[rlrhett]

I am in the early design stages (or is that the "dreaming" stage?) of building a new machine, and I ran into a problem I need help working out.

I would like to use 8020 extrusions because of their cost and rigidity. However, I got stumped thinking about how I would mount a motor through the FACE of an extrusion. I was thinking of using a belt drive system, and the motor would be oriented perpendicular to the axis of travel, unlike a screw driven system where the motor would be mounted in-line with the axis of travel.

If I was using a solid material, like MDF, I would simply drill a 3/4" hole partially through the face with a centered 1/4" hole all the way through. I would seat a skate bearing in the 3/4" with a 1/4" shaft coupled to the motor passing through the 1/4" through hole. The motor would turn the shaft, which would have the pulleys on it, and the bearing would support the shaft while allowing it to rotate freely.

8020 is not solid, and although I haven't tried it yet, I suspect that if I tried to drill a 3/4" hole on the face of the extrusion I would not end up with something solid enough for a skate bearing to seat into. Am I wrong?

If seating a skate bearing into the face of 8020 won't work, does anyone have a suggestion on how you would support a drive shaft the passed through the face of 8020?

[Darylb]

Can you modify the design to have the rod below or above the 8020? This is how some designs do it and you can build a support piece that bolts onto the 8020. This will allow you to adjust the location of the rod support easily too.

[RossMosh]

I suggest you look at this forum for solutions that are known to work. Also look at the light industrial machines available to see what they do. Take the ideas you like and apply it to your design.

Based on your idea, it sounds like you're trying to do something similar to what is seen on the Xzero machines. Do a search for them. They use solid aluminum for the ends and uprights. I don't think you'll find much joy using extrusion the way you want. If you want to use extrusion, look at the way the FLA-100 is made.

[vtx1029]

John (microcarve) drills a hole into the extrusions and attaches a bearing holder on the inside of the extrusion. Kind of hard to see, but here's a link.

http://www.cnczone.com/forums/1018853-post1040.html

[DonFrambach]

If seating a skate bearing into the face of 8020 won't work, does anyone have a suggestion on how you would support a drive shaft the passed through the face of 8020?

Could you seat a skate bearing into a piece of aluminum and then bolt that to the 8020 extrusion? I'm thinking of mounting the motor on one side of the extrusion and then the aluminum with the bearing on the other side of the extrusion.

CNCRouterParts sells a bearing mount that would easily bolt to the face of an 8020 extrusion. Just drill out the 1/4 x20 mounting holes for the cover plate. Here's a link: http://www.cncrouterparts.com/bearin....html?cPath=21 Alternatively, with a mill, you can easily make your own bearing mount.

[microcarve]

The 3075 I use is thick enough for me to tap directly for the motor
bolts, but the aluminum bearing plates should work as well on most any 8020.

You may need an extra outside plate for your motors to attach to, depending
on which extrusion you're working with.

(The third picture was before I started tapping the bolt holes directly into
the extrusion....it's an example of a motor plate I mentioned.)


John

[rlrhett]

Thank you for all the suggestions. A rather thick aluminum plate attached to the surface would seem to be the best solution. I am a woodworker, so I don't like the idea of milling more aluminum pieces. However, it does seem to be the only viable solution.

Thanks,

[microcarve]

Thank you for all the suggestions. A rather thick aluminum plate attached to the surface would seem to be the best solution. I am a woodworker, so I don't like the idea of milling more aluminum pieces. However, it does seem to be the only viable solution.

Thanks,

Metal is nice, but a thick piece of plastic will work every bit as well.


John