Precision hole drilling?

[sp1nm0nkey]

I need to finish a hole to within 2 or 3 tenths oversize, will a ream get me this? The hole is 5/8s of an inch, so I don't know if they make hones that size, and I don't trust myself to lap the bore to size. Any suggestions?

[Pres]

The right size reamer should do it.
Unfortunately, some reamers are ground larger than that when they are brand new.

Lastly, a "rule of thumb" is 1/2 the rpm and twice the feed of drilling speed and feeds.

hth,
Pres

[fpworks]

I need to finish a hole to within 2 or 3 tenths oversize, will a ream get me this?

Your tolerance is +0.0002 to +0.0003, for a total tolerance window of 0.0001, so no, a reamer will not get you this.

Jig grinding or honing will. You may want to bore the hole undersize and send it out for completion.

[ZipSnipe]

A reamer will get you your 5/8 exactly. To get your couple of tenths honing might be the trick or boring bar but that would require some serious setting up.

[rounsy222]

I agree with fpworks. A reamer will work under the right conditions but some much depends on your setup and loading of the parts, you can easily lose you tolerance. Always better to error on the side of caution. Best of luck!!

[DareBee]

If it is critical you jig bore.
If you like to gamble (russian roulette style) use a reamer.

[laka]

Agreed. I dont think you'd get consistant results within a few tenths with a reamer.

[Ken_Shea]

Would sneaking up on it with an adjustable reamer be viable ?

Ken

[Geof]

Are you doing one hole or lots of holes...lots as in thousands? You are wanting 0.6252 to 0.6253 which is a tolerance of +/-0.00005 and more or less impossible with a reamer.

If you are doing lots you could look into ball sizing. This is a finishing procedure where you get to within .001 to .0005 below the final size by reaming or boring then expand the hole to the final size by pushing a carbide ball through it. The ball also puts a very fine finish on the hole which is needed when you are dealing with very small tolerances.

[MrWild]

I'm willing to bet this super high precision isn't even needed. There are good engineers, and there are clueless engineers.

[little bubba]

There is a 99% chance that your customer's QC can't measure it, and the print is crap is anyway, and 3/4 hole would work, so (assuming MOST of my customers) I would use a .625 reamer, and a -.625 and a -.626 pin and call it good. Heck, if sombody farts in the QC room(at a tenth tolerance total), the temp will rise and you're hole is sCRAP anyways.

I'm sure there are times when a single tenth is called for, I'm not equipped to do it and I won't, I hope you are getting paid accordingly.