1236 Questions

Three jaw scroll is quicker for a lot of repeat work and for smaller stock, while a 4 jaw independent needs to be dialed in all the time. The 4J independent was really slow for me when removing stock in/out of the chuck a lot. Traditional 4J chucks are pretty wide/rough at the jaw tips, so not very good for holding small stock, say under 1/2". My go too chuck is an 8" combination 4 Jaw, scroll with independent jaws that hold stock down to 0.200". Getting stock in/out of the chuck is quick, and then one can tweak the TIR down in about minute. I use a 6" 3J scroll chuck which holds a TIR of better than 0.001", so it also just as well. I prefer it if I am do a lot of repeat widgets on the lathe. Round stock under 3/4", I almost always use a collet chuck system. Everyone has their preferences, I think getting a good quality chuck in the first place is more important to the user's experience.

I wired my DRO to my machine power on my mill and lathe. The mill has an accessory socket box tied to the main machine power switch, the lathe DRO is hard wired to my power terminal in the control box. Be aware that as to the DRO setting for 120V vs 240V, I Run 4 wire power to the mill and lathe. One switch shuts everything down. Spike current? should be no difference to the DRO if it is the machine power switch or the DRO switch, most electrical equipment have some forum of line filtering and inrush protection anyway.
 
3 jaws are very handy if you have something round or hexagonal you want to machine and can do all the machining ops without having to take it out of the chuck. 3 jaws almost always have some runout, but that doesn't matter if you're making cuts as the cut surface will be concentric with the spindle and other cut surfaces. It's only a problem if you need to take the part out and make another cut concentric to those other cut surfaces - here you'd be better of using a 4 jaw where you can dial in the piece with reference to one of those surfaces.

4 jaws are great but you can fiddle fart around for a few minutes getting the part running concentric when you could have mounted it in the 3 jaw and done the cut already. Each has their own uses. Collet chucks have the best of both worlds in theory - as accurate and repeatable as a 4 jaw but as easy to use as a 3 jaw. Downside with those is that they're limited in the max size of stock they can hold and odd shapes are difficult or impossible to hold. Every tool has it's uses!
 
Thanks for the info mksj and Matt. Pretty sure I follow... just need some time to absorb it all so my head doesn't explode :)

Matt, the collet chuck sounded interesting so I took a look online. Wouldn't an MT5 to R8 adapter (if they make such a thing) accomplish the same thing?

Added the following

Learn by doing... installed the 4-jaw for the first time and now I see what you mean about dialing it in. Trying to adjust the jaws independent of one another makes me just want to put it back in the drawer... forever!

I also just found out, once the locking pins are installed on the chucks, they're too high to fit back in the tool cabinet drawer. The only drawer high enough (and not very large) is used for machine oil, way oil, spray cans, etc. The 3-jaw has just become my best friend :wink:
 
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you could use an ER collet chuck made for mills, but then you loose the ability to pass stock through the chuck and your spindle. Better to get one (or make one, they're not hard) made for the lathe. I really like the ER collet chuck I just finished making :)
 
Can I have it? :encourage:

Guess I'll just have to add it to the list. BTW, which ER collet set did you make it for? I would think the larger the better but it looks like they get pretty expensive.
 
sorry, it's sleeping under my pillow :) I used ER25 as that's what would fit the stock I had and the largest ER25 collet (16mm or 5/8) is already larger then the through hole in my lathe's spindle (1/2). For a 1236 I'd go with an ER40. More money, but you might as well make the most of the machine. Save up for some half decent collets though - mine are ok, some better than others, but definitely could be better.
 
Don't worry about leaving the DRO on, let alone turning it on or off.
I ran two wires to my mill and lathe. A 220v main for the machine, and a 20A 110v line that powers 2 outlets.
The outlets get used for accessories like the DRO, a lamp, etc. No need to turn them off with a master power switch unless you have kids.
The are no more dangerous than a refrigerator, you can leave them plugged, on or off, and ignore them like you do a toaster when not in use.

4jaw chuck are only crazy-making until you understand how to adjust them. I use mine more than my 3jaw, with a little practice it takes only a moment to dial one in. There are many YouTube videos showing techniques for it. Abom is the master of it, you boggle at how fast and accurately he does it. The basic principle is to work the chuck in opposite pairs of jaws.
The 4 jaw will hold the work more securely with less pressure than the 3jaw. This means that you will leave fewer jaw marks on the work, and distort parts less with the 4jaw. I mostly only use my 3jaw for lopping repeated parts off the same stock, or gripping hex stock.

On the subject of collets. Make sure you do some good research on the pros and cons of 5C vs ER collets. Both have strengths and weaknesses, and the ER system has many limitations. You can't get expanding collets, square or hex collets in ER. The stock must also be the full gripping length of the collet in ER. 5C on the other hand have an extremely small clamping range, but the above mentioned collets are available and you can clamp stock of any length in them. ER is meant for tool holding and has been adapted to workholding by some pros and hobbyist, so there is little support for work holding commercially. 5C is meant for work holding and there is a huge range of work holding options.
 
Thank you both for the info... really helped a lot.

At the moment I'm trying my luck at threading but something isn't right. I've read the "PM-1236 Threading and Feed Rate Directions" pdf manual and so far I understand how to set everything and change the gears when needed... so no issues there.

Now I'm reading the "Auto Feed" section on Pages 23-25 of the "PM-1236 Setup and Use" pdf manual. I went through the movements of each lever to see how it all worked and the only issue is when it comes to "crossfeed" travel... it doesn't move under power at all. No problem cranking it by hand (with the levers in the correct positions) but when I set the feed direction (either left or right), disengage the half nut lever (up) and set the feed engagement lever (either up or down), it won't budge. I can see the leadscrew turning... and the half nut is open so that's not the problem... but nothing else is turning that I can see. But it seems like the crossfeed screw is engaged with a gear because the crossfeed handle won't turn... which should be correct.

Any ideas/suggestions?
 
Your 1236 should have separate feed and threading screws on the front. If you can indeed see the leadscrew turning, then you have the threading screw engaged, not the feed screw (smooth shaft with a groove in it), which is what you need for crossfeed.
 
That helped get me in the right direction Bill... and I found the answer with a little more trial and error and some additional searching. Turns out it has to do with one of the knobs on the front panel which I set to "M" according to the threading instructions.... not knowing what it did. Turns out the M position activates the lead screw and the S position activates the feed screw. Didn't get my threading done but at least I learned something else today. Thanks for your help.
 
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