largest diameter indexable face mill

Whats the best size indexable face mill for a Myford VMC Mill? Looking at getting a 45 degree but cant find an answer to the question of what the largest workable diameter for these smaller machines is. I guess the follow up question is then best insert shape and how many inserts , 4 etc. I'll be cutting mild steel and brass.

Maximum I run on my Bridgeport is 50mm diameter and that is power limited to small DOC. On the horizontal mill I run 63mm and 80mm but that is a much bigger mill; 5hp and 3500lbs, so one can take proper cuts in terms of depth and feedrate. Face mills are all about removing material as quickly as possible.

Andrew

The largest i have & use with some success on the small Tom Senior with MT2 taper is 63mm 5 inserts. I have 2. One has the standard type square inserts while the other has the round disc type. They both work very well, although i only take light cuts. I think the deepest i tried was 0.25mm but uisually less. I have shown them many times in use on my youtube video's. I also think JasonB has shown a few too. What i found was quality is the most important. I have a 50mm 5 insert i think imported version . It is both very noisy & sparks like a firework. The big ones are top quality ones Widax & work much better. Probably more down to the inserts than the actual cutter body. Hope this helps.

Steve.

I also find the insert cutters good for dealing with castings that may have hard spots not just covering large areas quickly as the carbide will survive where HSS will quickly blunt. They are also more durable when dealing with mill scale on "black" bar.

I have 40, 50, 63 and 80mm but have not used the largest on iron or steel apart from initially trying them out.

I run them at the high end of the right speed but adjust chip load(feed) and DOC to suit my X3 and SX2.7

For brass I use the 80mm one with the sharper inserts for Non ferrous and recent tests have shown that these inserts work well on ferrous much like the **GT ones do on smaller lathes.. Recent thread about facemills has the video

As for shape with the smaller DOC the smaller machines can take it won't make a lot of difference as you will probably be at or below the corner radius

Edited By JasonB on 09/10/2022 06:35:48

Thanks for the responses and links. With my VMC i think i should have good rigidity but not much power. Think that decent 50mm might be a sensible balance. Jason, can you explain the 90 vs 45 not making too much difference - are you are saying that with the shallow DOC my mill can manage that neither insert will be in contact with much of the cutting radius so it wont make too much difference?

Personally I'd go with 90° inserts. That way you can mill close to, or all the way up to a shoulder. With 45° inserts you can only mill on a flat face and considerable clearance is needed all round.

Rigidity is relative; I consider my Bridgeport to be flexible in more than one sense. Whereas my horizontal is pretty rigid. See here for some results on the horizontal using a 63mm diameter face mill from Arc:

Face Milling Results

Andrew

If you look at this sketch comparing a square insert set at 45deg and a APKT type insert you can see that when taking a 0.5-0.75mm DOC (20-30thou) the radius on the APKT is not a lot different to the angle being cut by the square insert. You would really only notice the difference if you were able to take say a 3mm DOC where for the same feed rate the square insert at 45deg takes a longer but actually thinner cut than if it were vertical.

As Andrew says the ability to cut up to or form a vertical edge is a big advantage

A shell mill which can cut a square edge is usually close to the stated size, but the 45 degree type with square inserts is measured to its extreme outside diameter. This means that, for instance, a 63mm size will only cut about 50mm wide when skimming a face.

The two mills at the museum have a 1hp three phase motor and a 1 1/2hp single phase motor. We can use 80mm shell mills, but the depth of cut is limited by the power. It depends what you want to do with a mill, either hog off masses of metal or cut wide swathes. If you want to do both, then get something with at least a 40 size spindle fitting and 10 hp motor

I'm happy to take shallow cuts and fewer of them so 90 degree and larger sounds like its reasonable from your replies (thank you). Now just to find a good affordable R8 shell with inserts that can be easily replaced at sensible cost.