Carbide Reamer Speed?

C_Claycomb

C_Claycomb

Joined
Dec 11, 2000
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For cleaning up a hole in a heat treated blade (drilled and reamed pre-HT to 3/16th) with a 3/16th solid carbide reamer, what speed and feed would you recommend? I know that for carbide drills many recommend running them fast and dry if you can't flood cool, and I have had better luck that way than running slow. Do carbide reamers work better dry, or with a little oil, given that I can't flood cool?

I will be using a milling machine (floor standing Warco) and clamping the blade down with toe clamps.

Thanks

Chris
 
I would not clamp the blade down because its very unlikely you will have the hole and reamer precisely aligned. Any slight misalignment will break the reamer. I would run the reamer at a very slow speed with slow feed and use machine oil as lube.
 
Okay, so I was being a little lazy in asking this :p. In the passed I have found such good information here, both more thorough and more relevant than by randomly searching the wider net, I asked here here first without doing a lot of my own research.

I found a couple of what look like pretty thorough texts on the use of reamers and have probably answered my own question.
http://www.gammons.com/useofreamers.html
http://www.cobracarbide.com/technical_info.htm

These seem to be in agreement on the speeds and feed for carbide reamers.

Material.....................Speed (SFM)......Feed (IPR)
Steel Rc 20 and under...60-90 .............0.005" - 0.010"
Steel Rc 30 to 40.........35-65..............0.004" - 0.010"
Steel Rc 40 to 50.........20-40..............0.003" - 0.006"
Steel Rc 50 to 60.........15-30..............0.002" - 0.004"
Steel Rc 60 or higher.....8-20...............0.001" - 0.003"

(SFM = surface feet per minute. IPR = inch per revolution)

rpm = sfm/Tool Cicrumference

So for the 3/16th reamer I was asking about.
Diameter = 3/16" = 0.1875" = 0.0156'
Circumference = C = Pi x diameter = 0.0491'

For RC 58-60 rpm = 20/0.0497 = approx 400rpm
(which was a lot faster than I was expecting, and a lot faster than I had been using my HSS reamer.)

Feed, difficult to judge for a manual machine I guess, but assuming 0.002 inch per rev and 0.14" thickness that means I need to complete the operation in about 10.5 seconds.

I am still in two minds about clamping the blade down. All I have read say that carbide needs a solid set up to prevent chatter. These sources also say that carbide does not hold up well to mis-alignment and that a floating mount can be useful. I am leaning towards a compromise. I have an aluminium tooling block, about 1.5 inches thick with holes drilled and tapped for mini-toe clamps, reckon it weighs about 2lb and can clamp the blade to that, but leave the block free to move a little on the mill table to allow for misalignment.

Thanks for prodding me into doing my own research. Once I have digested the information on those two pages I will be much better off than I would have been had someone jumped in here and spoon fed me an answer. :D
 
Use the drill you made the holes with in your spindle to align the blade and clamp down. Retract the drill and chuck up the ream. Run the ream about 800 r.p.m. use a cutting oil and feed about .003 per revolution, or feed by hand what feels comfortable. You will feel the tool cutting.
 
A good rule of thumb is half the speed twice the feed. If you are running your drill at 1600 rpm then the reamer should be run at 800 like melsdad pointed out. This is the rated speed for 1/4 inch HSS cutting mild, 3/16 will be a little higher. I normally run it a little slower, bout 25% slower. If you are using a drill press I would recommend running it slower anyway so 800 should be fine. Also drill your hole aprox .010-.015 smaller and make sure your drill is sharpened properly or you will drill too big of a hole. If you are reaming un-heattreated steel you could have used HSS vice carbide. Little more forgiving, not as brittle.
 
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