Ground Drill Rod

[whimsnag]

It takes a TriMike to measure 3 lobed out of roundness, a regular mike will measure it without measuring out of roundness; also a vee block and dial indicator will detect it, but not measure for size.

This question is a bit off topic: is the cross-section a Reuleaux triangle?

 

[T Bredehoft]

How out of round did it measure?

I figured it had to be a bout .0005 I couldn't have cut much less than that.

Reuleaux triangle ? the points were round, does that qualify?

 

[RobertB]

I figured it had to be a bout .0005 I couldn't have cut much less than that.

That is within specs of most drill rod. Most in the 3/4" to 1" dia. range have a roundness tolerance of + or - 0.001"
If you buy shaft stock it is usually -0.001 to 0" ( no oversize). Shaft stock also has tighter straightness specs than most grades of drill rod

 

[Illinoyance]

The only sure way to check for lobing is a 120* vblock and a dial indicator. It can mike dead nuts for diameter in all directions. If it is lobed you will see rise and fall of the indicator when the part is rotated in the v-block

 

[epanzella]

I put the extra piece of drill rod on on v blocks and it had lobes about .0007". What is the point of grinding this stuff if it's not round when they're done?