I am planning my machine, and wondering what I should plan for the offset for the wheels. I have seen a couple different plans with a relatively significant difference in the spacing. Yes I am getting eccentric spacers, but from what I can tell, one of these may be on the tight side of design, and the other on the loose side with not much adjustment left after wearing down a little. I am planning the solid wheels. Any thoughts on this?
I'm not quite sure what you're asking as your question can be taken a couple of different ways but if you're asking about the center to center spacing between the wheel mounting holes that has been somewhat of a moving target over the years. It started at extrusion width + 19.7mm then moved to e.w. + 19.4 (which was too small) then back to e.w. + 19.8 then most recently jumped to e.w. + 20.6mm. Taking measurements from an assembled gantry plate, adjusted to and riding on a piece of extrusion I generally get measurements varying from extrusion width + 20.15 to + 20.35mm. I tend to use extrusion width + 20.0mm on my own builds and this spacing has never let me down. But truly the best suggestion if you have a set of digital calipers would to be to set up a test assembly using final materials and measure it yourself if you are needing extremely accurate results. There are always minor variations in extrusion and wheel lots that when compounded can make a difference.
Rick, you hit it right on the head. I like your idea of the +20.0 mm option, and I think that is what I will use. Thanks.
