Custom hardware Configuration

Re: Custom hardware Configuration

Sun, 16 Sep 2012 12:53:43 +0000

Hey thanks for your fast reply, Taking on board what you have said, here is what i have.. Complete Gen4 makerbot Electronics, Extruder board, 4 stepper drivers, LCD display/control panel and 5 nema steppers.

What would you suggest for the rest of the machine, I do fancy the acrylic type, and where can i buy the suggested parts.

The thing is i will be usung the finished machine with a cnc touch probe and camera to scan in parts as well as print (well thats the plan when i get to know enough)

Rick

Re: Custom hardware Configuration

Sun, 16 Sep 2012 07:03:46 +0000

I also should share some advice, since I have lot's of lessons learned from adapting gen4 electronics to nearly any system. I personally think your lead screw is a bad idea. Between backlash, friction, and just the slow pitch itself (z axis stock runs true 8mm pitch) so your 2mm pitch is going to be 1/4th as fast at best. Those big NEMAs will be screeming to make the RPMS and had better be low inductance ones with good stepper drivers and likely strong 36 or higher volt power supplies, just to make stock speeds in the 30-40mm/s feedrates. Further, big mistake that a bigger machine is better, especially true with ABS. In other words, if you have visions of building large objects in ABS-best of luck. The thermal contraction alone will either cause inter-layer cracking or just warp large parts. PLA is much better, but there are limits there too. So the problem isn't just the mechanics of the machine, but rather, the very material you are attempting to print with. And since you cannot print fast, a large print of any size on your machine might take 5-20 hours depending on how big or tall you go. There is nothing that can prepare you for a print that fails due to thermal stress issues after 10 or more hours of printing. The thought that you just wasted 10 hours, plus the high price of plastic these days, then the thought of adjusting a setting or something and waiting 10 more hours will definitely put you in a good mood. Even the idea of heated chambers does not solve the problem. All you do is build stress into the part, fine if you keep it at 100c for life, but as soon as it comes out of the chamber and hits room temp, the sound of internal cracks forming can be heard from 2 rooms away. It's a sound that brings your blood to a boil.

Please don't take this as a knock, just some tips from someone who has played your exeriment game and realized, the area of the cupcake was just about right. It's a shame but I own many, many printers, all of them custom, but the cupcake is the one machine, i can print something and know it will come out perfect. Anything bigger and the confidence level goes way down.
As cool as this one below is, It doesn't get the usage that the cupcake and real original Ultimaker printing PLA gets. http://www.thingiverse.com/thing:10380

Reprap
http://www.thingiverse.com/thing:8957

Tom in plexi:
http://www.thingiverse.com/thing:7063
(And sorry, the guy who cut that for me never gave me the tall files)

This bot gets the most usage and that's because it's PLA only, no nead for heated build surface, (painters tape on glass), accelerated firmware (yet another "must" you don't have and could be the deal breaker on those NEMA 34s)
http://www.thingiverse.com/thing:10802
It looks good, prints fast, is quiet due to the acceleration firmware and general design, and PLA hardly ever warps.

Re: Custom hardware Configuration

Sun, 16 Sep 2012 06:35:33 +0000

The machine.xml file in the machines folder of replicator-g. There you will see the thingomatic.xml which is where I would start for and easy gen4 based electronics config.
I suggest you open with wordpad (not MS word, and notepad is too basic), Internet Explorer is the default to open *xml files but pain to edit that way.
An easy way to preview is to open the "machine information" under the machine menu from rep-g. You can't edit it there but a good way to see what file to edit, and what's in the file now. Note that the thingomatic have many drivers, I would use one that matched the extruder setup and heated bed option, then also rename it to match your bot's special name so it's easier to find the "correct" one after the edit.
You see the displayed driver name, and then below that, the axis info. The math calculation is right there but the actual number changing is steps/per mm. They used pulleys but on the z axis, yuo can see for a threaded rod. Again, in theory if you know you have 2mm pitch, then maybe it's say 3200 steps per rev (1/16th stepping) and then the other factor is number of starts which actually makes the pitch slower than 2mm (divide by 2 or 4 depending on how many starts)? The stock threaded rod is 8x8, but the first 8 is just 8mm diameter and the second number is 8mm pitch, but it's really a 4 start screw (look at the end) thus the math is back down to 200 steps per mm at 1/8th stepping (default t-o-m hardware). That's why your 2mm pitch may not be the real number, but playing with factors of 2 will likely get you where you need to be. Test by moving 10mm and measuring. Since you are using metric screws, it will be an even number at some point so not the hardest thing to figure out.

Note that a leadscrew with 2mm pitch may not mean 2mm per turn (AKA normally 200 full steps or whatever microstep multiplier) (200 times 1/16th is 3200 steps per rev). some have multiple starts (more than one thread looking at the end) that comes into play.

Also, you must close and re-open rep-g when changing those values for them to take effect (it parses the file only at startup).

Custom hardware Configuration

Sat, 15 Sep 2012 20:02:00 +0000

Hi there, I had a load of cnc bits in the workshop (Aluminium extrusion 20x20, nema23 steppers, 10x 2 trapezoidal lead screws and nuts)

Ive got the Y axis on a nema17 motor and 5mm belt with 15mm pulleys, that works fine.

The nema23's on the X & Z axis are attached to 10mm lead screws with a 2mm pitch, when i use the jog mode on the lcd, the Y axis it moves around 5 times the distance of the X & Z.

My question is where do i define the unique perameters of my particular machine so that the jog will move all axis the same amount..

Rick