Ok i have somethign majorly wrong here...

[s2jesse]

So im pretty ticked off. So far Ive spent a very long time researching learning and modeling up my first project. I goto cut it today and already destroyed my project. ar15 lower from a 6x9 hunk.

Im using pcnc1100 with an power draw bar and TTS. Im using brand new 1/2" 2 flute ticn coated end mills(niagra, cleveland etc). Im doing some slotting cuts at 0.1 depth, 2764 rpms, and about 13 ipm...

Lots of chatter and tool pull out. Ive cleaned the collets with alchohol tripple checked my draw bar tightness to the point where it wont even pull out without almost full psi. (just for testing)

EVERY slot chatters and tool pulls out. Ive tried it at much slower ipm still issues. Ive tried it with different holder and other 1/2" cutters still same thing. Not sure what to do. I cant even use my mill.

How deep / fast are you guys cutting with 1/2hss slotwise..

Also now when i release the tool with the pdb i get the hiss.... then a pop at release. Asuming its just sticking and poping out but not sure what that is normal.

heres a pic
Tool pull out not a ramp

Thanks for any help!

[TXFred]

Your feedrate and chipload sound OK. I got the same numbers as you did when I set G-Wizard to the most conservative setting.

If you get a pop, it's because the R8 taper is sticking. You need to put a light coating of anti-seize on the taper, the threads, and in a few other spots. Without that lubrication, you've only got about 30% of the maximum holding force.

(I just went through the same ordeal.)

Read this for more info.


I still haven't retested my mill. Been busy with a crisis today. But after lubing the correct parts, the operation of the drawbar is noticeably different. I suspect that you're dealing with the same issue.

Frederic

[s2jesse]

fred!

Thanks for info! So i lubed that up and that def took care of the poping noise and i was able to tighten it all up nice again.

Now ill try another cut test soon and lethca know how it goes.

Jesse

[s2jesse]

wow that was it now it cuts like a pro! (so far) ... i guess it must of been just barely not pulling the tts in tight which was causing the chatter... seems much much better now.

[jid2]

Yeah read that TTS white paper for sure. But sounds like you are on the right path.

Don't start/learn with the projects you care about!

[s2jesse]

well basically cut my first half of the ar-15 lower.. went "okish" after lubing up the proper areas collet, draw bar etc. I had no pull out but still pretty bad chatter. again running at 0.1" depth sloting cuts with 24 feed rate. Brand new ticn coated 2 flute cleveland cutter in a set screw holder. With flood coolant etc. also the chips that are being left in the slot make a horible crunching noise unless i kept them clear with compressed air. If its not a finishing depth will just letting it cut through some of the stray chips left behind be fine?

The second operation was flat land maching which also chattered pretty bad and left a fairly bad surface. i had it set to layer by height at 0.2 and a distance of 0.2.

Is somethig wrong or do I just need to experiment with feeds and speeds. Or i guess i should again ask do other make similar cuts without bad chatter?

[shred]

How much tool stickout do you have? How are you holding the part? Are you sure the tool is still sharp after a bunch of previous chattering?

[pete from TN]

But I am curious as to why you are not using the full RPM available in your machine? I would spin that thing for all it is worth with a 2 fluter in aluminum and then figure the feedrate from that. Also yes it does matter that you are recutting chips. Try to get as much flood coolant flow onto the tool as possible and try to optimize the coolant pressure coming out of the nozzle. If you have more than one nozzle consider using less of them with more flow. Also coming at the tool with the coolant from opposite sides can actually be counterproductive unless you have a deluge of coolant. If you have trouble in deep pockets back it up with compressed air. Are you making a finish pass in the pocket and is it full depth? You are really gonna need to break out a spare piece of material and just make test passes with a particular cutter to see what works and what does not. Also do what you can to optimize runout on your cutters. You would be amazed at what a good tight runout on a cutter can do for your finish. Good luck man...peace

Pete

[s2jesse]

Shred, yep brand new cutter.. I switched it after the first chatter / pull out issues... Tool stick out is about 1.6". In a set screw holder. It's a large piece 9x6x1.5. Held in a premium 6" glacern

[urbanimports02]

i have a novakon, rather then a tormach, but often have to cut 1.5" aluminum, and i would never attempt it with hss. i tried in my early days with my mill, and could not get anything close to a decent surface with those long length cutters. 1.6" stick out is a lot for any 1/2" cutter, especially hss. i run 3 flute aluminum specific carbide cutters both coated and uncoated, and with the 1.5" flute length, i find some work better then others. 3flute will run better then 2 flute when it comes to chatter. run it full tilt, and adjust your feed rate accordingly. carbide in aluminum likes to be over 1000sfm which these mills can not achieve, so max speed is still too low, but works fine with the correct feed. i do it all day every day, but find the occasional cutter that still chatters no matter what i do, so i have developed my favorites. i like the ma ford cutters, and have an older "usa" cutter from shars that is my all time favorite, but they switched vendors, and no longer carry the 1.5" length even though it is on the site. that thing has worked hard for 2 years so far... hth

[300sniper]

But I am curious as to why you are not using the full RPM available in your machine? I would spin that thing for all it is worth with a 2 fluter in aluminum and then figure the feedrate from that. Also yes it does matter that you are recutting chips. Try to get as much flood coolant flow onto the tool as possible and try to optimize the coolant pressure coming out of the nozzle. If you have more than one nozzle consider using less of them with more flow. Also coming at the tool with the coolant from opposite sides can actually be counterproductive unless you have a deluge of coolant. If you have trouble in deep pockets back it up with compressed air. Are you making a finish pass in the pocket and is it full depth? You are really gonna need to break out a spare piece of material and just make test passes with a particular cutter to see what works and what does not. Also do what you can to optimize runout on your cutters. You would be amazed at what a good tight runout on a cutter can do for your finish. Good luck man...peace

Pete

i'd say this is all good advice.

[pete from TN]

Why thank you man... I try!! I would also add that as the other poster said a quality three flute cutter can work wonders. I personally use the Maritool ones as they are priced reasonably and work very well. No affiliation just a satisfied customer. The three flutes seem to work better in full slotting scenarios in my machine. Peace

Pete