another new design

[austin.mn]

here is a design i drew up for my brother. he wants to get into cnc'ing after seeing the stuff i have been able to make. so i told him that i would build him a machine. he bought the four axis kit from www.hobbycnc.com and is now waiting for me to get his machine built.

the panels for the machine are a laminate of .125 aluminum and .75 MDF (anyone know what glue should be used to bond them together? i was thinking that gorilla glue might work or contact cement). the rails are Bishop Wisecarver #3. the leadscrews will just be .5 all-thread untill he decides to replace them. the drive nuts will be a plastic block that is split on one side so that it can be clamped down to eliminate backlash (i have used this method on previous machines and it works well enough). the holes in the perpendicular intersections are for adding a dowel for fastening the joint (mdf doesn't fasten well into the ends)

i still have a few dimensions to correct and i need to add the bits and pieces to the model to complete it, but you get the idea. if i can get the aluminum skins to laminate well it should turn out to be a nice starter machine. i thought about just running a single motor to run the gantry but i figure he only has 200oz motors and this way he shouldn't have to worry about racking.

[ger21]

Gorilla glue won't bond well to the aluminum. I'd use epoxy, and West System's aluminum etch for the best bond. I glued some 1/4" aluminum to blatic birch on my router, and the scraps that were left over, I was able to pull the aluminum right off the plywood.

[pminmo]

I 2nd Gerry, epoxy.

[denzil]

Interesting design. Very much the way I am thinking to go. I like the idea of laminating with aluminium. I was thinking of using formica but aluminium sounds good. In the past when making a kitchen worktop using mdf and formica i would use contact adhesive but leave an inch on the edges where i would apply use Cascamite now calle Extramite. This made for a good job and the Cascamite bonded well to the formica. I don't know if it would bond to alu. I will experiment. I have also found this link - see post by Craig Elias
http://www.woodweb.com/cgi-bin/forum...pl?read=442975

Steve