4x8 Steel and Aluminum - Belt Drive

[darrinp]

Here's my machine so far. I still need to do up a proper table top and dust collection though.

4'x8'x8", belt drive xy, screw drive z.
2x2 steel tube table frame
8020 and steel angle gantry
angle iron rails with v-bearings

It works better than I had expected and I grin like a fool every time I use it!

The vid shows it cutting a sign. The guitar is a project that I am doing on the machine currently.

[harryn]

Hi, nice work. Can you tell us a bit more about the belt drive details ? I am in the design / build stage of a belt drive my self.

Thanks

[SScnc]

Originally Posted by darrinp It works better than I had expected and I grin like a fool every time I use it!

Me too when I run mine! Very nice work. I currently have Kevlar belts on the X and screws on the Y and Z however I'm going to change the Y to belt also like yours. Do you have any problems with the Mach3 safety zones at the extents of your travels ? Mine just slams to a stop only on the X. Also I'd like to see what kind of drive reduction you have on your belt drives. Again, very good job.

SS

[darrinp]

Thanks for the comments guys! I used 3:1 gear reduction from the stepper which then drives a pulley along a tightly stretched piece of 3/4 wide belt - works much like rack and pinion.

The attached cad image shows my setup, sorry I don't have a photo at the moment.

[darrinp]

Originally Posted by SScnc Do you have any problems with the Mach3 safety zones at the extents of your travels ? Mine just slams to a stop only on the X. SS

Haha, no safety yet! It just slams into stops at the travel limits. I have limit switches but have been too busy making stuff to take the time to install them!

D.

[KOC62]

Do you have any picture(s) of your Z-axis design?

[darrinp]

Originally Posted by KOC62 Do you have any picture(s) of your Z-axis design?

I don't have photos, but here are a couple of cad images.

[KOC62]

darrinp,

Your stated performance looks good to me.

Some questions, if I may...

I can't see any means of holding the Z-axis on the rails. Do you have some means to prevent the Z-axis lifting up off the rails?

Secondly, do you need to grind/mill a v-shape on the top of the angle iron to match the v-shape of the truck wheels? It seems to have little contact with the angle iron rail.

Finally, where does one get that aluminum extrusion stuff in Canada?

Thanks,
KOC62

[Tweeker]

Originally Posted by darrinp Here's my machine so far. I still need to do up a proper table top and dust collection though. 4'x8'x8", belt drive xy, screw drive z. 2x2 steel tube table frame 8020 and steel angle gantry angle iron rails with v-bearings It works better than I had expected and I grin like a fool every time I use it! The vid shows it cutting a sign. The guitar is a project that I am doing on the machine currently.

This is some very nice work. I would love to see pics of the guitar when done. Make sure to post some of the work

[darrinp]

Originally Posted by KOC62 darrinp, Your stated performance looks good to me. Some questions, if I may... I can't see any means of holding the Z-axis on the rails. Do you have some means to prevent the Z-axis lifting up off the rails? Secondly, do you need to grind/mill a v-shape on the top of the angle iron to match the v-shape of the truck wheels? It seems to have little contact with the angle iron rail. Finally, where does one get that aluminum extrusion stuff in Canada? Thanks, KOC62

Hey KOC62 and anybody else interested,

If you look closely at the pics, there are aluminum blocks attached to the underside of the 8020 cross members which hold another set of v-bearings against the lower edge of the angle iron. See the image below...

As far as shaping the rails goes, I hand-ground them using a large whetstone, running it back and forth in long, smooth, uniform strokes, at a 45 degree angle. The bearings themselves seem to actually be work-hardening the surface somewhat, they're getting shiny like chrome now after some use. I know that it is not the ideal setup - I would much prefer blocks and rails - but it was pretty cheap to do and the performance is freakin' me out to be honest.

I have machined aluminum on it and the performance is OKAY... a bit of vibration due to 8" travel on my z. If I raise the aluminum up so the head doesn't come down so much, the performance is better. I also have 20 years experience cnc machining aluminum on industrial equipment so my expectations are high. I built this machine for wood and plastics and so far I am a happy camper.

If you are in the Toronto area, 8020 extrusion is available from IPEX Automation in Concord. It works out to roughly $11/foot plus $2/cut. Well worth it to let them cut it, all paired lengths are cut with a stop, so all the pieces matched perfectly. Their Cutoff saw is also built for this stuff, mine, not so much. They also carry a lot of other "fun" stuff. Depending on your budget, this is a place that could be fun for servos and stuff too. All industrial stuff, not so cheap.

If you are near Toronto, pm me...