--------- This is the WHY
I have been building a 2m x 1.5m MDF router for the past couple of weeks. While, on the side, playing around with SW to come up with new concepts, just for fun. Some of you may have read my build log "All steel, nut and bolted". That is a project ahead of me that i'll try to keep working on in the next few months. I thought that I'd first finish my latest first real build, get it running, learn from it and then move on to the next build.
I have been reading this forum, cnczone.com, and other websites on the internet for a few months now, researching about different setups, how to calculate what motors you need, what voltage you need, PSUs, control panels, etc. Honestly, the more I read, the more lost I get and the more complicated it seems :(
As my old electronics (blindly bought 4 years ago from buildyourcnc.com, when I didn't know much about CNC and was just a young boy too excited about buying some electronics and jumping into an unknown world) died some time while resting in my attic for the past two years, I'd like to replace them with new ones so I can finally get this MDF lady running. So, since I'm lost in the gigantic mass of info out there, I'd like you to enlighten me.
--------- This is the HOW
I got an MDF machine, for woodworking purposes. Footprint 2m x 1.5m roughly. Driven with 2m SBR 20 on X, 1.3m SBR20 on Y, 0.6m SBR20 on Z, coupled with 2 x 2m SFU2010 on X, 1.3m SFU1610 on Y, and 0.6m SFU1605 on Z. Gantry weighs 60kg (yes, it's a big lady, I'll start a build log when I get time to show you what has been going on for the past few months). Z weighs about 20kg with spindle. Spindle is 2.2kW Chinese water cooled. Now you've got a general idea.
I want to make this reasonably cheap. I know, CNC is not cheap by definition. I want something simple. I'd like a very very basic setup with which I can just run GCODE, control all axis, MAYBE switch on/off the spindle, so just run a simple machine, nothing fancy with Mach3 spindle speed control, smooth stepper, $300 bob, etc.
So, I need to choose a BOB, motors, PSUs and drivers. That's where we start.
I've seen about 1000 different models out there. But honestly, for a very basic setup like I want, I think the following BOB will work like a charm:
The only thing I don't get about this board is what the female plugs behind the axis screw blocks are meant for. Anyone can explain that to me ?
I think CNC4YOU uses those boards in their 3/4 axis kits, so I'm guessing they're not too bad. Plus, $9.5, free shipping, hard to beat :)
2. Stepper motors
I've already got some. I don't know if they all work, as I haven't figured out what went wrong with my old electronics yet, but I think that it's worth trying to keep them. They are 60BYGH303-13 from buildyourcnc.com. They're rated 2.8A, 3.1Nm, 7,5mH, 8 leads. What do you think about them ? Overkill ? Worth keeping ?
I need to complete those 3 motors with a 4th one, so if you think they're good enough, which motor could complete this set ? I was thinking about a SYS60STH86-3008BF from Zapp Automation. They're on sale right now, so for 50 Euros (shipping included) I can get them here. My only worry is that they're rated 4.2A wired in parallel. That's quite a lot compared to the 2.8A I've got. I know that they're rated more than half the mH, and I'm guessing that A and mH increase / decrease in opposite directions. Pus will be greatly impacted by this.
3. Stepper drivers
Well, there I'm lost. Honestly, there are a billion ones out there. I know you guys like AM882 or Gecko equivalents. But I think that would just be an overkill for the purpose of this machine. I know that CNC4YOU uses CW5045 in most of their kits. I can get them for $40 free shipping. Is that an option ? What is your opinion ? Keep in mind that I am trying to have something between a Lada and Mercedes, so let's say Toyota.
With the motors I've got, ideal calculated voltage is roughly 80V, but I might be wrong or have done something wrong in the calculator. But honestly, do I really need that much ? I was thinking more of something like 50V 10A regulated. Is it necessary to DIY an unregulated 80V 12A PSU like recommended by Boyan and Clive on a thread I started a few weeks back ?
So... let's summarize. I think the BOB choice is quite modest. Of course, I'm ready for some bad feedbacks about this board, as it's probably incomparable to other $100 BOBs.
For the rest, I'm guessing it's just a compromise. AM882 and unregulated DIY 80V 12A like Boyan suggested, or some other route ? I'm lost guys, please get me out of this huge pit !
Once we've agreed on a good setup, I'll buy everything needed, set up wiring diagrams and everything you require to guide me in the right direction.
Thanks a lot for your patience, forgiveness and help !
12-09-2015 #2The only thing I don't get about this board is what the female plugs behind the axis screw blocks are meant for. Anyone can explain that to me ?
You don't say what your driving the machine with ie ball screws etc slaved axis etc. ?
The steppers you have have a high inductance and the Zapp ones will be much better http://www.zappautomation.co.uk/elec...tor-48577.html
If you are going to build another machine and want to use the bits again go with AM882 at least as they have stall detect and run them at about 70V. Some of the newer drive can be run from AC as well.
Building your own PS supply will cost about £45 ish..Clive
Clive - you are right about the line of 5 sockets.
If anyone wants the Engrish language version of the BoB manual PM me with your email address and I will forward it to you. For some reason I can't upload it as the Adobe plug-in crashes on the uploader - Lee comment ?
Last edited by cropwell; 12-09-2015 at 11:06 PM.
What you are looking for is "linear power supply" as opposed to "switch mode power supply". Might help in a search. Commercially, the kind of thing you are looking for is "PS806-12 Linear power supply" from Zapp. I'm sure that you could build one for less, as already suggested, but the Zapp supply is the kind of specification that you need. I'm currently running an MDF router with one of these supplies, three SY60 motors, and M752 drivers. These drivers are old analogue boxes, now superseded by things like the AM882, but the combination is fine for this class of machine. The MDF structure can't take much more power anyway!
Now with due respect to Mycnc Forum members, who are ALL obviously highly intelligent by the fact they joined, but I know there are still lots of Muppets out there who watch but don't fully read or take time to ask or understand what's involved but instead jump in with both feet eyes shut.!!
Not something that is advised or I would want to be partly held responsible for when it comes to electricty that is often used in a dry dusty enviroment just itching to catch fire.!!!
Yes I help people build there own PSU and have done so for many but I do it privately and make sure they fully under stand before proceeding.
So if you get no joy just ask and I'll gladly help but I won't post it here. PM me then just you, me and one other will read it.!!
Last edited by JAZZCNC; 13-09-2015 at 09:39 AM.
I just checked and the M752 is very close to the AM882, but for $8 difference I think I'd rather go with AM882 :)
How heavy is your MDF machine, what is the area ? My gantry is a 1500 x 350 x 140mm torsion box (1 horizontal rib and 6 vertical ones) made from 22mm MDF. Approximated weight with Z and spindle is about 60kg. I think I overbuilt this haha.
Thanks to everyone for their kindness and the time they spent replying to me ! It's nice to see this lively community, that I will try my best to give back to when I get the opportunity.
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