Need Help!- 80/20 Grid Beam CNC Design Questions

[QuietStorm81]

I've got an idea. I want to build a CNC machine using the Grid Beam building philosophy and the 8020 HT framing system. The idea is that to build a CNC that can drill it's own parts and be built without welding and merely bolted together.

A few questions as I start drawing a design:

1. I'm looking for good sources of 8020 HT framing. Any ideas?

2. In the design, what sort of gantry ideas would be advisable for a bed that could be, in theory ranging from 4 to 8 foot square area of drillable surface?

3. On the same note, what sort of screw or bearing system would work for this idea?

4. For the Z-Axis I had thought to have a system that we could replace the whole assembly to switch between simple milling tasks and more complex CNC cutting work. Any thoughts?

5. Also, with Grid Beam the main issue in fabricating the parts is that you have to drill each hole first up. Would a compressed air drill assembly work well here?

I know this is going to be a bit of a hodgepodge design but if it works, I'd like to design more of them in a smaller footprint so we can make both CNC and Grid Beam a useable reality. Any help here would be much appreciated.

Thanks all!

Also, I've posted a similar thread in the 8020 metalworking board but considering the DIY stuff is here, I decided to make two threads. Here I'll design it but when I build it, it'll be documented there.

[QuietStorm81]

As I've been stymied a lot in getting files uploaded, here's a rapidshare link. Also, I've included a demo version of the Grid Beam components all made up like the specs in the book said for 1.5 inch tubing. Give them a try and see what you guys think. I'd love some ideas on where I should go next in designing this thing.

[QuietStorm81]

Is anyone willing to take these files on Sketchup and see what they can see? I really need some help designing this thing!

[OBHUR]

Originally Posted by QuietStorm81 Is anyone willing to take these files on Sketchup and see what they can see? I really need some help designing this thing!

hi ,
Yes i would like to see it in sketchup, can you post the link please .
Thanks

[pencilneck]

Originally Posted by QuietStorm81 1. I'm looking for good sources of 8020 HT framing. Any ideas?

I've purchased all of my 80/20 items from their eBay listings. I've found a few "out of spec" pieces that were brand new and dirt cheap. I screwed up on purchasing a wrong item and they canceled it for me without issue. Shipping prices have been very good as well. I've been VERY pleased with every purchase I've made with them.

http://stores.ebay.com/8020-Inc-Garage-Sale

[QuietStorm81]

Here's a new version of the link for those who want to see the files. Apparenly there's an issue with uploading files to this forum so for now, this is how I'll get these files out here.

As for sources, I've decided to use the Ebay page for my sourcing needs. Now I just need help making this thing a reality.

[QuietStorm81]

I've done some work and updated some of the design but I still need some advice on what types of linear motion would work well for this project. I'd like to use lead screws but I want to stay away from belt drives.

Also, finding components in Sketchup is difficult to do. I'd like to put the Y-Axis on the outside of the cutting area, not the inside. That will allow me to mount the Z-Axis on a fixed arm that I will fabricate later. More pics later but these will show you some of the progress I'm doing.

[skaos]

80/20 components Sketchup Library.

80/20 Aluminum T-Slot Extrusion Instant Quote - with Google SketchUp Support


skaos

[jsheerin]

Why not just use regular 80/20 and Ahren's bearings and drive components from cncrouterparts.com? Many here have built successful machines doing that. You can go lead screw drive or rack and pinion.

[QuietStorm81]

As much as I love the T-Slot extrusion series, I want to make it out of Grid Beam so that it is a truly self replicatable machine. My goal is to have a replaceable Z-Axis head that I can switch between a router head and a drill press head with a boring bit in it for the precision hole drilling that is necessary for Grid Beam fabrication.

Each one of the Grid Beam holes must be drilled in the piece before hand so having a CNC made from it's own parts that I can fabricate now does follow the tenets of the building philosophy.

My biggest concern is mounting the hardware to the Grid Beam frame, seeing as there are so many holes everywhere on the struts themselves. I wish the Grid Beam book was available for digital download so I could better explain why I want to build this way.

I think some shims in between the hardware for linear motion and my grid beam struts is probably the way to go. Any ideas?

Also, I want to go with a dual lead screw on the X-Axis and single lead screws on the Y and Z axis. Thoughts?

[Flateric]

My primary concern with "grid beam" material is flex and twist. In particular I think twist will be a problem with such a contruction material for this project.

I could be wrong, but thats my immediate concern.

[QuietStorm81]

Originally Posted by Flateric My primary concern with "grid beam" material is flex and twist. In particular I think twist will be a problem with such a contruction material for this project. I could be wrong, but thats my immediate concern.

Big thanks for replying!

You're right.Twist is my primary concern but this is why I configured the struts in such a way to minimize twisting. It might not look it from the prints but I've been really considering how to make the frame as rigid as possible without adding excess weight or cash to the build. With that said, I had experimented with the idea of making a more rigid 3/4 box frame around the feet to add some strength and/or tensioning the legs with wire and having those provide the stiffening.

Also, my primary use for this machine will be boring out a simple 4x4 area of holes in a square grid. Speed isn't a major necessity in this first version even though eventually I'd like it to be. I'll take a slower, more precise actuation and make the machine really fast in the cutting head as a way to negate the issue with the twist.

Finally, the plywood on the top of the frame should provide enough stiffness for the legs to do their job. MY main goal is making sure any gantry system is stiff and yet able to move freely.

Thanks for the good concerns!