rcferguson
Full Member
Posts: 182
Machine: Carve King
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Post by rcferguson on Feb 10, 2020 15:19:37 GMT
I almost exclusively cut aluminum on my Carve King, and I can tell you there is a huge difference (10-15 thousandths) in cuts if I face cut in both directions. The steps between passes are very obvious. If I face in only one direction it is much better. I presume this is because the machine is probably a little more rigid in one direction as opposed to the other. So I tend to face in one direction (90 degrees), for the finish layer, then do it again at 0 degrees.
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Post by Derek the Admin on Feb 10, 2020 17:14:58 GMT
My gut feeling is that your having a deflection issue. Your creating a large amount of resistance against the tool using a 1" facing cutter on that aluminum. I recall reading somewhere that the routers and/or spindles most are using on machines this size do not handle postive force in Z+ against them very well. It's not the rest of the machine so much as the spindle or router that's creating your issue I would guess. I would cite several things in support of this theory. First, your able to surface softer material that would pose less resistance without any issues. Second, notice that Blinsc said he has had no issues cutting aluminum with 1/8" or 1/4" endmills. The surface contact of those tools against the material VS what your attempting to use is drastically different. And 3rd, provided you are sure that everything is taunt and secure on your gantry, your tram looks great. Humor me and try the same toolpath with a .25 endmill with that same 50% stepover. Here it is with a 2FL .25 endmill, should have probably fed it a little slower but similar ridges are present. That looks a lot like the tool running out. Do you have a dial indicator you can put on the end mill and observe it for runout on the shank?
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Post by aquanub on Feb 11, 2020 2:41:32 GMT
Here it is with a 2FL .25 endmill, should have probably fed it a little slower but similar ridges are present. That looks a lot like the tool running out. Do you have a dial indicator you can put on the end mill and observe it for runout on the shank? Yes I do, I will check for it tomorow when I get some time. Thanks for the suggestion!
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agrpm
New Member
Posts: 32
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Post by agrpm on Feb 11, 2020 2:42:33 GMT
I feel like if you're getting a ridge in aluminum, that seems like it's a mechanical problem Short of checking the tool runout as derek suggested, I would begin to look in the above quoted direction. Perhaps something was overlooked that's loose causing your -Z- to not hold rigid when force is applied against it. That wouldn't show up when tramming the table rotating the tool by hand, but would be present once speed and pressure were introduced.
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Post by aquanub on Feb 11, 2020 11:36:44 GMT
So I tried surfacing from the other direction (x-axis) and this is what the surface looks like after running an indicator over it. I also recall noticing a dip in the center when doing the initial tram measurements across my flat surface but wrote it off as a bad surface Perhaps this points to a loose Z? Are there adjustments that I am grossly overlooking on the PR?
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jms
Full Member
Posts: 168
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Post by jms on Feb 11, 2020 16:39:59 GMT
Looks more like a sag in x axis rails. When assembling the x rails I used my vernier and measured from aluminum table to get them parallel. Just recently I had to correct binding in my z axis, near very bottom was binding and causing coupler to loosen up and slip. Of course after correcting that I have to re-tram everything.
Joe
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Post by aquanub on Feb 11, 2020 17:21:55 GMT
Looks more like a sag in x axis rails. When assembling the x rails I used my vernier and measured from aluminum table to get them parallel. Just recently I had to correct binding in my z axis, near very bottom was binding and causing coupler to loosen up and slip. Of course after correcting that I have to re-tram everything. Joe If it does turn out to be sag... can this be rectified based on what the profile looks like? Or would I need new rails? It just seems unlikely that the sag would be found in both x rails? Maybe I should at least loosen them up and re-tighten with a level.
I'll do some more investigating tonight. Thanks.
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jms
Full Member
Posts: 168
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Post by jms on Feb 11, 2020 17:51:41 GMT
I would say the shape you cut should reflect the sag in rail, if thats what it is. I don't think you need new rails , just loosen the 6 pairs or so of screws and true them up. Did you check preload of linear bearings? I just snugged mine up when assembling, maybe a 1/16 of a turn beyond touching.
Joe
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Post by aquanub on Feb 13, 2020 11:31:06 GMT
another thing that crossed my mind... since my wasteboard is essentially slats with spaces in between... could 3/8 thick acetal deflect enough during the surfacing passes to where that dip would occur? I am only taking off 0.005" to 0.01"?
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Post by tgattis on Feb 13, 2020 20:07:59 GMT
another thing that crossed my mind... since my wasteboard is essentially slats with spaces in between... could 3/8 thick acetal deflect enough during the surfacing passes to where that dip would occur? I am only taking off 0.005" to 0.01"? That would depend on if you are using an upcut or downcut bit, but 3/8" material will slightly bow between a span of 3-4" if there is enough pressure. Maybe try the tape and super glue attachment method to a piece of 3/4" MDF?
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petek
Junior Member
Posts: 72
Machine: Power Route
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Post by petek on Mar 22, 2020 18:20:14 GMT
When I go to surface my material, I am still left with ridges I can feel with my finger: __________ Switch to a bullnose endmill. You will always have these marks with a square end mill..
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petek
Junior Member
Posts: 72
Machine: Power Route
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Post by petek on Oct 28, 2020 5:33:22 GMT
I don't know if it's a tram issue.. Check the axial play in router. My Power Route's Dewalt 618 has about 0.0025" of axial play. I'm not surprised - because of the forces a router is usually exposed to. They use bits that usually have straight cutting edges (axially anyway), as opposed to most of our end mills - which have helixed cutting edges. A router's deep groove ball bearing can take some axial load, but it's mainly made for radial load. They aren't even spec'd based on any axial internal clearance (play), only radial. That's why I'm upgrading the main bearing in my Dewalt Router from a single row deep groove ball bearing to a pair of sealed ABEC-7 angular contact bearings, mounted back to back. In theory, that should eliminate the z-axis play. There isn't any measureable z axis deflection in the power route itself - even up to 5 kg (50 Newtons) of force - which is probably ridiculously high for axial load. Not measure-able w/ a 0.001" precision dial indicator anyway. Also, I recommend a bull nose (or radiused corner) end mill for facing. (see PDF pg 10 of 12 - www.canadacarbide.com/402endmills.pdf)Sharp corners of a flat end mill will leave marks unless you have a theoretically perfectly stiff and perfectly aligned machine, which will never happen in the real world. from the marks, it looks like the endmill is deflecting back forth .. sometimes the leading edge causing a scratch and sometimes the lagging side of the end mill.. As if it's "wagging" back & forth.. although that kinda sounds silly.. -Pete
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