View Full Version : Brain Teaser

Dave Opincarne
05-12-2003, 12:57 AM
Talking about pressing studs reminded me of this situation. A lot of you may know the answer so please give the other guys a chance to chew on it. I'll get back with the answer.

True event: I had to replace a couple of bushings in an aluminum layup mold used for locating index points on a composite part. The bushings were steel press type open ended (forget the designation) with a .025" ID and a .375" OD. As I said they were open ended (open at the bottom) but the hole in the mold was only slightly deeper than the bushing so there was no way to catch a bottom lip and pull the bushing out. I didn't have a welding setup available so I couldn't run a bead and shrink the bushing either. No thermal expansion was used either. It took me about 15 minutes to get the bushings swaped out. Any ideas how it was done?


05-12-2003, 01:42 AM
Fill the bore with grease or heavy oil and wack in a tight fitting punch.
Or clean the bore and loctite in the smooth section of a tight fitting stud and jack out with a nut and spacers after curing.

05-12-2003, 02:12 AM
A way to catch the bottom lip would be:
drill center hole in end of threaded stud or piece of threaded rod. Slip some spacers over rod and thread on nut. Drop an appropriate sized ball bearing into the bushing. Place rod in hole. Pound on rod so ball bearing enters center hole and expands end (like a Minnie Ball) then jack out with nut and spacers.
Why didn't I think of that! http://bbs.homeshopmachinist.net//smile.gif

Doc Nickel
05-12-2003, 06:05 AM
The grease-and-punch trick to hydraulically remove busings from blind holes is an ancient hotrodders' trick we probably learned from some old-timey machinist who in turn probably learned it from a competent blacksmith.

If the punch fits tightly enough to the bore of the bushing, almost all the force of the hammer blow is transferred to the grease, and therefore the bushing. I've only used the trick twice- once years ago pulling the clutch bushing from a small-block Chevy crank, and slightly more recently to knock the hardened and tapered indexing pin seats out of an old Logan lathe turret.


G.A. Ewen
05-12-2003, 07:42 AM
Did you thread in a 5/16 tap? http://bbs.homeshopmachinist.net//wink.gif

05-12-2003, 10:23 AM
If I understand what you are doing I would uas a slide hammer with a screw on the end and pop it out.

The grease and punch solution works well in removing pilot bushing in the end of crankshafts. Have done that many times.

Dry ice will shrink the bushing and it will fall out.

"There are many ways to go to town and they are all right".


05-12-2003, 01:13 PM
I'd second the option of tapping and using a slide hammer. I have found over the years that a hammer can be your best friend in many jobs (I must have over 2 dozen different types).


05-12-2003, 05:15 PM
Geez you guys are dumb - its a trick question. Get the chainsaw... http://bbs.homeshopmachinist.net//biggrin.gif

Dave Opincarne
05-12-2003, 06:54 PM
Thrud got it. That was ment to be a puzzler (ala car talk) for entertainment purpouses. Yea, grease and a pin. You guys are to damn smart.

05-12-2003, 07:42 PM
OK thrud, if you don't have a chain saw, and the hole is a thru hole but with a shoulder and bushing such that you can't use hydraulic pressure, or your welder or a puller behind the bushing...How the heck do you get it out then(the bushing)? I've done this through distructive means, but never have I been able to save the bushing.

By the way I learned both the welder trick and the hydraulic pressure trick from a farmer. The chain saw I've learned to stay away from due to a friend who seems to cut a body part everytime he picks one up.


05-13-2003, 05:10 AM
All the suggestions are good - I have used the grease and punch one on my Billet flywheels too remove the pilot bearing safely.

Sorry to hear about your friend - good thing he isn't into explosives if he is that sloppy. I was actually joking about the chainsaw. http://bbs.homeshopmachinist.net//biggrin.gif http://bbs.homeshopmachinist.net//tongue.gif I just did not think Dave would cave that fast...

I have seen hardened bushings removed with plasma cutters that were installed using heat/shrink fit with Liquid Nitrogen on the bushing and propane torches on the housing. This was in a German made pile driver. Definately destructive. (cool!)

[This message has been edited by Thrud (edited 05-13-2003).]

Dave Opincarne
05-13-2003, 07:31 PM
I didn't intend to cave, I guess I didn't make it clear I'd already solved the problem and was posing the question as a puzzle. Judging by the number of quick resposes I guess it was a little too obvious. Sorry


05-14-2003, 01:17 AM
Aw, I didn't get to this one quickly enough. I would have used a barbeque lighter, fed some gas into the bushing, then hit the spark. I probably would have done this many times before finding some other way.

05-14-2003, 04:38 AM
A more entertaining http://bbs.homeshopmachinist.net//biggrin.gif way to remove bushings would be a method of removing broken taps and drills that I read in "Standard and Emergency Shop Methods" by Colvin and Stanley; pack the hole with dynamite. http://bbs.homeshopmachinist.net//smile.gif

This was actually done during WWII production and worked very well on large forgings.

[This message has been edited by yf (edited 05-14-2003).]