Quote Originally Posted by deannos View Post
But whether you would get this much on a router to cause major problems, who knows.
I do and no it doesn't.!! Been using belts on my machine for years and they haven't stretched to the point I can see or measure. Had a hand in few belt drive machines and none of them suffer from belt stretch and they are spot on accurate and super reliable.
Must say doesn't work out much cheaper than ball-screws after you've bought all the belts,pulleys etc Unless like John S you can hob your own and have time.!

Was surprised to find the Jobs 5 axis machine I've been trying/about to buy connects to the ball-screws with 25mm timing belts and the moving head(X axis) on that thing must weigh 7-800Kilo. The bed(Y Axis) alone must weigh 200K and this thing was designed for machining titanium and precision moulds for Mclaren F1 to super fine tolerances.! So they wouldn't be fitting them on this quality machine if they stretched to any detrimental amount.! (That said they are probably something special and cost £500 each. . Lol)