end milll in lathe chuck?

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SE18

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I've got some end mills but don't have an end mill chuck and don't have collets. For light cuts using a 9A lathe (South Bend) and mill attachment, could I temporarily use the 6" chuck or perhaps one of the smaller Jacobs chucks to hold an end mill until I can acquire some collets?

I'm guessing that chucks holding end mills are frowned upon by most b/c of the high torque exerted and the possibility of them spinning in the chuck and obviously, collets have a tighter grip and are generally more accurate.

My end mills are from Enco, HSS TIN, 2 and 4 Fl, 3/16-3/4"

Thanks

Dave
 
You guess right. Hardened chuck jaws do not grip hardened end mills well at all. If you must, take very light cuts and have lots of material available (you will destroy some). The mill can be pulled out of the lathe chuck and bury itself in the material being milled. Pay attention to conventional milling vs climb milling. Conventional only, which in the lathe means milling by moving the work from the front of the lathe to the back or away from the operator. Don't ask how I know this...

Chuck
 
You can but you have to watch out for the end mill actually being pulled out into the work. Collets are much the same way but with less runout and better grip than the scroll chuck. The best IMO is to make some end mill holders in the chuck you will be using to remove the runout (mark jaw#1 on the holder) and provide a better grip on a larger shank. Pretty much make them all from 1" stock. That is a simple and fun job/project.

Steve
 
Steve, end mill holders? My SB9 uses a sleeve to convert MT3 to MT2 (kind of a long story why the conversion is necessary but it's a short MT3).

So what would an end mill holder look like? I'm thinking you mean one end would be tapered to fit into the spindle and the other end would have an opening for the end mill shaft and some sort of key inside to fit the groove of the end mill shank to prevent it from spinning?

Anyway, I've got a whole variety of shank sizes of end mills to deal with.

The thought of a hardened end mill shank spinning in a hardened chuck jaws isn't too appealing
 
Chuck, to prevent climbing, say I'm using the crosslide feed. Wouldn't I need to feed the crosslide toward me?
 
... Agree with all the precautions about hill climbing!


BTW: Collets are not an ideal way to hold endmills as the bit can pull out or get pushed in -but worse yet, the bit can spin and end-up ruining the accuracy of your collet. Endmill holders are the way to go if budget allows. Endmill holders are available for standard spindle types like MT (Morse-Taper), R8 etc. I'm sure they're aviailable in straight shank -and think I even have a few someplace.

Also, holding endmills directly in the chuck jaws is a dicey proposition too for several reasons. I've never seen a chuck that had adequately square jaws to do milling. How do you indicate the teeth/flutes of an endmill to know if it's centered?
 
SE18 said:
Steve, end mill holders? My SB9 uses a sleeve to convert MT3 to MT2 (kind of a long story why the conversion is necessary but it's a short MT3).
Click to expand...

You'd just be making a straight shank end mill holder. Don't use the taper! it'll pull out unless you use a drawbar also. Just take a piece of say 1" stock and chuck it in the 3 jaw, mark where #1 jaw is, drill and bore to 3/4" (etc) and cross bore a set screw. Very little runout since it was done on your machine (no matter the chucks runout as long as it is indexed to the chuck jaws).

Here's a link to some MT endmill holders you'd just be making them with straight shanks of suitable diamrter for the EM.

Steve
 
You could buy straight shank EM holders but you'd be stuck at the accuracy of your chuck until you got a collet system to run them. If you just make them they will run very true because the bore will be centered even if your chuck is .020" out. If you ever do get collets then you just bore the other end of your home made holders. Then they'd run true on the chuck or collet if you mark the ends.

Some people like to run straight shank EM holders because they don't have to remove the collet from the mill to change sizes, though I am not that industrious.

Steve
 
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