Let me start by saying Hi everyone!

I'm new to machining but have studied metal work for quite some time yet still can't seem to get by stupid little (not really that little) issues...

I currently run a Jet JMD-15 15" mill drill and during the milling process, despite 15 researched attempts to correct this, the chuck drops off the spindle.

Can anyone tell me why this is happening and what i can do to correct this? It's an r8 spindle taper and to my knowledge the chuck can't be pressed on...

Any help would be greatly appreciated.
Thanks
~Ryan

Are you using a drill chuck to hold the cutter? You say it has an R-8 taper. Why aren't you using an R-8 collet to hold it?

Are you using a drill chuck to hold the cutter? You say it has an R-8 taper. Why aren't you using an R-8 collet to hold it?

I'm using what was supplied with the mill... having looked through the manual again I just noticed it said "1/2" Drill Chuck..." I'm guessing it's a drill chuck lol.

thanks for the quick response
Ryan

Do not use an endmill in the chuck.

Clean the morse taper. Put a block of wood on the empty chuck and whack it with a hammer. That should seat it.

CR.

Do not use an endmill in the chuck.

Clean the morse taper. Put a block of wood on the empty chuck and whack it with a hammer. That should seat it.

CR.

I'm more interested in using it to mill instead of drilling (I have a separate drill press). Is the process the same for seating a collet?

No, you can't hold endmills in a drill chuck because drill chucks can't take side force. You need a set of R8 collets. Do a search on eBay or buy them from Enco. They're not expensive. There are literally millions of them out there. you only need the ones that you expect to need to hold the cutters you'll buy: 1/8, 1/4, 3/8, 7/16, 1/2, 3/4.

They look like this. There is no 'chuck'. The shank is held inside the spindle.
http://www.tormach.com/picts/product_picts/TTS/R8collet.jpg

The R8 collet will seat with a drawbar--Just like your chuck does.

There is also another option, the end mill holder. You get a set of endmills with the same size shank and they ALL fit one holder. The Tormach quick change system, (R8) which allows constant length, can use special collets or these end mill holders:

http://littlemachineshop.com/products/product_view.php?ProductID=2438

A 1/4, 3/8 and 1/2 will hold most end mills quite reasonably.

CR.

I think he's got the chuck coming loose from an R8 arbor. The Jacobs Taper on the drill chuck end probably isn't perfect either (making the grip weak).

I've had to hand lap some of the Chinese ones I've bought over the years. They'd even come loose when pulling a drill back out of a hole.

It looks like the guys have missed an obvious point. To remove the chuck "arbor" you will need to loosen the draw bar at the top of the spindle. That would be the hex at the top of the mill. Unscrew it about 1 or 2 turns and bop it with a solid hit (ball peen hammer onto a piece of aluminum scrap) this will unseat the arbor. Continue to unscrew the hex bolt at the top of the spindle and catch the arbor as it drops out the nose of the spindle. Now install the collet and darw it into the spindle with the cutter in place. This needs to be snug but not macho tight. The hex can break away from the draw bar if overtightened.

Hope this helps.

Thank you all for your help. As soon as i can give it a try I'll let you know what happens.