ORD Bot 3D Printer

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Re: ORD Bot 3D Printer

Postby mike » Mon Feb 13, 2012 3:54 am

+1 for Firkin!
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Re: ORD Bot 3D Printer

Postby mojomoney » Mon Feb 13, 2012 5:59 pm

I really like the simplicity of this design. It looks as though it will be pretty simple to build and maintain. I do see a possible flaw that can be easily addressed. The z-axis lead screws will have the weight of the x-axis carriage applying a thrust load to the stepper motors. Stepper motors were not designed to have thrust loads and the bearings will fail prematurely. This can be addressed pretty easily by adding thrust bearing like those used on the "Aluminum Mendel" http://www.thingiverse.com/thing:16076. The thrust bearings can be seen clearly in the exploded view here: http://thingiverse-production.s3.amazonaws.com/assets/e8/bb/25/09/a3/Printer_Exploded_Drawing.pdf. It looks to me as though using longer z-axis lead screws and adding a bearing block at the top of the upright makerslide extrusions would be an easy fix for this. Perhaps the life-span without the thrust bearings will be acceptable, but if the steppers fail prematurely it should be a relatively easy fix.
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Re: ORD Bot 3D Printer

Postby bdring » Mon Feb 13, 2012 7:15 pm

That is a good point and something I have always watched out for on my other designs. I may make an option for that on this design. On 3D printers that is a very low duty axis, so it will last quite a while. Maybe I will supply the bearing and the user prints the support.

What part number is the Alu-Mendel using?
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Re: ORD Bot 3D Printer

Postby frob » Mon Feb 13, 2012 8:12 pm

Maybe to reduce or avoid the need for a separate thrust bearing mount you could insert the thrust bearing between the flex coupler and the motor housing ?
That idea also leads me to wonder about how high-speed running & resulting dynamic loads might affect the z-axis "helical spring" style flex couplers -
do they have any compressive flex to them, or are they so rigid that it's insignificant?
It also makes me wonder if the flex coupling is really necessary, considering that the top end of the leadscrew is free-floating;
It seems possible that the motor mounting plate might have enough flex to it to prevent any slight misalignment from causing harm to the motor bearings-
especially if that plate is made of plastic.
Of course its also possible the flex couplings are dirt cheap too so its pointless to try to avoid them :)
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Re: ORD Bot 3D Printer

Postby bdring » Mon Feb 13, 2012 8:21 pm

I am using the flex coupling because I have them and they are cheap. I will probably change it. I have the shafts touching each other so the flex is removed from the equation. I am looking for a simpler coupling, but they are all coming up more expensive. If I buy a lot from my screw machine guy they will be cheaper. I am not 100% sure what size lead screw I am using yet. It works great for the Quantum, but I need to test it on the longer reach of the Full Firkin unit.
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ORD Family

Postby bdring » Mon Feb 13, 2012 8:28 pm

I finished the design of the larger version. Here is family rendering. The larger version uses the MK1/MK2 sized bed. It is a little taller than needed, but I wanted to reduce the extrusion length count, so it is the same length as the gantry.

I still prefer the look of the Quantum.

ord_family.jpg
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Re: ORD Bot 3D Printer

Postby JeremyBP » Mon Feb 13, 2012 9:18 pm

The quantum definitely has the cute factor.
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Re: ORD Bot 3D Printer

Postby Gijs » Mon Feb 13, 2012 9:47 pm

If you put these on kickstarter, I am afraid you will need to order miles of makerslide

Both look great, any idea how large you could go with these profiles?
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Re: ORD Bot 3D Printer

Postby frob » Mon Feb 13, 2012 9:53 pm

bdring wrote:..I am looking for a simpler coupling, but they are all coming up more expensive...

Id be tempted to try something elegantly crude like a cheap threaded nylon standoff -
@ 1/4-20 you can probably press halfway onto the motor shaft and and have plenty of grip to hold it securely in place
then you can thread the rod into one end with a locknut & locktite, and voila!
Plus the nylon is probably flexy enough to work well as a real flex coupling
Then if you really want to upgrade you can "bootstrap" and print out some fancier designed couplings with your new #D printer :)
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Re: ORD Bot 3D Printer

Postby georgehine » Mon Feb 13, 2012 11:09 pm

man this thing looks incredible!
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