Looks like its rubbing rather than cutting, what are the inserts like?

That's what you'd hope to see. If the "back" of the cutter didn't make any kind of contact, it would suggest your head isn't trammed correctly and you will end up with a slightly concave surface.

It's not possible to conclude anything solid from the comments and video. Opinions perhaps but you'd need to do some more objective / methodical tests to narrow down what's happening. So for instance, to see if all the inserts are cutting, you'd need to examine them and possibly mark them to see if there is any contact. And measure the runout, particularly the axial runout etc with a decent indicator. I think that's one thing John Doubleboost missed out on.

The speeds and feeds are important for these indexable tools. It's not clear if there were any calculations done or if the handles were just being turned. Even without CNC, it's got to be a good idea to set your power feed to the right speed range recommended by the insert manufacturers.

Murray

For reference, for mild steel I would be using 1000rpm and 0.1mm / tooth ie about 500mm / min for a 5 insert cutter. Good idea to use coolant or WD40 even.

Edited By Muzzer on 06/05/2018 20:32:38

I have a similar cutter bought from cskwin2015 on e-bay, and was using it this afternoon without problems. I do not have power feed available, and was using it at 1600 rpm, and approx 50 mm/min, maybe a little faster, one turn of the feed handle every 2-3 secs and 2.5mm per turn. Why such high rpm? Well I had the belts set up for a 6mm cutter and figured the tips could be worked very hard on a CNC machine, so could stand high heats, which meant fast speed if the feeds were low. And I was too lazy to change the belts. The chips came off blue.

I think Jason has it right in suggesting you check for concentricity in the machine. Also, put it cutters down on a flat surface and see if it rocks between 2 cutting tips, that would be a good indicator if one insert was too low and doing all the cutting. Check if the insert is over size, change if it is, but if not, consider complaining to banggood or remedial work with a Dremmel on the tool holder. Shouldn't be needed, but could save the day.

Regards

Richard.

Darn right, and true for any cutter, especially with conventional milling. If the feedrate is too low the teeth rub before cutting which wears the cutting edges in short order.

Andrew

Jason,

Can I ask where you get tips for the cutter in the last photo? I have a 32mm end mill with similar tips but one fell out after the screw loosened a bit under the initial vibration on starting a cut and is now lurking somewhere in the workshop. I have been unable to source a replacement – possibly because I have no idea of their acronym – how could one find a CCMT06 without putting the name in?

But.. Surely those tips are horrendously blunt compared to the AMPD1604's where the edge is shaped and thinned to present a chisel edge rather than a scraper.

Regards

Richard

Could not get a good shot of the edges but these are the triangular inserts

I think the edges are too blunt for our machines, they're designed to be ploughed into with a Bridgeport, which would have the rigidity to do that.

The type of cuts you need to take with a hobby machine dictate that you can't go too fast into the work piece or take a cut too deep, it's just the nature of the machine for most of us.

A sharp pointed tool like jasons example show how you could get a far superior finish and real cutting action at low feed rates and cut depths.

Anyone wanna try sharpening the originals and seeing the results?

Michael W

Just editing some video but what I have found confirms that not all inserts were cutting and that a hobby bench top machine just can't take feed rates that the Bridgeport and above can. Stay tooned!

I run a couple of face mills on my Bridgeport, a 40mm and a 50mm with three and five teeth respectively. Both use a triangular 16mm tip. Being a tight wad I buy TPUN160308 turning tips and grind them by hand on a diamond wheel. They cut well give a good finish and last well between touching up the cutting edge. Much more cost effective than designated TPKN milling tips.