Your Standard Cry For Help?

Hello all. First time poster, about a month long (20 work days) x-carve user, and daily forum reader.

Have finally reached the point of “wtf, please help.”

So the details.
-1000mm Machine - DeWalt 611
-Attempting to cut 1/4 inch Lexan
-Speeds(currently): DeWalt at top speed - Feed Rate: 40in/min - Plunge Rate: 9in/min - Depth per Pass: .0575
-Bit: 1/8in dual flute straight Onsrud

Attempts to rectify:
Several test cuts, using many different methods described within these forums. Many bit changes, based on recommended bits in this forum. Speed changes, etc. Belt tension, potentiometer adjustments, usb plug changes, leveling, re-leveling, vacuum table, no vacuum table. Eccentric nut adjustments, belt alignments, sprocket alignments, constant waste removal, rail cleaning, etc. Pretty much what im trying to say is ive tried probably every suggestion in these forums when it comes to cutting acrylic, plexiglass, plastics, etc. I have all the recommended bits, and have attempted all the recommended speeds.

Here is the problem:
SVG paths are created using Gimp and Inkscape and then imported into Easel. The first pass always seems to be perfect. The second pass however, almost every time, veers off course. Ill stop the cut, and send it home, but it never goes back home 100%.
Reset home, lower speed, reduce depth, etc, same scenario.
As of today, i had my first perfect cut. This was, i assumed, the results of tuning the potentiometers on friday. I tuned them, tensioned the belts, checked my nuts, ran my cut. Perfect. Removed stock, added new stock, first pass perfect, second pass, right back to where i was a week ago.

So I am here now, asking for some assistance, or any suggestions of something i maybe have not yet tried, or some guru to say, “hey, do this”.

Now i understand that this machine takes a lot of fine tuning to get it working 100% of the time, and even them it will still require attention to maintain that 100% capacity. I have just spent 8 hours of work day attempting to tune this fish, to still only have the same issues reappear.

If I am missing any details in this post, please let me know. I will be attaching pictures, but for some reason right now they not coming through my email properly.

Thanks in advance for any assistance. Any clarification needed, please just ask.

Phil hit it in the head I believe. Probably running you router to fast(guilty as charged when I first got started). Heating it up to the point of almost melting. It’ll grab your bit and pull you off course. That causes your machine to think your somewhere other than where your at. That’s probably your homing issue after the fact. I had it happen once. Ok maybe twice.

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When cutting acrylic I found that the smallest piece that gets on the rails can stop the v-wheels from rolling and cause the cut to veer off. When I jogged or tried to home it would skip. This happened to me numerous times and I thought my wheels were loose or my belts were slipping but they weren’t. When I blew the rails off with compressed air everything would be fine. I think it was melting the acrylic and making chips rather than flakes.

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It’s super important to make sure that you are cutting chips, and not melting them. Keep some air on the tool to keep it clear.

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I’ve attempted the 100in/min setting at the lowest Dewalt speed, and every cut appeared as if a rat chewed it. The current settings I have listed above give a some what clean finish, but I will try these settings again.

Yes, as stated, I have calibrated the motors. The belts are heat shrunk, havent applied ann y loctite, but that is a good idea.

Yes, ive noticed that the v wheels can get clogged up, and i have made pretty good attempts while cutting to keep them clear, like i stated, this veering off can happen just after the second pass, or 10 minutes into the cut…there seems to be no pattern. And keeping the rails clear and the vwheels is something im definitely doing.

There is a constant vacuum on the cut area, are you suggesting I blow air instead of suck chips?

We are using the waste board that came with the machine, which is attached to a table we built. The surface is pretty level, and we are clamping the material on the sides and in the middle. So it is being held in all potential weak points.

Thanks, we may have to try that…seems a little odd that the waste board sent with this machine would not be flat however, I mean I understand not all things are produced identically, and there could be variances, but even in those differences i can not see there being that big of a difference from one board to the next

The MDF absorbs moisture from the air and spots will swell leaving bumps. It will probably need milled down flat and over time it will swell again and need flattened again (more humid places will require this more often).

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Makes sense for sure. Our x-carve environment is basically a wood working warehouse, we already have a very low moisture area…and originally we had created our own waste board for the machine, complete with a vacuum table, but even in that scenario we having these issues. We are using the the waste board that came with it in the hopes that starting over and using the tools supplied, we would get better results…however, obviously this is not the case.

check those pulley setscrews! and do one of the many x-gantry stiffness mods

Also make sure to never let a part get loose on you, so use tabs and enough of them that the parts stay rigid
Hang in there

Hi Dale,

Would you be willing to export your g-code from Easel and share it with us, or share the Easel project? I’d like to try running the file.

Roger

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Unfortunately I can not share the project or g-code, for proprietary reasons. But if maybe you had a file I could run to compare, or at least see how my machine runs a particular file compared to yours, that may be useful…And i truly appreciate the request and your intentions, but for what we are using the machine and the cuts we are making, it really is something we’d like to keep in house. Again im sure you understand this.

Sure, no problem at all. See if you can execute this project from Easel - http://easel.inventables.com/projects/SRSwwWVU-5KDmLfVtSS_Tw. It’s a quick test pattern that I use to look for problems.

Have you verified that the wasteboard is actually level to the spindle and X/Y axes? It’s a common misconception to think it’s level because a torpedo level shows it’s good, but the more accurate (in this case) meaning is that the height from the spindle to every point on the wasteboard is the same. That’s why we tend to cut large pockets in the wasteboard.

On mine, I had a dip of about .030" in the middle that would reflect in my work. I would either have a more shallow cut in the middle, or a deeper cut on the outsides. That led to breaking a few bits and messing up some projects because my .050" cut actually turned into .080", exceeding the bit’s ability to cut and/or clear ships.

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Dale

I’m by no means an expert but I can say that I’ve spent a lot of hours dialing in my machine. I’m going to throw something out there that really messed me up in the beginning that no else has mentioned. If you are using easel as your g-code sender how strong is your internet connection? I know that it is said that Easel doesn’t require a Internet connection to run but I know from my own experience that to be a false statement. I ruined several pieces when I was first getting started using Easel and a WiFi connection. That’s why I use UGS now even though it has its own set of issues. I haven’t had your exact problem since I switched.

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Both.

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Having just completed a few projects in plastic I can only share my tips, many of which have been discussed already, but maybe there’s something else in them that you find useful.

  • Router on 1
  • 1000 - 1500 mm/m
  • DOC = .5x Bit Diameter

Stick the material to the wasteboard VERY WELL with double sided tape. I use carpet tape. Recently I’ve found a method I like where I cover the back of the plastic with painter’s tape, then use carpet tape on that. This keeps the adhesive residue from building up and gumming up the edges of the cut too much. Clamping or screwing it to the wasteboard tends to make it bow up in other places, causing it to bind and will cause your cutter to act funny.

I didn’t like using a straight flute bit for cutting plastics. The chips don’t eject from the cut path very well, and if you turn your head for a split second they’ll melt (especially at max speed!) into the cut channel causing problems for the next pass. Try using a 1-flute upcut bit, or a 2-flute upcut bit. I’ve had great luck cutting plastic with the single-flute bit Inventables sells, that I got as part of the starter kit.

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