Inventables Community Forum

Mesh Bed Leveling

I have seen a few threads on here about how to level the waste board, and how there is no real good way to do this.

With the introduction of the Z Probe, it should be much easier to implement now than ever before. Within Easel, I would love to be able to have the system choose several points on my waste board to measure the distance between the spindle and the waste board itself. This could help solve for the waste board not being perfectly level with each of the rails.

A great example of Mesh Bed Leveling implementation is that of the Prusa i3 MK2: https://youtu.be/rYrLT5G-a9I?t=92

I would imagine (just as Mesh Bed Leveling does) that it would factor itself into g-code and make all of its adjustments on the fly.

Thanks,

Rob

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Here is what I do.
Get some wooden shims. Home depot sells them. Or you can make them.
you will use 2 of them
if you have a depth gauge you can check the distance. If not use a feeler gauge and a blunt bit or one that is turned upside down in the chuck.
put your flat plate (aluminum or wood that you know is flat as can be.) on the waste board
(This will not work if your item to be cut is too thick. I plan on getting the plates that raise up the Z made to allow me the extra inch to do this trick.)
Then lock down the back side with your clamps but leave the clamps slightly loose.
use the depth gauge or feeler gauge to check the level and shim the front to get it flat. one shim per corner on the front.
I will do a video on how to do this when I get home.

Hey Stephen,

Thanks for the response. I too currently level my bed manually, however, it would be way easier to do the mesh leveling with z probe every so often as even the wedges and mdf can settle and it’s no longer level. This has potential to be far more accurate too!

This would be a great selling point for the z probe too! Of course, you could easily have a manual method just like they do when you are prepping to cut.

Thanks!

I use the wedge method prior to each job.
Its a hassle but I know the area is level to the bit.

So you are both cutting a large square that goes on top of your wasteboard (a second wasteboard if you will) securing that, and then securing the part you are cutting to the top of that piece? And @PhilJohnson, you are then shaving the top of that second wasteboard before securing and going to town on your actual work?

Seems like a better solution than the shimming im doing now, but still wouldnt beat actual Mesh Bed Leveling!

Very nice! I like the solution, and may try something along the lines of that myself. Trying different low cost solutions until something can officially be built into the software itself! Im not sure ill be able to swing a custom wasteboard on the bottom, but securing another sheet of MDF or something to the top and planing it is a more viable option for sure.

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I don’t think autoleveling is going to do much for you when you’re trying to mill most things. 3d printers are doing something very different, and autoleveling for circuit boards on a mill is used because you’re trying to do very shallow engravings on a non-planar surface. If you’re milling out a part, just knowing either the surface of the workpiece or the surface of the wasteboard doesn’t really help you much. (The surface of the workpiece isn’t going to track the surface of the wasteboard, in any case).

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@JamesMoore - I still feel like it would solve for a lot of the problems that people are running into with not cutting all the way through. I’ve seen countless threads of people shimming and having secondary wasteboards that they plane down. That is essentially doing the same thing, only you are physically solving for it instead of solving for it in the code.

Auto leveling works only if your cut is shallow.
If you are cutting deeper then auto level will make your cuts angled.
It may not matter to some but if your making pocket cuts that have to be higher tolerances then it will make a difference.
The bit used will also make a difference. I mean the shape. If you use some sort of auto leveling mechanism and your spindle or rails are off by .01" then the offset grows the deeper the cut.
What I am trying to do is make sure the spindle is at 90° to the bed and the perspective axis. Then you can shave the bed down like Phil does. This will make the work surface close to perfect flatness. From there the part you put on it should be run through a planner or you can use the machine to surface it to match the machine. This is what Phil and others are doing. You will not need auto leveling when doing it this way. However if your surface is uneven then you you will need to use compensation for that. The simple x-carve does not have any compensating features in the firmware so you will have to use something outside. Phil uses cad programs that you can get the bit to follow a contour. You can measure the part’s surface while its clamped down and then set the cad software to accommodate. This works fine for 3d but if your V-carving then you need to use a tool like Chillipeppr to do the measurement and it will do the compensation.

@BobJewell, sure that will work, but only if the surface that your workpiece is mounted to is perfectly level with the gantry and rails themselves. I measure and set depth accordingly every time, but if there is a low point on the work surface, and your work is clamped to that, there will be a low point on your workpiece. You now have the problem of it not cutting all of the way through. The software could solve for a low point and dip itself a bit further knowing thats a low point and that your material could potentially follow that curve.

Here is what I am trying to get at. If the waste board is not parallel with the gantry, the gcode can compensate for the extra distance, and know to plunge X more distance to compensate for that.

This is fine if your cut is shallow.
What I am talking about is using wedges to bring your work piece level and 90° to the bit.
The small grey block to the right is what happens with the cut when the top surface is not 90 to the bit. The left part of the image shows the wedge. You only need 2 if the back is correct and 3 if you need to adjust. You can use these wedge shapes and still clamp down the work piece.
the wedge is under a flat board that sits on top of your machine’s waste board. The work piece goes on top of the flat board.
Just a crude image here…

Steven is absolutely correct. Mesh leveling is great for 3D printers and PCB’s but if your workpiece isn’t 90* to the bit then the bit enters the piece at an angle.

I absolutely agree and his illustration is 100% on point. Maybe I am arguing a moot point, I just feel like your board would have to be seriously out of whack for it to really noticeably affect it. I feel like it could solve a lot of headaches otherwise with not cutting through all the way.

I understand the whole cutting through problem. Also understand your point. Chilipeppr has the option. (For PCB’s). If your cutting out parts of ,let’s say a box. When you glue them together they will not be 90* to each other. or if your milling out a 3D relief. it will come out “off”.

After doing additional research on CNCing and a lot of youtubing, I have to admit I am wrong. It looks like (as you all have mentioned) the concept of spoil boards to a CNC is a normal/common solution to the issue of bed leveling. Looks like I will begin going down that path.

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If you use the wedge method it will get you close for those signs and things that do not require precision. However if you are making a box or something you just have to make sure the waste board is level. Then put the flat work piece on top. You will have to check each time to ensure everything is within tolerance. No work around for it.
The wedge method will work well for most 3d and or other carving on larger items. However it is useless on small stuff such as PCB’s and the like as they require more precision.
The wedge method works well as you can clamp things down with the wedge in place. Use a dial indicator as well. Harbor Freight sells one that is digital and another that is analog. Either will work well. Thingiverse has a 3d printable mount for it. I have a 3d printer and anyone who wants one I will print one up for free and send it to you.

Yes Robert is correct.
The only issue I have is that your loosing depth that way.
One of the reasons I need to get some aluminum and cut those risers that Phil made to add height.
Inventables should not send a spoil board made from MDF. it should be like what Phil has on his. An aluminum plate with supports. Let the user go to the store for the MDF. But I guess they wanted to keep the price low. Me I would gladly pay 200 more for the more rigid bottom…

That is my concern as well @StephenCook, I have some 2.5" walnut slab I need to cut into and if I throw additional MDF in there without risers, it will not fit. I think I may try the wedge method first, however, I need some better clamps (any suggestions on style?) I also have a planing bit arriving today for the MDF method for smaller thicknesses.

for clamping you can use a variety of them they have here in other threads.
it depends on what your clamping down.