First time milling.. not sure what I'm doing wrong.

[Pcmaker]

Ok, guys. My mill arrived yesterday.

You think my vise is a bit big for my mill? It's a 5"

I have a cut off tool that will not fit in my quick change tool post holder. It's about .011 too big. I figure it'd be a good project to shave off .006 off each side.

So, I "zeroed" the Z axes by touching the tool with a 3/8" 4 flute HSS end mill, zeroed the graduated collar, backed off a few thou, went off to the right side of the tool, went down .006 below the zero, then started milling.

As I pushed the X axis into the tool, it became harder and harder to push in. I pushed it slow going in, then I noticed that Z axis was going up and the tool isn't being flattened. Like the end mill was being "wedged" into the tool, instead of it cutting the tool flush.

 

[4ssss]

Looks to me that your end mill is wiped out, because that cutoff is hard to some degree, or you ran the spindle speed too fast. A 2 flute cutter would have been better. Did you run a file over it 1st to see if it would file? If it slicked over it, it's hard, and you may get away with using a carbide end mill.

 

[pontiac428]

Also lock out your gib screws or travel locks, leaving the axis you are cranking to be only free motion possible. The head of that mill isn't massive enough to fix the tool on weight alone. Locking out the travel is necessary for all but the lightest work.

 

[benmychree]

Most all tool holders are hardened to one degree or another, otherwise to tool post screw would mush them over when clamping, I have not hardness tested them, but would guess at a hardness of mid to high 40s to low 50s Rockwell C. Yes, machineable with carbide, but not with HSS under most circumstances.

 

[markba633csi]

Yes this is carbide territory, or cobalt. Also, you must use some form of cutting fluid or oil

 

[SSage]

The PM end mills are plain jane HSS and good for mild steels like 1018. I would take a small cut at first and even up things. But limit the cut on hard steels. I would make my first (test try) pass at .002 slowly in that mystery metal, its probably hardened. That little 3/8" HSS end mill is probably deflecting and digging in deeper on one side. My 4 flute end mills from PM cut flat surfaces really well on annealed metal, I have solid carbide for hard stuff.

Use a 1/2" 2 flute if possible and make very light cuts till it evens out. Use cutting oil or coolant in a mister. You can cut deeper till the end mill complains, but that 4 flute is HSS and not the ideal tool for the job IMO. I have a light weight PM-727, I don't push it hard at all on surface passes. The short solid carbide 12 mm 2 flute slotting end mills can cut faster/deeper on those light machines.

Make sure the part is dead nuts level in the vise and always make a shallow first pass to check for low/high spots. That lets you know if your set up is good to go for a .004 pass etc. The smaller the end mill the more gentle and shallow the cuts must be. You don't want to put deflection into the end mill. I have a few things that require a 6 mm end mill for slotting, it takes time making gentle .004 cuts with HSS. Solid carbide is worth it, you can order decent ones over seas fairly cheap. DrillPro brand on bangood.com is decent, about $8 to $12 for the small solid carbide ones. I like the tungsten end mills with the grey coating, they work good.

 

[brino]

@Pcmaker ,

Exciting times...Congratulations on the new mill!

As above, it is likely hardened steel in your work piece.
Test it with a file to see if it cuts readily.

It does look like a job for carbide.

-brino

 

[Pcmaker]

Yeah, it's hardened steel definitely. I was running my file on it and it was gliding smooth. I need to invest in carbide end mills or cobalt.

Which ones are better for hardened materials? Carbide or cobalt? And what coating?

 

[Mitch Alsup]

Which ones are better for hardened materials? Carbide or cobalt? And what coating?

Carbide is better for hardened materials, but it comes with the necessity that the machine be sufficiently rigid, or that carbide cutting edge will simply crack and disappear.

Ask me how I know.......

 

[Pcmaker]

I just used an angle grinder to grind the tool down.

Do you guys keep the window on your machines? Mine has a switch where it shuts off the machine if it's on open position. It's hard to see through the plastic.