I slipped into this MPCNC rabbit hole a few days ago and have been studying this site and watching youtube videos since. Hope my wife doesn’t catch me cause there’s a bunch of unfinished renos in the house that have been dragging for years…
Anyway, I have a few questions on controller boards for the MPCNC. Seems there’s a wide and somewhat confusing mix of stuff that’s possible. I would like to build a smallish machine, with 1" SS tubes, no more than 18-20" square working area. Materials to cut would be wood, plastic, and aluminum in that order. The aluminum (and possibly brass) would be light cuts making nameplates and the like for machinery. I would never want to use the machine for 3d printing, and there’s a very slight possibility of using it for laser marking/engraving. I’d like to use a GRBL based controller. So - what are my options? I see there’s a nifty development for ESP32 based GRBL units and I quite like that, but I am not sure it’s a good point to start with for a newcomer (I am a retired EE so I can figure out the electronics etc. but don’t want to be crippled with lack of software features or software that’s not really prime time ready yet as I don’t have the time to delve into that) I have also seen Pi contraptions that are feeding the gcode to Arduinos, and of course there’s the old standard UNO with a 3 stepper driver shield thing. Are there others in the GRBL route that I should look at, or is one of these the way to go?
While I am banging out this post, I may as well ask another question regarding steppers. The ESP32 board seems to have 5 stepper drivers - one per motor. However, I have seen 3 stepper driver boards driving the same 5 stepper motors on MPCNC units. What’s the trade off here ? I suspect there’s a tradeoff if you are driving 2 steppers with 1 driver, as there never really is a free lunch in this world, but maybe someone can educate me a little on this.
Right, well, that’s about it for the moment and I am sure I will be back again with more questions as I work my way along learning about this and trying to decide what approach I am going to take. This looks like a fantastic design and one that has had a lot of evolution, thought, and time put into it. I’ve convinced myself that this is the ideal way for me to enter the CNC world in my home shop.
Why? I do not have enough experience to really comment on this, but typically we hear “because I read it is better for CNC”. While that MIGHT have been true a few years ago, I don’t think there is any validity to that now. Pretty sure they are extremely similar now as far as using some of each other motion equations. If you just want to learn and try it out, no problem, I am not sure the autosquaring is an option, the Bart’s ESP version looks close but I am not sure it is correct yet.
5 drivers and firmware that can handle them allows for dual endstops.
I have tinkered a little bit with GRBL but only flashing an UNO, firing up the serial connection to the PC, and banging away at the commands and listing settings etc. Some of the local lads I am aware of use it for a number of contraptions and there’s another local retired EE that’s into ESP stuff in a big way so I guess I was thinking these folks might be able to assist me if needed, or perhaps I could draw them into the MPCNC world as well if there were bits and pieces they are already familiar with.
Your comments on the autosquaring sort of went over my head - I mean I think I understand what it’s all about, but have no clue about what hardware/firmware uses and doesn’t use it. There is much to learn…
Thanks for the quick reply. I sort of felt like I sent a message to the website of KFC and Colonel Sanders himself wrote back to me when I saw your reply. I mean “the man himself” - LOL. You have created an amazing machine, and also back it up with a great bunch of documentation and support as well. Hats off to you sir…
One more thing - I doubt I will be able to start building until this fall, so there’s lots of time to research and plan, and perhaps some of the almost ready software options will in fact be completed by then… I have nothing against tinkering with Marlin as well though
I’ll elaborate a bit on this specifically: since the stepper drivers drive a controlled current, there is no problem getting the desired current through both motors in series as long as the supply voltage is high enough. With a 12 V supply there is no issue unless the speed gets to ridiculous levels that nobody ever reaches in practice. Theoretically the trade-off is speed, but practically there is no trade (electrically speaking). It is free.
Driving in series you do lose the ability to drive the two x or y motors independently. But this feature is an extra complication that is not recommended unless you know you need it.
I respect the 11 herbs and spices so that is a supreme compliment! It also means I am messing around on the computer instead of packing boxes…
Jamie nailed it. You have some time to poke around before you start your build so hopefully it starts to make more sense or we are able to more thoroughly document stuff. It does evolve pretty quickly so documentation is hard to keep up with (looking into other options), every time I want to clarify something there is another way, a different gcode, or heck a whole new board…or more commonly something way more fun than me trying to concisely word a feature or use case.
Thanks very much for the info guys. The motor wiring explanation has broken a little log jam in my head and I’ll continue on with my study of the docs here. Will be back when (not if) something else trips me up ?
Just had a conversation with the local stainless tubing supplier here in Canada, and he gave me some info that might be of some interest to others that are in Canada and thinking about stainless tubes.
The place is called Pinacle Stainless www.pinacle.ca and they are located in Calgary, Edmonton, Saskatoon, Toronto, Montreal and Dieppe.
Price quoted for 1" OD, 0.065" wall tubing was $5.00Cdn per foot but they only sell 20’ lengths
They will cut for “shipping” even if that means you show up with a Volkswagen Golf and need to jam it in the back (like me).
The surface is called "bright annealed’ - it’s shiny, but not mirror. He told me to go to Costco and look up over the refrigeration units and you’ll see tons of it to to get an idea of the “look”.
Finally, I was curious how smooth this stuff is. Without quoting engineering roughness specs, he calmly blurts out - “think stripper pole - strippers would love this stuff”…LOL I replied “that sounds smooth enough”…
Anyway, this info might be of some assistance to the Canadians on here that are looking into the stainless option…
Cheers, I’m in Edmonton and found my ss tubes at metal super markets. Pricing is the same as you found. Not sure if you moved on your tubes yet but if you need help with shipping I can offer to help. I hobby weld and am often at their shop so I may be able to save someone a few bucks on S&H if they’re out to lunch on pricing. They also do off-cut pricing on pieces under 4’ which would probably suit the mpcnc but I’d guess it’s not common for them to have much of this specific spec available in the bins.
Hi Brent - We’re a little distance apart - I’m in New Brunswick. Thanks for the offer of help. I’ll probably get the tubing at Pinacle here as they seem to be willing to deal with a small order without hassles. I’m not spending money just yet though. I have much to learn and figure out, otherwise I’ll end up with unused materials for sure (I’ve been to that movie before and am trying not to go again - lol)
I run GRBL for one reason, and one reason only (ok, maybe two).
The first, and most important one, is simply that I can use bcnc. So easy software squaring if I need to, and autoleveling gcode instead of MBL in marlin that must scan the whole bed. The second was especially useful when cutting a 50x30cm vinyl and couldn’t afford any dragging on it or it would remove the letters. I actually flashed GRBL just for that job, and hadn’t had a reason to switch.
Second, but that’s just a detail, CNCjs shows me the actual position of the cutter instead of where the line of gcode it’s running told it to. Also, feed hold that works.
