Quote Originally Posted by Jonathan View Post
The standard part libraries can be helpful, but I tend to draw things myself so I can be confident it is correct. I guess if I used SketchUp I might think differently.
Very true, many of the parts I used, such as the pulleys, timing belts, ball nuts, linear rails and slides were all over 50 times the size I needed and some not 100% right. I spent loads of time scaling the items as a whole and also separately in each axis so that they match what I had. The problem was in SketchUp, the scale function works as a percentage where as I wanted dimensions, so I had to resize, measure, resize again, measure again..... to fractions of mm's. Next time I'll make them up but then I suppose the same tedious task will be spent with my vernier calipers.

Regards the profiled rails, I think what I paid for these 'mini slides' was very good and I definitely won't be able to get larger ones for this price. I spent ages today trawling eBay for profile rails and carriages and found that I can get Thk and Nsk sets at similar length for around £150 with p&p. Problem is I had to constantly go to their manufacturer websites and check whether they got 2 or 4 rows of balls. Then you find out the balls also have 30,45, and 90 degree configurations. Plus I started mixing models like hgh, hgw, hsr, ssr, sr, lf, lu with the wrong manufactures.

I've seen Zapp is very reasonable with his Hiwin rails and carriages, which work out at £180 for a brand new set, hgh15ca and 500 rails, compared to £150 for similar spec second hand Thk/Nsk on eBay. I don't understand how there can only be £30 difference, are Hiwin a cheap brand compared to Thk and Nsk.

I'm also not sure what preload is suitable for my z axis, as gravity is always going to pull the carriages down especially when all components are connected to it. Does ZO, little preload, mean there is more play between rail and carriages then ZA, medium preload. I have no actual experience what any type of preload feels like, as I only have the second hand ones to go by, which you can blow from one side to the other.

Thanks
Adil