How to specify probe block height?

[mrX]

I would like to use Autoleveler for other types of material than wood.

Current problem I'm having is to understand how to specify height of probe I'm using, since material I'm engraving is wood. Autoleveler software does not make it easy for me to understand what is involved in that. It is possibly I'm misreading UI somehow.

The use-case is as follows:
- my probe block height is 19.75 mm
- surface is wood (can be any non-metal)
- workpiece is around 0.4 x 1 m

When probing is done, it seems that machine will execute engraving in air at height of approximately 20 mm. Is there any way for me to specify a height it needs to subtract (probe height) to achieve surface engraving?

[daedelus]

I think I see the problem. There is normally no probe block involved. You want to probe your entire work-piece not just a block. For a PCB this is simple because the entire copper surface is conductive and you can easily probe there. For wood or some non-conductive material, you might want to brush on some thin foil first, to create the conductive surface. You may then need to apply an offset in your original GCode file, i.e. before your get as far as the Autoleveller software.

[mrX]

Yes. I understand that Autoleveler was written with goal of making circuit boards, hence probe block offset is set to zero (or rather was not implemented as such in the first place). It is however limiting for software as other materials are already being asked for in this forum (plastics and what not).

Usage of foil is simply unacceptable. I'm looking for solution that would allow me to carve large pieces with autoleveling. Even with using foil it would mean either covering whole workpiece (more than couple square meters) or having probe made from circuit board material that would produce small depth offset (copper is too soft for touching with CNC repeatedly, nor stable against bending).

For now I have three solutions:
- flatten whole piece and shave off a couple of mms
- use offset that is set for probe height (rather large)
- submit a pull request to get feature in

[mrX]

I've created pull request for probe height feature: https://bitbucket.org/daedelus1982/auto ... ified/diff

So far it only affects old version of Autoleveler as I am unfamiliar with advanced version yet.

[daedelus]

Thats cool. I am checking it out now. Not sure how a probe block would work with probing though exactly.

I imagine you need to slide the block underneath the tool to "catch" each probe? Depending on the physical size of the probe block, this could lead to inaccurate probe results, not to mention the tedium of sliding the block. Or have I got the wrong impression?

[mrX]

You're correct in a way this would go. It should not the matter for the probe or where it is placed as it would behave the same way without height (aka for circuit board). And yes the idea is not to make it extremely precise, but have a more or less of a guess for the height as you don't need tight tolerances here.

Let's say I have a block of wood, 1m x 0.3m If we measure every 15 cm (or 30 cm is good enough) we will get quite precise map, compared to stock flatness. Unless one would specifically target badly warped wood you would not need to produce many probe points. Probing will take its time, but the result will be well worth it in avoiding deeper cuts and correction work after the cut on CNC.

[daedelus]

OK I understand. Thanks for the explanation and addition. Not sure how many users will need this feature but Im sure someone else will want it. I have approved and merged this pull request so others can use it sometime if they need to.

Please be aware though that Im not really working on the original Autoleveller any more, so feel free to add it to AutolevellerAE sometime as well

[mrX]

Here is pull request with same feature for AutolevelerAE: https://bitbucket.org/daedelus1982/auto ... ht-in/diff

I did encounter strange behavior on my USB controller, though the machine is industrial grade router with Mach3(XHC MK3).

[daedelus]

Thanks. I will check out the pull request tomorrow.

A USB controller causes many problems it seems. Some people have written Mach3 macros to get round the problems. Have a look here if you havnt before viewtopic.php?f=8&t=349

[daedelus]

Now that I have had time to think and sleep on it, I don't think it a good idea to add the probe block height as an option directly. Why?

Most people do not use a probe block and instead probe the surface of the work-piece, either this is a copper PCB or wood or some other non-conductive material. I don't think many/any one uses a probe block in the same way you do. Therefore the addition of a probe block field would be both unnecessary and confusing to users of AE.

Maybe the probe block option should be moved to the menu somewhere. But even there it might be confusing to some users as to why its there at all. Maybe the best place for it is as a separate branch off the main repo?

Anyway, I wont do anything yet. Let me know what you think.