View Full Version : Looking for some info on disassembling a knee mill spindle.

l u k e
04-30-2013, 05:58 PM
I have a 10 year old Grizzly knee mill that has something broken in the spindle assembly. It does not feel like a bearing as the mill still works and sounds fine. The problem is when I do a "Z" move up or down something in the assembly seems to slip, grab and bind up. You can on occasion move the spindle up and down rapidly and everything slips loose and back into place and works for a short time.

I would like to tear into it but can seem to find any instructions anywhere. I really dont want to start ripping it a part as possibly doing way more than whats necessary.

Can anyone point me in a direction to get me started? Thanks.

04-30-2013, 06:11 PM
Call Grizzly. They have a great tech support dept and I recently was able to purchase gears for my 16 year old horizontal bandsaw. They should be able to at least supply you with an exploded parts diagram. Did you look online? They had my bandsaw parts diagram on their website.

l u k e
04-30-2013, 06:28 PM
I have a diagram but it really does not explain how to dissemble it. For instance, can I remove the motor and pulley assemble as a unit? I'm really just looking for a few pointers to save some time. ;)

04-30-2013, 07:04 PM
I guess it would help if we knew what the machine looked like...Is it a Bridgeport knockoff?

l u k e
04-30-2013, 08:18 PM
Like the post above says, a Grizzly Knee Mill.
I went ahead and started tearing it down, got down to the low speed gear and cant remove it. Need a tool of some sort, cant make one cuz the mill is in pieces, might have to buy a strap wrench or something...

05-01-2013, 06:33 AM
Like the post above says, a Grizzly Knee Mill.

They have been making various models for over 20 years....forget I tried to help.

l u k e
05-01-2013, 09:45 AM
I didn't mean to offend, I figured there two designs when it came to knee mills, belt or variable speed. I didn't know they went through radical changes in drive and spindle design.

Its a G4027

05-01-2013, 02:03 PM

You don't need to take any of the top part of the mill apart to do just the spindle, You can take the quill out from the bottom, just disconnect the quill lever, & the quill stop, there may be some other parts to take off on your mill, but should not be much more than I have said, Then slide it out, you will have to tilt the head in the X axes so you have enough room the slide it out

05-01-2013, 03:43 PM
I see it is a step pulley. I only have a BP manual for the 2J head. I can PDF that to you if you PM me your e-mail. The lower end of the head should be the same anyway.

l u k e
05-01-2013, 03:52 PM
I have the top end off, I need to make a strap wrench to get the low rpm gear off. I tried various way and I cant lock the pulley down to break the nut loose.
Thanks for the heads up on the quill mactec.
I'll let you know polar if I need that PDF.

So far it's pretty straight forward, if I get stumped I'll post up, thanks.

l u k e
05-01-2013, 06:46 PM
I got the nut of the low RPM gear (impact wrench, duh), do I need a puller to get the gear off?
I don't want to mess with it too much because it's aluminum, it does not seem to want coaxed off with a pry bar.
Any ideas?

05-01-2013, 07:18 PM
Heat the pulley around the shaft and use some penetrating oil and you should be able to coax it off, if not you might need to use a gear puller.

Sent from tapatalk

l u k e
05-01-2013, 09:12 PM
So the heat worked great to get the gear and cover plate off.
After that I was studying the diagram trying to figure out what all needed removed up top in order to remove the spindle. And realized that the bearings and sleeves that I believe need replacing are actually in the upper head/hub assemble that is part of the pulley drive system, which was already removed. I had originally believed it to be inside of the head. So I ran the spindle up and down in Z and there was no binding or grabbing. :idea:

My theory is I have a busted sleeve(s) and or a bearing. Although the "feed back feel" is that a sleeve(s) is broken. I'm not sure why I think that but that's what I thought even before I looked at a diagram and started dis-assembly.

I'm going take that assembly apart tomorrow before I strip it any further.