Face milling on Warco Gearhead Universal (RF45 clone)

Good evening all

Thinking my machine was up to the task, I bought a 50mm 5 insert SEKT face mill to use on some cast iron.

I was running at approximately .002" DOC, About 3/4 of the tool cutting, conventional milling, manual feed.

Part way through the cut, I started to get vibration and it just felt.. sketchy. I turned the machine off, and it appeared the cutter started to dig in to the material.

All unused ways were locked. The material was tight in the vice.

What I'm wondering is: (a) is this tool suitable for my machine (b) perhaps I should have roughed the surface out using an end mill and then finished with the face mill (although I'm skeptical this would help, the DOC was very small to begin with).

It's hard to describe, but running the cutter just felt sketchy. It felt like it was on a knife edge - like the slightest bit of interference would cause a problem and chatter and potentially cause the cutter to grab.

Other things to mention: I've checked spindle runout, all is good. Obviously the mill was screwed on tight, drawbar tightened appropriately, etc.

Ay suggestions to point me in the right direction would be appreciated.

Thanks

P.s. I've added some photos, one of which you can see where the tool started to dig in, and another where you can see how this big piece of cast iron is in the vice etc. 

Edited By Jak2g on 06/04/2022 22:15:38

Edited By JasonB on 07/04/2022 06:58:23

Jak the second image shows the quill to be quite extended, perhaps try lowering the head and reducing the quill extension?

Robert Butler

I'd agree with Robert, waaaay too much spindle extension on the tool. Plus the work isn't really clamped tightly enough for running a face mill. Lastly 2 thou depth of cut is not really making the inserts work properly. Combining any two of the three is probably enough to induce chatter. This is the ideal for face milling, rigid tooling and everything clamped down:

Andrew

Also, it looks like you are getting over near the unmachined surface of the cast iron block, so your .002" depth of cut would not be getting in below the hard "skin" that cast iron usually has. Usually works best to get in below the skin level and machine it off in one go.

Is there a reason the stock is so high in the vice? It looks like you were only intending to skim off about 1/8".

I would especially want stock as large as that is in relation to the vice to sit as low as possible to maximize the surface area doing the clamping and being clamped.

0.002" is also a very light cut and given the "blunter" edge of the insert tools you may well have been rubbing rather than cutting. Swap the inserts around and take a 0.020" cut.

Secondly where did it come from, I had some very poor inserts from one of the cheap far eastern market places in my 50mm head, changed for some better ones and it transformed the cut.

Quill may well be fully retracted as they do have a fair amount exposed anyway particularly if R8 and looks like its been sawn from a larger section so should be no skin.

Edited By JasonB on 07/04/2022 07:20:18

Edited By JasonB on 07/04/2022 07:23:04

Hope not! 60 passes @2 thou a time - that should wear out the edges rather more than a good cut!

I can’t see much that is right with that set up. One parallel (why even one?. A hard rod (at least why not in the jaw groove, as well?). Excess hang-out of the quill. Did ways include the quill? Conventional cutting direction? Origin of the face mill?

Before anyone else says the quill is too far extended here is a shot of an RF45 type mill. When you extend the quill the gap opens up above the bracket around the quill, we can't even see the bracket let alone if there is any significant gap above it. All we can see is the rotating end of the spindle

Or hover your mouse over the end of the spindle on the image that comes up here

Edited By JasonB on 07/04/2022 07:43:14

Movement of the part under cut. Cut point forced the part up to hit the inserts behind that point. I have a GH Universal and have a 50mm face mill on a R8 holder and use a depth of cut of at least 0.5mm at 1000rpm and hand feed. Rather than cutting along the vice jaw, x-axis, try cutting across into the fixed jaw, y-axis. That said I do think the part would be helped with putting more support under the part.

You need to get rid of the round rod as a first step, it's doing no good at this stage & if the block is too uneven to grip add copper or brass packing as required to get a firmer hold.

Tony

Looks at the lower part of the photo like the saw cut has eased away to nothing before the edge of the cast block, leaving the rough cast surface intact just on the edge half inch or so. Or perhaps that is rough corrosion since it was cut? Looks more like the cast surface, but hard to tell from pics of course. That would leave some depth of hard "skin" perhaps even on the saw cut area as the saw cut looks to have been only a few thou deep in that area.

But a stouter set up and deeper cut should help, either way.

Look at the bottom corner it's rounded as you find on Cast iron bar and section. Other corners are square so it's been sawn from a larger section otherwise all corners would be rounded. I've not found a hard skin on this type of continuously cast bar unlike you may get on a sand casting.

Here's one I cut earlier

Edited By JasonB on 07/04/2022 10:25:37

I would like to point out that the difference between a fly cutter at this diameter and a 5 insert face cutter is that the rate of feed for a given RPM needs to be 5 times faster. These multi insert cutters are designed for rapid material removal and require a suitable feed rate to get the best use out of them. They need to be worked reasonably hard.

So as stated above you probably need to have a bigger depth of cut, an RPM in the region of 425RPM and a feed rate in the region of 65mm/min. I don't know what your lead screw pitch is but if it is 5mm then you are looking at a handwheel being turned close to once every 4 seconds. You should be seeing obvious chips coming off rather than dust.

Martin C

OK. Must be corrosion after the cut was made then. Sure looks nasty.

Work holding.

Differing heights of insert in the head = duff face mill

Bad inserts.

You don't need parallels for the first cut.

PS hard spots are all shiney.

Hi all

Firstly, thank you all for the input. I would have responded sooner but did not even realise there had been replies (no emails received for some reason). Anyways..

The reason I'm use one parallel and a rod is to avoid a camming action. Perhaps naievely I'm trying to square the block as precisely as possible, and this is what I've seen done (oxtools on YouTube demonstrates this, as do others). Perhaps I should leave the 'precision' squaring for after I've got it reasonably square by using the whole of the vice. So, that's why one parallel - I do have two to hand, lol.

Regarding the quill, Jasonb is bang on. The quill is extended only enough to allow engagement of the fine feed mechanism. In other words, very little.

I DEFINITELY think depth of cut and feed have something to do with it. The inserts are from APT. They are coated SEKT inserts for steel. The min cut on the box says 2mm, but that ain't going to happen on this machine. I believe the geometry is right, as it is nice and positive. Some people have commented before on how the ground inserts for aluminium work well on smaller machines, perhaps this would be something to try? I have used the face mill on steel, and I was getting very good chips flying everywhere - but with the cast, it's more like dust.

I switched over to a 50mm hss cutter, and noted that the tool was much sharper feeling than the inserts. The HSS cutter at that depth, and deeper felt like it was slicing through nicely, and good chips were produced. This has made me re-tnink carbide tooling, but I would like to find out where I am going wrong. Can the conclusion be that the cutter and gemoetry is good for steel, but not cast iron at the DOC this machine is capable of? Or perhaps I'm being too reserved and should try a deeper cut?

NB - this is continuously cast gr 17 cast iron, like what JasonB is holding.

Edited By Jak2g on 07/04/2022 18:42:24

Your machine should be quite capable of a 1mm depth of cut using the whole width of the cutter if needed, My lighter X3 can do it so yours should be able to as well.

I think we can rule out poor inserts.

What sort of speed and feed were you using.? I have a 50mm 4 insert face mill and run that between 100 and 125m/min surface speed so that is 600-800rpm. feed about 100 per min, yours could be feed 25% faster. This gives a chip load of 0.02-0.03mm (approx 1thou) and that is a true load as you are using over 50% cutter width so no chip thinning to ease things.

Here it is taking 1mm depth off a 45mm wide bit of poor quality CI then steel then ali with ali inserts. Cheap holder, decent inserts

Edited By JasonB on 07/04/2022 18:58:49

Edited By JasonB on 07/04/2022 18:59:39

Chip loads seem low, I normally run face mills at 0.1mm chip load and upwards. The inserts need to cut, and that is achieved by a combination of depth of cut and chip load.

Andrew

Would stall my mill dead and can't be faffed doing loads of shallower passes

Jason - I can most certainly tell you that I am feeding slower than any of those videos, probably half as fast. Unfortunately I do not have power feed, so my knowledge of feed speed is relatively low. Regardless though, it shouldn't have bitten in to the material should it, I mean, theoretically I could run feed as slow as I like, get a crap finish, but still it shouldn't dig in. Wondering therefore if it is simply not mounted ridgidly enough, it's a heavy piece, but tightened down well.