Teach me about reamers

Stew

Stew

Well-Known Member
Hi Guys,

I know that reamers are used for making holes more round than you get from a twist drill.

However, what I don't know is what size pilot holes are appropriate before reaming.

Does anyone have a chart?

I've had a wee search but can't find anything!

Also, a specific job that I have is that I need to turn a number of 3mm holes into accurate 4mm holes. Any suggestions on the procedure to use? Could I ream the 3mm mill hole to 1/8" then ream to 3.5mm and then ream to 4mm?

All help appreciated!
 
I would also like to one this too. I would love to find a pre-drill chart for reaming. I have been drilling my pivot holes about .005 under and then reaming to size.
 
I usually drill .003-.005 under and then ream to size.On folder bushings I ream to size and the use a barrel lap to get exact fit.
Stan
 
The amount to drill undersize depends on a few things.

Part Material
Tool Material
Machine used to do the drilling and reaming, rigidity, runout, RPM, etc...

Depending on the material, I personally would open a 3mm hole to app. 3.8mm before reaming...

On smaller holes like that, a pretty good rule of thumb is 6 - 10 thousandths (.15 - .25 mm)
 
What do you consider small?
I've seen reamers down to about .010"

McMaster-Carr, and Enco are pretty reliable sources.
PFSJUN Gets free UPS at Enco this month...
 
MSC! o placed an order last night as there was a free shipping, plus 35% off coupon. i got a pile of new reamers. MSC always has great deals on, just keep an eye out.
 
Interesting..

MSC Surface Plates Length: 9 Width: 12 Thickness: 2 Grade: B Material: Granite 66.95 ea'

Enco
Surface Plates Length: 9 Width: 12 Thickness: 2 Grade: B Material: Granite $38.98

Same company , yet majorly different pricing...why ?
 
I've always figured it was because of an Enco "stigma", and the fact that LOTS of companies have MSC accounts, and not Enco accounts.

MSC is a "preferred" supplier to many companies, esp. big oil. Being preferred means the purchasers don't even shop around for comparison, they just fill out PO's and buy.

So, they get big money from big guys, and small money from small guys this way.

They even get big money from the small guy who thinks "since it's from MSC, it must be better."
 
Good thread. I would like to know what tapered reamer to get for using 1/8 pins to hold bolsters etc. have not had much luck locating small tapered reamers. Thanks jim
 
SteelSlaver said:
Good thread. I would like to know what tapered reamer to get for using 1/8 pins to hold bolsters etc. have not had much luck locating small tapered reamers. Thanks jim
Click to expand...

For 1/8" (0.125") tapered holes for peening bolsters I use a 2/0 taper pin reamer (small end: 0.1137", large end: 0.1462"). You can find them at MSC (they are fairly expensive so it's good to get them when they have a special-offer code)... and I also believe that Tracy sells them at usaknifemaker.com (click HERE).

Erin
 
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