Problem: X-Carve goes to side with every pass in Aluminum

Hi. I assembled my X-Carve several days ago and started tests on wood first. The machine is wery well built and everything works really well. Inventables have done really good job here. I made several complex 3d parts from wood using 1/4 inch HSS end mill. Everything was super clean and tolerances were ideal.

I am using 3D Max, MeshCam and Universal GCode sender.

Now, I am trying to do same parts from aluminum. I lowered feedrates and depth to 150mm/min and 0.5mm/pass first, and after unsuccessfull attempt lowered it to 100mm/min and 0.3mm/pass. In both cases it cuts aluminum very well, but I have one big problem. Every pass it makes goes a little bit to side, so after 20-30 layers I am getting stairway from one side and super straight wall from other.

I reasembled my V-wheels several times and tried different tensions with excentric nuts. Don’t know what to do now. With wood it works perfect. What am I doing wrong with aluminum?

Thank you for any help. Roman

Aluminum is harder task then Wood of course. You forgot to mention what kind of spindle you have.
Several possibilities are;

  1. Loose belts
  2. Low stepper power
  3. Loose stepper pulley set screw.

Thanks for the reply.

I am using DWP611. Nema 23 Steppers. Tried belts tightening several times. Will tighten pulleys and will check again.

I checked everything again and tightened x-pulley, it was a little loose. Also 1 belt screw was lose also. Tightened everything, added threadlock to all screws.

I tried to cut the part again, and got exactly the same result. Please see photos. What is interesting, it starts straight and goes to side after 20 passes. Deeper it goes more to side it takes. All my attempts were giving exactly the same curved offset.

MeshCam simulation shows everything right and G-Code senders visualization also shows it straight.




You are definitely loosing step somewhere. Did you go true voltage adjustment procedure on those pods.

No, what is that?

Also you have uneven cut on the surface, tells me your router is not 90 degree angle to surface, or your X rails are not Rigid.

Let me find link for you. Give a sec.

When I cut from wood everything goes well and I get excellent finished part.

Because wood doesn’t take that much vibration and stress. Try to go over this link.

I forgot to mention that, Working with Aluminum is way higher level. You must go all the steps to make your machine solid like a rock, X Rail rigidity, Voltage adjustments, V Wheel space and movement adjustments, fine tuning and leveling, good is not enough, perfect quality aluminum cutting tools are name of some. You may want to follow this forum’s Aluminum cutting posts.

Noticing that one side of your cut seems good. Was it in a separate tool path or part of the one which is also producing the errors?

Aluminum milling with the XC is not impossible but it does take great care to get good results and frankly the stock mill does not do a very good job at it. The controller can be very buggy and you will need a chip clearance system (forced air works great). What size mill are you running? Milling aluminum on the 1000 or larger XCs is really a challenge due to how much flex they have.

What sort of end mill are you using? How many flutes and what brand? Are you seeing chatter in the areas where you are having issues or is it cutting fine but just out of place?

You can look here for a bit more info for aluminum milling overview: Production level aluminum milling with .8KW water cooled VFD But get back with me and I will see if we can hep find the issue here and help you fix it.

Please tell us what axis you are having the problem with, X or Y
I am guessing that it is the Y axis and that you need to adjust the current pot for the Y axis. The power required to machine wood is much less than machining aluminum. This means that your current setting for the Y axis is OK for wood but low for aluminum.
If this was a tool deflection problem you would be seeing the stair steps on both sides of the boss. You still need to make sure that the amount of tool stick out from the collet is as small as possible.

Are you using some WD40 to keep the tool from welding alumimum to it.

Dave
Ariel, WA

That’s why I can’t cut aluminum, I was using KY. :joy:
That’s basically what I told him Dave. I’m not Aluminum cutter but At least I know my limits. I just start riding a bicycle, not ready for Harley Davidson yet. He needs expert Advise from pros like you, Travelphotog and some others. I’m off the hook for this matter.
Respectfully.

You know KY might work. The wife may question why you are buying KY though. :wink:

All the advice on this thread has been good and I expect that the OPer will discover what is causing the problems and get them solved.

Dave
Ariel, WA

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Thank you all for your help. After reding suggestions I have done several things and it cuts aluminum like butter now.

So, what I did:

  1. Increased current with pots. I found the lowest and highest values where steppers stopped responding and chose a value between center and the higher one. Now when I run air carving test I can not stop it or force it to skip steps with my hands. Motors get warm, but not above 35C. Controller chips are also max 45C.

  2. I changed the end mill. One I had was 2 flute HSS 1/4 end mill. So, after I started cutting aluminum it became dull and therefore the pressure on motors rised and they started to skip steps. Now I use Kodiak 3 flute Zirconium coated 1/4 end mill and it cuts aluminum so easly. Con is its price, around $50.

  3. After some tests I changed feedrates. I noticed that mill hits the material very hardly while diving into it, but cuts easily after. So, now I am using 200mm/min feedrate and 25mm/min plunge rate. I am going 0.5mm depth and 50% stepover. This all happens with DeWalt DWP611 at speed setting 5 (around 23000 RPM, I think). This spindle has built in fan which blows air pretty well and the end mill nor the aluminum peace become even warm, maybe 35C.

So the job is running and I will post some photos tomorrow.

Wish you all the best.
Roman

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Nice work Roman. Looking at the photos, he clearly had a problem on the plunge - not losing steps, he was flexing on the plunge. That’s why a few of the sides looked good.

Depending which way you are cutting, the forces involved could make the cutter miss steps in only a certain direction/angle. The angles that your machine can handle are usually diagonal since 3 motors are pushing the gantry. So on those angles, you end up taking full depth passes at a width of whatever the lost step(s) added up to. The root problem was stepper motor current, for me at least (when I experienced this). Also, you need to ramp/helix into any cut you make if you want to maintain any sort of accuracy though, the Z (or is it X?) can certainly deflect if not.

Almost finished the job and, unfortunately, the material just moved and I was forced to stop the job. Wooden clamps were flexing and were loose at the end. I shoulded check them, but who knew… Maybe this loose clumps contributed in my initial problem also.

Will find a solution to fix my aluminum piece more firmly. Also, will hook up current meter to all motors and will tune the current to motors as you advised (more scientific way). Then will start the job again. If successful, will post some pictures.

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I always drill holes in the aluminum and secure it FIRMLY to the bed. Can you get a slightly bigger piece of aluminum and drill holes so you can fasten it down?