Starting a Prusa Mendel build

Hello All!

I've been reading various blogs of RepRap builds and some builds listed here on the forums and they have inspired me to share my Prusa Mendel build.

I'm currently sourcing the parts I need, I think i have most of it covered:

- Prusa Mendel Frame
  * Plastic Parts: Sourced from my brother who is printing the Prusa Mendel parts from the CupCake-sized plates.
  * Vitamins: Sourced from UltiMachine
  * Belts: Sourced from UltiMachine
  * Heated Build Plate: Sourced from UltiMachine
  * 4x Stepper Motor: NEMA 17 Sourced from UltiMachine
  * Bushings: two options...
    + My brother is printing some of the new bushings that can hold felt, i would need to glue them on the standard prusa parts...will that work?
    + I can also order some PLA bushings from ebay
- Extruder
  * Plastic Parts: Sourced from my brother who is printing Greg's Hinged Accessible Extruder
    + I modified the holes to fit the MakerGear hot end mount according to the comment by "hbs" on the thingiverse page
  * Vitamins: Sourced from MakerGear (Wade Hardware Kit)
  * Hot End: Sourced from MakerGear 
    + 0.35mm nozzle
    + Fully assembled
    + Wade wooden mounting plate
  * Stepper Motor: NEMA 17 Sourced from UltiMachine
  * Hobbed Bolt: Sourced from ebay user :RTQ:US:1123" target="_blank"  rel="nofollow">dude_146
- Electronics
  * RAMPS Fully Assembled w/Arduino Mega: Sourced from UltiMachine
- Power Supply
  * I'm sure i have an ATX power supply somewhere around here...

I am getting the big order from UltiMachine on Friday. Won't be able to do anything with it though as I'll be out for the weekend. Next weekend I will be stopping by my brother's place to pick up my plastic parts. I will have the MakerGear hotend and a stepper motor to bring, so I may put together the extruder at that point. Either way, I'll being assembling the entire machine once i get back from his place (we live ~1700 miles apart).

Once I can print usable stuff, I'll print an extra set of gears for the extruder and some sort of spool holder...but that's a ways off.

So far I only have the MakerGear hotend. It really looks great though...hope it works as well as it looks Will post some pictures of the hotend tonight and if i have time i'll post pics of the UltiMachine shipment tomorrow.

Some of these pictures are big...looks like the forum is cutting off the right side of them, you may want to open in a new window or tab. Also, i'll shrink my photos next time!

My brother's first attempt at printing Prusa parts at the bottom of this photo, at the top of the photo are two gears he printed after fixing backlash in his x and y axis:




The rest of the Prusa parts my brother printed:






The MakerGear hotend with insulation:

the ultimachine package came in today!

i hooked up the stepper motors to the RAMPS board and gave them a spin. i ended up loading the sprinter firmware.

all of the stepper motors and drivers work just fine. i can exercise each one by manually sending the appropriate gcodes over a serial terminal. i can also connect to RAMPS using ReplicatorG, Pronterface and RepSnapper.

One problem...during a "print" the extruder stepper never turns. When i manually execute a gcode for the extruder, it works. It seems that the generated gcode is wrong or my firmware isn't configured properly.

I think it might be the generated gcode because i see this message from pronterface after i load an STL file:

The exported file is saved as D:\3dPrinting\gregsHingedAccessibleExtruder\small_gear_export.gcode
It took 31 seconds to export the file.
0 mm of filament used in this print

That last bit says 0 mm of filament will be used...i didn't change any of the extrusion settings in Skeinforge. Is this why my extruder motor never turns during a "print", or is that message just a meaningless quirk?

Any ideas?

here's the first few lines of the gcode. it looks like it's telling the extruder to go, but i'm no expert:

(<alteration> )
(**** beginning of start.txt ****)
(This file is for a MakerBot Thing-O-Matic)
(**** begin initilization commands ****)
G21 (set units to mm)
G90 (set positioning to absolute)
M108 S255 (set extruder speed to maximum)
M103 (Make sure extruder is off)
M104 S225 T0 (set extruder temperature)
M109 S110 T0 (set heated-build-platform temperature)
(**** end initilization commands ****)
(**** begin homing ****)
G162 Z F500 (home Z axis maximum)
G161 X Y F2500 (home XY axes minimum)
G92 Z80 ( ---=== Set Z axis maximum ===--- )
G92 X-57.5 Y-57 (set zero for X and Y)
(**** end homing ****)
(**** begin pre-wipe commands ****)
G1 X52.0 Y-57.0 Z10.0 F3300.0 (move to waiting position)
M6 T0 (wait for toolhead parts, nozzle, HBP, etc., to reach temperature)
M101 (Extruder on, forward)
G04 P5000 (Wait t/1000 seconds)
M103 (Extruder off)
(**** end pre-wipe commands ****)
(**** end of start.txt ****)
(</alteration> )
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M105
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(<procedureName> raft </procedureName> )
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(<perimeterPath> )
M108 S102.0
G1 X52.0 Y-57.0 Z10.0 F1920.0
G1 X52.0 Y-55.0 Z10.0 F1920.0
G1 X52.0 Y-30.0 Z10.0 F1920.0
G1 X51.93 Y-29.43 Z0.5 F1920.0
G1 X45.38 Y26.16 Z0.5 F1920.0
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M101
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Looking good. I like the gator tips!

3dyeti Wrote:
-------------------------------------------------------
> Looking good. I like the gator tips!


and that would be my brother

pictures of some of the stuff I got today ><

The right side of the pictures is getting cut off again...

You gcode has no E parameters in them which is why your extruder isn't working.
Turn on Dimension in Skeinforge.

---

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

Thanks Bob! I'll try that out when I get home on Sunday.

Here's the copy of Greg's Hinged Accessible Extruder that 3dyeti made for me, sent me this photo this morning:

Looks like some new parts came in the mail yesterday and today. Got the hobbed bolt for the extruder as well as the rest of the extruder vitamins. Also got a nice big spool of ABS

Will post pictures tomorrow.

rhmorrison Wrote:
-------------------------------------------------------
> You gcode has no E parameters in them which is why
> your extruder isn't working.
> Turn on Dimension in Skeinforge.

This did the trick Bob!

Extruder stepper is now turning

Some pictures of the new parts.

I've previously tried mocking some prints with the endstops and stepper motors connected to my RAMPS 1.4 board. Surprisingly it worked. Had an issue with the extruder stepper, but fixed that by enabling Dimension (don't know why that would have been disabled by default).

Printing with ReplicatorG 25, the steppers move at a fairly quick pace. When I execute the same print with Pronterface and SFACT, it is incredibly slow.

Can anyone point me to the right settings in SFACT to increase the print speed? Maybe I can just compare all the settings between ReplicatorG (Skeinforge) and SFACT and see what's different. But that might not pinpoint which settings are causing the slowdown.

This weekend I'm traveling to my brother's house. Going to get the plastic parts and assemble the extruder. Won't be able to do much with it until I get back though.

EDIT: I got the wrong hobbed bolt...doesn't fit my extruder. Need to find a different one...

Well, first thing i noticed was that the bolt head didn't grip the gear properly, there is a few degrees of movement that the gear can move in. The gear expects an M8, but the bolt is not metric.

Second problem, the hobbed part is way too close to the bolt head, it does not align to the filament hole even when no gear is attached. With a gear attached, it is completely hidden in the bearing.

Either of these issues makes the bolt pretty much unusable. Here's a picture of the bolt in a wades extruder base with no gear:




Edited 1 time(s). Last edit at 09/25/2011 01:34AM by hardtoe.

I also found that the large driven gear that comes with the Prusa files from github has a very large hole which is very loose even on an 8 mm bolt. It doesn't seem to change with the configuration.scad file. I haven't had time to go through the scad file yet. Perhaps the hobbed bolt you got was made with a 5/16 bolt. That's what I used and it's working for me. Try removing the washer. It might light up with the filament hole without the washer.

Does anyone have an STL setup for a 5/16 bolt head for a Wade's? It's not the one in the SAE github.

The difference is so small between an 8 mm and a 5/16" bolt that I don't think it's necessary to make a special one. The standard Wade works well enough for me. One thing I found is that it's better to sandwich the gear with two nuts so that it doesn't have any play. Mine is set up in the order bolt head-washer-bearing-wade body-bearing-nut-gear-washer nut. The nut cavity in the gear faces in.

Thanks brnrd, you convinced me to try my hobbed bolt again and I was able to get it to work. I turned it around and put a nut on either end of the gear. I attached the hot-end and was able to extrude some plastic!

However, I made the mistake of assuming the sample plastic from Ultimachine was ABS...it's not. It's PLA. So I was extruding PLA at 230 degrees and it got messy fast. The PLA didn't seem to burn too much (though there was a steady stream of light smoke coming out...), instead it melted to a liquid and drip-dropped out of the nozzle.

After I realized my mistake I gingerly backed out the PLA and let the hot-end cool. Then I got some ABS fed in and warmed up the hot-end. I wasn't sure how to make the PLA -> ABS transition...it was pretty awkward. I tried to time it so I was pushing out the PLA before it got real hot. Not sure if it matters, I was mostly afraid of charred plastic blocking my hot-end.


The assembled extruder on the x-carriage:




Orange is the PLA...I made a bit of a mess with that. White is the ABS.




Ohh yeah, I was also able to assemble the frame! It was fun, the pieces went together easily. Didn't feel like it took any time at all. I don't have any epoxy for the bushings, so I'm going to get some today so I can get things moving! I also need to work the PLA bushings a little bit...they are really tight on the smooth rods. I'll probably heat up some smooth rod to loosen them up a little bit.



Edited 1 time(s). Last edit at 09/27/2011 04:38PM by hardtoe.

I've heard people run the PLA bushings on the threaded rods to loosen them up.

---

__________________________________________________________________________
"I like to be, what I like to see, in you and me.
I am the Stallion, Mang."

ISTAR Scope Club

Hey Hardtoe,

This thread is really fantastic - thanks! I'm just starting to really look at details on getting/making a 3D printer, and it's great to watch your progress.

A couple questions if you have the chance...

- About how much do you think you'll have spent once you are up and running?
- What kinds of technical knowledge did you find yourself using, besides coding?

Thanks.

BoriSpider Wrote:
-------------------------------------------------------
> I've heard people run the PLA bushings on the
> threaded rods to loosen them up.


You can also somewhat heat up the smooth rod end (for instance in boiling water) before sliding the bushing in.

Thanks for the tips guys!

I used my hot air gun to heat up one end of a smooth rod, then I placed the PLA bushings on the hot end of the rod and let it sit for a little bit before moving the bushing to the cool end. It definitely made the bushings run smoother, but I don't think it was enough...

Last night I glued the bushings to the bottom print plate using some epoxy. Then I attached the motor and belt according to the instructions. The platform does not move smoothly. I used pronterface to move the y-axis back and forth, it has jerky motions. I noticed that the y motor bracket flexes a bit; supporting the bracket with my hand helped a little bit, but the movement was still not smooth. I added generous amounts of lithium grease to the smooth rods, still didn't help.

Tonight I'm going to try to get the platform to run smooth by using the heated smooth rod again. I think I'll use boiling water this time to ensure that I'm getting the right temperature. If the boiling water isn't enough, I'll try running the bushings through some threaded rod, that should help out.

To answer Macguffin's questions:
- By the time this printer is running, I'll probably have spent 600-700 USD. I've needed to buy some tools like a decent wrench set and will probably need to get some more things that I haven't yet thought of.
- So far I haven't needed any specialized skills. I haven't needed to code anything. My hot-end was pre-assembled. My electronics came assembled and preloaded with firmware. I have since flashed a different version, but I didn't need to write any code for that. You'll need to be able to work through problems installing software on your computer...that's not too bad. I'm sure I will run into many more build problems as I try to get the y-axis running then the x and z-axis.

I think the most important aspect will be identifying problems, tracing them back to their root, then identifying a solution (finding it online or creating my own). Putting the bits and pieces together is easy...solving the issues that pop up is where I will spend a lot of time.

Also some lubricant could help. Not sure what is best for PLA on metal, but take care that what you use don't eat the plastic.

Got the y-axis to slide smoothly I tightened the belt, heated the PLA bushings and added a zip-tie to the y-motor mount. Now the build plate moves every time i tell it to move 0.1 mm in Pronterface.

I was also able to get the z-axis up and running. Things are moving very smoothly right now! I just glued the PLA bushings to the x-carriage, waiting for that to set before I move on to the next step.

Maybe I can make a test print tonight or tomorrow! If I do it will probably look the the stuff I naturally extrude every day....on the can. I don't yet have my kapton tape...we'll see.


Here's the current state of the machine (on my messy workbench):




Time for dinner! Complements to my wife:

Awesome all around! Thanks for the info.

Well, I tried to print last night and this morning.

It went just as I expected, horribly

At first the extruder was trying to push the filament way too fast; this caused the bolt to grind the filament and get the teeth full of plastic bits. I slowed the feed rate down in SFACT to 10mm/s. It seems that that would have helped, except my extruder has a nasty habit of reversing the filament all the way out every time a print is initiated or resumed.

So I've been trying this with Pronterface host software and Sprinter firmware. Any idea why the filament would reverse like this? It will reverse again if I pause the print and resume it.

Going to give it another try tonight.

Set extrusion to Absolute and in your startup zero your extruder "G92 E0".

---

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

Well that explains a lot, thanks Bob!

I took a look at the Sprinter "Configuration.h" file and saw this:

//// MOVEMENT SETTINGS
const int NUM_AXIS = 4; // The axis order in all axis related arrays is X, Y, Z, E
float max_feedrate[] = {200000, 200000, 240, 500000};
float homing_feedrate[] = {1500,1500,120};
bool axis_relative_modes[] = {false, false, false, false};

Just as Bob implied, Sprinter was expecting absolute values for the extruder. I might just configure Sprinter to use relative coordinates for that axis by setting "axis_relative_modes[3]" to "true" and see if that works. Otherwise I will follow Bob's recommendation.

Anyone know of an advantage of one or the other? Seems like it shouldn't make a difference as long as the firmware and GCode are using the same mode.

Edited 1 time(s). Last edit at 09/29/2011 12:05PM by hardtoe.

Ehh...looking at the Sprinter code I don't think my configuration change will work.

Going to try Bob's suggestion tonight.