reamer vs core drill whats the difference?

rickseeman · Jul 31, 2018

I have some reamers and I have some core drills. (Some core drills are 3 flute some are 4, I don't know the difference.) When do you use one vs the other? I'm thinking you drill to a 64th under and then ream. And maybe with a core drill you can have leave more to remove than that. Thank you for your help.

michiganbuck · Jul 31, 2018

Also core drills have more back taper so they can get hot and not stick with a heavy load job.
Back taper is getting smaller diameter going back away from the end.
Core drill are often used to open a hole and to open a pair of holes as in an assembly of two parts..
Cores are often used to size a drilled hole to a loser spec than would be a reamed hole.

Reamers with less back taper can hold close to size for a longer time and endure more re sharpinings with not losing much OD size..
Reamer might lose .0002 diameter in the first inch so to be a loose fit reamer as brand new and a tighter fit reamer perhaps 1 1/2 inches back, but still usable if needed.

Tyrone Shoelaces · Jul 31, 2018

I thought another use of a core drill would be to open up a cast hole in a casting.

Regards Tyrone.

sfriedberg · Jul 31, 2018

Maybe obvious, but I'll say it anyway. Reamers are a finishing tool. Core drills are a roughing tool. If you have a cast core to clean up, core drill it to just under finished size, then ream to finished size.

Core drills can take a very large chip width (DOC), just like a regular drill. I prefer to keep reamers to a 0.005" chip (radius, each side), although I have taken 0.010" (radius, each side) with a reamer when I didn't have a better-sized drill.

CalG · Jul 31, 2018

throw a bridge reamer in the mix for "completeness". They are used to match holes for the insertion of red hot rivets.

Core drills are often used to complete the drilling of oil passages etc, in iron castings such as crakshafts. That is, drilling down through the rough "core" passage that had been cast into the part.

John Dunn · Jul 31, 2018

Used both, one after the other, replacing integral cast iron valve guides in the 70s. Core drill had a pilot section to follow the old guide and reamer finished to size for press fit replacements.

tnmgcarbide · Jul 31, 2018

the difference is that one is a DRILL - a roughing tool. made to accomodate bolts
and such. finds it's center in a cast or otherwise located hole. typically
i expect to be +.010 oversized, sometimes the location may be sketchy in the first place. very robust and doesn't care that the centering is sloppy.

a reamer is a finish tool.... no chip clearance to misalign the thing .

thermite · Aug 1, 2018

tnmgcarbide said:
the difference is that one is a DRILL - a roughing tool. made to accomodate bolts
and such. finds it's center in a cast or otherwise located hole. typically
i expect to be +.010 oversized, sometimes the location may be sketchy in the first place. very robust and doesn't care that the centering is sloppy.

a reamer is a finish tool.... no chip clearance to misalign the thing .

+1 "Core" drill was originally the literal term. It HAD TO HAVE the "cored" hole in a casting as a starting point, or it could not "go". Those holes were near-as-dammit ALWAYS of variable surface and variable hardness.

The casting holes WILL do their best to wedge (cored holes have draft angle to them..) or otherwise tear the s**t out of a normal helical twist drill, and DID so when the best one had to-hand were only HCS drills.

Or when one knows better, but is pushing yer luck, even with decent HSS. The 10EE base casting ate one of my 3/4" Silver & Demings just the other year whilst cleaning-up for the three-point skate / leveling screw mounts. Two holes OK, one bad, buy new Silver & Deming. Damned poor economics were I a "revenue" shop.

Do this often (as I once did do - no longer..) you will want core drills in yer drawer. Else not so much.

2CW

CarbideBob · Aug 1, 2018

They may look somewhat similar on the outside edges but everything is different.
I would not know where to start.
No cut anywhere is ground the same on these two type tools. This is not apples and oranges. More like apples and beef steak.
Bob

thermite · Aug 1, 2018

CarbideBob said:
They may look somewhat similar on the outside edges but everything is different.
I would not know where to start.
No cut anywhere is ground the same on these two type tools. This is not apples and oranges. More like apples and beef steak.
Bob

Actually.. I dare keep the few I DO still have right next to each other. No chance of confusion, after all.

They are as different as reamers and core drills!

Or drills and endmills - even spot-facing drills and "plunge" endmills, come to think of it..

Not everything with flutes is even made for machining work at all.

Some are yuppie rifle barrels. Others are orchestras or marching bands.

Tyrone Shoelaces · Aug 1, 2018

CarbideBob said:
They may look somewhat similar on the outside edges but everything is different.
I would not know where to start.
No cut anywhere is ground the same on these two type tools. This is not apples and oranges. More like apples and beef steak.
Bob

Correct, try using a reamer when you need a core drill and a core drill when you really need a reamer.

Regards Tyrone.

rickseeman · Aug 1, 2018

My thanks to everyone that responded. Now I have a better understanding.

thermite · Aug 1, 2018

rickseeman said:
My thanks to everyone that responded. Now I have a better understanding.

So do we, thanks!

"too soon, we forget..."

Search

Largest Manufacturing Technology Community on the Web

Search

reamer vs core drill whats the difference?

rickseeman

Cast Iron

michiganbuck

Diamond

Tyrone Shoelaces

Diamond

sfriedberg

Diamond

CalG

Diamond

John Dunn

Aluminum

tnmgcarbide

Diamond

thermite

Diamond

CarbideBob

Diamond

thermite

Diamond

Tyrone Shoelaces

Diamond

rickseeman

Cast Iron

thermite

Diamond

Similar threads