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Posted by rustynoob 
February 06, 2017 08:35PM
I have this crazy idea for a one side coreyz using 3 linear rails a bunch of pulleys and 3 belts.
The y axis would just be a liner rail attached to the z axis at one end with a mount for two pulleys on the open end.
Mounted to the bearing block would be the y carriage made as light as possible ether by use of a bowden tube or a geared dc extruder.
The z axis would be another linear rail probably backed by a frame of some sort. The y and z motors would be mounted at the base of the rail one to each side the belts would go up behind the z carriage over two pulleys and back down the front side where they would go around pulleys along the y axis where one goes around the end of the axis and attaches to one side of the y carriage and the other just goes along the y axis and attaches to the other side off the y carriage. at the other side of the carriage the belts continue back to the z axis and return to the motors.
so one belt goes motor, z max, z carriage, y carriage, y max, z carriage, motor
the other goes motor, z max, z carriage, y max, marriage, z carriage, motor
I guess technically they start and end at the y carriage but you get the idea.
The x axis would be driven by a third stepper mounted in the base. The bearing block would be mounted to the base and the rail along with a few belt attachment points would be mounted to the print bed.
The electronics could all be mounted in the base.
The end result should be a printer with minimal frame requirements and a very low moving mass.


Re: coreyz/2
February 07, 2017 10:05AM
I think you need some visual aids to help with explaining your idea..... It's very hard to comment on how light or strong your design is with so little reference to the frame and design (or is that the point? no frame?). If no frame, I would suggest using beefy linear rail. But then rail is more expensive then frame, so you havn't won much except for a simpler BOM.
Re: coreyz/2
February 16, 2017 04:49PM
I'll have to work on that.
I guess my main thought is that if you can keep the mass low enough you get to a point where it might not be worth adding a frame to the linear rail and at the moment I am trying to figure out where that point is.
Reducing the moving mass also has the advantage of reducing hysteresis from mass changing direction which is my goal in this thought experiment.
Also I have the electronics and belts from my last design that I never could quite get to work and i'm thinking of getting some linear rails and making a slightly more traditional design. lol

Re: coreyz/2
February 16, 2017 08:13PM

This is basically what I have in mind as far as the drive belt layout. It has been simplified somewhat to draw it in 2d. imagine the grey belt and the black belt run in different planes so they don't have to cross. There are a few variations of the layout that should work.
My other question is whether including the z axis in the coupled pair problematic? I am concerned about the layer resolution.
I am thinking that the z axis would probably be attached to some form of extrusion or even a steal frame since I have steal available and it will be non moving mass which is good. The drive motors would be mounted facing each other at the base of the mast. The drive motor for the x axis would be mounted with it's back to the mast the power supply would be mounted on one side under the print bed and the electronics would go on the other side

edit: The more I think about it I keep coming to the conclusion that combining the z and y and moving the bed on the x axis will result in too much moving mass in the bed for the added complexity of core style drive mechanics to be make sense. I am now trying to decide if a one sided mount with the corexy style drive makes sense. You certainly lose the simplified frame.

Edited 1 time(s). Last edit at 02/16/2017 10:58PM by rustynoob.

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