Smoothing? <resolved, bad ballscrew support bearing>

[JayCNC]

Problem is, I get the same results contouring 1/8” thick aluminum too.

If looked at closely enough, there’s a pattern to it. It may not show in pics, not sure.

[todd432]

Jay I bought a refurb(Lenovo Thinkcentre M73 (TFF) Ultra Small Form Factor Tiny PC - Core i5 (4570T) 2.9GHz Dual Core CPU - 128GB SSD - 8GB RAM -) thread 1983) from new egg to replace the suspect pc. Good so far.

My sons old gaming rig is a Frankenstein of parts, E8500 intel water cooled 1315 thread, 4 gig ram, and a ATi HD 5970 graphic card, I used the onboard Ethernet port for my test.

One last thing ... I know its frustrating as all get out. I posted reports and pixs and video and was hoping for a quick fix too.
But my problem manifested it self as motors or drives and when that didn't fix it I was feeling pretty down and on my own.
I knew that it had to be something else... to many guys running just fine with Acron , I even asked a forum member to run my file to double check the code.
Tried all suggestions and settings to no avail. In the end it was something stupid ,the DAM PC.
So as my signature says check your assumptions ..........should have taken my own advice before dropping 2000 on servos????

[JayCNC]

Ok, so here's the g-code for anyone that wants to check it out.

Feed/speeds I've tried are all over the map. Finish pass has always been .01 stepover, .55 doc. I use g-wizard and have tried 1/4 3F YG and 5/16 3F Lakeshore both for aluminum. The pattern I mainly see is almost like ocean waves, and after playing with smoothing settings I can get it to just a chatter look without the higher consistent ridge. I've done finish passes as slow as 13ipm to as fast as 75ipm without much change.

Todd- thanks for the inspiring words, I'm sure I'll figure this out at some point.

To everyone else that's responded, THANK YOU for the suggestions, that's exactly what I was looking for. Just a little expert advise on where to start and where to go with this. I wasn't trying to be an ass. I'll try to get out there to check again for any movement, but I've already checked twice now and everything seems pretty solid.

Pictures of the machine are on page 2 btw.

[JayCNC]

Current machine configuration

[tblough]

Just using the vise for scale, it looks like the Z-axis has about a 8" span between linear bearings and a 12" overhang. That could be a source of rigidity problems. Could be some twisting going on in the Z structure which is why cuts look good in the X direction and in the Y direction but not at angles. I'd run a series of cuts starting parallel to the X axis and moving towards Y in 10 degree increments. My guess is the chatter will be the greatest around 45 and reduce as you get closer to both X and Y. Truss work on the Z carriage is beautiful, but stiff in only two directions.

I looked at the code and it's pretty simple. The linear moves are just that - one single G1 move from point to point, not a bunch of line segments that some might have suspected as causing problems, and something that smoothing will have no effect on. My guess is this is most definitely a rigidity issue.

[JayCNC]

Just using the vise for scale, it looks like the Z-axis has about a 8" span between linear bearings and a 12" overhang. That could be a source of rigidity problems. Could be some twisting going on in the Z structure which is why cuts look good in the X direction and in the Y direction but not at angles. I'd run a series of cuts starting parallel to the X axis and moving towards Y in 10 degree increments. My guess is the chatter will be the greatest around 45 and reduce as you get closer to both X and Y. Truss work on the Z carriage is beautiful, but stiff in only two directions.

I looked at the code and it's pretty simple. The linear moves are just that - one single G1 move from point to point, not a bunch of line segments that some might have suspected as causing problems, and something that smoothing will have no effect on. My guess is this is most definitely a rigidity issue.

Thanks for the response! Off the top of my head those numbers seam about right. I think I was 12” outside to outside of the bearing blocks so 8” sounds about right between them with an 11” overhang, hence the trusses to make it rigid. I won’t be able to check with an Indicator until tomorrow evening if there’s any side to side movement at the bottom of the Z, and if there is I’m not sure how to go about stiffening it either. Any ideas? I’ll run a test block starting at 10 degrees and working to 45 like you suggested, I think that’s a good idea. I still don’t understand why playing with the custom smoothing setting would change the finish on the same part though. Sorry I keep coming back to that but I’ve seen different results from doing it so...

[Dan M]

Been reading this thread and I was curious if you were using a different controller with the router prior to the Acorn?

[JayCNC]

Been reading this thread and I was curious if you were using a different controller with the router prior to the Acorn?

No this was a new build with the intent of running Clearpath Servos and Acorn

[JayCNC]

I was just thinking.... If I had rigidity problems wouldn’t you think it would show up using a 2.75” fly cutter or a 2” facemill?

[Dan M]

Post a video of it cutting, maybe someone will have some better suggestions after seeing the machine cutting. Just a suggestion since like Marty always says, we can't see what you see.

Maybe it will be something obvious to some of the experienced machinests that are on the forum? Also have you looked at the recommended feed and speed and chip load and sfm for your endmills? I know my endmills have a manufacturer calculator and it's way different than the g-wizzard calculator. Like not even close once I looked up the manufacturer specs. I don't use it anymore, I just use the formula based off my tooling recommend specs.

Have you tried using a larger endmill with a clean up pass just to see what happens?