I’ve just started using my MPCNC in earnest. My intention was to use it for foam cutting, but a number of people have asked for wooden plaques to be made, so am going to do a couple of those. To be honest, one of them is a “No dogs allowed” but it’s a start
I’ve glued two bits of pine together as a test to try and get a larger piece to work with. That’s gone well and I have just surfaced the 320mm x 240mm piece.
I realise that the grain of the wood is in the Y axis but I am surfacing across the X-axis, basically across the grain.
Have I committed a cardinal sin or will it make no difference at all? It feels fine, though I can see a little shadow across the wood as each pass of the 25mm surfacing tool is made. I set Estlcam to a 20% overlap and it is flat, but I wonder if in future I should surface with the grain.
I also do need to get my dust show designed. The amount of sawdust created in surfacing is enormous.
It shouldn’t matter much. Hopefully your bit is sharp enough and it will be moving fast enough to not really care. Especially in pine. It anything, you just want to be careful cutting to the edge of a board where you might get tear out.
The grain shouldn’t matter much, if at all. If your tool is not perpendicular to your X/Y plane then you might get artifacts that depend on the direction of cut.
Suppose your tool were tilted slightly in the +X direction. Then if you cut in the +Y or -Y direction you will be left with edges where the +X side of the tool cut deepest. If you cut in the +X or -X direction you will have very shallow scallop pattern where the deeper part of the cutter cuts a shallow elliptical trough. In addition, cutting in the +X direction will cut using the outside leading edge of the tool, while cutting in the -X direction will engage the bottom of the tool since the deepest part of the tool is trailing. This is less than ideal and can leave scorch marks.
The general advice is to square your tool to avoid these issues. When I surfaced my spoil board most recently I did a test to see which way the tool was leaning (if at all) and then oriented the cutting path accordingly. To choose the cutting path direction I wrote a simple program to generate the tool path.
Thanks for this explanation. I think my Z-axis isn’t quite at 90 degrees to the bed as I think it has a very slight lean and is leaving slight scorch marks.
Is there a recommended way to get the Z axis at 90 degrees, or is it a case of slightly tightening bolts and seeing what happens?
I had seen the G-Code Test Pattern Generator before and hadn’t realised that you had written it. Many thanks for this. I used the rulers to calibrate and will use it again.
I also hadn’t realised there was a surfacing option. I was looking up Gcodes to write a simple one myself as I think it’s such a standard workflow task that this should be as simple as possible, doing it in Inkspace or Fusion 360 and then importing into Estlcam and then exporting is at least two (three?) steps too many for me
I also saw the perpendicular tool that somebody had put together for a DeWalt (along with the comment from @jeff3b). I can see now how to check for whether the Z axis is perpendicular.
To help I’ve designed a parametric version in Fusion 360 to check it out.
My version is 6mm and just screws in the collet. However you can change the parameters and use it in 1/4", 4mm or whatever. I left a small hole in the arm to put a panel pin or hot needle through at one end.
If you can’t feel them, I wouldn’t worry about it. You can also get funky lines like that depending on the direction the cutter is moving, kinda like the stripes you get when you mow the lawn.
+1 not being able to feel it is about as good as you can expect. It’s sandpaper from there if you want a cosmetic surface.
Was this passing in a single direction or cutting back and forth? It’s conceivable that climb milling vs. conventional milling could make a difference, although I’m not sure if that is a major effect you would see.
I generated the facing using Estlcam bit next time I’ll try your program. I’ve printed off my little tester to see if the z axis is perpendicular but at the moment I’m doing my first ever commission, three “No Dogs” signs for the village park. When I say commission, it’s 0% commission which is a long winded way of saying “free”.
The proper (i.e., patronizing) way of saying it is “for the exposure”… Since it’s for the civic good, I say good on you. If it was for a private entity, you should get paid. Just like any other artist/craftsperson should.
Even if you give your time for free, it’s fair to charge for raw materials. And unfortunately the raw materials are marked up quite a bit by a shell company in the Bahamas (which we won’t mention is also owned by you) so the raw materials cost ends up at about $200 for a chunk of pine.
I live in a small village in North Yorkshire and what goes around, comes around
The village works well together, I offer free IT help as needed, other people run the local playground and park (as a charity), we have a local community owned village shop (which does quite well now), during the lock down, the village really rallied around the older folk and made sure they had food delivered from the shop, that they had access to video calling for getting in touch with their families, their dogs were walked and people regularly checked to make sure they were OK.
We try to do the right thing and as this is Yorkshire, people will soon let you know if you’re straying off course. To be honest, the fear of mild disapproval, perhaps a fractionally raised right eyebrow, from one of the elderly folk in the village is significantly more scary than the full on wrath of the permanent secretary at the govt dept I work in as to why his project has gone over budget by $100M and is now an extra six months late (I’ve had both). People will forget IT projects, but the village memory lives on for decades, Sicilian family feuds that go on for generations have nothing on old ladies disapproval.
And now I’ve discovered that the slightest flaw in your Gcode can induce your router to try and dig it’s way through my plaque and spoilboard, rats, no idea what has just happened, but I’ve managed to destroy my piece of wood I carefully glued together and surfaced. That’s really frustrating. It does demonstrate that you have to watch every single step on your CNC machine.
Oh well, I have another one being glued so will start again tomorrow night.
I did that and it worked OK. the first time, there’s something in Marlin about how is ‘releases’ the hold on stepper motors, I always do a slight movement using the console to ensure the motors are engaged. I might have forgotten to do it this time. I still need to get my workflow sorted out. Rats.
