PM1228 Chuck

[Bryan40g]

Looking for thoughts on the 6” chuck that comes on the machine. As well as the optional 8” 4 jaw chuck.

I’ve got til mid May when my machine arrives and I’ve noticed that the 6” chuck has solid jaws and not two piece. So I’d need another set of jaws. Not sure I like the idea of buying jaws hoping they’ll fit correctly. So I’ve been looking at 6”chucks. Considering a Gator 6” 3 jaw with 2 piece jaws. Have not heard anything but good things about their chucks.

I guess my question is are you happy with the 3 jaw chuck that comes installed? How is the runout?

 

[Chewy]

The 3 jaw has around .0015-.002 run-out. You can play around to keep it on the low side. I only use the jaws that came in the chuck. Went digging around for a gear and saw another set that came extra with the machine. Some time in the future I will figure out what they are.
I use the 4J more then the 3. I'm working on more practice to get tolerances down as far as possible. I usually dial in the 4J to around 2 tenths. No complaints about either, both chucks have 1 piece jaws. Don't see the problem with that.

 

[Ischgl99]

I have the 1236T, not sure if my 6” chuck is the same as yours, but it came with two sets of jaws. The runout is higher than I expected at 0.007” for one set of jaws, and 0.005” for the other. I also bought the 8” 4 jaw chuck and it works well and mostly use that. I have only been using it a few weeks, so it is still stiff, but with practice I am getting quicker at dialing it in. I would not hesitate recommending the 4 jaw chuck.

Since your machine comes with the 3 jaw chuck, you might as well try it when it arrives and then purchase something else if it is not good enough. I am considering buying a smaller 4 jaw chuck or collet chuck since a lot of what I do is on the smaller side and the 8” chuck closes down to just under 0.4”. If you plan on holding something smaller than that, it won’t fit in the 8” 4 jaw.

 

[Bryan40g]

Thanks for the reply Chewy. So it’s possible that it does come with another set of jaws. Hope so as I’d rather spend money on a nice 4 jaw independent. If it doesn’t then I may splurge for a replacement 3 jaw with two piece jaws and just get the 4 jaw later.

 

[Bryan40g]

I have the 1236T, not sure if my 6” chuck is the same as yours, but it came with two sets of jaws. The runout is higher than I expected at 0.007” for one set of jaws, and 0.005” for the other. I also bought the 8” 4 jaw chuck and it works well and mostly use that. I have only been using it a few weeks, so it is still stiff, but with practice I am getting quicker at dialing it in. I would not hesitate recommending the 4 jaw chuck.

Since your machine comes with the 3 jaw chuck, you might as well try it when it arrives and then purchase something else if it is not good enough. I am considering buying a smaller 4 jaw chuck or collet chuck since a lot of what I do is on the smaller side and the 8” chuck closes down to just under 0.4”. If you plan on holding something smaller than that, it won’t fit in the 8” 4 jaw.

That is definitely higher runout than I’d want. Since Chewy has much lower runout it’s probably a crapshoot on whether my chuck will be high or low. I’ll guess I’ll find out.

 

[Chewy]

Like I said I only use 1 set of jaws for both inside and outside clamping. What Ischgl99 said is correct. If you want to do real small get an ER32 straight shank chuck or collet block. Alternative is 5C collet blocks. Clamp them in the chuck and then you can go down to 1/16" with out trouble.

 

[Chewy]

Just thought of this. When I put my chucks on, I dial in the face. I put them on finger tight and than tap the chucks "true" and gradually tighten to proper lock position. Found that made a big difference in runout. D1-4 mounting. Also red marked the 4 jaw for the 0 position when I found the lowest face run out.

 

[Ischgl99]

My 3 jaw chuck jaws have different serial numbers, so it is possible there was a mix up at the factory and a matched chuck gives better results. I took mine somewhat apart this weekend to clean out to see if it gets any better, if not I am going to call PM and see about getting it replaced.

 

[Aukai]

One of us took apart their 8" 4 jaw PM chuck wire wheeled everything, possibly deburred too, and said it made an improvement in his chuck. I did not go that far, I bought a used Pratt of Ebay that was smoother, and not notchy feeling like the PM. For accuracy in the 3 jaw most brands have a "tru adjust" version that can be dialed in similar to a 4 jaw. When making these types of decisions, and I find something on Ebay, or where ever, I bring it here for advisement on it's suitability. There are a lot of educated eyes here that know what to look for.

On the jaw serial numbers, I may be wrong, but each jaw is numbered 1-2-3, and fits the same number slot in the chuck, would that give each a different serial number?

 

[Ischgl99]

One of us took apart their 8" 4 jaw PM chuck wire wheeled everything, possibly deburred too, and said it made an improvement in his chuck. I did not go that far, I bought a used Pratt of Ebay that was smoother, and not notchy feeling like the PM. For accuracy in the 3 jaw most brands have a "tru adjust" version that can be dialed in similar to a 4 jaw. When making these types of decisions, and I find something on Ebay, or where ever, I bring it here for advisement on it's suitability. There are a lot of educated eyes here that

On the jaw serial numbers, I may be wrong, but each jaw is numbered 1-2-3, and fits the same number slot in the chuck, would that give each a different serial number?

There is a number in addition to the 1, 2, 3 for the jaws that are usually serial numbered to the chuck so you know which chuck it belongs too. I don’t know if they do that for these economy chucks, but higher end chucks have the jaws ground to a specific chuck body and will not give good results if used in another chuck. Here is a picture of the #1 inner and outer jaws with the different serial numbers.

I cleaned the chuck as best I could and the runout did not change, so I suspect these jaws belong to a different chuck than was shipped to me.