Ground Drill Rod

[epanzella]

I got a hunk of 7/8" ground drill rod and a pillow block for an indexing stetup on my new HF round column mill. I was disappointed to find it straight but it wasn't round. It would jam in the bore of the pillow block jet still wiggle side to side. I spent an hour and a half stoning the rod to the PB bore last night and I still have 4 inches to go. The fit is perfect now but I thought buying ground rod would spare me this task. I guess I'm asking what can I expect from "ground drill rod" as far as size, straightness, and contricity.

 

[T Bredehoft]

It is "centerless ground". This leads to it being "tri-lobed". I have a piece of 3/4 O1 Drillrod I turned just a tiny bit off from,it still measures .750, but you can see where the piece wasn't truly round. You want "Thompson rod" for your project. It is round.

 

[Latinrascalrg1]

.. please delete

 

[RobertB]

How out of round did it measure?

 

[Bluedog]

I just finished a project with pillow block bearings and I used 303 SS bearing shaft in 5/8” and 1” from Speedy Metals. It worked well.

 

[RJSakowski]

When buying precision stock, it is wise to look at the tolerance specifications. For example precision ground flat stock usually does not specify flatness. Assuming that it is flat can cause some serious problems. In the case of drill rod, a diameter spec. does not necessarily mean that there is a roundness spec. The trilobar material that Tom mentioned can have a fairly tight diameter spec. but a poor roundness spec.

 

[benmychree]

How out of round did it measure?

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.

 

[epanzella]

I stuck a dial caliper on there but couldn't really measure anything off. I knew it wasn't round because I could stick it a half inch into the bore of the pillow block with it totally jammed and it could still wiggle side to side. Anyhoo, I'll finish stoning it tonight. Thanks, all!
Ed P

 

[Tinkertoy1941]

For precision Shafting I use 1045 Turned,Ground and polished in 22 foot length from Alro Steel and a bearing will slide the 22 foot length every time!!
It is worth the little extra cost that the labor cost to make a egg shape shaft work.!

 

[epanzella]

Another half hour tonite and the bearing slides end to end smooth as glass. I wasn't looking forward to stoning that shaft but I guess the other options are a lot more $$$. The 3 ft of 7/8 drill rod was about $25 as I recall.