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Fret Marks on Finisher Toolholder - Speedio

cosmos_275

Hot Rolled
Joined
Jun 9, 2015
I'm not sure what I'm doing wrong. I happened to check the toolholder that my finisher (for AL) lives in and I find fret marks. It's not all that old and has only housed a couple end mills. I don't do much besides finish passes with it. I run it at 8000 RPM and 80 IPM so about 3 thou per tooth. My roughers (run at 9k RPM and shown above in picture) and facemills which do far more work have no fret marks.

My only thought is it's a frequency thing with the 8000 so I'm going to slow it down and put a new holder in there. Any ideas what could be going on here? S500X1 no dual contact.



FRET.jpg


Another observation, as I'm taking the end mill out, I ground a small flat for the set screw and it's pretty close to the tail of the end mill, about 3/8" from the very end. I'm wondering if that's a no-no. I going to move it up 1/4" which is all I can before the flutes go into the holder.
 
I'm not sure what I'm doing wrong. I happened to check the toolholder that my finisher (for AL) lives in and I find fret marks. It's not all that old and has only housed a couple end mills. I don't do much besides finish passes with it. I run it at 8000 RPM and 80 IPM so about 3 thou per tooth. My roughers (run at 9k RPM and shown above in picture) and facemills which do far more work have no fret marks.

My only thought is it's a frequency thing with the 8000 so I'm going to slow it down and put a new holder in there. Any ideas what could be going on here? S500X1 no dual contact.



View attachment 330750


Another observation, as I'm taking the end mill out, I ground a small flat for the set screw and it's pretty close to the tail of the end mill, about 3/8" from the very end. I'm wondering if that's a no-no. I going to move it up 1/4" which is all I can before the flutes go into the holder.

Always put tooling as far into the holder as you can and still have clearance to machine the part.
Have I held onto a tiny bit like you are doing? Yes, I'd say we all have at times but it's not good practice.
 
Hmm. Ok. The set screw is about 3/4" back, so 7/8" of shank minimum to use it. The End mill only has 1.25" of unfluted shank. I will try choking up on it as much as I can. Thanks
 
Hmm. Ok. The set screw is about 3/4" back, so 7/8" of shank minimum to use it. The End mill only has 1.25" of unfluted shank. I will try choking up on it as much as I can. Thanks

Right, you want the set screw making full contact.
Make sure you grind your flat at a slight angle so that the end mill cannot pull out. (make the angle deeper toward the flute end)
 
Now... why are you running at such low RPMs?

If it is a 10k machine in the aluminum, everything should be at 10k. 16k machine? 16k basically all the time.

You paid for a Speedio, not a Slowio!
 
Now... why are you running at such low RPMs?

I do run most smaller stuff at 10k. The amount of time I'd save by going 20% faster on the finishing pass is trivial. I'm not running 3 shifts of production over here. My machine hauls plenty of ass, don't worry ;)
 
Choke up on everything as much as possible and are you seeing any fretting in the tool bore? I think of fretting as the surface turning red with rust, what you have isn't quite fretting as I don't think you have missing metal.

If you are on the edge of too much cutting forces then going to the stubby sidelocks would make a big difference.
 
I run everything at 10k in aluminum on the s500. 1/2" x 2" loc 3 flute stays in the turret all the time. Both roughing and finishing. I've never had to grind a flat using a set screw holder yet. I use the torque spec on the Maritool site for BT30 pull studs. 20 foot lbs if I remember correctly. Haven't seen any fretting yet.
 
Choke up on everything as much as possible and are you seeing any fretting in the tool bore? I think of fretting as the surface turning red with rust, what you have isn't quite fretting as I don't think you have missing metal.

Ok, sorry for terminology mistake if it's incorrect. No missing metal, just white lines running longitudinally. I actually created some on a tool holder recently by running some A2 tool steel at mild steel settings. I had the whole machine vibrating nicely before I decided to back it off. The marks in question happened prior to that and as I said it's life is mainly a finish pass so seems odd to me.

I will check the bore, but I'd think it it were coming from there, it's be on the other tools that run harder.


Pull stud torque?

Not much. My torque wrench got stolen last year, so I'm eyeballing it. I think I was doing 12 ftlbf.. pretty light.
 
I don't think I'm seeing any fretting here either, just a used toolholder. The line towards the pullstud ends of the taper is just where the spindle contact ends. Agreed that this could be an issue of filtering/ taper cleanliness.

Someone with more experience please chime in if my assessment is incorrect here.
 
I've never had to grind a flat using a set screw holder yet.

You're just asking for the tool to spin or pull out on you. It's a miracle that you haven't had an issue so far. Then again I've never tried your way so I'm only guessing as to how much would be needed for that end mill to move.
 
If it were coolant, I'd think I'd be seeing it on more than just this one holder.

I'm having a hard time getting a good picture of the marks. Crapphone camera not so good.

The "flat" I put on is really crude, just with a grinding wheel on my buffer. It's not very flat, but that thing is not coming out. I do it anytime a set screw is involved.

You can see how far back my "flat" is on the EM and off to the side the marks on the holder.

20211005_100717.jpg
 
As we have already said, WTF are you sticking the endmills so far out of the holders for? Also as has already been said, that ain't fretting, those are just marks. The last photo is a bit more interesting to me. I have basically the same marks but about 8 times more pronounced on some of my own tool holders but it is from pushing the tools as hard as I can. I was also getting fretting between the tool and bore, to the point the tool would get stuck in the bore. The finish tools wouldn't do that to the tool holders, just the roughers that I push till they break. I also like that it looks like there is more pressure on the holder at the big end, and no sign of a tight pull stud. I would say keep the tool holder as I don't think those marks are measurable, as in there is no missing steel. First, chuck up on the tools as much as possible, next get shorter gage length holders or change the cutting parameters if this continues. From my experience with my machine I don't think you are doing any harm to your spindle, but I would also try avoid those marks if that were my spindle.

I do find this strange as your cutting parameters for this tool are pretty conservative. If you want to experiment a little try holding the end mill as deep in the holder as possible first to see if that makes a difference. Pinching the very end like that is a bit iffy, in my mind at least. As far as flats on the tools go I have heard from a few people that they are not needed. This is something I am slowly playing with, slowly. 3/8" sidelocks get torqued to 17 lbs religiously, no guessing.
 
As we have already said, WTF are you sticking the endmills so far out of the holders for?

It can only go in another 1/4". I was using a stubbier one, but I can't reach much and coolant gets blocked. I'll shove that puppy in farther and get back to it. I got a new holder so we'll see if it comes back. Thanks
 
Chuck up the suspect toolholder in a manual lathe and Scotchbrite off the marks. If it's just fines, they'll come right off leaving a nice shiny taper.

Also reseat the pullstud with correct torque, 8-10 ft-lb.

Then run it for awhile and see how it looks.

Regards.

Mike
 








 
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