ORD Bot 3D Printer

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Re: ORD Bot 3D Printer

Postby AJ Quick » Sun Feb 05, 2012 6:47 pm

This is one of the best 3D Printers I've seen. Great work on it!
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Re: ORD Bot 3D Printer

Postby rabeck » Mon Feb 06, 2012 9:33 pm

Love the design, is this a computer rendering or a photo of the real thing? If a rendering, what did you use to do it in?

You mentioned you are waiting to try out PLA. Do you have photos of the complete printer posted anywhere to look at. I.e., With extruder, all electronics, filament roll holder, etc.?
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Re: ORD Bot 3D Printer

Postby bdring » Tue Feb 07, 2012 12:12 am

The first few images of this post are real photos. The are a few other photos sprinkled about. The rest are renderings. I use Bunkspeed Shot to render.

I should have the PLA late tonight. Getting PLA was the hardest part of this project. 1 lost shipment and 2 orders cancelled because at the last minute the supplier did not realize they "ran out".
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Re: ORD Bot 3D Printer

Postby frob » Tue Feb 07, 2012 1:06 am

I like this - Its a nicely elegant design. Cost optimizing is so engrained in me I cant help noticing the dual-motor Z-axis and wondering if that could be made work with only a singe motor-leadscrew to shave the cost down even more. Have you considered using the parallel-rule cable mechanism like drafting tables used? It only takes a few pulleys and some aircraft cable- you could use single bearing makerslide v-groove wheels for that.
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Re: ORD Bot 3D Printer

Postby bdring » Tue Feb 07, 2012 1:21 am

It turns out that steppers are pretty cheap. Wholesale cost of a motor is about $6-$7. The other thing you want is a very easy way to square the Z. This is about the easiest way. You simple turn the motors independently to square it up. It is probably the reason it is such a popular method with repraps.
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Re: ORD Bot 3D Printer

Postby frob » Tue Feb 07, 2012 1:52 am

Makes sense... although when you add the extra flex coupler, leadscrew, acme nut, brackets, i'd expect it would add up to quite a bit more. Or not, if you're using plain threaded rod :) I was thinking too with no mechanical coupling between sides, one shaft could "accidentally" get turned putting it out of square later, though it unlikely to happen often in real life. I guess the firmware could "auto-calibrate" at the start of printing too. But i do like the simple symmetry this way.
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Re: ORD Bot 3D Printer

Postby BenJackson » Tue Feb 07, 2012 2:23 am

Prusa realized that the cost of the RP ("reprap printed") parts and belt to tie the left and right Z leadscrews together in the original Mendel (now usually called the Sells Mendel) exceeded the cost of another stepper (which Bart points out is cheap) which can be driven with zero additional electronics.

In practice I find it's annoying. Easy to square? Yes, and just as easy to get out of square. Need to move Z? You have to do it with the electronics because you can't really turn both Z's in sync at any speed. Want to optimize the speed of the Z axis? Oops, if you stall it in the process prepare to square it up again. But every RepRap design represents the goals of the individual designer. A dual Z motor is cheap and easy to reproduce.
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Re: ORD Bot 3D Printer

Postby canadianavenger » Tue Feb 07, 2012 3:25 am

Using an H Bot type configuration could be interesting here. [there's probably a more correct name for it, I just don't know it]

imagine what is shown here standing on the motor end:
http://www.youtube.com/watch?v=ei4lPk_aM9Y

It would give you the benefit of the dual-Z stepper rigidity, without the cost of an extra stepper, as now you run X off the same two steppers. Leaving Y on it's own stepper. This would also make the X stage a little lighter. [though not likely an issue in this application] It also may allow for the same motor bracket to be used with all 3 steppers. You give up the two lead screws for a single long belt (or cable), and a bunch of idlers.

If I can find some time, and [preferably, to save time] the necessary 3D models I'll see if I can CAD it up and post what I'm suggesting.
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Re: ORD Bot 3D Printer

Postby bdring » Tue Feb 07, 2012 3:52 am

Ben is right about how easy it is to get the Z out of square. You almost don't trust it when you come to it each day. I have been using a trick to square mine. I have two metal rods of equal length that I place under the on the motor brackets. I drive the z down manually until I hit both rods. It takes about a 30 seconds.


The Phlatboyz are working on an h-bot printer. It does take a whole new control scheme. It is not simply using existing Reprap code.

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Re: ORD Bot 3D Printer

Postby canadianavenger » Tue Feb 07, 2012 4:33 am

Indeed it would not work immediately with the existing reprap code. Though I wouldn't say it needs a whole new code base, the changes should be relatively straight-forward, as long as the code base is properly abstracted between the various software layers. So yes I will admit there is an extra hurdle here.

Since I opened my big mouth, and probably inserted my big foot into it. I will take it upon myself to make the appropriate changes to the code, and build a prototype unit. It'll be a good first project for me to get into using makerslide :) (I've been wanting to do an H-Bot design for a while now too)

I'll CAD my thoughts up over the next few days and hopefully be able to get in on the next order for parts.
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