finished D1-4 Adapter Plate 7-878-084 for 8" Chucks




					www.smalltools.com


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## ThinWoodsman

I bought a 6" Bison combo chuck from Logan - I was buying the (threaded) backplate from them anyways, and the price they quoted for the chuck was not much more than anyone else was asking. The 6" version is pretty uncommon though. Shipped directly from the factory.


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## 6061T6

Thanks!
Since these have both a scroll and individual adjustments, don't they open a lot wider than just a regular scroll chuck or 4 jaw independent?
If so, I should be ok getting a chuck one size smaller, right?


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## mksj

No really a lot wider, and you are limited by hitting the bed.  At this spend level I would recommend an 8" for a lathe in the 13-14" swing, you have a larger through hole. You always need to be careful with the scroll and also an independent that you have at least 3-4 teeth  engaged, otherwise you can break the teeth. The scroll plates jaw travel on the 8" combination is around 2.5" per jaw, and maybe 2" on the independent. The scroll plates are rectangular so they will interfere with each other when closing the jaws, this limits some of the overall travel of the scroll portion.

Interestingly they now make a combination 3J that I have not seen before.





Review of the 4J combo


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## lasterixsuedois

Hi,
I have got myself a Hardinge HLV H without any chucks only 5C collets.
Would you recommend a 5" combination chuck as a reasonable substitue for a 3 jaw scroll chuck and a 4 jaw independent chuck?
For doing regurarly round turning above collet size and occasionally turning non round parts (small casting and some eccentric turning)?


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## 6061T6

I have the 5” 4 jaw combination chuck in my Chinese lathe which has the same work envelope as the hlv-h. It is my most used chuck. By far.


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## mksj

I was not aware that they made a combination chuck in 5", the smallest I have seem is 6" (125 mm). They are very nice chucks, but I feel on your size machine you would be better off with two separate chucks. The stick out from spindle will be less and about 1/2 the weight, also significantly less expensive. I do like using the combination chuck, but in a smaller size I feel there are better options such as a high quality set-tru type 3J and the collets, get an inexpensive 4J independent for the infrequent use.


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