Build Your Own SLA/SLS

Hey guys, totally new to the forum, and the technology for that matter. I have an abundance of questions but as i'm in the early stages of designing my Stereolithography Bottom-up style 3D printer i thought i'd start with the basics. Some back-round about myself.. My name is Tony, i'm a programming engineer at an orthopedics instrument manufacturer. I was also a CNC service engineer for two years along with a dealer applications engineer for Citizen-Cincom. So naturally, this new to me technology is very exciting. I use major software titles like Esprit and Solidworks on a daily basis. Admitted i don't do a lot of 3D custom curvatures but thats all learning!



Right now i'm trying to spec out some specifics on stepper motor and drivers. Let me outline a few things...

-I would like to use the arduino uno.

-With that the CNC Shield

The only difference being i would like to run a different driver and i'm wondering if i'll have any compatibility issues in doing that? If i use the Grbl firmware, will i face any challenges?

Next the reason i would like to use a separate driver is im looking at going with a NEMA 23Y stepper.


***http://www.motionmarketplace.com/literature/motors/stepper-motors/high-torque-stepper-motors/23Y.pdf

At 54$ is has 175 oz-in bi-polar torque


Its compatible Driver

MBC05641
Bipolar Microstep Driver

***http://www.motionmarketplace.com/literature/motor-controls/stepper-motor-drivers/MBC.pdf

That comes in at 64$ and supports up to 1/64 microstep!!!


To clarify the design i'm doing is going to have a heavy Z axis as i'm thinking about making the slide axis built into the Z. This is why i'm choosing a slightly larger motor and the driver supports some pretty fine stepping for flexibility.

Also to add to accuracy, I don't see a lot of DIY kits utilizing the counter weight concept... Even though i will have a beefed up Z axis drive system i believe i will still use a counter-weight that accounts for roughly 80% of the weight of my entire Z (not accounting for work piece) connected via cable with pulleys over the top of the Z to decrease load on the Z axis motor. This will give a surprising amount of accuracy potential back to the Z and should help with "drift".

Next, the ball screw I've chosen.

It's a 20mm OD ground ball screw with a 4x recirculating ball nut. This screw boasts a 5mm pitch.

Here's my main question in conjunction with my first question above.

1) Will the arduino board with a cnc shield easily tie into this driver and work properly with that stepper?

2) If the driver supports 1/64 stepping on my 1.8 degree step motor, and i have a 5mm pitch ballscrew... Does the math below mean i can control steps down to 0.000390625mm in 64th step mode? Now that a little insane, and i dont need that per say, but do i have this correct in concept?

((5.00/360)*1.8)/64 = Step increment?

Again i havent played with the software or firmware at all yet. So do i have at least control of outlining these parameters of steps and ballscrew pitch?

I'm curious to hear your thoughts!

As i'm looking at the 'defaults.h' in the grbl firmware, i see this dec

#ifdef DEFAULTS_GENERIC


#define DEFAULT_X_STEPS_PER_MM 250.0
#define DEFAULT_Y_STEPS_PER_MM 250.0
#define DEFAULT_Z_STEPS_PER_MM 250.0


So given my ball screw pitch and if i were using 1/64th stepping my steps per mm would look something like this

#define DEFAULT_X_STEPS_PER_MM 2564.0 (Possibly my slide over- wont have a fine stepper like this anyway so this is redundant)
#define DEFAULT_Y_STEPS_PER_MM 2564.0 (No Y axis used)
#define DEFAULT_Z_STEPS_PER_MM 2564.0 (5mm pitch on 1/64th of 1.8 degrees)

Look correct guys?

I think you are really over estimating how much power you need. a little Nema23 or even 17 would be more than enough for this type of printer. Also 20mm ballscrew is much too large.

Just for an example, I was using a nema23 with the RAMPS board, my ballscrew was only a 12mmx10mm pitch. It could easily lift 100lbs no problem. If you are having to lift that much weight with a 3d printer youre doing something wrong.

My suggestion, dump the Uno, get the Arduino Mega with the RAMPS 1.4 shield. Whats the counter weight for? really I think youre thinking you need this cause its used in the CNC world, but theres no point to it. Over complicated.

The problem with going the way you want is the software to run it, you wont be using Gcode for a 3d printer. You will want something like Creation Workshop and that you'll need to use ramps for easy setup. IMO youre over complicating things.

Just my 2c..

Yeah, basically thats what CW does.. But it works with the RAMPS board, Trying to use another CAM program to make your Gcode is not going to work. So setting up the 3d printer as a CNC to work from regular Gcode will not work like you think. Easiest to use RAMPS and CW.


Yes the RAMPS board can run a NEMA24 stepper. It will only put out 8-35v and 2A. But like I said, there really isnt much forces to deal with. I have a printer with 2 NEMA23's and the RAMPS board, I have no problems powering them. The Pololu's on the RAMPS board also support 16x microstepping.

I recommend RAMPS, and 12mm ballscrews.. the RM1204 series of ballscrew are nice, cheap and have a 4mm pitch, so 0.00125mm resolution if you wanted to go that high. Which you wont..

If you do want to continue down the "Uno / GRBL" route, check out the LittleRP, they are using Arduino compatible microcontroller (Uno + custom shield) with GRBL v0.8

http://www.littlerp.com/?page_id=22

If you still think you need more power, you can get the to use with your RAMPs. These can operate from 8-45v. and 2.5A (With forced air cooling). I helped retrofit a commercial plasma cutter () with these drivers, and they did the job easily.

Okay guys, thanks for the recommendations. I really appreciate it. I canceled my order for the Arduino uno and placed an order for the Arduino Mega2560. I'm still trying to decide who i want to buy the ramps from as im seeing varying quality over different makers based on user comments/reviews.

If you don't think i need the higher amperage, again ill take the recommendation, so should i go with the simpler A4988? Even though i will still use the nema23 motor?


ps. This may be a silly question... but if i'm only running two axis (z + tilt) do i need more than two pololu's connected to the Ramps? I'm thinking ill buy 3 right off the start.

uhg. Also, is a external power supply still recommended?

I'd pick up a complete RAMPS kit on Ebay or something. They come with everything you need, like the stepper drivers (A4988), wiring for steppers, limit switches and such.

The A4988 can power the NEMA24 with no problem, thats what I have on my first printer. I am also only using 2 drivers, you only need to install the drivers you need, the rest can be left out.

You will need an external power supply of your choosing. Im just using the 12v supply I have in the printer, it runs everything, steppers, cooling fans, LCD, and my relays.

I'v already began sourcing components. Besides if i ever produce a number of them, ill want reliable vendors of each component anyways to list in the BOM.

My plan is to run off of the 12V rail on a standard atx powersupply. I have quite a few laying around from pc's over the years. Any issues in doing that? I'm guessing 12v on a single rail will supply around 20amps.