R-8 Self centering chuck for a mill?

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negatronix

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Hi! I am looking for some help with a R-8 Self centering chuck.

I have seen mini-chucks available at Shars/Grizzly and am curious if I can expect one to work for me and my basic needs. Is it possible to really clamp down tight with a mini-chuck.

I am looking to take 1-1/2" solid round 4130 and make some bungs for tierod ends on a suspension project. The bungs will be 2" long, have a 5/8 -18 threaded hole through the entire length of the part, and be stepped to fit into a piece of tubing.

Are there any R-8 adapters that would allow me to buy a 4" or 6" self centering chuck and bolt it up for use on my mill.

Sorry for the total noob question. I am just starting out, and have much to learn.

Thanks,
-Kory
 
I would recommend a set of ER-32 collets and they will definitely hold it tight and centered. That Is the best way to do it and will give you consistently repeatable result if you are making more than one. I got my ER-32 set for my MT2 machine pretty cheap and it works great!!!

Bob
 
Don't worry about the questions, they are the cure for noobism :)

So, in essence, you want to use your mill for an vertical lathe, with cutting tools held on the table or in vise.....right? I can't say I'd be too crazy about doing that. Chucks can be had with a variety of mounting systems, but I don't think an R8 is made. Of course, the beauty of machining is that many times we can simply make what we need or want. To adapt a plain back lathe chuck to a mill you would need to do some lathe work. I am guessing you don't have a lathe yet, hence this situation.

If you did manage to cobble something together, bear in mind that it would be very light duty and limber. Mill spindles are built differently than lathe spindles.
 
I've also never seen a commercially made R8 adapter for a lathe chuck (until now ↓) but I have seen chucks used in mill spindles. But usually not that big, probably 3-4" might be ok. A 6" chuck seems way to big & heavy for an R8 spindle to me.
 
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Another option if you have a boring head for your mill you can install the boring bar facing inwards and turn the part that way.
 
kd4gij said:
Er40 only goes 10 1 1/8".
Click to expand...

I'm sure you meant 1-1/8" but I maybe you were thinking of 5C? Normal max capacity for ER40 is 1.00" for standard & 26mm for metric collets. However Maritool does make "special range" collets larger than the normal range that go up to 1-3/16" for standard & 28mm for metric. They are the only ones I have seen that make "oversized" ER40 collets.
 
I've lathed on my mill. The finish could have been better, but it worked. I suggest that rather than mounting a chuck you make a mandrel and mount your part by the center hole. Drill and tap the part, screw it onto the (threaded) mandrel, and lock it with a nut.
 
That's a new one on me too. I'd still be a little leery of the duty rating, especially on a benchtop machine.
 
I am not shure where we ordered them from and there is no room for a size stamp but we had 10 er40 collets that a will hold a 1 1/8 gauge pin or a 28mm pin. Where ever thay where ordered we got them in 3 days. Now thay could of come from the machine manufacture. I worked on rotery transfer machines.
 
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