homemade CNC, what dimension?
 

hey guys, I'm in the process of building my own overhead gantry CNC machine and struggling on an important point... what size to build it. It must be able to make any motorcycle, car, LM or F1 and maybe some smaller aircraft molds for composite work.
what is the largest part that you know that exist (forget airplane)? I do not find a part larger than maybe like 4x4'. Minimum should be 4x8 to machine std 4x8 MDF. Still need more space for the 5 axis so consider 5X10 to be base (plus can machine 3 axis on 5x10). I'm thinking at least 4' for Z. I found a picture of an actual machine that share my design concept for reference:

http://www.5axiscncrouter.com/images...%20ohg_lrg.JPG

Hows bouts one like this here???

http://www.scaled.com/services/cms_mill.html


Paul

the one at scaled composite is used for aircraft parts (aka wings).
way to big for me. I do not need for exemple a machine to build a car plug for wind tunnel testing.
Still, it is exactly the same concept (overhead gantry)

Noticed the control on that one, Fagor. Our 5 axis has that control and I hate it. It is built on top of a stripped, proprietary version of windows NT. Constantly giving us fits with memory errors.

Our machine is a 10FT x 5FT table. The machine travel is large enough to kick the head 90 degrees and still machine 10FT x 5FT block. In other words, it travels more than the table size as to not limit you when the head is kicked for 5 axis.

I would think that for automotive and motorsports use that would be a minimum acceptable size. This machine has done 90% of the patterns for the 08 Champ Car project and the same for the 09 Super League project.

We have also used this machine for drilling the hard point locations in both mentioned chassis. We have 44" from the table to the gantry. This has forced us to think a bit when drilling the underside of the tubs. 4FT would be better.

Any roofed car would more than likely be done in multiple pasterns so you would not necessarily need a machine the full size of the car.


http://www.quintax.com/5axtwin3c.jpg

so my approx of 5x10(plus 90 with head)x4' was pretty good...
anyway, for exemple an f1 car has a bunch of small panel to be able to quickly change a section (Unlike the DP-1 race car http://www.dpcars.net/dp1/img012.jpg ...)
what is of particular interest to me is, what is the other 10% that you couldnt make?

as for as control is going, its going to be running open source EMC2 under ubuntu.

We could have done all if time permitted. Side pod patterns were not done by us. We did however to the top and bottom halves of the tub patterns. They were the largest of anything pattern wise.

Tub drilling is the largest since it is both halves and roll hoop structure all bonded together.

I understand what you are saying about smaller pieces. Nose Box, Side pods, Engine cover, Airbox, Floor sections, cockpit surround, inlet ducts and damper cover are all smaller patterns done separately.

We did a full scale model of the super league car from foam. It was still split in sections and glued together. http://superleagueformula.net/


https://farm3.static.flickr.com/2375...923165.jpg?v=0

ok, awesome thanks
last question, when you said ''
Tub drilling is the largest since it is both halves and roll hoop structure all bonded together.'', I assume this is where you struggled with the 44 inch vertical Z limit (and that 48'' would have been much better) ?

Yes sir, With the tub upside down and supported front and back with fixture plates the bottom of the tub is almost to high. Some tooling had to be made in order to work. A regular 4" or 5" long drill was to long.

One setup for the rear of the tub had to be done with the tub pointing forward so all the work was done without the tub trying to go under the gantry and hit the roll hoop structure.

-billy