# 10” chuck on PM-1340GT?



## cday2021 (Aug 22, 2021)

Has anyone tried a 10” chuck on the PM-1340GT? If so, what have you tried and how is the stability?


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## Bob Korves (Aug 22, 2021)

The problem with larger chucks on lathes is that the jaws sticking out of the chuck with larger work will eventually be in the way of the bed ways.  That is no problem when machining smaller diameter parts, and you do get a bigger area to mount work to, but with larger parts the jaws will hit the bed ways.  Small chucks give different tradeoffs.  The chucks that come with lathes are typically the "Goldilocks" size -- not too big and not too small for varied work.


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## 7milesup (Aug 22, 2021)

A 10" chuck on a 13" lathe would seem huge to me.  I would hate to lift that dang thing up to, and off, the lathe.


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## cday2021 (Aug 22, 2021)

Bob Korves said:


> The problem with larger chucks on lathes is that the jaws sticking out of the chuck with larger work will eventually be in the way of the bed ways.  That is no problem when machining smaller diameter parts, and you do get a bigger area to mount work to, but with larger parts the jaws will hit the bed ways.  Small chucks give different tradeoffs.  The chucks that come with lathes are typically the "Goldilocks" size -- not too big and not too small for varied work.


I have about 10 rounds of 8.5” diameter 4” long aluminum round stock I want to chuck up, so I think the jaws would remain inside the 10” diameter.


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## cday2021 (Aug 22, 2021)

7milesup said:


> A 10" chuck on a 13" lathe would seem huge to me.  I would hate to lift that dang thing up to, and off, the lathe.


Me too! Ha!


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## benmychree (Aug 22, 2021)

It would fit like a saddle on a sow--- more appropriate would be a 6 or 8".


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## cday2021 (Aug 22, 2021)

benmychree said:


> It would fit like a saddle on a sow--- more appropriate would be a 6 or 8".


Neither will hold the 8.5” rounds I want to chuck up... unless I can find/make extended jaws (which @davidpbest suggested)


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## wrmiller (Aug 22, 2021)

My PB is 8 1/4" and it works really well. It's been the primary chuck since I set up the lathe. I think it's plenty big for this lathe, but that's just me.


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## Aukai (Aug 22, 2021)

Get an 8" chuck with 2 piece jaws. The 8" chuck already hits the cross slide, you would be able to chuck 8 1/2, but there is still jaw stick out. I went out and flipped my 2 piece 6" and it just made it to 8".


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## Bob Korves (Aug 22, 2021)

cday2021 said:


> I have about 10 rounds of 8.5” diameter 4” long aluminum round stock I want to chuck up, so I think the jaws would remain inside the 10” diameter.


It depends on which way the jaws are mounted.  If you are OK with just mounting the parts on the short steps of the jaws, (edit 'instead' of with the work resting against the face of the chuck, then go with it, though it can get very dangerous.  With the large diameter part resting against the chuck face, you will have long threaded shanks sticking out of the chuck, poorly supported as well as dangerous.  It will actually decrease the size able to be mounted compared to the "Goldilocks" size chuck.  The chucks that come with new lathes are usually chosen by the maker to give the widest possible range of mounting sizes in the standard chuck configuration.


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## mksj (Aug 23, 2021)

The 1340GT is a light weight lathe and already a bit top heavy with a narrow stance, so it is much more sensitive to imbalance. I had a Chinese 8" chuck that I couldn't get past 400 RPM, so unless you have a higher quality chuck and everything is dialed in, I would not recommend a 10".  The issue with an 8" 4J independent (and also 10" 3J scroll) is there is a recommended stock holding range, and it is around 7.5 to 7.9" with the jaws reversed. Two piece jaws seem to give a bit wider clamping diameter when reversed, so you would want to check the model.  A 10" 4J independent with 2 piece jaws as well as solid jaws will hold a 8" disc. If you are clamping an 8" diameter and the jaws stick out more than an 2" beyond the diameter that gives you a 12" swing, my understanding is that you want at least 5 jaw teeth engaged for safety. I probably would keep the RPM under 400.

This is a relatively inexpensive 10" plain back 4J that may be worth looking at and asking it's hold diameter.








						10” 4 Jaw Independent Manual Chuck Plain Back TMX Brand 3-850-1000  | eBay
					

TMX 10” 4 Jaw Independent Manual Chuck Plain Back 3-850-1000. - Notes: Manufactured to TMX specifications. - Jaw Type: 1 Piece Solid Reversible. - Spindle Mount: Plain Back. - Type: Manual Chuck. - Recess on Back of Chuck: 4.33”.



					www.ebay.com


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## parshal (Aug 23, 2021)

I'm going the opposite direction now; looking for a 5" adjustable 3-jaw.  One of the 8" chucks has vibration at certain speeds that drive me nuts.


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## cday2021 (Aug 23, 2021)

mksj said:


> The 1340GT is a light weight lathe and already a bit top heavy with a narrow stance, so it is much more sensitive to imbalance. I had a Chinese 8" chuck that I couldn't get past 400 RPM, so unless you have a higher quality chuck and everything is dialed in, I would not recommend a 10".  The issue with an 8" 4J independent (and also 10" 3J scroll) is there is a recommended stock holding range, and it is around 7.5 to 7.9" with the jaws reversed. Two piece jaws seem to give a bit wider clamping diameter when reversed, so you would want to check the model.  A 10" 4J independent with 2 piece jaws as well as solid jaws will hold a 8" disc. If you are clamping an 8" diameter and the jaws stick out more than an 2" beyond the diameter that gives you a 12" swing, my understanding is that you want at least 5 jaw teeth engaged for safety. I probably would keep the RPM under 400.
> 
> This is a relatively inexpensive 10" plain back 4J that may be worth looking at and asking it's hold diameter.
> 
> ...



Yeah, I was eyeing that 10" chuck... I assume I would couple it with one of these and drill/tap the holes to fit the chuck?









						SHARS 10" SEMI-MACHINED BACK PLATE D1-4 FOR ALL PLAIN BACK LATHE CHUCK NEW R  | eBay
					

Find many great new & used options and get the best deals for SHARS 10" SEMI-MACHINED BACK PLATE D1-4 FOR ALL PLAIN BACK LATHE CHUCK NEW R at the best online prices at eBay! Free shipping for many products!



					www.ebay.com


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## wrmiller (Aug 23, 2021)

No surprise with the Chinese chuck. I've spun my 8" PB to just over 1800 rpm with no issues. Quality makes a difference I guess.


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## mksj (Aug 23, 2021)

That eBay 10" chuck does not take a full size back plate because the step is not on the rim of the chuck, it would take something like a 160 mm (6.3") back plate and you would machine the step with a diameter of 4.33" to match the chuck recess. Then tap the 4 mounting bolt holes. You might check with Small Tools, Inc. directly if they have a D1-4 back plate for that chuck. Otherwise might look at the Grizzly SB back plate which is a bit thicker for the step. Although the chuck is made in China, the TMX is a bit better made then the typical generic ones with really lumpy castings in the back.





						Small Tools Incorporated
					

Small Tools Inc. is a Leading Distributor of Industrial Metalworking Machinery, Lathe Chucks, Hydraulic Cylinders, Rotary Tables, Vises, Vertical Mills, Chuck Jaws, CNC Machinery, Industrial Supplies, & more. Representing over 20+ Industrial Brands at Low Prices.




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						6-1/4" D1-4 Back Plate - Thick at Grizzly.com
					

<h1>SB1394 6-1/4" D1-4 Back Plate – Thick</h1> <p>Made thicker for use with adjustable chucks, this extra thickness allows a large step to be machined on the front of the plate for use with the adjusting screws on the chuck.</p> <p>The remaining material safely supports and secures the chuck</p>...




					www.grizzly.com


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## cday2021 (Aug 24, 2021)

Does anyone see a problem with the 1340GT handling the weight of a 10” chuck?


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## Aukai (Aug 24, 2021)

It's a matter of mass on the braking, and starting....


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## mksj (Aug 24, 2021)

I ran an 85lb Bison 8" combination chuck with it for years with no problem, and Bill runs an 8" chuck which is a similar weight. As Aukai mentioned, it is more about balance and speed, and if you hit an oscillation point which is more likely to occur when using a VFD. As long as the chuck is running smooth, I do not see an issue. I would be uncomfortable running that size chuck at higher speeds, maybe over 600-800 RPM if it is running balanced, there is also a lot more centrifugal force/momentum with a large diameter chuck.  If using a VFD I would set the braking to something like 3 seconds otherwise it may trip an over voltage error.


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## cday2021 (Aug 24, 2021)

mksj said:


> I ran an 85lb Bison 8" combination chuck with it for years with no problem, and Bill runs an 8" chuck which is a similar weight. As Aukai mentioned, it is more about balance and speed, and if you hit an oscillation point which is more likely to occur when using a VFD. As long as the chuck is running smooth, I do not see an issue. I would be uncomfortable running that size chuck at higher speeds, maybe over 600-800 RPM if it is running balanced, there is also a lot more centrifugal force/momentum with a large diameter chuck.  If using a VFD I would set the braking to something like 3 seconds otherwise it may trip an over voltage error.


Excellent point on braking. I implemented your two stage braking switch on my panel so should be easy enough to switch between my normal setting (1s I think?) and a 3s setting.

One of my concerns with a bigger/heavier chuck was on the bearings and if that presents and issue at all for this lathe? The more I look at my options the more I'm looking at spending a bit of change on a nicer (bison perhaps) chuck with 2-piece jaws. My current idea is a 4-jaw independent chuck with 2-piece jaws. I don't think I'd be using it that often so an independent jaw seems like the right way to go for maximum versatility when I do use the chuck... although I am eyeing 3-jaw chucks too (with 2 piece jaws).

That TMX chuck is extremely tempting, but I'm concerned about not having a 2-piece jaw... I'll be chucking up aluminum, so soft jaws would really be ideal. My first piece I plan on making is a mounting plate for a 3-jaw chuck on the rotary table. I'll have to turn and face then start to part a disc off... but given the depth of parting cut I'll just need to make a small groove I can take to the bandsaw and finish the cut. Then I'll re-chuck and face the sawn side. I'm guessing my edges would be all mared up trying to re-chuck and face the second side with a solid jaw chuck. From what I've researched it seems like a pain in the butt to use soft shims with a solid jaw in a 4-jaw chuck and dial things back in again... so leaning heavily toward the 2-piece jaw.... but some of these prices for really nice chucks are certainly make me think twice about the TMX chuck!


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## parshal (Aug 24, 2021)

cday2021 said:


> ...my normal setting (1s I think?) and a 3s setting.



Not trying to derail the thread but, Mark, what should be the "normal" setting?  I leave mine on 3s figuring it's easier on the gears and resistor.  With the prox sensor it uses 1s anyway.


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## Cletus (Aug 24, 2021)

I must have been about 7 or 8 years old, I remember going with my dad to collect a South Bend No. 4207 4-jaw chuck.  Dad bought it to DIY a Christmas Tree stand (I kid you not).  I held on to it, and got a back-plate for it when I got my Grizzly 9x20 lathe.  Yes, I run it on the 9x20 with success, albeit at low speeds.  Has worked quite well for me time and again.  There she is on the Griz


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## Dabbler (Aug 24, 2021)

I have an ultra light 12X37 lathe (just under 750lbs), and have an 8.25" 4 jaw chuck and an 8" 3 jaw chuck for it.  Never had any problems running up to the 1800 RPMs it can go to.

At 300 RPM I put an off center billet of aluminum to make a 4 shot (in a row)  injection mold, and then used a 5" billet to make a 6 shot mold by holding it off centre in my 4 jaw chuck.  No significant vibration, but I think I slowed down the bigger one to 250 RPM.  

I think it can work, if you are sensible about how you use it.


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## mksj (Aug 24, 2021)

parshal said:


> Not trying to derail the thread but, Mark, what should be the "normal" setting?  I leave mine on 3s figuring it's easier on the gears and resistor.  With the prox sensor it uses 1s anyway.


Normal braking time for mine is also 2.5-3 seconds, for threading and speeds below 500 RPM mine defaults to 1 second with the proximity stop. With a 10" chuck and holding large/heavy stock I would use 3 seconds stopping or maybe longer. Depending on the settings, VFD brand/model, braking resistor and program parameters the VFD may adjust the stopping time to prevent an over voltage event. It is more of a warning to not expect crazy fast stop times with large chucks and/or large loads, and also run the RPM conservatively.  So I normally run 2-stage braking at 2.5/3 seconds and single stage at 1 second. The 2nd stage is activated by a separate VFD input. My systems/E-Stop deactivate the run inputs and the 2 stage braking for faster stopping times, but default 2-stage is switched in most of the time.

There are a few other factors to consider that are often overlooked, if you have a VFD set to stop at 3 seconds, this is the stopping speed at the maximum RPM (Hz), as you turn down the speed pot it also shortens the stopping time in a linear decrease. So 3 seconds at 80 Hz will be 0.75 seconds at 20 Hz. Braking time just sets the slope of the deceleration. Repeated quick braking can also cause the VFD to trigger a fault, so if you have several fast stops in quick succession, it is possible that the braking could fail.

The resistor will not fail, and I have never seen mine get past mildly warm, because the braking times are so short relative to the run times. It can add some mechanical stress to the drive train, but people use the mechanical brakes often minimal consequences.  I still do not see the need for super quick stops if not necessary, so 2.5-3 seconds is fine. There are also some adjustments one can make to the braking curve, to soften the beginning and end of the stop (S-curve) but I use a linear stopping for the VFD because it gives a more predictable stopping distance when using a proximity stop system. If just manual stopping, then the typical default S curve is fine.


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## wrmiller (Aug 24, 2021)

mksj said:


> I ran an 85lb Bison 8" combination chuck with it for years with no problem, and Bill runs an 8" chuck which is a similar weight. As Aukai mentioned, it is more about balance and speed, and if you hit an oscillation point which is more likely to occur when using a VFD. As long as the chuck is running smooth, I do not see an issue. I would be uncomfortable running that size chuck at higher speeds, maybe over 600-800 RPM if it is running balanced, there is also a lot more centrifugal force/momentum with a large diameter chuck.  If using a VFD I would set the braking to something like 3 seconds otherwise it may trip an over voltage error.


No reason for you to remember my setup, but you set up my braking with both a 1 sec and a 3 sec braking time. I use the 3 sec (when using the Big Chuck) any time I'm over 6 or 7 hundred rpm. When I'm running above 1200 rpm even the 3 second braking time can't stop this thing. It's a pretty big chuck. 

You mentioned 'oscillation point'. Mine is just under 600 rpm to maybe 650. The only reason I notice it is because I have my light mounted to the back splash and it can wiggle quite a bit at the 'sweet spot'. Not much vibration though when I place my hand on the headstock. I consider it more of an annoyance than anything.

Oh, and this heavy arse chuck has been on this lathe for most of the last 5-6 years or so, with no adverse effects. Matt said this was a stout spindle, and I believe him.


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## cday2021 (Aug 24, 2021)

wrmiller said:


> No reason for you to remember my setup, but you set up my braking with both a 1 sec and a 3 sec braking time. I use the 3 sec (when using the Big Chuck) any time I'm over 6 or 7 hundred rpm. When I'm running above 1200 rpm even the 3 second braking time can't stop this thing. It's a pretty big chuck.
> 
> You mentioned 'oscillation point'. Mine is just under 600 rpm to maybe 650. The only reason I notice it is because I have my light mounted to the back splash and it can wiggle quite a bit at the 'sweet spot'. Not much vibration though when I place my hand on the headstock. I consider it more of an annoyance than anything.
> 
> Oh, and this heavy arse chuck has been on this lathe for most of the last 5-6 years or so, with no adverse effects. Matt said this was a stout spindle, and I believe him.


how much does your stout chuck weigh? and what size is it?


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## mksj (Aug 25, 2021)

Bill (wrmiller) has the 8" PBA Setrite chuck I mentioned earlier, it is 48 lbs and the back plate is 14 lbs. I use the 6.3" version on mine, they are very nice chucks and hold tight repeatability/accuracy. The 8" Bison combination chuck is about 20 lbs heavier than the 8" PBA. There are also direct mount 10" chucks in a D1-4 configuration which run around 65 lbs. The eBay 10" TMX is incredibly low priced compared to other major brands like the Gator listed below with 2 piece jaws.








						PBA 825300 8
					

PBA Setrite Universal Chucks with Hardened Jaws for Maximized Clamping Force. The self-centering Setrite universal chucks from Pratt Burnerd America constitute a forged steel body, and they are manufactured with high accuracy for error-free mounting on adapter plates. These chucks assure double...




					www.travers.com
				











						PBA 805021 8
					

FeaturesFully machined. †  Ships direct from factory.




					www.travers.com
				











						New SCA Sweden 10" 4 Jaw Independent Lathe Chuck. D1-4 Direct Mount $1805 List  | eBay
					

Find many great new & used options and get the best deals for New SCA Sweden 10" 4 Jaw Independent Lathe Chuck. D1-4 Direct Mount $1805 List at the best online prices at eBay! Free shipping for many products!



					www.ebay.com
				











						10" Bison 4 Jaw Lathe Chuck Direct Mount D1-4 +Hard Jaws  | eBay
					

Find many great new & used options and get the best deals for 10" Bison 4 Jaw Lathe Chuck Direct Mount D1-4 +Hard Jaws at the best online prices at eBay! Free shipping for many products!



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						Gator 1-301-1000 10-Inch 4-Jaw Independent Manual Lathe Chuck, PI4-10"A  | eBay
					

Find many great new & used options and get the best deals for Gator 1-301-1000 10-Inch 4-Jaw Independent Manual Lathe Chuck, PI4-10"A at the best online prices at eBay! Free shipping for many products!



					www.ebay.com


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## wrmiller (Aug 25, 2021)

Thanks Mark. That is a much better answer than I would have typed.  

Edit: The Setrite chuck and backing plate are a bit more stout than a plain-back setup, but I'm not sure my arms would know the difference. I swear my PBA gets heavier every year...


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## cday2021 (Aug 25, 2021)

Honestly I'd probably prefer an 8" chuck with oversized jaws (like @davidpbest pointed me to): https://monsterjaws.com/10-oversized-extension-american-standard-tongue-groove-jaws-aluminum-2-ht/) as an 8" chuck seems better for general use.

There doesn't seem to be any oversized options for the 8" chucks, but there are for the 10" chucks (at least from monsterjaws.com)... since I don't have an 8" chuck I don't know if these jaws would actually fit on an 8" chuck. If anyone who has an 8" chuck can comment on if these would fit their chuck that would be helpful. Here's the dimensions:






@mksj -- I seen one of your older posts from several years ago on this forum commenting on the Gator chucks... I did a bit of forum research in addition and I feel like I should steer away from these chucks. I've seen that SCA and bison you listed above on ebay, but they have solid jaws and I'm leaning heavily toward the 2-piece jaw design. This bison chuck fits the bill to exactly what I want for a 10": 

https://www.ebay.com/itm/153991945320?hash=item23daa29c68:g:F2QAAOSw6D9e~i9f 

but $1500 for a chuck I'll rarely use is hard to justify...


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## Janderso (Aug 25, 2021)

When I decided to buy a 4 jaw chuck for my 15" lathe, I asked around to see what I should get, 8", 10" or 12".
I settled for a 10" Bison with the T-slots.
I can barely lift the 10" I have the D1-6 adapter as well.
Something to consider


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## Cadillac (Aug 25, 2021)

I have a 14x40 and I run a 10” bison 4j sometimes. Was lucky and found a fella selling on CL acouple years back. Nice chuck 2pc jaws practically brand new with a integrated D4 mount and has back bored out for weight reduction and balancing from the factory. Would let go for the right price.


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