10” chuck on PM-1340GT?

[mksj]

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

 

[parshal]

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.

 

[cday2021]

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

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

 

[wrmiller]

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.

 

[mksj]

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.

www.smalltools.com

6-1/4" D1-4 Back Plate - Thick

<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

 

[cday2021]

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

 

[Aukai]

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

 

[mksj]

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.

 

[cday2021]

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!

 

[parshal]

...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.