Bed auto-leveling issues, and a possible solution: Adjustable feet

My RoBo3D R1 arrived two weeks ago, and has the latest upgrade with the "auto-leveling" feature. It printed just fine, most of the time. However, since a few days, I kept running into a weird problem: Whenever I started a print job, and the print head was lowering from the park position (35mm up in my case) for the bed level calibration, one of the Z-axis switches would, quite regularly, disengage way before the nozzle hit the bed. Subsequently, the entire calibration procedure would take place mid-air, about 2cm above the bed... And so did the actual print job, which would fail, of course. The only solution to this was to manually lower the print head, in little steps, before running the job (I've seen others reporting the same problem in the forum).

I tried twisting the Z-rods, thinking they might be "out of balance"... But no avail, when lowering the carriage, it would invariably, at some point, jam on one side, get slanted, and disengage the calibration switch.

What else could cause this effect? Maybe an unleveled printer? After all, if the Z-axis rods are not perfectly vertical, it's easy to imagine that the carriage could jam on one side during its way down.

So, I went ahead and used my laser meter (it has a pretty good digital level) to measure the level of the printer's base plate, and found it to be a whooping 0.8° off along the X-axis (the Y-axis was even worse, 1.1° off).

At first, I blamed the feet I had just printed off thingyverse... But no, I had been using them before the problem showed up. Then I remembered that I had just upgraded my office/lab/workspace with two new desks, one of them specifically for the RoBo3D. And... When I measured its surface level, turns out that it's exactly 0.8° / 1.1° off! I'm not sure if the problem is with the desk itself, or with the parquet floor in the corner of the room where the desk is standing, and I didn't even bother to check.

Granted, a straightforward approach would have been to level the desk (with leveling wedges, or scraps of carboard )... But I decided to take the more general solution to the problem "RoBo3D on unleveled/warped surface", and came up with adjustable feet (to replace the static feet I had used before).

All you need (in addition to the printed parts) are 4 M8 bolts (25mm or 30mm) with matching nuts (6mm thick), and, optionally, but recommended, 3mm nuts as jam nuts / locknuts.

The feet can be adjusted with a 17mm wrench (or just with your fingers). For tightening the jam nuts, use a 13mm wrench. I was thinking of also designing/printing the matching wrenches.

The diameter of the feet is 26mm, in case you want to stick felt or rubber protectors to them, like what I did.

Please see the attached photos, they should be pretty self-explanatory.

If anyone is interested, I'd gladly upload the STLs... Either here, or on thingyverse. Just let me know what's more appreciated.

Edit: I've attached the STLs here, for now. RoBo3D_AdjustableFeet.stl contains all four base and foot pairs. I've also uploaded two files with the individual parts, in case you prefer to arrange them yourself.

 

Did it fix your issue?

Yeah, you should put your STL's on thingiverse and tag robo3d. Great job.

 

Oh sure, sorry, forgot to mention: Before making the adjustable feet, I did of course try leveling my printer with some bits of scrap PLA and ABS (I have lots of those in various sizes and shapes )... And yep, that did fix the issue.

Will do. Thanks.

 

Thanks! This will be very helpful when I make the bed leveler mod. I posted in the support area a reference to this thread and a suggestion that this be added to an updated FAQ.