Tri-Polar Bot Concept -- Meet Wally

FWIW TrinityLabs' hobbed pulley is a standard MK7 hobbed pulley, so any pulley made to Makerbot's MK7 dimensions should work. I know TrinityLabs, Makerbot, and SeeMeCNC all carry their own versions of the MK7 hobbed pulleys.

Okay, I realize that I the filament drive can be a source of confusion. I am using a modified QU-BD MBE without the heatsink or fan. All you need is the UHMW block and a polished set screw.

All that said, this is not a great solution. I just so happen to have 40 of these UHMW blocks so I am designing for them. However, I think any number of other filament drives could be better suited for Wally. This is on my list of thing to work on but first I need to deplete my stock of these UHMW blocks. :-)


How do I setup the firmware?
Disable all the end stops. Calibrate the steps/mm for the z. Set the xy steps/mm in such a way that the firmware thinks one rotate is 400mm. (No real reason for this. I just had to pick something.)

How to calibrate Wally?
I am working on that. If you look at the software file, you will see that I store what the bed position is for the extruder touching at the front of the plate and at the back of the plate. This was just a quick proof of concept hack. I really need at least 3 touch off points so I can account for side to side tilt. (I actually have a 1mm drop from the right to the left.) Additionally, I don't have a published procedure to determine the actual mechanical advantage. I am working on a few ideas. For now if you want to play, you can do the front and back calibration and print some smaller artistic pieces like a squirrel.

How do I run Wally?
Pull the arms all the way out and push the bed all the way down. (That is the reference position.) Make sure the z string has all the slack removed. Put normal gcode through the segmentizer. Run the gcode you get of of that.

I realize this is all pretty vague but you are on the bleeding edge. :-)

Edited 2 time(s). Last edit at 11/01/2013 11:45AM by nicholas.seward.

If I correctly understood you, at the moment I can't start G code from Repetier-Host through USB? Only through Flash card?
And what about Simpson? (your prize-winner) I too printed it. And too I want to start.

Edited 1 time(s). Last edit at 11/01/2013 10:50PM by Vladimir_Lukashuk.

You can run the transformed gcode from SD or USB. No difference.

You can make short video? I not absolutely understand as to transform and start up Gcode from Repetier-Host

Sure, I can make a video but it won't be soon. I am slammed right now.

I understood as to start segmentize.
I don't understand some things.
trailer switches aren't present, when dumping all axes =0,
it is necessary to lift a bed up to a nozzle (to move in + near 130-at me it is an emphasis in a back wall), after wally segmentize at the beginning there is a G92 X0 Y0 Z0 E0 team (to nullify value of axes). bed in the top, there are teams further where Z all the time increases (where? the bed already rested! )
The printer isn't able to move in a minus.
It seems to me that at the beginning there has to be a team - to go in Z 130 (virtual 0) and segmentize has to recode at the real increase in Z in reduction.

At the beginning of X=0,Y=0, Z=0. The bed is below and it is a constant.

In Repetier-Host or other program (only at a control stage) we lift a bed to a nozzle. We write down value Z in the segmentize variable. What does it give us? allow if a bed at a nozzle and Z = 129 (we have to understand that is virtual Z=0) and if after a slayser of G1 Z0.2 - segmentize has to write G1 Z128.8. so we will make a binding to Z0.
I am not able to program on Python. I hope for from you it not a problem.

Forgive for my bad English.

Edited 1 time(s). Last edit at 11/05/2013 05:48AM by Vladimir_Lukashuk.

Простите 2 раза записалось сообщение

Edited 1 time(s). Last edit at 11/05/2013 05:49AM by Vladimir_Lukashuk.

Quote
Vladimir_Lukashuk
The printer isn't able to move in a minus.

Correct, but you can reverse Z stepper

"Correct, but you can reverse Z stepper"
Explain, what you mean? describe the decision more precisely

There are two coordinate systems. The system that the steppers use and the standard Cartesian system.

I picked the (0,0,0) point to be when the bed was at the bottom and the arms are all the way out. I picked it because I don't have any electrical end stops and these are the only physical stops that I have. I made it so that all steppers can only move in a positive direction away from the reference point. There is really no reason for this other than I prefer being positive. :-)

Segmentize takes the Cartesian gcode and transforms it into this weird system. I have a video in the works that will take you through the "calibration" and the printing sequence.

Nicolas! I don't doubt correctness of your decision, it works and it is important. I simply don't know it, and asked clarifications.
Probably that I badly know English. And the translator not correctly translates.
your decisions. not mine

Edited 2 time(s). Last edit at 11/05/2013 01:49PM by Vladimir_Lukashuk.

Quote
Vladimir_Lukashuk
"Correct, but you can reverse Z stepper"
Explain, what you mean? describe the decision more precisely

One picture is better than thousand words, here it is:
[mir-cnc.ru]

This is for bipolar stepper.

Edited 1 time(s). Last edit at 11/06/2013 07:46AM by Serenum.

After attempting a Wally arm print twice
1 curled on ends 2 got poped off bed

There has got to be a better way?

A scrap chunk of wood
Forsner bit just the size of 608 bearing
Drill / Mill disk sander
9 minutes Wood Wally Arm



Ligher than printed (unfinished-- it popped off bed)

Quote
cozmicray
After attempting a Wally arm print twice
1 curled on ends 2 got poped off bed

There has got to be a better way?

A scrap chunk of wood
Forsner bit just the size of 608 bearing
Drill / Mill disk sander
9 minutes Wood Wally Arm

Ligher than printed (unfinished-- it popped off bed)

There is no doubt that you can RepStrap Wally faster. However, once you figure out how to print a Wally once you can repeat the process with much less human time required.

I look forward to seeing a wooden Wally. I like your arm and am ordering my own metric forsner bits for doing stuff just like this. Good luck on your build.

FWIW, I just printed an arm with WALLY on it and had no problems with it adhering well to the build platform. Printed in 1 hr 45 min. 3 perimeters, 15% infill, 0.3mm layer height, 65C bed temp for first layer, dropped to 60C after that, hotend at 205-210C, used hairspray on the heated bed. I'm getting close to having Smooshed's parts done now.

Shane

Quote
cozmicray
After attempting a Wally arm print twice
1 curled on ends 2 got poped off bed

There has got to be a better way?

A scrap chunk of wood
Forsner bit just the size of 608 bearing
Drill / Mill disk sander
9 minutes Wood Wally Arm

[attachment 20909 Wood_Wally.jpg]

Ligher than printed (unfinished-- it popped off bed)

Whoo Hoo!

Out of curiosity, what printer are you using, and what filament?

Quote
sgraber
FWIW, I just printed an arm with WALLY on it and had no problems with it adhering well to the build platform. Printed in 1 hr 45 min. 3 perimeters, 15% infill, 0.3mm layer height, 65C bed temp for first layer, dropped to 60C after that, hotend at 205-210C, used hairspray on the heated bed. I'm getting close to having Smooshed's parts done now.

Shane

Quote
cozmicray
After attempting a Wally arm print twice
1 curled on ends 2 got poped off bed

There has got to be a better way?

A scrap chunk of wood
Forsner bit just the size of 608 bearing
Drill / Mill disk sander
9 minutes Wood Wally Arm

[attachment 20909 Wood_Wally.jpg]

Ligher than printed (unfinished-- it popped off bed)

I'm using a combination of printers: I printed half the parts on my Prusa i3 (https://github.com/josefprusa/Prusa3-vanilla) and the other ones on my Prusa/Graber i3 (https://github.com/sgraber/Graber)

Filament: [seemecnc.com]

I had to switch printers mid-print as I had access to 1.75mm filament but my Prusa i3 uses 3mm filament. However my Graber i3 had a 1.75mm hotend (just not hooked up), so I spent some time this past week, got it running right, and am now cranking them out.

Shane

Quote
smooshed
Whoo Hoo!

Out of curiosity, what printer are you using, and what filament?

Quote
sgraber
FWIW, I just printed an arm with WALLY on it and had no problems with it adhering well to the build platform. Printed in 1 hr 45 min. 3 perimeters, 15% infill, 0.3mm layer height, 65C bed temp for first layer, dropped to 60C after that, hotend at 205-210C, used hairspray on the heated bed. I'm getting close to having Smooshed's parts done now.

We printed our first Wally arms with blue tape on a cold glass bed, and all the ends curled. The pull was so strong that it peeled the tape off the glass. The fix was to retrofit the printer (OB1.4) with a heated bed (QU-BD silicone) and a heavier glass bed, just in case it tried to curl too. We ran at 70C dropping to 65, with a PVAc wash on the glass and got beautiful, flat bottoms with no splitting. We are going to use the curled arms for the bed supports, I don't think there will be any issue there, and keep the flat ones for the arms.

FYI I just added renders of all the STLs in the Wally git repo to the RepRap wiki page: [reprap.org]

Shane

With Nick off designing and developing other printers Simpson, other delta's, and others,
is Wally and orphan?

How many out there working on Wally's?

tnx

Wally isn't an orphan. You guys will just have to indulge me from time to time. To ask me to stay on point and never play around would prevent me from coming up with things like Wally in the first place. :-)

Is there anything in particular that you need clarification on for your build? Currently, I am focusing on getting the STLs done for GUS Simpson and then I am back on Wally's assembly instructions.

@ Nicolas! There are questions on insertion control.
You wrote earlier - the printer has to suspect 400 mm one turn of the step engine. It as?
1) Give Configuration.h
2) give comment in segmentize.py
square_z=75
l=150
L=250
d=200 #print diameter
y_offset=37.5
mechanical_advantage=9.5

Well, I'm working on Battleship Wally (so named because it''s going to be on an aluminum frame). Not much to see yet, but as progress is made I'll start a build thread so folks can see that there is some activity :-)

Quote
cozmicray
How many out there working on Wally's?

tnx

Quote
Vladimir_Lukashuk
@ Nicolas! There are questions on insertion control.
You wrote earlier - the printer has to suspect 400 mm one turn of the step engine. It as?
1) Give Configuration.h
2) give comment in segmentize.py
square_z=75
l=150
L=250
d=200 #print diameter
y_offset=37.5
mechanical_advantage=9.5

1)
I won't upload the Configuration.h (yet) that I have because it is pretty suspect. I turn on eeprom so I can fiddle with values there. 400mm/turn is right.

2)
square_z=75 #z height when the bed arms are perpendicular to the backboard
l=150 #length of arms
L=250 #center to center distance between XY arm mounts
d=200 #print diameter
y_offset=37.5 #distance from the center of the bed (0,0,0) to the plane that all the arms bolt into the bed.
mechanical_advantage=9.5 #!pproximately the ratio of the big pulley to the small pulley. String thickness also comes into play so this needs to be calibrated.

I was wondering how Wally builders are fastening parts to the Back boards?
Using inserts then using standard bolts?
Using T-Nuts on backside?
Using screws? What kind? Screws into MDF can be tricky.

Tnx

@cozmicray: I did it all with M3x16 SHCS. There are nice nut traps in all the plastic parts. I wanted to keep it simple and standard. You can get M3x20 if you aren't in the mood to countersink for all the heads.

There are two exceptions. I had to use M4 bolts for my power supply. The other exception are the M8 bolts that hold the top of the triangles on and the arms.

I'm working on an amputee wooden wally... Just the X/Y stage to use as a relatively scalable laser cutter, made out of scrap ply with cordless drill and hand tools.... Great design for that, 1 arm done, 1 arm, plus base to go... really bad phone pic attached

Quote
cozmicray
How many out there working on Wally's?

tnx

[/quote]

Edited 1 time(s). Last edit at 11/21/2013 11:45AM by shez.

Ok, I finally had time to take photos of the parts I printed for Smooshed. See attached. These are BIG parts!

Here are the full parts:



Here's a shot of the arms:



This one shows the layer height and smoothness of the print:



Printer settings:

0.4mm nozzle
0.3mm layer height
3 perimeters
15% infill
3 solid layers top and bottom

Shane

Nice parts, and nice photos, too!

Thanks