4'th axis question

[2muchstuff]

Has anyone mounted a stepper driven rotary table between the z-axis and their spindle. I know this has been done on commercial machines but has anyone done it on a D.I.Y. router? My reason for asking is that I build radio controlled scale model boats and would like to cut out hulls or blanks to be fiberglassed over, there would be a lot of concave and convex surfaces. Any idea what software would allow me to do this?

[thats_right2]

Check these out:

http://www.rainnea.com/cnc.htm
http://groups.yahoo.com/group/CNC_Toolkit/

[buscht]

I have a 4th axis that I am in the process of debugging.
Here's some CAM software
http://www.deskproto.com/features/newinv4.htm
MESHCAM is working on multi-sided machining.
http://www.meshcam.com/
The 4 axis machining is not quite ready, but you can manipulate the code manually to get it to work.
These packages use the 4th axis as an indexer and you route in a 3 axis mode, rotate the part and route some more.
There are more efficient ways of doing this, but it works fine.
MACH 2 or TURBOCNC will control more than 4 axis on your machine.

FYI, I first set up my 4th axis with a wood lathe. I replaced the drive motor with a stepper motor. This works well as long as you keep the spindle exactly over the top of the 4th axis. In multi-sided machining, the spindle moves in both X and Y and I once I started cutting off-center my stepper motor wasn't strong enough to keep the axis locked in place. An indexer with worm gear seems to solve this problem as the worm gear provides the holding torque.

[turmite]

buscht I did basically thi same thing except I designed my 4th axis specifically for a given product. Tried to run it direct with a 300 oz motor with a 4X reduction. Didn't work and I ended up having to do a multiple gear and belt reduction to a 17:1 or vice versa. I don't really know which one is supposed to be in front! At 17:1 it will work but it is at the edge of not being strong enough.

Now to the first question. Yes you can mount the 4th axis that way but it will be much easier to make a 4th axis like we have been talking about and hold the hull between centers. There will of course be a little trim work after the hull is carved, but you are going to have that however you hold the foam. If I weren't so busy right now I would offer you a free carving so you could see what we are talking about....but I just can't right now. If you are not in a hurry I might get time in about 6 weeks.

Mike

[buscht]

Mike, I reread the post and see that I misunderstood the question.
That's right2 has the only approach that I'm familiar with.

Trent