Grounded Experimental Delta Printer

Re: Grounded Experimental Delta Printer

nicholas.seward — Thu, 19 Dec 2013 21:47:14 -0500

There is some action over here. [forum.conceptforge.org]

I personally am abandoning this thread in regard to specific builds. (It would just get too messy with all the variants. GUS, THOR, BOB, LISA, etc.) We can keep this thread alive for general discussion of ideas regarding the grounded delta format.

Re: Grounded Experimental Delta Printer

dpharris — Thu, 19 Dec 2013 21:31:40 -0500

What's happening with this project? Things seem to have died off. Expect it 'tis the season.

Re: Grounded Experimental Delta Printer

nicholas.seward — Mon, 09 Dec 2013 15:01:07 -0500

I posted a bounty for GUS's documentation. I am working on it anyways but a little extra money will definitely help in the motivation department.

Re: Grounded Experimental Delta Printer

TBog — Mon, 09 Dec 2013 10:59:13 -0500

[www.acronymfinder.com]

Re: Grounded Experimental Delta Printer

nicholas.seward — Mon, 09 Dec 2013 10:58:28 -0500

OSHW: OPEN SOURCE HARDWARE (Sorry I was getting lazy.)

Re: Grounded Experimental Delta Printer

Ralphxyz — Mon, 09 Dec 2013 10:55:57 -0500

And what exactly is OSHW, sorry but some of us (especially me) do not know the acronyms used so often here in the Reprap forum.

I was taught that one should always define an acronym on first usage, just for ignorant souls such as myself.

I really like to understand what you are talking about.

Ralph

Re: Grounded Experimental Delta Printer

nicholas.seward — Mon, 09 Dec 2013 10:24:50 -0500

Quote
Quazzer

Quote
nicholas.seward
For those builders that haven't made it over to [forum.conceptforge.org] should do so. ...

Setting up ConceptFORGE forum is admirable and should be a great place for Conceptforge activities that you've hinted at in the past. But please keep all of your great work alive here on the Reprap forum.

No worries. I plan to keep all my RepRap related activity here. I just needed a good place to coordinate lot of concurrent builds. It didn't seem like that could be done here organically.

I also need a place for my nonRepRap stuff. Stuff like CNC mills and laser cutters. I am committed to OSHW. I have lost some investors due to my insistence that I release everything under a GPL compatible license. Luckily all are not as short sighted.

The idea of ConceptFORGE is to eventually allow collaborative OSHW developement (and low bar monetization oportunities) just like sourceforge does for software.

Re: Grounded Experimental Delta Printer

Quazzer — Mon, 09 Dec 2013 03:44:15 -0500

Quote
nicholas.seward
For those builders that haven't made it over to [forum.conceptforge.org] should do so. ...

Setting up Conceptforge forum is admirable and should be a great place for Conceptforge activities that you've hinted at in the past. But please keep all of your great work alive here on the Reprap forum.

Re: Grounded Experimental Delta Printer

nicholas.seward — Mon, 09 Dec 2013 00:20:32 -0500

There is a bad singularity when the shoulder joint and the hub joint are at the same z level. You need to stay above it or below it normally. You could traverse it by building up some momentum but you can't print within +/- 25 mm of it or so.

Re: Grounded Experimental Delta Printer

dpharris — Mon, 09 Dec 2013 00:13:36 -0500

Quote
pjoyce42

Quote
dpharris
I had a similar thought re mounting GUS in Lisa. GUS build height could be more easily increased with a elevating base.

Maybe another silly question ... Can GUS's arms reach below the ground plane? Could we increase the printing height by mounting the base of the arms above the ground plane?

theoretically there is nothing to stop GUS from printing a depth below the plane nearly equal to its maximum height above the plane. However, the ground plane represents the widest XY plane within GUS' printing envelope. What this means is that lowering the printing plane relative to the arm mounts will shrink the maximum printable foot print, so you could print more tall skinny things, but fewer wide/long short things. In practical terms, if you lowered the printing surface too much, GUS would not be able to self replicate because the arms would be too big.

While I am happy with the design, raising the mounting point might suit th vase brigade.

Re: Grounded Experimental Delta Printer

pjoyce42 — Sun, 08 Dec 2013 22:00:48 -0500

Quote
dpharris
I had a similar thought re mounting GUS in Lisa. GUS build height could be more easily increased with a elevating base.

Maybe another silly question ... Can GUS's arms reach below the ground plane? Could we increase the printing height by mounting the base of the arms above the ground plane?

theoretically there is nothing to stop GUS from printing a depth below the plane nearly equal to its maximum height above the plane. However, the ground plane represents the widest XY plane within GUS' printing envelope. What this means is that lowering the printing plane relative to the arm mounts will shrink the maximum printable foot print, so you could print more tall skinny things, but fewer wide/long short things. In practical terms, if you lowered the printing surface too much, GUS would not be able to self replicate because the arms would be too big.

Re: Grounded Experimental Delta Printer

nicholas.seward — Sun, 08 Dec 2013 18:50:03 -0500

For those builders that haven't made it over to [forum.conceptforge.org] should do so. Thanks to Brandon Heller there is now a experimental branch in the repository that integrates the kossel mounting holes so you can use all the accessories that people have already modeled. You can also use a JHead.

[plus.google.com]

[attachment 22633 KOSSEL.png]

Re: Grounded Experimental Delta Printer

dpharris — Sun, 08 Dec 2013 15:42:01 -0500

I had a similar thought re mounting GUS in Lisa. GUS build height could be more easily increased with a elevating base.

Maybe another silly question ... Can GUS's arms reach below the ground plane? Could we increase the printing height by mounting the base of the arms above the ground plane?

Re: Grounded Experimental Delta Printer

TheTechnicalNoob — Sun, 08 Dec 2013 15:41:44 -0500

What will be the first official print? Bart simpson from the simpsons tv show? :D but then you'd probably be sued for copyright infringment.

Re: Grounded Experimental Delta Printer

Quazzer — Sun, 08 Dec 2013 15:25:44 -0500

BART sounds good to me!

Re: Grounded Experimental Delta Printer

nicholas.seward — Sun, 08 Dec 2013 07:05:05 -0500

@jason.fisher: Yes! Yes you could. There are a few immediate problems.
*You need a 2D joint at the shoulders. (Not really a problem.)
*Your tilt is limited to be perpendicular to plane that goes through all three shoulders. This plus arm length restrictions could keep the tilt angle fairly small. (<30 degrees?)
*The arms will be able the now come past the screws so the PVC supports will probably have to be moved back. (That is not really an issue.)

So the only "real problem" is the limited tilt. After rolling it around in my head for a while I think we could probably get a pretty decent tilt. I will play with the geometry some. It wont be quite as easy as bolting some GUS arms onto LISA. You could actually do that but the volume and tilt wouldn't be that great.

NOTE: This will be a bot with 6DOFs but as far as effective DOFs you will only have 5. What I mean is if you can move the motors right, every single one of them will be moving while the effector stays still. In fact that will be a great way to calibration and will be a great demonstration of its coolness.

Any thoughts on a name? BART (Bad Ass Rostock Thingy) :-)

Re: Grounded Experimental Delta Printer

jason.fisher — Sun, 08 Dec 2013 06:34:12 -0500

If you mounted these arms (steppers and all) on LISA's lead screws, would you have 6DOF? :)

Re: Grounded Experimental Delta Printer

nicholas.seward — Sat, 07 Dec 2013 17:18:11 -0500

I merged the branch since I trust owens that it works so no more bridging.

I am fairly sure you couldn't do it with just a 2D arch.

Re: Grounded Experimental Delta Printer

brandonh — Sat, 07 Dec 2013 17:14:57 -0500

Quote
owens

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nicholas.seward
@pjoyce42: You can print it in the orientation given. Most printers can bridge that far. It may sag but you have tons of layers until you get to the gear part so most printers will self-correct.

However, there is an untested version here. I am not sure if the tuner can be inserted. I think it can.

No issues at all putting the tuner in; there's plenty of clearance. I'm printing my third motor arm now. . .

Glad to hear that! Do you think the tuner would fit if the cutout was a 2d one that matched the other side? It's a minor aesthetic thing, but a symmetric design would look good.

Re: Grounded Experimental Delta Printer

owens — Fri, 06 Dec 2013 22:49:02 -0500

Quote
nicholas.seward
@pjoyce42: You can print it in the orientation given. Most printers can bridge that far. It may sag but you have tons of layers until you get to the gear part so most printers will self-correct.

However, there is an untested version here. I am not sure if the tuner can be inserted. I think it can.

No issues at all putting the tuner in; there's plenty of clearance. I'm printing my third motor arm now. . .

Re: Grounded Experimental Delta Printer

Annirak — Fri, 06 Dec 2013 18:54:19 -0500

Quote
A2
@nicholas.seward

Simpson 3d printer calibration:
What does calibration involve, after thinking about it I don't have a clue :S

If I were to guess calibration would entail some of the following:
Accurately measure the center to center distance of pivots (arm lengths).
Temperature control of hot end and platen.
End stop firing.
Stepper motor voltage, amps.
Platen leveling.
The amount of nonlinear movement of the end effector.
Range of motion (envelope perimeter).

Or is it about testing sleeve pulleys for the string, and things of that nature?

The sort of calibration that a delta printer needs depends on what you're trying to control. For GUS simpson, I'm most worried about inaccuracies in the coupling gears. If you can trust the bearings between the arm and the effector, then you can map the entire movement of the set of gears by using a probe to map the platen. As a bonus, you get bed levelling and z height calibration for free.

I imagine it will take some interesting math to translate a large number of z points into x/y calibration, but it believe it is possible.

Re: Grounded Experimental Delta Printer

DaveGadgeteer — Thu, 05 Dec 2013 17:42:54 -0500

I would think that build quality (especially the strength of the inter-layer bonding) could depend strongly on the ambient temperature in the build volume.

I've tried searching for information on that subject, but get buried in other "temperature" hits, and haven't figured out how to find relevant stuff.

Does anybody here know of some relevant work on this topic?

I could imagine that even the temperature vs Z profile could matter.

Bridging ability should also be sensitive to ambient temperatures. Blow cool air upward??

Re: Grounded Experimental Delta Printer

nicholas.seward — Thu, 05 Dec 2013 15:10:03 -0500

@pjoyce42: You can print it in the orientation given. Most printers can bridge that far. It may sag but you have tons of layers until you get to the gear part so most printers will self-correct.

However, there is an untested version here. I am not sure if the tuner can be inserted. I think it can.

Re: Grounded Experimental Delta Printer

pjoyce42 — Thu, 05 Dec 2013 14:05:19 -0500

@dpharris: I just checked the GUS arms, and they will fit on the Twoup with no problems as long at your print diagonally. As for the OneUp, it is not at all possible to print the GUS arms without major redesign, and breaking them into 3-4 sub-parts. As for the LISA Simpson you could easily print the arms in two pieces on the OneUp, and then couple them using some embedded nuts and threaded rod. This give you the advantage of being able to adjust the arm length so they are all exactly matching.

@nicholas.seward: Regarding the arms for GUS, what is the orientation for printing? There seem to be a large unsupported area on the motor arm that would prevent it from being printed as shown in the wiki.

Re: Grounded Experimental Delta Printer

A2 — Thu, 05 Dec 2013 11:42:25 -0500

Quote
dpharris
Getting non-printed arms absolutely equal length might be hard.

Method to drill two holes a specified distance apart with reasonable accuracy:
Using a 2d paper printer, print a blueprint with center marks 200 mm apart. An 8.5x11 inch piece of paper should work fine.
Glue the paper to your piece of wood.
With a awl (sharp point), create a center mark in the wood.
Then drill a pilot hole with a small diameter drill that fits into the center mark created by tha awl.
Verify that the drill is perpendicular in two planes to the wood. An assistant will make this easier.
The pilot hole will work as a guide for the larger drill.

You can perform these steps on three piece of wood, or alternatively you can use one piece of wood (3X thickness of one arm plus 2X the thickness of the saw kerf)
Cut the wood in thirds to create 3 arms with identical hole spacing.
Mark the end of the arms before cutting, and assemble with like ends in the same orientation.
Doing it this way it's really important to drill perpendicular holes.

Re: Grounded Experimental Delta Printer

dpharris — Thu, 05 Dec 2013 11:13:55 -0500

I have ordered the Two-up, so it looks like I may just be able print the GUS's arms diagonally. However, it will be close. By eye, it looks like Lisa should be able to build a GUS. Also, Lisa looks eminently scalable by extending her arms. Changing the arms to printed end pieces, and supplying the length with plastic, wood, extrusion, etc would appear to be relatively easy. Getting non-printed arms absolutely equal length might be hard. Can the math deal with unequal length arms?

Re: Grounded Experimental Delta Printer

nicholas.seward — Thu, 05 Dec 2013 08:55:55 -0500

LISA's arms are currently 200mm from center to center so 228mm total. There are a few options. You can split the arms in half. You could also make them out of wood in 2 seconds if you have a 22mm forstner bit.

Re: Grounded Experimental Delta Printer

TBog — Thu, 05 Dec 2013 01:55:55 -0500

Quote
pjoyce42
I will probably get a QU-BD OneUP [...] then I will probably start working on a GUS, or Lisa Simpson.

The max travel for the OneUp is approximately 100x100x125mm while the TwoUP has 175x175x125mm.

You will need to build a smaller GUS if u get the OneUP. I don't think it's a small task to downsize a printer...

I'm not sure about LISA but the arms look the same length as the Simpson has. Maybe someone with more experience can check if you can print the parts of LISA on a 100x100x125mm bed

Re: Grounded Experimental Delta Printer

A2 — Thu, 05 Dec 2013 01:48:49 -0500

@nicholas.seward

Simpson 3d printer calibration:
What does calibration involve, after thinking about it I don't have a clue :S

If I were to guess calibration would entail some of the following:
Accurately measure the center to center distance of pivots (arm lengths).
Temperature control of hot end and platen.
End stop firing.
Stepper motor voltage, amps.
Platen leveling.
The amount of nonlinear movement of the end effector.
Range of motion (envelope perimeter).

Or is it about testing sleeve pulleys for the string, and things of that nature?

Re: Grounded Experimental Delta Printer

pjoyce42 — Wed, 04 Dec 2013 22:10:10 -0500

@A2: Thank you very much for the summary. I have a pretty good idea of what would be involved with building a Simpson, I just wanted to get a definitive answer for myself, and others. Thanks.

@nicholas.seward: Thank you as well for the summary. I do feel that Simpsons will be a great beginner printer, and I feel that a 1 year timeline is a good goal. As for me getting a first 3D printer, I will probably get a QU-BD OneUP because of the small form factor, low price, and QU-BD's reputation. Once I get that I will (around March or April) familiarize myself with its capabilities and limits, then I will probably start working on a GUS, or Lisa Simpson.