Buying/Building My First RepRap

My power supply is rated for 305 watts of DC output. The sticker says that it can supply 18 amps at 12 volts. I don't have any problems running my heat bed and Gen6 electronics on it (although I've never tried to measure the temperature of my heat bed). I use one 12V wire and one ground wire for my Gen6 board and another 12V and ground for my heat bed. I pulled both sets of wires out of the ATX connector.

There's really no harm in trying to run it with your power supply if you're worried it's under powered. If it just doesn't run, the heat bed is too cool, or the motors don't have enough speed or torque, then you'll know you need a higher capacity power supply.

Edited 1 time(s). Last edit at 06/05/2012 11:33AM by MaFraL.

Wow, thank's a lot! I'm planing to build a Prusa Mendel, and I'm looking at makerfarm too.
It's good to know it's a good place to order from.

I'm trying to figure out if it's better to get some parts locally, but I'll see.

This thread it's gonna be very helpful!

All right, I'm ready to order the Prusa kit from makerfarm.

One question, should I order the steppers from makerfarm itself or from sparkfun? You recommended to order them from sparkfun, but if they already have ones in makerfarm I would save the shipping costs.

Any other parts that I may need or suggestions? Thanks!

I'm guessing the steppers from Maker Farm would be okay. I bought most of my RepRap from them and haven't had a problem with those parts. I didn't buy mine from Maker Farm because they were out of stock when I bought my kit. Akhlut recommended the SparkFun steppers earlier in this thread and those do work well for me.

Edited 1 time(s). Last edit at 06/08/2012 12:18PM by MaFraL.

I got mine from here and had good luck

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Ryan
Quality Engineer & Hobbyist
thingsandtrains.blogspot.com

Ok, I will order them from the makerfarm site and report back here how did they turned out.

With international shipping, the Prusa with linear bearing and .35mm Nozzle, RAMPS electronics (without the arduino) and 5 stepper motors: $593.

Well, that doesn't seem so bad. That, plus the rods, some spare parts and lots of tape xD.

Cheers!

Me and my friend just finished putting together a SAE prusa medle v2 with greg's accessible extruder from MakerFarm. It took us about two days to get it assembled and two days to calibrate. Most of our time was spent putting different connectors on our stepper motors because the ends weren't the correct type and also getting the extruded ABS to stick.

Some basic extruding advice: (we overlooked this idea for a while)
To correctly adjust the height we moved the z-axis endstop till the hotend head was about a millimeter from the printing surface. The we loosened the bolts with springs as it was printing (pausing to adjust) until the plastic was being smeared flat on the surface. It should not be laying out as a cylinder but should be flattened against the printing surface.

In the Sprinter application we had to adjust a few configurations.f file settings:

#define THERMISTORHEATER 6 (for EPCOs 100k thermistor, 1 is the default for a generic 100k thermister)
** not sure if this changed the reading because we changed it before printing

// SAE Prusa Mendel with Wade's Accessible extruder by Greg
float axis_steps_per_unit[] = {62.3, 62.5, 1133.858, 454.808};
**We changed the z-axis because we had 5/16 threaded rods with 18 thread size.
**We changed the e-axis because the accessible extruder bolt calculation is a little different.

Thanks for the advice. I might need to look at my configuration again, and I've been having trouble getting bigger prints to stick. I think I've been allowing it to extrude as a cylinder rather than making it flat.

It should smear the plastic to about the thickness of your layer thickness. I now print at .28mm layer thickness, and when I peel off the first layer its about .28~.30 as a cylinder it doesnt squish at all and you get less surface area on the bed.

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Ryan
Quality Engineer & Hobbyist
thingsandtrains.blogspot.com

I now print with the bead not quite a smear but definitely a very flattened track.

The way I have gotten my prints to stick lately is to lay blue painters tape and run over it with my finger nails in all directions to flatten out all bubbles and rough it up.

This has the prints sticking so well, that I have to replace the tape after some prints as the tape rips off when I remove the print.

I have been able to adjust the amout of adhesion to a point with the amount of rubbing over and the temp of the hot bed.

I can't reccomend enough the usefullness of a z stop adjuster. There are many on thingiverse that should work well.

I have to adjust my z endstop slightly nearly everyday I start printing and sometimes after 2 or 3 prints. This adjustment is as small as 1/4 turn of the screw but without this adjustment, the bead will either be too high and just follow the tip around or too low and the tip will rip into the tape.

I have a 10mm ply bed with heated plate and then 2mm window glass on top, I assume the ply wood changes slightly with atmospheric changes causing it to swell or contract slightly. Others will no doubt have a different theory...

The sparkfun steppers are 0.9 degree. I don't know about the makerfarm steppers, probably 1.8 degree. What's the difference? The 0.9 degree steppers have 400 steps per revolution vs 1.8's which have 200 steps per revolution. So the sparkfun steppers offer twice the resolution out of the box. Microstepping will theoretically allow the two motors to perform the same, but you can reduce the microstepping on the 0.9's and get the same resolution as the 1.8's.

So let's say you use 1/8th microstepping. For the 1.8's that translates into 1600 steps per revolution. For 0.9's that translates into 3200 steps per revolution. So if I want to achieve 3200 steps per revolution with 1.8's, I'd need to use 1/16th microstepping.

Hardware resolution is better than software resolution.

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- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

I finally bought a thermocouple for my multimeter and measured the temperature of the glass plate I put on the heat bed. It was only around 85C. I had it connected to a 12V and a ground lead from the ATX cable on my power supply. I connected two 12V leads and two ground wires to it to increase the current capacity and hopefully temperature but I'm still only getting around 85 or 90 degrees. I guess the glass is acting as a heat sink. The piece I used it 4.5mm, should it be thinner?

I'll need to try printing one of those z-stop adjusters too.

Edited 1 time(s). Last edit at 06/13/2012 05:51PM by MaFraL.

Actually, my glass is getting to around 105C now. I noticed that the heat bed wasn't pressed completely against the glass. I added more of those large black metal paper clips to hold it down and the temperature increased and held fairly steady. By the way, does anybody know of a better way to connect the PCB to a sheet of glass without having a way to drill holes in, or mill, the glass?

I'm noticing that my filament doesn't stick to anything quite as well as the print head. I've tried printing on just glass and I've tried laying down fiberglass tape (which is textured). The print head always collects a glob of plastic and I have trouble starting a print because the first layer frequently gets pulled off by the print head. Any suggestions?

Edited 2 time(s). Last edit at 06/13/2012 07:35PM by MaFraL.

I use 2mm picture glass as it is lighter and will have less thermal resistance.

I use four small bull dog clips. The PCB wants to dome upwards in the middle because the solid sheet on the top expands more than the zigzag on the bottom. That means it only has to be held at the corners for the rest to be pressed against the glass.

If it sticks to the nozzle rather than the glass it could mean the nozzle is too high for the first layer.

If you are trying to print ABS directly on glass you need to use ABS juice.

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[www.hydraraptor.blogspot.com]

Wow, I started using Scotch Blue Painter's Tape without heat and I'm getting much better adhesion than I ever had on hot glass. I've also started using Slic3r, it doesn't seem to have as many advanced options as Skeinforge, but it's definitely easier to work with (also, more newb friendly). My prints are quite a bit nicer now.

Edited 1 time(s). Last edit at 07/21/2012 12:55PM by MaFraL.