Z-axis design - help sizing materials please!

[Ross77]

Having now seen it fit so well on the mill I think you would be better for off building a VMC, but optimised for wood, 400mm z axis on linear rails bolted to a column would be be no problem. The other way to deal with the large Z axis you need is to fit a 4th axis and then rotate the blade to the tool, I've seen furniture machinces work like this.

Are you going to be making a lot of these blades? if not it seems like you are building the machine to make a part but limiting other useage (hope that makes sense)

nice work so far, is that your workshop?

[Jonathan]

Having now seen it fit so well on the mill I think you would be better for off building a VMC, but optimised for wood, 400mm z axis on linear rails bolted to a column would be be no problem. The other way to deal with the large Z axis you need is to fit a 4th axis and then rotate the blade to the tool, I've seen furniture machinces work like this.

Erm, it doesn't really fit so well on the mill. To do that 0.7m blade I had to do half of the length at a time on each side - so a total of 4 setups which is less than ideal since getting it aligned is a pain.

4th axis...yes! I had that in mind. It's one reason I want a large Z travel to be able to fit a 4th axis, either directly to the Z axis or onto the base.

Are you going to be making a lot of these blades?

Hopefully - I'm not sure. I would like to make them to sell however I'm not sure how much of a market there is.

is that your workshop?

Yep I've got that 'CLARKE CMD1225C' milling machine which I've converted to CNC, plus a Sieg C3 mini-lathe and pillar drill, bandsaw, wood lathe plus the big router we've been discussing all in a 20'x10' workshop! Space is limited to say the least. The workshop was originally intended for me and my dad, but I've kinda taken over a bit...

Here's my latest plan for the Z-axis:



I've changed it so that the rails move and the bearing are stationary. This significantly reduces the weight / cost. The supports in the middle of the rail limit the travel to 75mm, so I'd remove them when I need the full travel. I guess I'll mount the stepper motor on the top of the slide - shame about the added moving mass there.
The aluminium plates in that drawing are 15mm. I'm thinking I could make the bigger one 20mm thick, to better resist torsion, then *if necessary* add side pieces like in the previous design.

So, do you think I should go ahead with this design, or spend another whole day designing :lol:?

[FatFreddie]

Here's my latest plan for the Z-axis:

How about putting the bearings either side of the centre rail support? That way you increase stiffness but still get reasonable travel.

[Jonathan]

How about putting the bearings either side of the centre rail support? That way you increase stiffness but still get reasonable travel.

I think that would increase the length of the rails too much. Either way I've just found this on eBay, don't know how I missed it before:
http://cgi.ebay.co.uk/ws/eBayISAPI.d...id=p2759.l1259

I've emailed the seller to list 600mm - that should be cheap enough :)