Grounded Experimental Delta Printer

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A2
@nicholas.seward

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

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.

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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. . .

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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.

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.

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

Edited 1 time(s). Last edit at 12/08/2013 06:40AM by jason.fisher.

@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) :-)

BART sounds good to me!

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

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?

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]

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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.

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pjoyce42

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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.

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.

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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.

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Quazzer

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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.

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

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

[www.acronymfinder.com]

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.

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

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.