Hi, Need some help with the black box 4 and homing. I'm converting a lathe into sort of a rotary. The problem I'm having is during the homing sequence it's looking for the Y limit switch and there is not one so it errors out. I know that I can flash the firmware for two axis but that disables the Z axis which I need. I want to keep the "rotary" as Y so I can wrap it in V Carve. Anyone know a way to deal with this? TIA.
turn homing off and use the 'fake the home' method instead. this means home is where it turns on or resets, so you only need to make sure to park it in the right place before turn off so that it is correctly homed next time you turn on. How to 'Fake the home'
Thank you for taking the time to reply. I was wondering if that was going to be my only solution. I will give it a read. Again, thank you.
You can recompile Grbl to change the homing sequence (we have precompiled to disable Z but with a custom compile you can set any axis to be included or excluded from the homing sequence. Or add a homing limit. Glue a magnet to the chuck backplate, add a hall effect switch behind it. Allows spinning past it but can still home
I was lazy and added a momentary switch on my lathe for the Y homing switch. I wait until X is done and when the rotary starts to turn I push the button.
Thank you for the reply, I'm a bit late to ask a follow up question as other things became a priority. Could you elaborate on "homing limit". I thought about using a hall effect sensor but could not get past the idea that the next rotation would just trigger it again, is there a way around this? Thanks again.
That is definitely the right way. I installed the wiring because I always intended (and still do) to figure out a way to add one to the rotary axis.
I'd like to ask you a question if I may. I am using the only warping pp I can find (it;s call something like "rotary demon") and have done the math to convert the steps per mm to steps per degree. The problem is that I am still having issues with Vetrics "rounding" gadget not producing a full circle. Do you change the steps per mm setting for each new stock diameter you use? I have not tried an actual carving as of yet, maybe the pp works in that situation?
No. The steps/mm stays the same (because they are converted to degrees, the machine will cut a little beyond 360 degrees for endmill diamete, then turn back the other way. If you want to do wrapping, then you have to do all the math and enter diameters. I only use mine to cut .stl files so I have never had an issue.
I'm a bit confused here (again). If you design a 3d object in Vetric or import a .stl., you don't mess with the steps/mm and use the standard GRBL post processor or do you use the "Rotary Demon" post processor that you posted in your build? Do you use the "rounding" gadget at all to turn square stock into round prior to carving, or just carve from square? Thank you for taking the time hold my hand here.
I only use the rotary demon post processor and all the designs I cut are in the .stl format. I do not use the rounding gadget. I have Vcarve Desktop so I can't use gadgets. A lot of the materials I carve are already round (or "round-ish"). A bad storm brought down some hardwood trees in my yard so I have a lot of firewood and round materials to carve from. Usually, I will measure the diameter of the thinnest side (most branches are not perfectly round). I will use this as my work stock diameter in Vectric. Then I import the stl file and scale it to fit in to that diameter. If I am cutting from something like a 4x4, I will set my table saw blade at a 45 degree angle and rip off the corner edges making an octagon. On my first roughing pass, I will turn the speed of the spindle up just a bit if it is a real hard wood like oak since the first roughing pass removes more material than the others. Then I will turn it back down. On softer woods, i do not worry about it. I do not know if you have seen this post, but it may help you visualize my process. LEAD Lathe As you can see if you read the post, I choose the "Zero at cylinder axis" option rather than Surface. Again, that is because I am not starting out with pre-rounded stock. Also, If there is a tool change, you do not need to worry that stock has been removed and now you can not get an good Z zero. If you use the rounding gadget, you may need to use the grbl mmpost processor, but then you would need to change for regular steps/mm rather than the the value for the steps/degree the Rotary Demon post processor uses. But, since I have never tried, I do not know. If you look at this, there are good resources for this post processor to include a continuous rounding Excell tool to generate gcode to make your stock round, but I have not used it because I have not needed it yet. Rotary Demon Training If you have any other questions, ask away. I am more than happy to help.
One 'gotcha' I have found with Vectric software is that if you have multiple sheets in the same rotary job file, and one sheet is set for a different material radius (e.g. a sheet for squaring the stock from a larger block, then a sheet for doing the job cut), even when you use a valid rotary post processor, it swaps to using the millimetres value of each sheet size (which will be 2*pi*radius long) as the degrees value and does not do the conversion (i.e. says degrees=mm rather than degrees= 180*mm/pi/radius).
Thank you both, I have been using the rotary demon with the rounding gadget that may be the issue. It appears that I may be trying to mix my units here. I will try skipping the gadget and going straight to the carve and see if that works. I have perused both the build page and Rotary Demon's page but have not tried the spread sheet as Vetric had the gadget but I'll take a closer look now.
I really need to test that spreadsheet out myself. I have been meaning to, but have been so busy with family stuff I have not had a chance.
I gave it a cursory look, it's clearly not finished. There are no explanations and it appears to only feed in on the Z and rotate the Y. I'm not sure if the author intended the X to spiral or step. Either way I don't think it's usable as is. but I'm no coder.
It is a spiral that moves down the x axis. It sends the cutter X= 11.875 inches and Y42660 (I believe degrees = 118/5 revolutions) as a spiral at 200 inches per minute. Whole picture of spreadsheet if someone smarter than me wants to chime in:
Yeah, the problem is (as far as I can tell) that it does not seem to move, it just repeats the same numbers?
I just looked at it again and yeah, I can't figure it out either. That is too bad. It would have been a handy tool. When I have wanted to make round stock in the past, I just created a simple cylinder stl file in Fusion360. So, If I was cutting an object from a 4x4, I would make my cylinder 3.5 inches in diameter. then using this chart, I would say I was starting with a 4.95 inch thick piece:
I made a plugin for bCNC for rounding stock in a 4th axis. initial trials went ok, but it is very much alpha. You can use this to just generate the gcode, no need to actually use bCNC as your controller, in fact you can run it on any computer to just generate the gcode.
