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View Full Version : Dowel pin extraction from B'Port crank



Bill Hopcraft
04-07-2010, 11:53 PM
Ever have something that's bothered you for years and then the day finally comes when you have to do something about it? That's me and one of the x-axis cranks on my Bridgeport. The crank barely engages and only with constant pressure can you use it to move the table. I just couldn't stand this any more! Looks like the problem is twofold: first, the dowel pin on the backside of the crank barely protrudes enough to engage the slot in the collar on the feed screw. Second, the slot in the collar is worn, apparently from the pin always slipping free from it. I can easily repair the slot by grinding it square. The pin is another story. It needs to be pulled out, but it's in a blind hole. There's not enough of the pin exposed to attempt grabbing and pulling. Any ideas? I really don't want to drill into the crank from the other side.

lakeside53
04-07-2010, 11:55 PM
Drill it, tap, insert a decent (like grade 8) hex socket machine screw and either jack it out or use a slide hammer.

Bill Hopcraft
04-08-2010, 12:12 AM
I'm worried that the pin is too hard to do this.

ADGO_Racing
04-08-2010, 12:25 AM
Pins are usually case hardened, not through hardened. It may be good to use a carbide drill to get started, or grind some off the end first before using a HSS or cobalt drill. But the core is usually tough, but not hard.

Machinist-Guide
04-08-2010, 12:45 AM
A trick we use at work to pull broken dowels from die sections.If you have a Tig welder or know someone that has one. weld a small screw to the dowel and attach the slide hammer to the screw.