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Drill rod swelling?

I needed a 1" shaft 14" long in a hurry. I picked up a 3' length of 1" O-1 drill rod at my local machine shop supplier. One end of the 14" gets a

5/16" x 2" keyway and the other end gets a 1/2" x 20 tpi tapped hole off-center by .200". We go to put the shaft into the 2 pillow blocks and...the tapped hole end has swollen by .004" in the last 2". This might have been the factory end, we don't know as is was cut and faced by one of the techs. Could drilling and tapping the hole have swelled it? It never got hot. Or could it have come that way? Never seen this kind of thing before and drill rod has always been dead on for me. I know it's not super shafting steel but gee, it's less than 100 rpm and short. Overkill if anything. We filed and polished it down but we're still wondering. It seems like I'm getting more than my share of problems with things that I should take for granted. (Gunner Luck...Arrrggghh)
Reply to
Tom Gardner
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Drill rod is available both ground to close tolerance and ground to remove decarb. The tolerance on the decarb-free is pretty loose on the plus side.

Ned Simmons

Reply to
Ned Simmons

"Tom Gardner" wrote in news:lCRyg.77282$ snipped-for-privacy@newssvr12.news.prodigy.com:

Tom, It is possible the machining could have deformed the rod some. It was probably not so much oversize as it was oval.

Reply to
Anthony

Are you sure you didn't use Ground All Over (GAO)? It's way cheaper than drill rod, but available in the same grades of steel. The diameter is less accurate. I often buy it in 12 Foot lengths.

Steve R.

Reply to
Steve R.

It could have been the tapping operation. 1/2" hole in 1" shaft .2 off C/L gives .15" wall. Should be OK but if the tap's not too sharp or fluteless type, it could cause it. Too late to measure now but it may have been oval as suggested..

John

Reply to
John

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