Chuck Removal for a BT800

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TechTony
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Joined: Wed Aug 31, 2016 7:11 pm

Chuck Removal for a BT800

Post by TechTony » Sat Sep 03, 2016 7:59 pm

Watched a youtube vid on removal of an MT3 arbor, broke out the drift, locked the mill head in the down position, and tried to slot the drift. It won't go in. Was able to take a look in the slot with a flashlight and was able to confirm that the head was aligned correctly and the interior hole was aligned with the exterior hole. In the center of the shaft it looks like a piece of vertical all thread and it completely blocks any ability to slot the drift. Ideas?

I also reviewed the exploded diagram on Bolton's site and didn't get any insights... not real sure how to proceed but I gotta get this chuck out. I hate to do it but I might have to use a wrench and a deadblow directly to the chuck unless someone here has some wisdom to share....

TechTony
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Re: Chuck Removal for a BT800

Post by TechTony » Sat Sep 03, 2016 9:00 pm

Exploded view - just in case it helps...

http://www.boltontools.net/pdf/BT800.pdf

spro
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Re: Chuck Removal for a BT800

Post by spro » Sat Sep 03, 2016 9:08 pm

That is your drawbar or part of it.

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10KPete
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Re: Chuck Removal for a BT800

Post by 10KPete » Sat Sep 03, 2016 9:23 pm

I looked at the drawing; no help.

Based on what you describe, it sounds like you have a draw bar down through the spindle. That would make sense for a milling machine. The slot you describe would be for using the drift on a MT3 shank drill with a tang; common for a drill press.

Since this is a mill-drill head it all makes sense, except the drawings don't show the draw bar!

So, look at the very top of the spindle. Remove covers if you have to. If you see a hex, like a bolt head, up there, about 9/16" or 5/8" in size, hold the spindle and loosen the bolt head. I will be a right hand so turn anti-clockwise. If it loosens, remove it completely. Now look in the slot. If the "all thread" is gone we have winner!

Pay attention now!!! Screw the drawbar back in all the way and hand tighten. It should engage 6 or more turns. If it does, then
loosen the draw bar no more than 1 1/2 turns. Use a fairly heavy soft metal hammer, say two or three lbs., and give the top of the draw bar a sharp rap. The arbor should pop out of the spindle. This is standard with MT milling spindles. DO NOT haul off and bash it with a huge hammer!! A sharp rap is the ticket. If you don't have a copper or brass or lead hammer then put a bit of same or aluminum on the top of the draw bar as a pad, then hit the pad.

Now, since it's never been out it may take a couple of tries with harder hits each time, to get it to pop.

When it's out, clean off any gunk the factory put on/in there and when you re-assemble it lightly oil it. Make sure to tighten up the draw bar pretty snug.

Pete
Just tryin'

TechTony
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Joined: Wed Aug 31, 2016 7:11 pm

Re: Chuck Removal for a BT800

Post by TechTony » Sat Sep 03, 2016 10:06 pm

So.... I followed your instructions and they were close enough that I was able to figure it out but yea ---- the drawbar bolt head exists.... but it's threaded into the top of the MT3 shank! So fully removed the bolt and the arbor fell right out. So thanks for the assist.

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10KPete
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Re: Chuck Removal for a BT800

Post by 10KPete » Sun Sep 04, 2016 12:14 am

Yes, the drawbar is what hold the chuck shank in tightly. It also holds in MT3 collets. Which, by the way, are fairly inexpensive and hold very tightly! End mills just don't stand a chance of coming out of a MY collet unless something is wrong.

When properly tightened, a collet or tool shank should NOT fall out on it's own! When you put it back in make sure to tighten up the draw bar!

Good luck and happy machining!!

Pete
Just tryin'

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