mvaughn's 2nd machine build

[mvaughn]

Yesterday I began cutting out the pieces for my second cnc router. The initial plan from the start of the 1st machine was to learn, have fun and build something the would build itself a bigger and better brother.

It's taken me a few years to get to this point but now it seems the hard learning curve is over and now I can have some fun. I haven't totally finallized the design but I figure now is as good a time as any to see what you all think.

After I get it done, If there is anyone interested I'd be happy to share the plans if anyone is interested. It's the least I can do...

[joecnc2006]

I see no problem with it, I know the concept works, its what i have done on my latest machine.

http://www.cnczone.com/forums/showthread.php?t=38220

Joe

[joecnc2006]

Looking again, if you can extend these two pieces upward to the top of the Gantry, I would think it will:

1) keep the carriage side pieces from warping.
2) add additional support and stiffness to the gantry.

Joe

[mvaughn]

Originally Posted by joe2000che I see no problem with it, I know the concept works, its what i have done on my latest machine. http://www.cnczone.com/forums/showthread.php?t=38220 Joe

Thanks Joe. Ever since that old hardware store thread got started I've been wanting to go the torsion box route for my next router. I tossed around the idea of making the x-axis pipes mounted on top and below the table and not relying on the side pressures of the gantry to keep it all together. When I saw your hybrid, I knew right off that I should stop thinking about it and get to work.

My current router only has a working area of 18 x 23 inches. I designed all the parts for this router so that they can be machined in those constraints. I'll be cutting the torsion box stringers in sections and joining them with dovetail joints.

The new machine will have a footprint of approximately 63 inches by 44 inches and a cutting area near 48 x 30 inches.

[mvaughn]

Originally Posted by joe2000che Looking again, if you can extend these two pieces upward to the top of the Gantry, I would think it will: 1) keep the carriage side pieces from warping. 2) add additional support and stiffness to the gantry. Joe

You are correct. The C shaped pieces of the y-axis carriage are just small enough to cut them on my current router. I originally designed them to be the full height of the gantry but didn't have the resources to cut them. After I get the machine up and runnning I'll cut some replacement parts to reinforce it.

I will extend the rectangular part as per your suggestions.

[mvaughn]

Joe, have you noticed a problem with stiffness or warping on your hybrid in the area I have elipsed? I took some styling cues from your design as you can obviously tell.

[spalm]

Hey mvaughn,

Good to see you moving on to a new, fun one. Ahhh, the old hardware store thread…

I really like that you went with the pipes on top and bottom, seems better for the bearings and the whole thing does not have to be kept in tension. It also should help with possible gantry rocking.

Since you asked for comments:
One thing that I noticed potential problems with on mine was the pressure plate thingy. It is kind of just floating out there in space on a couple of screws. People have improved it with guide plates and such, but it seems like it needs something more. Instead, I kind of like the idea of firmly bolting the bearing trucks, and then spreading the rails for preload. This requires splitting the supported rails into two, adjusting them for preload, and then tightening the supports to the frame. I donknow, just a thought.

Anyway, looking good. And good CAD skills too!
Steve

[joecnc2006]

Originally Posted by mvaughn Joe, have you noticed a problem with stiffness or warping on your hybrid in the area I have elipsed? I took some styling cues from your design as you can obviously tell.

i do not have any problems there, the top is bolted to the 80/20 and the bottom section has through threaded rods plus its all glue together.

Joe

[eloid]

Originally Posted by mvaughn Joe, have you noticed a problem with stiffness or warping on your hybrid in the area I have elipsed? I took some styling cues from your design as you can obviously tell.

i like this design for your cnc machine is there a theard with design build
to read up on or to et more pics of the build

[mvaughn]

Originally Posted by eloid i like this design for your cnc machine is there a theard with design build to read up on or to et more pics of the build

Yep.. you're looking at it.

I jumped the gun a little on starting the build thread. I am still finalizing my design. I like everyone's comments so far. I wanted to make any changes in the design before I started cutting too many parts. I'll post the photos as I build. so far, it's only a CAD drawing.

[mvaughn]

Originally Posted by spalm One thing that I noticed potential problems with on mine was the pressure plate thingy. It is kind of just floating out there in space on a couple of screws. People have improved it with guide plates and such, but it seems like it needs something more. Instead, I kind of like the idea of firmly bolting the bearing trucks, and then spreading the rails for preload. This requires splitting the supported rails into two, adjusting them for preload, and then tightening the supports to the frame. I donknow, just a thought.

Hey Steve,

The pressure plate is an area that could use some improvement. I'm not sure how though. The gantry will have the pressure plates surrounded on all four side to capture it. The entire gantry will have to fall apart before the pressure plate will come loose. The third alternative would be to design the machine to exacting dimensions with no room for adjustment other than shims?

[spalm]

Hey,
I don’t want to hijack your thread but… (Don’t you love it when people say that?)

I don’t think exacting dimensions with no room for adjustment other than shims is workable. Mike Hide’s solution was to make a solid beam holding the two rails and bolting it to the frame. If this beam was cut into two, and was allowed to be spread apart with treaded rod before tightening the bolts, preload could be controlled. This would lead to both the bearings and the rails to be firmly attached. This also allows some adjustment for parallelism if things don’t go just right. Here are pics of his machine:

http://www.cnczone.com/forums/attach...3&d=1178433304
http://www.cnczone.com/forums/attach...4&d=1178433304

Enough on that, it looks like your solution will work just fine. How are you planning on attaching your bottom pipes? What are your plans for the Z?

Steve