Reply with QuoteMy first guess would be loose gibs.
My mill was noisy and chattering like that, and as soon as I snugged the gibs, the problem went away.
Put an indicator on your table, and wiggle it by hand. You should have less that .001" play in your table.
question about surface finish, mainly, why did this come out so baddly?
it doesn't really matter here, my question is more for my own education, I may only be a hobbyist, but it sometimes doesn't hurt to learn...
so as can be seen by the pic below, my surface finish sucked big time... lots of chatter... noisy as all get out too...
now, there were no finish passes, just roughing, as I dont really care about the surface finish here, but still am I correct in thinking that looks a bit rough even for a roughing pass
this was using:
Center Cut End Mill - 17mm
31810 - TTS M8 - Medium
tooling
at 0.100" DOC, 40% width of cut, 5100RPM and 43ipm
my uneducated guess is that is a lot of force on the relatively long tool?
I have one more part to do, would it be good to drop to say a 20% width of cut?
or could my inserts be getting dull or something? (if so, that would be great!!! be the first time I ever had a tool die of old age, vs a violent death! be a cause for celebration I would think?)
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NOTE:As one wise professional something once stated, I am ignorant & childish, with a mindset comparable to 9/11 troofers and wackjob conspiracy theorists.
Re: question about surface finish, mainly, why did this come out so baddly?
My first guess would be loose gibs.
My mill was noisy and chattering like that, and as soon as I snugged the gibs, the problem went away.
Put an indicator on your table, and wiggle it by hand. You should have less that .001" play in your table.
Re: question about surface finish, mainly, why did this come out so baddly?
What material is that? Did you use coolant? Looks like steel and from the brown spots it got way to hot. How did you arrive at your feeds and speeds? Without knowing more it's hard to make a guess as to what caused that horrible finish. I would hazard your spindle speed is 2-3 times what's appropriate for your material. Feeds are accordingly to fast as well. Try 2000 rpm and 12-15 ipm and see if that improves things.
Ben
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Re: question about surface finish, mainly, why did this come out so baddly?
Your guess is right, too much force for a long tool. Stiffness reduces with length to the 3rd power. So if you double the length of the tool it will deflect 8x with the same force applied, or you need to reduce the force 8x to have the same deflection. I run that same tool at .030 DOC .500 WOC 3500RPM, 35IPM with good results. It is right on the edge or chatter and will do so when going into a corner and WOC momentarily increases. A good starting place is to reduce either your DOC or WOC to where the product (DOCxWOC) is = .015 and adjust from there.
Re: question about surface finish, mainly, why did this come out so baddly?
thanks for the responses,
first and foremost, I should of mentioned that the material is 6061, so easy cutting...
the "burn" marks are from Tormach's Patented "Amazing Paint Stripping, Aluminum discoloring, coolant", they are not real burn marks...
I haven't really checked my gibbs per se, my back lash on both X & Y is only a couple tenths of a thous, less than 0.001" so I would guess they are ok, will go push on table just to see, buy I am thinking they are probably fine? and if I am actually trying for a nice surface finish, it is easy enough to achieve... I was just surprised how bad this one came out...
speeds & feeds came from gwizard.
IMT, your suggested F&S/cut is generally in line with what I use when I am going for a "nice" surface finish, I just thought I would try and push it harder as all I needed was to hog out the insides a bit. and I don't have one of those fancy shear hog tools...
where does the 0.015 value come from?
NOTE:As one wise professional something once stated, I am ignorant & childish, with a mindset comparable to 9/11 troofers and wackjob conspiracy theorists.
Re: question about surface finish, mainly, why did this come out so baddly?
DOCxWOC of what has worked well. .030x.500=.015. If you want a larger DOC then reduce WOC. If they multiply to the same number then the cutting force is roughly the same (assuming the same chip load).Originally Posted by SomeWhatLost
.100DOC and .150WOC would have roughtly the same force as .030DOC and .500WOC.
Also you are pocketing so you need to consider the actual WOC and the actual chipload which will be different when cutting the inside of an arc than when cutting straight.
Re: question about surface finish, mainly, why did this come out so baddly?
ok, that makes sense, thanks.
NOTE:As one wise professional something once stated, I am ignorant & childish, with a mindset comparable to 9/11 troofers and wackjob conspiracy theorists.
Re: question about surface finish, mainly, why did this come out so baddly?
Chatter will leave a finish like that especially with a cutter that large with your speeds and feeds on a Tormach. I run a .250 cutter at .125 doc, full slot without chatter at 40 ipm but the cutter has been shortened up, I cant do it with a regular length cutter without chatter.
1/2 & 5/8 cutters I run much slower, around 20 ipm and 3500 to 4500 rpm .050 doc and use a finish pass of .007 to .010, without it, the finish doesnt look so good.
My rule of thumb is if the cutter chatters I lighten up on the woc doc until it stops, thats when I can have a problem with pullout, as long as there is no chatter I get no pullout. I am not saying its right or wrong, just the way I do it............
mike sr
Re: question about surface finish, mainly, why did this come out so baddly?
Agree with pops, no chatter, no pull out, I do the same thing. I generally run bigger bits at lower RPM, except for the shear hog, it's worth the money for sure BTW. I'll add that, on my 1100, I've started to grab a 3/8in em rather than a 1/2in. and been very happy with the change.
Qualichem; your best friend!
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Re: question about surface finish, mainly, why did this come out so baddly?
I have never really had a problem with pull out, it happened once, I did the stuff in that white paper that tormach had, then haven't had an issue since...
oddly enough, I do have a shear hog... just arrived Monday... missed the weekend/when I needed it by that much... oh well, was close I guess...
as for worth the money?
I have my doubts...
but on the bright side, as a hobbyist, I don't need to justify the cost, I just need to decide that "I want that!" makes things so much easier this way
I have floundered between the two... the 3/8's seems more forgiving of some of sprut's more questionable tool paths...
but when the 1/2 is humming a long, it really makes quick work of things...
I have been wondering about that...
is it really that much better than Tormach's Patented "Amazing Paint Stripping, Aluminum discoloring, coolant"?
how well does it strip paint and discolor aluminum?
and rust my mill/tools?
NOTE:As one wise professional something once stated, I am ignorant & childish, with a mindset comparable to 9/11 troofers and wackjob conspiracy theorists.
Re: question about surface finish, mainly, why did this come out so baddly?
Qualichem is the best thing I spend money on...period, end of sentence. It smells and feels nice on your skin, I know what that sounds like but I appreciate that aspect, it's a lot nicer than most others in that regard. Your surface finish will be as good as it possibly can be with QC, but you should have no more issue with rust, I don't at all but I've used it from the beginning. I use 251c (aluminum primarily) and 291 (for titanium an aluminum), I mix thin over each other as well, doesn't matter.
I've been doing runs of 1000+ parts that require a good bit of roughing but I can't fit the shear hog, I used to use the half but I spent a lot of time deciding and I can get about 15-20% more aluminum removed in the same time with the 3/8in end mill, INCO Streaker is the best I've found. I have a thread here called "best half inch rougher" take a look, I'm doing 0.4in DOC, 0.085WOC, and it will hang at 100 IPM - 105IPM all day long.
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Re: question about surface finish, mainly, why did this come out so baddly?
so, this weekend I had time to try out my shiny new shear hog....
my reviews are a bit mixed...
on the one hand, Holy Mother of All Material Removal Rates!
on the other, it got about half way through the pocket (same part as above, just substituted shear hog for the 17mm) it yanked the part out of the 4 jaw chuck and tossed it against my stock side flood coolant shield thingy which is now slightly bent out of shape...
while looking at what happened, I noticed the side wall cut quality sucked big time... looked like someone dragged like a #4 screw around in there...
so then I look at the shear hog...
ok, so why does the insert screw stick out so far?
not a great pic, but you can sort of tell that the corner of the screw is apparently supposed to be a cutting surface... I guess that is the American made quality that everyone goes on about?
so anyway, I thought that was stupid, so I ground it off/flatish...
re-ran the op from the top, no other changes...
1st thing I noticed is that it re-cut the side walls in the previously 'done' areas... it is almost like something was holding the cutter away from the walls the first time around? completely cleaned up the 'screw' looking marks, still not much of a surface finish, it appears the shear hog is more of a roughing tool.
2nd thing I noticed is once it got past the point were it self destructed the first time around, and started doing 'full' cuts again, it just sounded much better this time around...
over all, I am not sure if I can say it was "worth it" or not... I do like it... but that is one pricey tool...
NOTE:As one wise professional something once stated, I am ignorant & childish, with a mindset comparable to 9/11 troofers and wackjob conspiracy theorists.
Why are you trying to cut so fast? The object here is to CUT the material not push it out of the way.it doesn't really matter here, my question is more for my own education, I may only be a hobbyist, but it sometimes doesn't hurt to learn...
so as can be seen by the pic below, my surface finish sucked big time... lots of chatter... noisy as all get out too...
now, there were no finish passes, just roughing, as I dont really care about the surface finish here, but still am I correct in thinking that looks a bit rough even for a roughing pass
this was using:
Center Cut End Mill - 17mm
31810 - TTS M8 - Medium
tooling
at 0.100" DOC, 40% width of cut, 5100RPM and 43ipm
my uneducated guess is that is a lot of force on the relatively long tool?
I have one more part to do, would it be good to drop to say a 20% width of cut?
or could my inserts be getting dull or something? (if so, that would be great!!! be the first time I ever had a tool die of old age, vs a violent death! be a cause for celebration I would think?)
I have WAY better luck at 3500 to 4000 RPM and 25 to 30 IPM using a 3/8 3 flute end mill and flood coolant.
Re: question about surface finish, mainly, why did this come out so baddly?
My Shear Hog numbers for aluminum 6061 adaptive clearing
5100 RPM .250" deep .300 step over, 16IPM full flood
You can push this to 25IPM but it sound hard on the machine, at 16IPM you can just walk away and let it do its thing. I leave .004" of material for a clean up pass with another tool unless its doing an adaptive clear on a surface with a curve. Adaptive clear likes to make the tool path a little course and it will eat into your final dimension so I leave about .010" of extra material with curved surfaces.
Think of the shear hog as a mini fly cutter. You can get a really nice bottom finish but your sides will be stepped. Your chatter looks nasty, when any of my cutters start to scream it means I'm either to deep or have to much step over.
