problems with CNC 3018 Prover SainSmart ?

Hello,

I am not a professional user,
it is a CNC for making single and double-sided PCBs.
All my tracks are erased according to the position of my PCB on the board.

I contacted the manufacturer. I’m waiting for their answers.

I’m not going to be able to straighten the tray that’s deformed, it’s impossible to do manually
I think we need to change it and adjust the flatness with wedges under the tray.

Not easy to do, because I have 0.592 mm of gap on the left rear relative to the right rear.
I have 0.470 mm of gap on the left front relative to the right front.
Big trouble to adjust all that.
Thank you for your advice.

Sincerely.

Welcome to the Router Forums N/a.

As David points out that is a low-end CNC machine so the specifications might be within the manufacturing tolerances if they even have any. Quality control for these low-end machines is also nonexistent, it is actually cheaper for them to accept a few returned machines than to pay someone to look for flaws in the product.

There is one solution to give you a flat a work surface, that even the more expensive machines use. Add a sacrificial spoil board or strips to the bed and trim that surface flat and perpendicular to the spindle. If you add strips then you can still use the T-trac clamps to hold your workpiece. If you use a solid one-piece spoil board then you need to decide what work holding technique you want to use. The big problem here is the limited Z-axis height of these small machines. Since you are using it for PCB cutting it will not be as much of a problem. You can use double-sided tape, or what people refer to as the "blue Painter's tape/super glue" method for work holding but these have been known to fail if you don't make sure the tape is down good or the surfaces are not clean, so make sure you prep the surfaces and that the tape and glue are used correctly.

Whichever method you chose to use, strips or solid spoil board, make sure it is mounted well then use a pocket toolpath to trim the worksurface flat using an endmill. This being a small CNC it is probably limited to 1/8" shank bits so it will take a while to trim the spoil board. Once it is trimmed you should have a flat surface to work with.

Just remember the results of using one of these low-end CNC machines might not be perfect but if you do some testing with the different bits you will be using you can find the limits of your machine. If you stay within those limits then you should be able to do some acceptable work cutting the PCB projects.

Ah, Yes, the infamous 3018 Chinese "engraver". There are many things about this design that are truly mediocre. Foremost among them is vendor support.

There are thing you can do to get it working better. I would go through and tighten everything you can (though don't over tighten). Then install a sacrificial spoil board that Mike mentioned above and skim flatten it with the router so your bed is basically flat with respect to the X and Y axes. It sounds like you will probably need to shave off about a half mm at the high spots.

Personally, I would toss the electronics and use real drivers and a low cost Grbl controller but you can probably make what you have work.

You mentioned milling PCBs. This needs a very flat bed but that's not enough as it is hard to mount FR4 PCB material exactly flat. I used double sided tape on the whole piece and they still have irregularities. In general, you are removing 14/10000 of an inch of copper and typically cutting about 4 mils deep so you need to dial your machine and process in pretty well. What I do is height map the mounted PCB and then transform the GCode to follow the height map. I use this GCode Sender on grblHAL and a 3D probe to create the height map and transform the GCode. 3D probes aren't cheap but you can do it by hand with a cheap contact probe or even a home made one. The Sender has manual support for height mapping. See the attached image - height map shown is a portion of my spoil board after skimming. The different between high and low is only .1 mm. I will get easily 2 or 3 times that with a mounted PCB blank. Don't forget to use high quality, sharp bits - those 10 for $15 ebay specials are a joke.

FWIW, I only mill PCBs for quick little tests when I don't want to wait for the fab. They come out OK but there really is no substitute for a real PCB with solder mask and silkscreened legends.