Face milling on Warco Gearhead Universal (RF45 clone)

Feels like a combination problem to me - bit of work-holding, shallow cuts, the material and maybe the inserts.

What do the team make of this table from the 1204 datasheet?

I read the table as describing an insert optimised for wet cutting Stainless Steel and Titanium at moderate feed rates, that can also cut steel when run fast and hard. Could it be the rake and edge angles are completely wrong for cast-iron?

Forum friends occasionally blame poor quality Chinese insets for a new tool's disappointing performance. Possibly nothing wrong with the inserts, the problem being they're the wrong specification for hobby machines cutting hobby metals. The same inserts might be brilliant fitted to a machine correctly set-up to plough efficiently through Titanium!

Dave

Hrmm.. Im wondering whether I would be better off with different inserts. This is what the general description is for the SEKT 1204 insert:

Carbide Inserts for Milling PVD Coated Grade NK135 (P35–M35–S15 + PVD TiN (Ti–Al–Si)N Coating) Main application – Carbon & Alloy Steel, extended application – Stainless Steel & Hi–Temp alloy

Whereas, the SEHT 1204 Is this:

SEHT 1204 AESN Carbide Inserts for Milling in Grade UM25 (P25 M25 K30 S15 + NaCo3 PVD Coating) Main application, Steel & Stainless Steel, extended application Cast Iron and High temperature Super Alloys (HRSA)

I'd be inclined to try different inserts too. Your set up may not be the stiffest possible, but it's not unreasonable either. The mill isn't a weed, chilled cast-iron isn't likely, and others get on ok with that type of cutter. It ought to do better than it is.

I'd try faster deeper cutting first though. Might be that simple, and inserts aren't cheap!

Dave

80mm Facemill cutter with x brazed carbide tips:
I assume this is not by ar a good cutter compared to indexable cutters. I used feeler guage to line up tips, which I know is not 100% ideal, but the Dial Test indicatoe here don't really work for me lining up the tips.

Hi, I carried out the following further experiment with a 80mm facemill cutter with 4x brazed carbide tips I got with mill before I venture out and buy a indexable cutter wait for options from dealer.

1-I used a 30x30mm aliminium bar about 15cm long clamped in vice. I took 0.1mm cuts and find it to be rough and it keeps on cutting les and less going through it up to x times without adjusting depth further.
On removing and inspection of bits they were blunt and tips weared off from 5mm steel I cut off before.

2-I resharpen them with a dremill diamond blade..Thats what I had and it works great.The tips were sharp.
-I found it now cuts freely, however even my cranking speed as slow as I can do with hands, it still leave scratch marks....Tips too sharp. I noticed on cranking X-axis back it hardly re-cuts with sharpen tips.

3-I then sharpen tips again with small roundish corner. Now I get a much better surface finish, and dont need to recut actually, but if I do it takes off onle where I probably cranked with varying speed.

4-I then resharpen tips again with a mouch rounder point, and now I start to get the finish I was looking for.
Its cutting freely at 0.1mm cuts. I also tested this on metal and was surprised as well.

5-Next step is to resharpen at even more larger round tips.....

The dealer suggest I buy a 50-60mm cutter, choices to make, however I was thinking if IN stick to a 80mm cutter the surface speeds will be higher for same revelutions of mill, and that may benifit me cutting larger areas as well as smaller more interrupted ones.......Not sure yet. I am now a bit confused about which inserts on indexable cutters-??

I tried something today I thought about before but forgot about it,

Aliminium:
I chose a lathe 12mm toolholder(Cheap chinese type)=PSBNR1215H09 with insert=41005V and bolt it just like that into the 80mm facemill brazed carbide cutter( brazed holders) and start cutting with the other 3 retracted.

This gave me a good finish as I could ever wished for. I rotate the insert for a new fresh point to cut, and it was only very slightly hardly noticable better. I took a no adjust finish pass in each case, on return it don't seem to cut.

I tried two 10mm shorter toolholders I though might work and gave good finish on lathe, but no it did not work, finish simmilar to original carbide holders before sharpening. I dumped the feeler guage method and bolt them with scratch method on work to holder-This was the best result from the brazed carbide holders but dont match the Lathe toolholder results.

I saw a video from DoubleBoost where he re visited an indexable facemill 50mm I think and did a scratch test on work to see if all inserts cut. They all did make contact, but did not remove the same with of material, I thought this was interesting.

Edited By Chris Mate on 10/04/2022 17:22:12

Edited By Chris Mate on 10/04/2022 17:23:34

Edited By Chris Mate on 10/04/2022 17:27:17

The cutter is soft cutting because of the 45 degree edges, although I would have tried an 0.5mm, 0,020" depth of cut. The inserts might not be optimum, they look uncoated in the picture. I was concerned by tool length, but you can only have the quill as short as possible and locked before each pass. Lock the Z axis also. Also, that rod on the front side vise jaw would not be helping the stiffness of the clamping. If the work does not fit well between the jaws of the vise, an old trick is to put some soft aluminium wire between the work and the jaws which gets crushed and fits the uneven gaps. The work could be lower in the vise if the parallel was on its side.

Check the tightness of the SHCS holding the shell mill on its arbor and the insert screws (only use the proper tool to limit the tightness of them).

 Now you have part of the surface flat, could you turn the work the other way up with a couple of thin  parallels under the finished part, it would sit down better then.

If the sides are sloping outwards requiring that rod, it might be worth while squaring up the sides first so the work sits better when you mill the larger sides.

Re reading your first post, did you raise the cutter from the work before or after turning the machine off?

Edited By old mart on 10/04/2022 19:18:01

Edited By old mart on 10/04/2022 19:23:17

Edited By old mart on 10/04/2022 19:26:46

On my ZX45, I had a 50mm cutter and it was useless on my mill. Then I got a new body that has the uneven spacing between the teeth and it works alot better. I find that the sharper grade for cutting Ali, works very well on the low powered ZX45 compared to the higher powered cnc that uses the normal for industry inserts. I find that placing a piece of card on the fixed jaw, allows for some inconsistency in the surface. With the rod on the back, I have a piece of round stock that has a flat on one side that faces the jaw, and depending on the surfaces I also have a ball with a flat on to use for the 1st two sides of squaring up stock. The flat sits on the moving jaw face. The round rod with a flat , is only 2 inches or so long. So sits well in the centre of the jaw width. The uneven spaced cutters greatly reduce chatter and harmonic vibrations setting up in the workpiece and the machine as well. Definitely some mill drills are more ridgid than others. My friends one that he has, is way better than mine. I think now the reason for that is related to the clearance of the quill to the housing or casting clearance.

If you extend your quill nearly all the way to the bottom of it's travel using the fine indexer to hold the quill down, with no drag from the lock, how much does it move? On my ZX45, that movement is 0.15mm , when the quill is near the top, so extended out 10 mm , the movement in my ZX45 is around 0.04mm to 0.05mm depending on which direction I push on. My machine is worse in the direction of the lock so inline with the table is worse than front to back. As far as I can see for my mill, this is an area that is not specified for its manufactured tolerance. Have a look at my HM50 thread about the quill.

Your HSS cutter will have less cutting forces than your inserted cutter does with those inserts. If you look at them, they will have a slightly rounded cutting edge. They work on the cutter running fast enough that the plasticising of the material as it cuts with most of the heat generated going into the chip itself. They do sell cast iron specific grades of inserts. The ones I saw were quite sharp on their edges and were a flat looking insert relying on the cutter body geometry for the positive rake or angle.

I think it's a couple things. Firstly, the inserts aren't ideal for cast. That probably didn't cause the main issue though. Second, and primarily, I think the work shifted in the vice. I say this because it happened today, again, whilst using an hss shell mill (50mm). I had face milled almost everything required, and then when I was coming in on the work it visibly lifted the part and stalled the machine. I think I underestimated how when the sides are not completely parallel, even if you REALLY clamp down the piece, it could have little surface area being clamped and therefore it's actually not in there very tightly after all. Second, with the workpiece extending so far out of the vice, it acts as a lever - thereby compounding the problem.

I'm used to using small milling cutters, mainly 10mm and below - this is my first foray into facing. What I'm most surprised by is how much force the cutter has on the piece. You have to be very careful to have it clamped TIGHTLY with full contact on the jaws of the vice. Also, the work has to be as low as possible. This makes working on a piece projecting high up out of the vice difficult to some extent, but I think that if the sides were parallel and contact secure on the vice this shouldn't be a problem.

Put some copper or aluminium between moving jaw and work as that will deform to take up any slight difference in the work

Also make sure you have the vice screw in the right notch to give maximum sideways force not downwards

Ok, this vice is new to me and tbh I didn't even think of that. Always used a standard milling vice. Can you explain further? I presume you want the screw to extend underneath the part and as far back toward the fixed jaw as possible to ensure maximum side force? Cheers 

Edited By Jak2g on 10/04/2022 21:02:49

I suspect you really need to be using a hefty machine vice rather than a toolmakers vice.

Andrew

Yes if you must use that type of vice get the pivot bar that the screw goves into as close to the fixed jaw as possible so there is as much horizontal force on the movable jaw as possible.

As Andrew says a milling vice would be better, the only times I can remember work moving in a vice it was with the toolmaker's type not my milling vices. But their usually deeper opening to a compairable sized milling vice does make them tempting to use.

Edited By JasonB on 11/04/2022 07:10:56

Exactly, and a more general purpose insert as well

+1 A photo of the SEKT insert shape shows it's not what I would call 'general purpose'. A wide cutting edge, presumably designed to remove metal quickly with a powerful rigid machine.

Looking at a few specifications suggests the SEKT family is distinctly specific, for particular metals and to be run at particular feeds and speeds. One version is Aluminium only, another is Stainless. The SEKT 1204-MS ET602 is for steel, but says:

Will Cut Steel? (P-Blue): Yes
Will Cut Stainless Steel? (M-Yellow): Yes
Will Cut Cast Iron? (K-Red): No
Will Cut Heat Resistant Alloys? (S-Orange): Yes
Will Cut Non-Ferrous? (N-Green): No
Will Cut Hardened Steel? (H-Grey): No

Surprising that a insert cuts Steel but not Cast Iron. However, there it is.

I think Jak2g has an insert that's unsuitable for cast-iron in a multi-cutter head that needs more power and rigidity than his machine and vice can manage - a combination of disadvantages, adding up to a poor result.

The mill might work OK with this insert on cast-iron with fewer cutters in the head, perhaps only one. Or invest in SEKT 13T3AGTN ET602 inserts, which are 'General machining - first choice, best for steels and cast-iron'. I notice the minimum speed for cast-iron is three times faster than carbon steel: the inserts seem to be right fuss-pots.

Dave

The cutter head takes 12 size tips therefore these that Jak refers to will at least fit , the 04 refers to the cutter tip radius or 0.04mm puts them in the semi finishing / finishing zone, whereas 08 is usually for roughing.

Actually 0.4mm; in another thread weren't the proponents of the metric system saying it avoided hiccups due to the simple multiplication factors?

Andrew

Andrew,

Finger trouble must try harder.

I think the inserts should be zero rake,with flat faces,and no chip breakers,and spun at 400 rpm for a 50mm dia cutter, the cutter is protruding way too much from the spindle quill,and the quill should be fully retracted. Andrews Adcock and Shipley with 40 int spindle is the ideal machine,they weigh more than 1.5 tonnes,I used to own one, though should not be compared to ligwtweight hobby mills. When I was involved with maching cast iron donkeys years ago, the Clarkson deadlock cutters had large 45degree chamfer on the cutting edge ,it stopped chipping of the faced edges of castings,and was supposed to improve finish.Where I worked a mill smaller than a A/S 2e would never be used on cast iron and cannot remember small mills being used on cast iron in the various sub contractors I used to visit. So if one has only the space for a small mill treat it with respect and do not expect too much from it.Even with my Elliot 00 I would probably machine a c/i block of size in a four jaw on the Colchester.

Let's just set something straight for the record: the quill is NOT EXTENDED beyond maybe 6mm at most. It might look like it, but it isn't.

Second I don't see why a small RF45 style mill could not machine cast iron. It can, no doubt about that. I've just finished milling out slots with a 6mm end mill, no vibration whatsoever and the cuts have a great finish. This particular carbide shell may not be suitable, but previous comments contain videos showing certain shell mill / cutter combos work fine.

Personally, I'm satisfied my problems were caused by poor workholdong setup coupled with the wrong cutters.

You will have no difficulty milling the cast iron with your machine, just listen to the sound of the motor and reduce the feed rate, or use a lower gear if needed. The vise is indeed not really intended for general milling, more those little high precision jobs. You are on a learning curve and as long as you can use common sense and take advice, there is very little you won't be able to accomplish.