Cut quality

[Web Goblin]

I am cutting some spindle mounts for someone and although they will be happy with them I am trying to improve the cut quality.

This photo is of the bottom of the mount. The only difference between this edge and the others is that there was no material on the other side of the cutter. The cut was positioned close to the edge of the material so that I could get two parts out of it.
8130

The next photos show other edges of the cut which seem to show some vibration from the top down but it dissappears approximately half way down.




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The material is aluminium 20mm thick, 12000rpm, 700mm/min 1.5mm DOC with a 0.2mm finish pass. 6mm single flute cutter.

[JAZZCNC]

last 2 photos look like chip re-cutting/rubbing marks how was you clearing chips.?

[Web Goblin]

I was following the cut round with the vacuum so I think I did a good job of clearing most of the chips. Gave it a fair amount of lub as well. But seeing as the first photo shows a good cut and this bit did not have anything to hold the chips in that might be the problem. I might have to rig up my compressor and try a bit of air blast to see if that helps.

[Tenson]

Welcome to the club ;) If you already have an air compressor then it seems that is the best solution and I believe is what Jazz uses?

Can one use the normal water coolant nozzles (the blue flexible ones) for compressed air or are they too leaky?

P.S. you have a lot of cutters there WebGoblin! Do you sell them?

[JAZZCNC]

I was following the cut round with the vacuum so I think I did a good job of clearing most of the chips. Gave it a fair amount of lub as well. But seeing as the first photo shows a good cut and this bit did not have anything to hold the chips in that might be the problem. I might have to rig up my compressor and try a bit of air blast to see if that helps.

By the looks of the dents then I'd put a small wager on it.!! . . .Loads of air does the trick you have to blast the suckers away then bit of coolant just helps stop cutter stickage.!


Welcome to the club ;) If you already have an air compressor then it seems that is the best solution and I believe is what Jazz uses?

Can one use the normal water coolant nozzles (the blue flexible ones) for compressed air or are they too leaky?

Leaky is not the problem I find with them it's they arent stiff enough and they move with the blow back pressure.!!

[Web Goblin]

If it comes down to having to use air I have a compressor but its fairly big with a 100ltr tank. I dont fancy having to run it constantly. I wonder if a 280ltr/min magnetic air pump would push enough air to clear the chips away?
The blue flexi connectors can be used for air. We use them on a few of our machines at work for exactly that and also for coolant.
The cutters are boxes of drills and taps. I have loads of them and some are up for sale. Drills are from about 8mm to 23mm morse taper shank and taps are from 5mm to 16mm I think.

[JAZZCNC]

The cutters are boxes of drills and taps. I have loads of them and some are up for sale. Drills are from about 8mm to 23mm morse taper shank and taps are from 5mm to 16mm I think.

What size morse.?

[Web Goblin]

If I remember correctly they go from No1 for some of the smaller drill up to No3 for the larger ones.

[JAZZCNC]

If I remember correctly they go from No1 for some of the smaller drill up to No3 for the larger ones.

PM me price if you have any large drills with No2 taper.

[Web Goblin]

pm sent.

Wanted to just say pm sent but found out that I cant post a message of less than 10 characters.

[wilfy]

looks like you need to hurry up and sell some stuff... chewing on aluminium cant be good for your teeth.. :witless:

[Web Goblin]

The chips aint too bad with a bit of warm milk!
I really do need to get them sorted out out and sold off. Had them for a while now and havent gotten round to it. Thats what I get for doing non paying jobs I suppose.

[oscar]

As others have said, looks like chip recutting.
Did you run a spring/reflex cut to finish? If not this may help tidy it up a bit, depending how deep the damage at the top is.

[Web Goblin]

Did you run a spring/reflex cut to finish?

I have never heard this term before. Is it the same as finish pass? If so then yes it had a 0.2mm finish pass at full depth cut.

[oscar]

A spring cut is when you run the cutter around the part again after your finish cut so that the cutter isn't under any load.

[oscar]

Silly question, but. What's the flute length of your cutter?

[GEOFFREY]

Have you tried climb milling on your finishing pass? G.

[Web Goblin]

Oscar the cutter flute length is 27mm.
Geoffrey I would need to check the file to see how it was milled. Does climb milling improve the surface finish much?

[oscar]

Oscar the cutter flute length is 27mm.
Geoffrey I would need to check the file to see how it was milled. Does climb milling improve the surface finish much?

That's ok then. It's not the shank rubbing.

[oscar]

Does climb milling improve the surface finish much?
I climb mill on everything, can't remember the last time I didn't. The finish is always good, if everything is set correctly. Also if the cutter does deflect its pushed away from the part, leaving metal safe (nothing a spring cut wont sort out). Rather than conventional milling where the cutter can pull into the job making it undersized.

[Web Goblin]

Thanks for the info guys. I have been doing a bit of reading up on the subject and so far it seems like most prefer climb milling for rough cutting and conventional for the finish pass. I dont think I can change the cut type on Sheetcam TNG though but I've only been using it for a short time so maybe I've missed it. More test cutting required me thinks.

[JAZZCNC]

I have been doing a bit of reading up on the subject and so far it seems like most prefer climb milling for rough cutting and conventional for the finish pass.

Mostly Climb milling gives better finish than conventional but Really depends on what your doing or more the type of cut and cutter length.
For longer tools then rough-climb/conv-finish because conv gives less tool deflection but with shorter tools then it doesn't give better finish than climb.

Climb milling is easier on the tool wear and also requires less spindle power, throws chips backwards not forwards, tends to push work down not lift.
Negative is it deflects the tool away from material so can be less accurate and why you should always use a small finish or spring pass. It's also not good for machines that are sloppy and have Backlash and will easily show in the finish quality if you have any. Also risk the tool breaking or material snatching due to cutter being pulled into material by the backlash amount if high backlash.!! . . Scary shit if bad.!!

When I'm working I'll use Conv if doing lots of full Slot work or higher than 75% step over has it's easier on the tool and climb for things like pockets etc where only 45-50% step over.
I always finish with Climb unless very long tool.

Another thing I always do is only try to have just the amount of tool needed for cutting depth plus bit of clearance sticking out the collet. Tool deflection plays a big part in finish quality.

[Web Goblin]

Thanks Jazz. I'm going to try a few things at the weekend to see if I can improve the cut quality.