Proper spacing on arms

How do you guys handle your spacing and gearing for your arms? Seeing a lot of slop and inconsistency in the arms my team has made. I have a a few pictures.

I want to help my kids make their arms look a lot cleaner, and work a lot more efficiently. What would be some good starting points for them?

One of the main issues I see immediately is how youre towers space out farther is they go up. This causes a lot of friction and ideally you would want to make your towers parallel. This can be done with standoffs or c-channel. Other than that just make sure the spacers around all of the gears are able to spin freely and aren’t binding as this will also cause unwanted friction.

Also try to limit the amount of gears used. Use low strength when possible as they reduce friction. If i were you i would place the towers closer together.

Ill post a picture of one of our twoers later. They’re as close together as possible

By placing the tower closer together, do you mean deceasing the holes in between individual tower. (by this I mean if you only look at the left tower, by decrease the holes in between the two pieces of metal.) The actual tower distance is fine. But to save weight and limit the shafts from bending you will want to make each tower metal closer together.

You need cross-bracing to hold a consistent distance between all the elements. That is, to keep the tower uprights parallel. It will also serve to keep the tower elements from twisting, since the structure will be much stiffer.

There are two distances to consider: the distance between the towers and the distance between the c-channel uprights which make up each tower. Our build experience is that having the c-channel uprights close together so that you can use shorter axles with fewer spacers on them will result in a better, lower friction build.

The distance between the two towers is less important, so long as you tie the entire structure together so that it can’t shift like a parallelagram.

Heres a picture of one of our towers