Originally Posted by yukonho  You can not use anything but hardened rod for linear bearings, sorry. You can do a search on it and read up for info, or just trust me that people have tried it and the balls always dig into the shaft on anything but hardened shaft.
For what it's worth, your machine is far too big to be thinking of milling aluminum like you are talking about. Cuts will take forever and the machine will flex a lot. Machining marks will be ugly and chatter will be everywhere. A CNC mill like the X3 can be had for a couple grand now and will do the job you want it for. Check out Syil, they have ads here on cnczone.
I am not trying to pop your bubble here, but I think it is important that you hear this so you dont make a big mistake.
colin |
Ok, I broke out the pens, pencils and paper and laid out my own design. I will still be using the T slot, but for pure material mounting/retaining only.
All the frame parts will be 3/4" aluminum.
The uprights will be 35 cm long at the base and semi tapered at the top. They will also have 2 cross supports connecting them, the rear one will be 20 cm tall with a retaining screw every 2 cm. The bottom brace will be 14 cm with a retaining screw every 2 cm. The Z axis will employ the use of two (one per side) double sized linear bearings. Everything else will use single sized, 4 per axis (2 per rod).
I am not sure what I was looking at before on mcmastercarr.com but it certainly was not what I thought it was. The 3/4" hardened rods and 24" supports will only be around 180ish. Again I am keeping the size mentioned before, hence why I am adding the supports 4" long centered every 20".
I would post the actual design but I have not gotten used to autocad yet and translating all those paper dimensions can get confusing for readers.