The minimum angle between rods and tower?

Hi,

Building and designing my printer from the beginning (but not electronics and firmware). Will attach som pictures as the printer takes shape further on. Have recently build a carriage (printer head) with integrated Z-probe that works well. I use the nozzle as probe and ball bearing as a stable pivot. Microswitch for leveling works without problems. Will probably end up at thingiverse later on.

But one question that will affect the design is my choice of lengths for horizontal upper and lower beams. On my attached picture I have a glass bed of 300mm in diameter and there is 200mm from the center of each tower to the middle of the round glass. Rods are 275mm between center of ballheads.

If I put the nozzle far out on the glass plate the beam at tower A becomes almost vertial and the rods at tower B and C are nearly horizontal. Will this become a problem?

Should I put longer horisontal beams at the bottom and top of my printer to make the distance between towers and center bigger? I suppose that the carriage at tower A in this position only keep the printer head parallel to the glass plate and that the carriages of tower B and C is making the motion toward or away from tower A. (at the attached position of printer head)?

The closer the printerhead is to a tower the less force in XY-direction can be produced from that tower but on the other hand the other two towers generates more force in X,Y direction. But how close is possible to go to a tower?

Of course I could make longer horizontal beams but I like the printer to have the smallest possible footprint

Best regards
Wretan

Edited 1 time(s). Last edit at 01/29/2014 02:37PM by wretan.

The rods can go to "negative" angles (past vertical) in some designs. As long as nothing hits, there's no magic maximum angle. Look very carefully at what's going on for interference.

Hi Uncle Bob!

Thank you! Perfect! That was exactly what I was hoping for! GREAT!

Best regards
Wretan

Hey, I really like the idea of the bearings on the rods. Thanks for posting

Nice idea

What are the advantages of this design vs. the other column types?
What are you going to use for the vertical rods?

You could use 6 bearings vs. the 8 on the carriages, reducing the total count from 24 to 18.
I think it will be more forgiving of geometric imperfections.
Have you included a spring to allow two of the bearings to float?

You could also use one bushing-ball bearing on one shaft, and 2 ball bearings on the other to prevent rotation of the carriage.

I like your rod end bearing design, I saw this on another machine and there were springs across both sides top and bottom, do you have any thoughts on why? I am thinking of changing mine to this design. I'm using 250mm long rods with a 200mm bed diameter,

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rm2014
I like your rod end bearing design, I saw this on another machine and there were springs across both sides top and bottom, do you have any thoughts on why? I am thinking of changing mine to this design. I'm using 250mm long rods with a 200mm bed diameter,

why there were springs across is because the join is a ball (or magnet) and the rod with a cup just cover the ball join to give the maxinum angle movement. Therefore, a spring is require to hold two rods together.

Edited 2 time(s). Last edit at 02/07/2014 01:34PM by okaydoke.