seriously stuck drive center

[Chris Haas]

i was looking at an older general 26020 today, and came across a problem, the drive center looks like it hasnt been removed for years, and it is frozen in.

after beating the back of a makeshift knockout rod repeatedly, i still saw no progress. question is, once your convinced you cannot knock it out, what is the next step?

heating the spindle threads?
anyone ever done this?

just looking for some insight. thanks, Chris

[alex carey]

get a bigger knockout rod.

[Mike Campbell KS]

I've got the same situation with an old Craftsman tube lathe that wasn't used since the gentleman who owned it passed away in 1984. I want to make it into a permanent buffing station. I have tried beating it with a hammer, and soaking in penetrating oil, but nothing has worked yet.

[Chris Haas]

Im a carpenter, and i was hitting the knockout rod with a 24 oz hammer hard, and i mean hard. so i dont think hitting harder and bigger knockout bars is the way to go, not without perminant damage that is.

[Mike Golka]

Heat the drive center, not the spindle. This will cause the drive center to expand but because it cannot expand in all directions, the spindle prevents that, it will only expand in the direction not restrained. When it cools it will contract evenly and that should free it up. Remember the trick is to put more heat into the center than the spindle. In my trade as a welder I have used this method many times to free frozen metal items.

[Robert Snowden]

You can also use dry ice to shrink the the drive center.I have used propane to shrink metal.

[Richard Madison]

Excessive hitting may indeed result in need for new spindle bearings. Good luck with Mike G.'s suggestion and please report back. Sounds like it could work like the proverbial charm. I needed this idea about 7 years ago with a piece of farm machinery.

[Steve Vaughan]

Heat on the end of spindle is what I was thinking too. I'd think though, be sure to let it cool completely before trying to knock it out...maybe the dry ice trick would work to take it from the most expanded size to the most reduced size before you beat on it. Good luck!

[Bob Boettcher]

Here is some data on rust busters that you may find helpful.

From the April/May 2007 edition of Machinist’s Workshop. They tested various penetrating oils and measured the force required to loosen rusty test devices.

The best one was a 50/50 mix of Automatic Transmission Fluid and Acetone!!!!!

Penetrating oil Avg. Load Price per fluid ounce
None 516 pounds 0
WD-40 238 pounds $0.25
PB Blaster 214 pounds $0.35
Liquid Wrench 127 pounds $0.21
Kano Kroil 106 pounds $0.75
ATF-Acetone 53 pounds $0.10



Bob

[Dan Henry]

Chris See if you can get some Kroil oil. it will do some very serous losing of frozen rusted parts. We used to use on old airplanes that had frozen bolts and bearings. Use an air impact tool on the knock out bar, the vibration seams draw the oil into the joint, it may take a day or 2 for it to work.

Dan

[Don Geiger]

Before you start beating on anything and taking the chance of ruining the bearings, I think sparying PB Blaster into the spindle and around the MT of the drive center would be a good start.

I have restored a couple of old cars and always rely on PB Blaster to penetrate tight nuts and bolts that haven't been turned in 50+ years. I always apply it a couple of hours before I try to loosen the nut or bolt. I think it works better that other brands.

PB Blaster is available at most automotive parts stores.

[Jim Underwood]

The other thing that hasn't been mentioned here, is that besides impacting your bearings, a heavy beating might "mushroom" your center, and tighten it even more. Does that happen?:confused:

Sounds to me that the heating/cooling trick might be the way to go.

[Dennis Ford]

At this point, its probably too late to worry about the bearings, they need replacing. Heating the drive center as mentioned should work. As far as penetrating oils, plain old diesel fuel is hard to beat. If you take the headstock off and position it so that you can fill up the spindle with diesel, that will help a lot (after a couple of days).

[Steve Mawson]

I had a spur center stuck and put the spindle in a press to remove. Of course I had to remove the spindle from the headstock which took a little time and then replace after I got the spur center out. I dont use the spur center to start bowls any more.

[Rich Aldrich]

I agree that the bearings should be changed. It makes me cringe seeing people pound on bearings - it initiates bearing failure because the force is transmitted from the inner race through the rollers to the outer race.

I would disassemble the headstock. You can then use a press to push out the stuck drive center. The inside of your headstock can be polished up before you reassemble.

Normally, the rotating race is press fit and the stationary race is a loose fit. To press the inside race on, you press on the inside race only. Do not push from the outside race or you damage the bearing to start. The same goes for the outside race. Although the outside race is normally loose, we are talking 0.0005 to 0.0015 on most of these smaller size bearings, so it is difficult to get the race lined up square so it just slides in.