Reamed hole diameter accuracy

[metman]

I believe that expected hole size for a reamed hole is + - 0.0001" diameter varience from actaul measured reamer diameter for less than 3/4" dia.

For example: If I use a High Speed Steel or Carbide tipped reamer that measures 0.6250" and ream a hole thru 1/2" thick 7075-T651 with proper reaming technique (slow rpm and minimal dwell time in the hole), what will be the expected actual final hole size limits?

No guesses allowed. What has been your actual experience.

 

[damc]

The tolerance for the manufacture of most types reamers are not as close as the tolerance you wish to hold. For example,according to ANSI B94.2-1977 a .625 chucking reamers outside diameter is +.0001 to +.0005.
My experience has been to allow .001 for reaming holes unless extra care is provided such as guide bushing, piloted reamers, floating tool holders etc.

 

[metman]

txi,
Thanks for for you reply. I especially appreciate yoour comment about the drill bushing. That sounds reasonable but I am looking at this from a slightly different angle.

We have a hole approx 5/8" dia with toltal tolerance of .0007". To achieve this they are single point boring which is very tedious and time consuming. I believe that this could be accomplished more efficiently by raeming with an accurate reamer.

Let me restate the question:

For example: If I use a High Speed Steel or Carbide tipped reamer that measures 0.6251" eexactly and ream a hole thru 1/2" thick 7075-T651 with proper reaming technique (slow rpm and minimal dwell time in the hole), using a guide bushing, what will be the expected actual final hole size limits?

Jesus is THE life,
Leonard

 

[damc]

Is you tolerance .625 +.0007 or .625+-.00035. If it is +.0007 you should be able to hold it with a bushing and possibly without one. .624 Dia. reamers are readily available and may put you in your tolerance zone.
Another possibility is having a reamer ground to suit. It would certainly be more efficient than boring.
Dowel pin reamers are made to a minus tolerance.A good Cutting tool Distributor should be able to get you what you need. STAY WITH TOP BRAND NAMES.