Getting a New PM-1054 Going

[erikmannie]

I got off to a rough start. I selected a 1” R8 collet (my 1” endmill holder is on back order) and a 1” shank, 1” diameter solid carbide 4 flute stubby endmill.

Long story short, I thought the x-axis power feed was in the *lowest* speed possible, but it was turned up to the *highest* speed possible. As you can imagine, this caused a crash. The weak link in the chain was the R8 1” collet. Even though it was brand new, it is now split/cracked and broken (see photos).

 

[erikmannie]

I switched to a 7/8” R8 collet and a 7/8” shank, 7/8” diameter solid carbide endmill. I was still in back gears, but I turned the RPM down to 220 RPM. I used very slow power feeds. Using the quill (and thus with no access to the DRO), my DOCs increased from .020” to .050” in proportion to my confidence in the setup. Here is a photo of that:

This worked nicely, but I was not happy with the finish.

 

[Ischgl99]

I've paid the stupid tax several times with my equipment too. If you don't make the same mistake twice, it is a good learning experience.

That vise is huge, my 4" vise would probably fit between the jaws lol

 

[rabler]

I'd be turning that end mill at least 600-800 rpm for carbide

 

[erikmannie]

Now I am using the same cutter, but I increased the RPMs to 470, and I am using the z-axis (i.e. the knee) with the DRO so I can really dial down the DOC, looking for a better finish.

We note that this mild steel plate is 1” thick, but my cutter is only 7/8” diameter.

 

[erikmannie]

I'd be turning that end mill at least 600-800 rpm for carbide

I was going to ask!

 

[Ischgl99]

I was going to ask!

Little Machine Shop has a speed and feed calculator that will help get you in the right range. You might need to adjust based on what your machine and cutters can do, but I've found it to be fairly accurate.

Speeds & Feeds

The premier source of tooling, parts, and accessories for bench top machinists.

littlemachineshop.com

 

[rabler]

RPM = SFPM * 12 / pi * diameter. I use SFPM * 4/diameter as it is easier to figure in my head, and just looking for ballpark.
I use 100 SFPM for HSS in mild steel, 200 SFPM for solid carbide in mild steel, and 300 SFPM for carbide inserts in mild steel, as quick starting points. Double that for aluminum. Again, quick starting points, there are detailed tables and apps, and the recommendation of the cutter manufacturer. Although many of those are based on removing the most metal in the least time (production), not hobby use and longest cutter life. For a solid carbide cutter in mild steel, I just use 800rpm/diameter. Again, quick starting points.

 

[erikmannie]

RPM = SFPM * 12 / pi * diameter. I use SFPM * 4/diameter as it is easier to figure in my head, and just looking for ballpark.
I use 100 SFPM for HSS in mild steel, 200 SFPM for solid carbide in mild steel, and 300 SFPM for carbide inserts in mild steel, as quick starting points. Double that for aluminum. Again, quick starting points, there are detailed tables and apps, and the recommendation of the cutter manufacturer. Although many of those are based on removing the most metal in the least time (production), not hobby use and longest cutter life. For a solid carbide cutter in mild steel, I just use 800rpm/diameter.

I knew to use a much higher RPM for carbide inserts on an engine lathe. I just learned here and now to use a higher RPM for solid carbide cutters on a milling machine.

 

[erikmannie]

I am still working on the same surface that I just milled flat. Now I am using a 3/4” shank, 82° included angle solid carbide cutter in an R8 collet at 700 RPM (high gear). The DOC in the photo is .120”.