[4]

Shopmade O1 Cutter Feeds and Speeds

[3]
[10] Like what you see?
Click here to donate to this forum and upgrade your account!
I have a shop made cutter from O1 tool steel. It is a concave radius cutter for profiling the outside of gun parts. It has 4 straight flutes. I used it with my cnc to round over a lever and I had to go extremely slow to avoid chatter and burning it up. I believe my end result was about .010 WOC, 30 sfm, 120 rpm, and max about .5 ipm. I had to throttle feed down to about .1 ipm at the end of the lever as the cutter went around the small radius. With this WOC it took me about 5 passes to fully clean up the outside profile. I would have liked to run the tool slower at about 60 rpm but the mill did not have enough torque at this speed.

Independent of my specific tool what is the recommended SFM for an O1 cutter? I could not find any data online as most results are for using HSS or carbide to machine O1. I was using ~20-30 sfm at the recommendation of my mentor, who also made the cutter.

Here is a picture of what the setup and cutter look like.

IMG_20181214_191624981.jpg
 

Comments

I've no numbers for you, but I have made and used O1 cutters. I alwasys figured RPM should be as slow as possible on steel, feed ditto. You don't want to be in a hurry, you want that cutter to live as long as possible. High sulfur oil wouldn't hurt, either.
 
Plain carbon steels are tricky. They will overheat, dull, rub and heat more at even very low sfm if they are fed too hard. It's all over in an instant. Typical goof ups are with drills and boring bars. For example, if a boring tool is fed too shallow after entering the hole, and it is adjusted in the middle of the cut, it will suddenly dig at the larger depth and start cutting. If you do this with the lights off, you can see the tip glimmer red for just an instant. Like I said, at that point, it's all over. HSS, even the Harbor Freight junk, is fantastic.
 
That is a neat looking cutter!

Question for you. I'm about to make some (simpler) O1 profile cutters. One thing I'm recognizing is depending on where I place my relief slots relative to tool axis, this a yields specific rake angle the tooth sees relative to the material. What rake angle is your cutter? These are low speed but relatively high line contact area. A tap might not be the best example but pic provided just to illustrate the relief slot geometry.

SNAG-12-19-2018 0001.jpg
 
High speed steel is the answer, you can make an insertable body to hold HSS cutting tools. Really, just one cutting edge is enough, like a fly cutter. You will have a lot less problems, and not too difficult to build. Save the O1 for cutting softer metals and for other projects.
 
I made a similar cutter for radiusing trigger guards, from a discarded 1/2" 6 flute reamer.
 
Bob are you saying grind the profile from a rectangular HSS blank & this then gets held in matching slot in the arbor, basically a carrier/holder for the cutter?
 
Bob are you saying grind the profile from a rectangular HSS blank & this then gets held in matching slot in the arbor, basically a carrier/holder for the cutter?
Yes, like a square tool in a flycutter, but without the shank protruding from the holder, rather one or two sides of the square formed to make your form cutter. Really, just about like what your cutter looks like in the pic you posted, but with a single square HSS tool ground to shape and mounrted in a vertical keyway. Set screws at top and bottom of slot to hold the cutter. Have the cutter offset so one flat is on the tool center line, that flat is where the tool makes contact with the work.
 
[6]
[5] [7]
Top