Hi folks, Here's a quick question about v-slot wheel orientation: Can they be used horizontally instead of the usual vertical orientation? What do I mean? Vertical = the standard gantry type router builds like the Ox. The wheels ride above and below the rail; mounted on a plate that is parallel with the rail in an upright position. The weight of the gantry pushes the top wheels down into the middle of the rail slot, applying pressure to both edges of the wheel. The wheels on the bottom don't hold gantry load, and act as stabilisers. Horizontal = an atypical setup, virtually the opposite of vertical. I want to know if you can think of any reasons why I shouldn't do it this way - because this is my preference! To be clear : the mounting plate will be oriented horizontally; as is the rail. The wheels will be on the sides of the rail (rather than top/bottom), and the load will be applying pressure to only the bottom sides of the wheels. [Relatively, there will be twice as many wheels under load, as all wheels in the assembly are loaded.] How much load are we talking about? I expect roughly 25lbs / 10kg. The wheels are the solid delrin type, rather than the v-wheel. Appreciate your consideration!
Hi I should start with I'm not a structural engineer! My understanding of the bearings in the Wheel setup used by the V-slots is that they are internally designed to take weight on the plane perpendicular to the axle and not from the side in line with the axle. Using them the way you describe would put the main load on the side of the bearings if I understood your description. hope that helps
Actually this is more of a mechanical engineering issue than a structural one. Bearings are designed to handle a small amount of lateral force but how much is hard to say. It's likely a function of the depth of the groove the balls ride in. Testing may be the only way to get to the answers you seek.
Rick and Wizzard, many thanks for your thoughts. You are clearly correct in identifying the bearing specifications in investigating this issue!
I'd be nervous about 10kg, but thinking of trying a camera slider with 1-2kg. An alternative might be for vertical wheels supporting the load and horizontal wheels providing guidance. A non openbuilds alternative might be the Igus W rail. http://www.amazon.com/DryLin-W1040-A-Linear-Camera-Slider/dp/B0044DUCVG
You are talking about radial vs axial load on the bearings. The standard usage is to load the bearings radially and most bearings are designed for this. You want to use them with an axial load and the bearings you have are mostly probably not rated for much, if any, axial load. One thing I've seen done is to use three contacts points. A top bearing is the one handling all the actual load with the side bearings doing guide work. (Which, not that I re-read, is what @Duane said)
I came across a product called the Zenslider today. From the limited information on the the site it appears to use v-slot and solid delrin as the guide. Again, I have no idea how much weight this would handle but seems to work okay with various size cameras. http://zenslider.com/zenslider/ Does anyone know what would be involved in machining or extruding delrin to match the extrusion profile?
Duane - Check out SlideRap. I think the slider idea could work well for light load situations. I've got a piece of delrin I may experiment with. May require lubrication. PTFE could work well dry. As far as horizontal wheels go, I think it's fine with a light load. Angular contact bearings in the wheels would better handle the axial load, but hard to find in that size and probably too expensive.
