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uncle_bob
I'm probably missing something very basic about mounting the motors and bearings. My approach is based on NEMA-23's and putting the bearing on the plate that's above the motors. The bearings should be small enough in O.D. to fit inside the bolt pattern on the face of the motor. Drop a few hollow spacers between the motor face and the board above it. Put bolts through the motor face holes, through the spacer, through the plywood, tighten them down.
How are you assembling the bearing to a piece of plywood?
Will you epoxy the bearing to the wood, trap the bearing between plates, etc?
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nicholas.seward
I am at a loss at how you can do it with the hub offset.
What caught my attention were the parameters (variables) that had a declared offset value.
What I don't understand is why both of the offset values are not the same.
I figured there was geometry that I couldn't see in the videos.
Your confusion, is because I don't know exactly where the hub_offset dimension is taken from.
I made the assumption that if both of the input values could be changed to zero, that would be
the equivalent of the arms being located in-line with the center lines of the lead screw, and the end effector.
I assumed that the math wouldn't bomb if I deleted these two variables.
Based on your comment, it sounds like I should use the hub_offset parameter.
"""PARAMETERS"""
shoulder_offset=37.5
hub_offset=50
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uncle_bob
If the arm is going to be able to drop straight down, the other two arms need to be a bit longer. More or less the arms get into the 1X rod spacing rather than 2/3 spacing vicinity. That either costs you build height or makes the machine taller. To be same / same I think you need to compare equal build heights.
I agree, you give up build envelope volume by placing the arms in-line,
and it should be compared to a Cartesian external printer footprint, and print volume size.
I have a couple of in-line joint design in mind to maximize the space.
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uncle_bob
I don't think you are back to the "built into Marlin" math. I haven't dug into it, so I may be wrong there.
Why not?.... I think you're correct in your reasoning. :D
I had to watch a few belt driven delta printers operate, and in-line arms look to my eye to be equivalent to the belt/string deltas.
Motor rotates, belt moves a distance.
Motor rotates, nut moves a distance.
Does this mean that there could be two approaches to achieve the same calculation.
Use the g-code preprocessor to calculate only the distance.
or
Create a line of code, or add a table in the Marlin firmware of the ratio of steps to distance traveled.
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uncle_bob
Bronze nuts for the Hi-Lead screws came in today. No screws to try them on yet.
They are bronze colored and heavy, beyond that nothing really useful to report about them.
Hopefully the screws will get here soon.
It might be beneficial for use at a latter date, to make an impression of the ID of the Roton nut with maybe some thing like Oogoo.
How much were they, and the shipping cost. I would like to add this expense to my BOM. This will allow me to compare the cost of having the nuts printed or making my own.