4R8's table build

[4R8]

(11-14-2012, 11:01 AM)Mayhem Wrote:

(11-14-2012, 10:51 AM)4R8 Wrote: ...what's the plural of axis?...

Axes

ah, I knew it's be something simple! Thanks

back to some details. I was asked about 'V rails', the method I'm using for the motion of the machine. I'll follow that with a bit on the carriages so far.

V rails 101.

thee profile of a V rail is seen below



A V bearing is used to run along it



Generally you want to build a bit of adjustment into the machine to take up any play in the resulting mechanism. The most effective way I've encountered and used is via an eccentric bush.
In the photo above and below, the hex piece has been turned down on the lathe and an eccentric bore drilled through. By backing off the button head bolt and turning the bush, the bearings can be forced into the V rail, taking up any play in the motion.



another point to note with V rails and one of the best features for plasma and routing applications is their self cleaning design.
Any dust that settles on the rail is literally 'swept' off by the bearing as it passes. The angled surfaces also mean larger pieces simply fall off, not settling and causing an issue.

Standard roller bearings have no sweeping motion on the flat surface they run on. This means and debris on the surface is not removed, instead it can be embedded into the surface and can build up over time. Larger pieces may cause a jam/stall and ruin a part.

The ability to easily join sections together and change any singular bearing should one fail makes the V rail system extremely attractive to many builders and myself.

There are many other options to consider and all have their pros and cons.

skate bearings on flat bar, round bar or angle, linear bearing systems and slides. Namely the round hardened rails and Hiwin style slides can all be used but I've chosen V rails