My new bridge

[duluthboat]

This is how I have ended with the bridge. I'm starting to machine the parts so I’ll see what happens. The second pic is with the beams I have decided to put the center beam on edge and go with one rack on the X axis. I’ll keep you updated even if it’s a flop.

Gary

[duluthboat]

Pic 2

[Dan S]

duluthboat

Are you rasing and lowering the entire bridge?

[duluthboat]

The whole upper cross beam will go up and down on two lead screws driven by one stepper.
Gary

[Dan S]

what lead you to this design?

[ynneb]

I have wondered about having a moving table that moves all 3 axis and has a fixed router, But I never ever thought of raising the gantry up and down.

What are the advantages that you see with this design?
Wont it use more parts than a conventional design?
Good ideas are made by those who are willing to experiment.
If it is a success then you will be a pioneer.

I have wondered about hydraulic drives like that on a earth mover but only smaller. It would need linear encoders. I dont know if it would have any advantages except that it would go against the norm. Fancy trying that one out too?

[duluthboat]

Dan,

This is something I thought about for a smaller moving table design. Then as I was working thru some things I didn’t like about my large machine, I couldn’t help myself.

Benny,

This is a 4’ by 8’ moving gantry with a fixed table. It has a few disadvantages, like requiring a fair amount of custom machining. The additional complexity will be worth it if it works. The advantages would be a lower CG while cutting and a very flexible set up allowing many spindle options. I may want to later add a fourth or fifth axis, or possibly a gang spindle with multiple cutter heads.

Gary

[marvinstov]

Hi Gary,
I like the concept. This way, the gantry doesn't limit the "Z" size of material, instead the "Z" travel limits it. As on my machines, 4" & 5" gantry clearance but 6" "Z" travel. The only thing I question is the spacing of the "X" axis bearings. Would it be better if they were farther apart and have larger angle bracing to the uprights? But then the part of the gantry that is below the "X" rails might need to be taller I guess. Maybe that woudl be overkill, I'm not an engineer. Nice going, I'll be following this.

Marv

[musicmkr]

It's cool to see "outside the box" designs. The only problem I could see with the moving "bridge" would be when you want to drill/mill at a depth that would cause the bridge to crash into the part. Your working depth is limited to the distance between the tip of the tool, and the bottom of the bridge.

I guess you have the same probelm with the bottom of a router clamp too.

Looks cool, and nice renderings.

Good Luck!

[marvinstov]

Gary,
Have you seen this? Kinda the opposite of what youa re doing.

http://www.homemetalshopclub.org/new...html#eccentric

See: A Large Numerically Controlled Router Table at bottom of the page.

Marv

[duluthboat]

LOL! I think the idea is great. But I'll not be teased into anymore changes. Well, maybe some small ones.

Gary

[cncfoam]

This is Eric, Im the guy that grew up in Duluth.

check out my thread on spinning nuts, you seem to think of different things. Let me know what you think of this thread and give some imput.

Eric