2" Banggood Face Mill Issues

[tonydi]

First off, your mill is not the most rigid thing in the world (not an insult - mine isn't either) and running a 2" facemill might be flexing the column, head, spindle, etc.).

Second issue is the tool itself. How much runout (TIR) does it have. It is likely you are only cutting on one insert. Same goes for the axial positioning of the inserts. Are they all pretty close to flat or does one stick out further?

Finally I question how accurately the insert pockets are machined. Are the inserts being held at the correct angle for cutting. This one is very hard if not impossible to measure at home. High end indexable tooling is very expensive and there is a good reason for that.

Oh heavens, no offense taken, I'm well aware that these little mills are very limited in many areas, including rigidity. I got the model with the solid column rather than the one that tilts just to get a little more rigidity.

The R8 mandrel has .0015" runout as does the mill head (meaning the head is actually spot on). I still wonder if that runout is due to how it fits in the spindle.

Yeah, no way for me to evaluate the pockets or even the angles but axially they are all the same.

FWIW, I have that exact same face mill and use those Blue Nano inserts for steel and these inserts for aluminum.

I get a very nice finish when limiting DOC to 0.010" and using 200SFM for steel and 400SFM for aluminum.

My mill is an old Enco BP clone - so maybe that's the difference. Also, I wonder if your material is mild steel. Looks like it might be something harder than 1018?

Thanks for the link, Bill. I got the Blue Nano ones because someone said they were using them with good results on aluminum and that's primarily what I use when I make stuff. I tested with the steel to evaluate the tool/inserts because it wasn't working well on aluminum. The inserts you linked to look much different on the cutting edge, more like what I'm used to on my lathe inserts that work great on aluminum so I'm hopeful these will make the tool give the results I had envisioned, like your picture shows.

Yeah, definitely could be mystery metal but it's the only steel I have. I've milled it with regular 4 flute HSS endmills and had good results. In fact, I made a height gauge base for my little surface plate out of the same hunk of steel and it's very smooth and didn't require much hand work to the bottom surface.

When you take a .010" DoC, is the work piece actually .010" thinner than before the cut? In steel? In aluminum?
Do you lock the Z-axis when you make a pass with the face mill?
Edited for clarification... hopefully.

Good question, Tom. I touched off on the insert that I measured was the "highest" and sure enough, a .010" DOC resulted in the part being .012" thinner. That jives with my measurement of the height of one of the other inserts being about .015" lower.

Lock the Z axis? Shoot, I lock Z, lock Y and even put some pressure on X to limit as much movement there as possible. I even lock the garage door! ;-)

 

[cjtoombs]

I got one of these off eBay. Try a little bluing on the inserts and try a very light cut. I think you will find that the angles on the milling head are wrong for the inserts and that it is rubbing on the back of the insert, or the insert isn't even hitting the work and the milling head body is. The body on mine was hitting, so I relieved it, then found there was no clearance angle on the cutters, so the back edge of the cutter was dragging, the cutting edge never touching the work. I threw mine in a drawer and ordered a few lots of used cutters off eBay and got a good one I could find inserts for. Also, I looked for inserts in that size that had the proper clearance angles, none available. Short of grinding clearance on the inserts (you would need a cutter grinder to do it accurately) the milling head was worthless.

 

[Jake2465]

Ok, it's making more sense now. I did not realize that you are running a tabletop mill. I would suggest that you stay away from inserts as they tend to require a little more power and rigidity. Something like what you are running would do well with a 3/8" end mill for facing and probably something like a 1/4" end mill for regular milling. If you get variable geometry end mills, that will help out.

Insert cutters will be a lot of trial and error with your machine as you will need to find a mill/cutter match that will not set up an amplified resonance. If you decide that you wish to go for it, then I would stay away from face mills that are larger than 25mm in diameter.

My mill is a 3200lb Bridgeport CNC and it is not fond of 2" face mills. It has a 2hp spindle and that gets soaked up pretty quick with a face mill of that size. Actually, I have the best success with my 1.5" face mill that uses TPG inserts for aluminum and then I have an APKT insert mill that is 1" in diameter that I use for steels.

 

[tonydi]

Try a little bluing on the inserts and try a very light cut. I think you will find that the angles on the milling head are wrong for the inserts and that it is rubbing on the back of the insert, or the insert isn't even hitting the work and the milling head body is.

Good suggestion. I blued the bottom of the inserts and head and ran a .005" pass on aluminum. Here's the result....

I think a lot of the marks are because it's still smearing the metal which builds up on the surface. But it doesn't seem terribly out of line with what I'd expect to see. Also, there are no marks on the head so it's not rubbing.

I've ordered some of the aluminum inserts that Bill suggested. Just looking at the way those are designed makes me think it will do what I need. Banggood refunded the cost of the face mill because they couldn't get me a R8 mandrel that was made correctly (or maybe it was just easier for them to do it this way) so at this point I figure I'm playing with house money and the $12 for proper inserts is worth a shot.

 

[Buffalo21]

I had a face mill, that basically had a minimum .020” doc, if you tried anything less than that, all it did was smear the metal, I sold it to a small job shop, they had the same issues. They finally started to use it in heavier cut operations and it works great.

 

[macardoso]

When I had a Sherline mini-mill (really mini!) I would use a 1" carbide tipped square wood router bit for facing. It gave excellent results in aluminum and worked fine for the limited amount of steel I did at the time. Cutting forces were very low and they are cheap. Not bad for a machine that struggled to push a 1/4" endmill.

On my G0704 I use a 3/4" endmill. I know some do use 2" facemills with moderate success but I know my particular machine just wouldn't like the cut.

 

[tonydi]

When I had a Sherline mini-mill (really mini!) I would use a 1" carbide tipped square wood router bit for facing. It gave excellent results in aluminum and worked fine for the limited amount of steel I did at the time. Cutting forces were very low and they are cheap. Not bad for a machine that struggled to push a 1/4" endmill.

Yeah, I've seen others say wood router bits work pretty well but I've never tried one. My mill is somewhere in between the Sherline and your Grizzly. Going in I always knew that I'd be limited by the rigidity and horsepower and I was prepared to work around that by not expecting super tight tolerances and accepting that I wouldn't be hogging out a bunch of metal on each pass. As I said, I was hoping this face mill would get equal finish to using an end mill without having to wear my right arm out cranking the table back and forth so many times.

Guess we'll see in a few weeks! I'll come back and update with whatever success or failure I run into.

Thank you to everyone who popped in here to offer help and great advice, I really appreciate you all!

 

[tonydi]

Ok, back to wrap this up!

Got the inserts that Bill suggested. Turns out they were actual Korloy pieces, something that the eBay listing didn't mention. So that was a big plus and nice surprise.

Now to the moment of truth......

Plugged the new inserts into the face mill and checked that, yes, one is still slightly closer to the workpiece than the other three. So that's definitely an issue with the face mill and, as mentioned, probably nothing I can do about it.

I took a .010" DOC pass at around 600 RPM and the finish was great! I could easily tell it was actually cutting rather than rubbing because I got real chips. Tried it again at 800 RPM, still great. I cranked it up to 1400 RPM and manually fed it pretty quickly and here's the finish.

I'll have to play around and find the sweet spot but it really didn't seem to matter. It cut so effortlessly that I'm sure I can go way more than .010" but that's all I really need.

So as disappointed as I was in this purchase to begin with, I'm completely 180° now. It's going to be nice to have this weapon in my arsenal.

Once again, thanks to everyone (especially you, Bill!) for their great advice.

 

[NCjeeper]

So to recap. The original inserts were junk?

 

[tonydi]

So to recap. The original inserts were junk?

Welllll, hard to say. The ones that came in the mill were definitely for steel. The Blue Nano inserts that I bought because reviewers said they worked fine for aluminum didn't work any better. And, it could be that the one piece of steel that I had is some sort of alloy that doesn't machine well.

I need to find some steel of known origin to test those inserts with.

These Korloy's are waaaaay different in that the cutting edge is a razor sharp point, not the fairly large radius that the other two have.