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Tri-Polar Bot Concept -- Meet Wally

Posted by see3d 
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cdsteinkuehler
Re: Tri-Polar Bot Concept -- Meet Wally
November 22, 2013 05:17PM
Great looking parts, Shane! I'm almost done with a set out of natural PLA. It doesn't look as cool as your blue, but it's kind of neat to see the honeycomb infill (I'll post pics when I've got a complete set). I've also got some Cotten Candy and Sky blue coming soon (hopefully today!) that's slated to turn into Walley parts.

Can you weigh all the parts? I get 871 grams, including the support material for the xy forearm (calculated...I'm still printing some of the arms). That doesn't leave a lot of room for mistakes out of a 2 lb spool from the ProtoParadigm folks...too bad their spools aren't 1Kg.
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sgraber
Re: Tri-Polar Bot Concept -- Meet Wally
November 22, 2013 05:44PM
I checked and my parts weighed 789 grams before support material. With support material, it was pretty close to 820 grams.

You're right: it doesn't allow for much more than 1 mistake on a large part before you'll need a second spool!

Shane


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cdsteinkuehler
Can you weigh all the parts? I get 871 grams, including the support material for the xy forearm (calculated...I'm still printing some of the arms).
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creativeautomaton
Re: Tri-Polar Bot Concept -- Meet Wally
November 24, 2013 11:38AM
thinking about making a wooden wally, maybe.

Edited 1 time(s). Last edit at 11/24/2013 11:40AM by creativeautomaton.
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cdsteinkuehler
Re: Tri-Polar Bot Concept -- Meet Wally
November 25, 2013 11:14PM
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sgraber
I checked and my parts weighed 789 grams before support material. With support material, it was pretty close to 820 grams.

I goofed on my calculations, now that everything's printed I get about 930 grams: [github.com]

I finally got all the parts printed clean, but I don't think my layer alignment is as good as yours. That's one of the reasons I'm interested in printers like Wally and Simpson, I've had about enough of aligning parallel rods to prevent binding! smiling smiley

Hi-Res Photos: [plus.google.com]



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cdsteinkuehler
Re: Tri-Polar Bot Concept -- Meet Wally
November 26, 2013 06:18AM
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sgraber
I checked and my parts weighed 789 grams before support material. With support material, it was pretty close to 820 grams.

Shane: What nozzle size are you printing with, and what's your single-wall thickness? I'm using 3mm filament with a 0.5mm nozzle, so I've got perimeter extrusion widths of 0.50mm and infill widths of 0.70mm (according to Slic3r). I'm thinking my 3 perimeters is probably a fair amount thicker than your 3 perimeters if you're using a smaller nozzle.
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sgraber
Re: Tri-Polar Bot Concept -- Meet Wally
November 26, 2013 07:33AM
I'm printing with a 0.4mm orifice and my best guess at wall thickness is somewhere around 1-1.5mm with 3 perimeters. Default extrusion width is set @ 0.5mm.

Shane


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cdsteinkuehler
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sgraber
I checked and my parts weighed 789 grams before support material. With support material, it was pretty close to 820 grams.

Shane: What nozzle size are you printing with, and what's your single-wall thickness? I'm using 3mm filament with a 0.5mm nozzle, so I've got perimeter extrusion widths of 0.50mm and infill widths of 0.70mm (according to Slic3r). I'm thinking my 3 perimeters is probably a fair amount thicker than your 3 perimeters if you're using a smaller nozzle.
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cdsteinkuehler
Re: Tri-Polar Bot Concept -- Meet Wally
November 26, 2013 08:07AM
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sgraber
I'm printing with a 0.4mm orifice and my best guess at wall thickness is somewhere around 1-1.5mm with 3 perimeters. Default extrusion width is set @ 0.5mm.

Thanks! I measured one of my many failed prints, and I get 1.7mm for the three perimeters. I'm guessing that's where my extra weight is coming from (or I've just got really heavy PLA!). smiling smiley
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sgraber
Re: Tri-Polar Bot Concept -- Meet Wally
November 26, 2013 09:50AM
What's your % infill? How about solid top and bottom layers? I run 15% infill and 3 solid top/bottom layers.

Shane


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cdsteinkuehler
Quote
sgraber
I'm printing with a 0.4mm orifice and my best guess at wall thickness is somewhere around 1-1.5mm with 3 perimeters. Default extrusion width is set @ 0.5mm.

Thanks! I measured one of my many failed prints, and I get 1.7mm for the three perimeters. I'm guessing that's where my extra weight is coming from (or I've just got really heavy PLA!). smiling smiley
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cdsteinkuehler
Re: Tri-Polar Bot Concept -- Meet Wally
November 26, 2013 09:57AM
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sgraber
What's your % infill? How about solid top and bottom layers? I run 15% infill and 3 solid top/bottom layers.

I'm running the same. My Slic3r config file is in the github repo for reference: [github.com]

That doesn't include my filament settings (2.90mm) and extruder details (0.5mm nozzle), but it's got most everything else.
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sgraber
Re: Tri-Polar Bot Concept -- Meet Wally
November 26, 2013 10:14AM
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cdsteinkuehler
I'm running the same. My Slic3r config file is in the github repo for reference: [github.com]

That doesn't include my filament settings (2.90mm) and extruder details (0.5mm nozzle), but it's got most everything else.

Main differences I see:

* I use rectilinear infill (you use honeycomb)

* My external perimieter speed is 20mm/sec (yours is set @ 60%)

* The rest appears to be similar, except speeds which we each have slightly different values.

Shane
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cdsteinkuehler
Re: Tri-Polar Bot Concept -- Meet Wally
November 26, 2013 10:18AM
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sgraber
Main differences I see:

* I use rectilinear infill (you use honeycomb)

Hmm...I like the honeycomb infill, particularly at low infill ratios (since all layers are supported), but I wonder if that's it.

I'll slice and print a couple arms with rectilinear and see what happens.
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sgraber
Re: Tri-Polar Bot Concept -- Meet Wally
November 26, 2013 10:23AM
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cdsteinkuehler
Hmm...I like the honeycomb infill, particularly at low infill ratios (since all layers are supported), but I wonder if that's it.

I'll slice and print a couple arms with rectilinear and see what happens.

Just slice a single WALLY arm with Honeycomb and another with Rectilinear (both @ 15%) and compare print times and filament usage (filament usage information is at the very end of the gcode file).

Shane

Edited 1 time(s). Last edit at 11/26/2013 10:24AM by sgraber.
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cdsteinkuehler
Re: Tri-Polar Bot Concept -- Meet Wally
November 26, 2013 10:38AM
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sgraber
Just slice a single WALLY arm with Honeycomb and another with Rectilinear (both @ 15%) and compare print times and filament usage (filament usage information is at the very end of the gcode file).

Yep...already there, but I'm printing a set with the rectalinear fill to see how it comes out vs the honeycomb.

Details for quantity 2 of the "xy wall arm" part with varied nozzle size and infill type. All other settings are identical:

0.5mm Nozzle with honeycomb infill:
; filament used = 12198.5mm (80.6cm3)

0.5mm Nozzle with rectalinear infill:
; filament used = 11558.6mm (76.3cm3)

0.4mm Nozzle with rectalinear infill:
; filament used = 10394.2mm (68.7cm3)

WOW! That's over 17% difference! That totally accounts for the difference in our part weights.

It looks like I need to get a smaller nozzle and use rectalinear infill! :-)
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sgraber
Re: Tri-Polar Bot Concept -- Meet Wally
November 26, 2013 10:49AM
FWIW if you want to compare your filament usage and print times, take a look at a page I setup for myself while I was making plates for printing for Smooshed:

[dl.dropboxusercontent.com]

It's a bit convoluted, but it gives you an idea...

(Edit: I need to update the print times as since making this I have tweaked the printer to print faster, thereby saving ~5-7 hrs over a 45 hr print.)

Shane

Edited 1 time(s). Last edit at 11/26/2013 10:50AM by sgraber.
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cratos
Re: Tri-Polar Bot Concept -- Meet Wally
November 26, 2013 12:43PM
Is Wally usable at this point? I thought the kinematics were not finished?
If he is, how does he perform compared to a good cartesian bot?
- How is layer alignment (in the Z axis)? I find that layer alignment makes a massive difference in terms of perceived quality. Is the bed movement more consistent since it's just a pivot and no rods? Or does the math mean there is rounding error?
- How is the repeatability/slop/backlash/etc (x/y axis)? Do the arms flex/bounce/etc?
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cdsteinkuehler
Re: Tri-Polar Bot Concept -- Meet Wally
November 26, 2013 03:37PM
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sgraber
FWIW if you want to compare your filament usage and print times, take a look at a page I setup for myself while I was making plates for printing for Smooshed:

Great page!

As expected, the rectilinear fill parts weigh in at 94 grams a pair vs. 102 grams for the honeycomb infill version. So it looks like I'll be re-slicing when I print these again, and maybe switching to a smaller nozzle. IIRC, I've got a 3mm Ubis hot-end sitting around that should have an 0.4mm nozzle.
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cdsteinkuehler
Re: Tri-Polar Bot Concept -- Meet Wally
November 26, 2013 03:43PM
Quote
cratos
Is Wally usable at this point? I thought the kinematics were not finished?
If he is, how does he perform compared to a good cartesian bot?
- How is layer alignment (in the Z axis)? I find that layer alignment makes a massive difference in terms of perceived quality. Is the bed movement more consistent since it's just a pivot and no rods? Or does the math mean there is rounding error?
- How is the repeatability/slop/backlash/etc (x/y axis)? Do the arms flex/bounce/etc?

Usable? I suppose it depends on your definition. Nicholas has gotten Wally printing (I saw a video on the internet, so it has to be true!), but I'm pretty sure Wally isn't ready to be dropped into a 'bot farm and start cranking out parts.

AFAIK, the kinematics have been done for a while, with the exception of maybe some tweaks to get everything working properly. There's a python processor in the github repo, but I'm going to run LinuxCNC and use a version (I have not yet) written in C.

As for mechanical details, we'll have to build a few up and see. Nicholas has indicated the mechanism is robust, and I trust him to know what he's talking about. I've got the parts printed and waiting for my Beta kit to arrive (should be this week) and will know a lot more once I start putting in bearings and tightening bolts. Meanwhile, there are three or so others with parts printed or printing, so expect some real-world feedback soon!
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cratos
Re: Tri-Polar Bot Concept -- Meet Wally
November 26, 2013 09:01PM
Of course, I too have seen it printing. Though, I am anxious to get some of my questions answered about the bed movement being more/less consistent than rods, and how accurate Wally will be able to print. There has been a lot of talk lately about how using the wrong lead screws (imperial) will cause small layer misalignments because of rounding errors. I wonder if Wally will have those same types of problems trying to line up the y movement of the bed and the other kinematics that go along with the polar movement. I cant wait to see some hard core testing. smiling smiley
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nicholas.seward
Re: Tri-Polar Bot Concept -- Meet Wally
November 26, 2013 09:17PM
The imperial vs metric screw talk is completely unfounded unless you have naively setup a cartesian bot. Even then I would have to really try to make it an issue. Rounding error is so much smaller than microsteps.

The only thing that I have heard that is even remotely valid is that it is advantageous to pick layer heights that are multiples of a full step. You better believe you can do that with imperial or metric screws.

All that said. Wally uses software leveling so that makes it a none issue.
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cratos
Re: Tri-Polar Bot Concept -- Meet Wally
November 26, 2013 11:01PM
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nicholas.seward
The only thing that I have heard that is even remotely valid is that it is advantageous to pick layer heights that are multiples of a full step. You better believe you can do that with imperial or metric screws.

This was specifically what I'm talking about. I'm using 1/4"-16 lead screws. 1/16in = 1.5875mm per rotation. So 200 steps = 1.5876mm. So 0.0079375mm per full step. You cant really come to a nice layer height that is a multiple of (full) steps, right? When I say nice, I mean something that goes out to less than the thousands place. Stop me if I did something wrong... But at 16x microsteppng that's 0.00049609375mm per step. At that rate, for example, a layer height of 0.254 works (512 steps). Layer height 0.1905 also works (384 steps). The other problem though, is that steps/mm is about 2015.7480314960629921259842519685. So the numbers just don't work out. The hardware cant represent a number to that precision. Now, I don't really know how/if this translates into real world 'banding' as they call it. I've yet to do any testing.

The software leveling of Wally sounds interesting. Did you make a post about it somewhere that I missed? Do you just mean to compensate for the Y movement of the bed?
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nicholas.seward
Re: Tri-Polar Bot Concept -- Meet Wally
November 26, 2013 11:18PM
@cratos: Using metric screws to make the "prefered" layer heights "nice" is reasonable. However, the controllers can handle more floating point precision than you need. Again, for any none Cartesian bot this is not an issue. Additionally, any Cartesian bot that uses software leveling (which could be any Cartesian bot) will also not have any banding issues unless you have a perfectly level bed. (I still question the cause of the banding. I am quite sure that imperial screws are a red herring but that is a topic for a whole other thread.)

It would be pretty hard to physically level the bed on Wally so I just touch off the platform at 2 (soon to be 3) places. It is surprisingly good and very easy to do. (I like this much better than using springs and screws. Those lead to a shifting platform.)
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cozmicray
Re: Tri-Polar Bot Concept -- Meet Wally
November 27, 2013 01:24PM
Can someone update Wally fastener BOM to show
what type of nuts / bolts (hex head, button socket, stop nut, etc)

Anyone have a good inexpensive fastener supplier?

Tnx
smiling smiley
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nicholas.seward
Re: Tri-Polar Bot Concept -- Meet Wally
November 27, 2013 01:36PM
All my nuts are nyloc stop nuts. All the M3 bolts are SHCS. All the M8 bolts are hex head. I buy from McMaster-Carr. Someone told me Bolt Depot has good prices for allowing the purchase of individual bolts.

Note: use the STL files for reference if you are unsure about the bolt type.
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cozmicray
Re: Tri-Polar Bot Concept -- Meet Wally
November 30, 2013 03:15PM
Is there an assembly drawing out there for Wally?
or
How to make one?

Left, right, top, front line drawing?

confused smiley
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smooshed
Re: Tri-Polar Bot Concept -- Meet Wally
November 30, 2013 03:38PM
Since I don't have Inventor on my workstation at the moment, I've been using Inventor View (free, but windows only) to get a handle on how Wally goes together.

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cozmicray
Is there an assembly drawing out there for Wally?
or
How to make one?

Left, right, top, front line drawing?

confused smiley
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cozmicray
Re: Tri-Polar Bot Concept -- Meet Wally
November 30, 2013 04:44PM
WALLY Backboard

Why do holes in the backboard need to be only 5mm from edge?

Hard to hold a hole in MDF very close to edge?

Perhaps a mod here?

I may make my backboard bigger to have holes more inboard.

I should have looked closer at WALLY at NYCMF?

smiling smiley
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nicholas.seward
Re: Tri-Polar Bot Concept -- Meet Wally
November 30, 2013 04:47PM
1/2" Birch Ply is suggested over MDF.
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cozmicray
Re: Tri-Polar Bot Concept -- Meet Wally
November 30, 2013 04:50PM
Edges on any plywood are terrible.

Was the Wally at NYC MF birch ply?

Tnx




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nicholas.seward
1/2" Birch Ply is suggested over MDF.
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cozmicray
Re: Tri-Polar Bot Concept -- Meet Wally
November 30, 2013 04:55PM
I am "on the cheap" with respect to CAD sketchup TurboCAD

Did all you guys get a deal on AUTOCAD or are just lottery winners?
Got a URL for free Inventor --- I will move from my Mac to my Win machine.

Would really like an assembly drawing in PDF, would make it easier, to put WALLY together.


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smooshed
Since I don't have Inventor on my workstation at the moment, I've been using Inventor View (free, but windows only) to get a handle on how Wally goes together.

Quote
cozmicray
Is there an assembly drawing out there for Wally?
or
How to make one?

Left, right, top, front line drawing?

confused smiley
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nicholas.seward
Re: Tri-Polar Bot Concept -- Meet Wally
November 30, 2013 05:01PM
It is/was 7-ply Birch which IMO is just one step removed from Baltic Birch. Most big box stores usually have some really nice looking 1/2" ply.

Inventor view is a great option as you guys wait on me to put diagrams together.
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