[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]

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]

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]

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]

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]

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]

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

[mvaughn]

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

lol... it is pretty funny, but seriously isn't that what these threads are for?

How are you planning on attaching your bottom pipes? What are your plans for the Z?

Steve

I'm planning to have the pipes on the x and y axis longer than the torsion box so they will be captured by the sides of the gantry and the end plates of the table. I still have to draw up the table end plates... I left them for last because I haven't decided to make this a table-top machine or have it free-standing.

For the z-axis, I'm going to go with the method that Andy used on his machine. I'll try to machine some bushings out of UMW, acetal, or delrin...
http://www.cnczone.com/forums/showpo...2&postcount=16

[mvaughn]

Joe or anyone...

I seem to have misplaced my calipers. Can you tell me the actual outer dimensions of the 1 inch id diameter pipe you use for your x-axis.

I've been using a measurement of 1.31 inches in my drawings, but I'm seeing conflicting dimensions here on the zone. I took a measurement off your e-drawings a see you use 1.34. is that oversized or exact?

[joecnc2006]

I have 1.32" for the O.D. and use 1.34 on the MDF seemed to work best for me.

Joe

[joecnc2006]

Nother question I have, how are you going to attach the X-Axis rail to the machine, because of the vertical arangement gravity will work a little more against you on the bottom rail rather than with it on the sides line the CNC Model 2006.

I has also found you do not need as big a dia. pipe, I am using 1/2" now on mine, the roller bearings seem to lock better around the pipe.

Joe

[mvaughn]

Nother question I have, how are you going to attach the X-Axis rail to the machine, because of the vertical arangement gravity will work a little more against you on the bottom rail rather than with it on the sides line the CNC Model 2006.

I has also found you do not need as big a dia. pipe, I am using 1/2" now on mine, the roller bearings seem to lock better around the pipe.

Joe

I'm attaching the lower x-axis rail to the bottom the same way your lower y-axis rail on the Joe 2006 is attached. It will be captured in pockets on the end table supports. The idea is that the gantry will keep it snug wherever the gantry rolls. If that doesn't work they can be epoxied into the supports.

Another idea is to install turnbuckles between the pipes to pull them together. The turnbuckles could be connected to eye bolts threaded into the pipes.

I like the way the 1/2 inch pipe is captured by the bearings in your diagram. I wonder how much rigidity is lost in the machine when going with smaller diameter pipes. Is is a mute point since the torsion box is plenty rigid by itself?

[joecnc2006]

The turn buckle is a good idea, just keep it snug, no real force or may deform the straight line.

Joe

[mvaughn]

Progress has been a little slow, I'm not able to make it into the workshop as often as I'd like. I have finished designing the parts for the machine. I'm sure that I'll find plenty of room for design changes, but the'll come during the build.

My first machine is working very well but it's a little slow. I don't want to push it past 25 inches per minute for fear of stalling. It's resolution seems very tight except for in the z-axis. The unsupported rails seems to sag ever so slightly when I have the gantry in the middle of the table. It shouldn't effect cutting out the parts for this new router since I'm only cuting 2D parts anyway.

This new machine will be 60 inches long and about 48 inches wide overall. My first machine can't cut some of the longer pieces necessary for my new router so I'm going to chop the longer pieces into sections and put dovetails in them so I can put them together like a jigsaw puzzle.

[mvaughn]

Slowly i'm accumulating a pile of parts for my new machine. Progress is so slow it's painful. Too many other projects have to share my time.

So far, I have cut the sides for my z-axis, the parts for the y-axis torsion box and a few of the stringers for the x-axis

Because my current machine is not large enough, I'm cutting the longer parts for the new machine in half and will be mating them together. The joints have mortice and tenons that will hopefully add some strength to the joint.