How much can I take out?

[Pcmaker]

I have this block of mild steel that's 1.5 inches thick, 5 inches in length and 4 inches in width.

I have a PM25MV mill and using a 2" indexable fly cutter that has carbide inserts. My RPM is around 600.

I've been taking off .020 - .025 at a time and it's taking forever to get the workpiece to what I need.

What should my RPM be at and how much should I be taking off at each pass?

 

[dtsh]

It is my understanding that:

(CS X 4)/D
CS = Cutting Speed surface feet per minute of mild stell (350 with carbide, 100 with HSS)
D = diameter of the cutter in inches

So for your setup, I get 700RPM
(350 * 4)/2 = 700

That should get you in the ballpark.

 

[JimDawson]

Try 0.050 DOC and see if your machine likes it, then try 0.075. The cutter will take about 0.200 or better in steel, but your machine won't. @dtsh is correct, about 700 RPM is where I would start.

 

[Pcmaker]

I tried .050, but the cutting tool kept "seizing up" on the work piece. I have to take off this much and it's taking me forever to do so.

What's the best way to take off this much metal?

 

[Al 1]

PC, A band saw would be another solution. Finish off with mill. Al.

 

[bill stupak]

A roughing end mill will take material off pretty quickly

 

[JimDawson]

Sounds like you are just running out of horsepower. But that machine frame will only take so much. A 1/2 inch roughing end mill might be faster. You could go full depth in one pass with a reduced feed rate.

I just spent 2 hours shaving 1/2 inch off of a 1 1/4x4x9 chunk of 4150. I needed it to be 0.750 thick. Used a 1/2 rougher and did it in 2 passes but could have used a cutter like yours at about 0.050 DOC.

Since you have to take that whole piece out, start from the outside and step over about 40% of the cutter. I'll bet it will take 0.050 or more if you do that.

 

[mikey]

I'm with Al 1. I would bandsaw the bulk of the material and finish off with an end mill or flycutter. Anytime you can debulk with a saw, you should.

 

[lordbeezer]

If no bandsaw drill all the holes you can..

 

[Mitch Alsup]

I tried .050, but the cutting tool kept "seizing up" on the work piece. I have to take off this much and it's taking me forever to do so.

What's the best way to take off this much metal?

Cutting fluid, or slow down in one dimension or another.