[kreativjustin]

I have had the reamed hole come out smaller on me twice now. Once was a .501" and this time was a .376". Both times the part was at least 2" thick. I can start the dowel pin in for the first 0.5"-1" then it gets progressively smaller.

My feeds and speeds are SFM - 15 and Feed at 0.008" IPR. My pre-drill was a "T" HSS, or .358" - I am drilling/reaming this in A2.

I do not normally ream that deep unless the pin has to pass thru the entire part.

Am I not pushing hard enough, or what? I do not remember having this issue on anything less than 1", so it's kind of mind boggling right now.

Any help is appreciated!

Cheers,

Justin

[mactec54]

I have had the reamed hole come out smaller on me twice now. Once was a .501" and this time was a .376". Both times the part was at least 2" thick. I can start the dowel pin in for the first 0.5"-1" then it gets progressively smaller.

My feeds and speeds are SFM - 15 and Feed at 0.008" IPR. My pre-drill was a "T" HSS, or .358" - I am drilling/reaming this in A2.

I do not normally ream that deep unless the pin has to pass thru the entire part.

Am I not pushing hard enough, or what? I do not remember having this issue on anything less than 1", so it's kind of mind boggling right now.

Any help is appreciated!

Cheers,

Justin

Is, your reamers carbide, don't leave so much for the reamer to take out, you could lap the hole from the back to get it the right size for a fix

Does sound like your readers are worn, A2 can be tough on reamers

[kreativjustin]

I forgot to put that I am using HSS reamers. I did lap the back end to get it to slide thru nice, but just an extra step unfortunately. On the good note, I am a tool maker, so I am not having to lap a lot of parts. It had to be tenths of a thousandth, because they opened up really quickly. I'll throw in a new reamer and see if it does the trick. There was 2 .376" holes on this part, and they both did the same thing.. I was always taught to, and have practiced it for the past 10 years, to give around 1/64 for reaming. Just not used to reaming that deep, normally I would wire EDM the holes on a part like this.

[mactec54]

I forgot to put that I am using HSS reamers. I did lap the back end to get it to slide thru nice, but just an extra step unfortunately. On the good note, I am a tool maker, so I am not having to lap a lot of parts. It had to be tenths of a thousandth, because they opened up really quickly. I'll throw in a new reamer and see if it does the trick. There was 2 .376" holes on this part, and they both did the same thing.. I was always taught to, and have practiced it for the past 10 years, to give around 1/64 for reaming. Just not used to reaming that deep, normally I would wire EDM the holes on a part like this.

If you know what size your drills are making the hole, you only need a max of .008" for the reamer, I use most of the time between .005' and .006" I use carbide reamers some HSS but never leave more than .006 in a hole though, yes in the old days they left a lot for the reamer to do, but is not need, just wears the reamer out a lot quicker, you can also ball burnish the holes if they are under size, much quicker than lapping, I have a range of .0001" reamers under and over to get the perfect size hole

[kreativjustin]

Nice I'll start going a little smaller on the drills. Thanks buddy!

[mactec54]

Nice I'll start going a little smaller on the drills. Thanks buddy!

Bigger less material to remove for the reamer, do some test holes with different drills and check the hole size

[metalmayhem]

I have had the reamed hole come out smaller on me twice now. Once was a .501" and this time was a .376". Both times the part was at least 2" thick. I can start the dowel pin in for the first 0.5"-1" then it gets progressively smaller.

Are you measuring the holes , if so what is the difference between top mid point and bottom . On a depth of 2" I'd suspect tool wander . You'd be best off doing that with a boring head , or at least take a rough cut with a boring head to straighten up the hole before passing a reamer through

[kreativjustin]

I did not measure the hole, but I was able to tap the dowel pin through with a punch, and it took very little to no effort to do so - it just was not a slip right thru like it should have been.

This time around I threw a U drill in there (.368) and it came out fine all the way thru. Thanks!