Crane's Next CNC

[lgalla]

Alex I am working on your project.
Larry

[crane550]

Hmmmm.... I like it! Seems abit small tho...

[jjacstcy]

Man that's a lot better than my design, but I think mine will work better!

[crane550]

Actually, after thinking long and hard all day about this I think I need to go in a new direction. After looking at some other builds and a frank conversation with my hair stylist, it has been decided that this build needs a touch of flare.

Here is my new and improved design:

[mmcp42]

nah flares are soooooo 60s!

[crane550]

All right, in all seriousness here is the plan:

This is the start of a 5x10 table. It will be powered by rack and pinion, ride on 20mm THK SHS and HSR rails, and be built to be solid.

Much of the credit has to go to a guy named Ron, who lives here in Boise, ID. After showing me his machine it became clear that this was a better option then the Shop Bot, Mech Mate, and where Ahrens stuff is awesome this was better suited for my needs.

Rons machine can cut a 4x8 sheet, and move down to the end completely out of the way. That was something I really liked. My favorite aspect of it was there was no "crib" to reach into. Send the machine to 0, and slide a sheet right on. Done.

That, coupled with the stiffness and weight seemed like a good idea.

The rail blocks, 4:1 reduction transmission, motor mounts, and such are already made for the X and Y. It is an identical unit that was made by Ron for another machine, which he lost interest in. A lot of those parts are bought from him.

Once again: I cannot take all credit for this design! Ron, here in Boise was the mastermind in the power transmissions, rack and pinion design, and use of rails. Thanks Ron!


Here is HIS machine:







Anyways, I will be taking some liberties with his design. There are a few things I will change. For one, he used 25mm rails. I will use 20's. My gantry will also bit a tad bit wider. All in all, I probably will not build my machine quite as heavy as his, but it will still be heavier then most.

Here is my design for the frame. (so far)





This is not set in stone yet, but should be pretty close to what I end up with.

Alex

[crane550]

Alex I am working on your project.
Larry

Don't weld it yet, I'm going to make some changes!

[jjacstcy]

Looks a lot like a multicam, except the linear rail is mounted on top of the frame instead of the side.

[lgalla]

Alex that large tube design is used on very high end routers such as Komo.
You should have 3 tubes across the shorter dimension.
Assuming the tubes are 8"X12"X1/4" they will cost about $1200 for the whole machine.The weight would be also around 1200lbs.I didnot include the smaller cross members.
Larry

[crane550]

The linear rails for the Y are already purchased. They are two HSR20's at 80" each. It makes to sense to cut them down, and price of material is minimal when considering the extra cost of making the table 48" vs. 66". 80 minus the width of a 12in carriage puts me at 68, and I figure I will just add two inches to be safe. I am more then happy with 66.

The argument that making the gantry wider then needed (the initial goal was a 4x8 sheet) would have it's disadvantages when it comes to more weight and flex. It is true, there is an extra 18 inches of steel, rack, and guides to move. Not to mention the extra flex.

On the other hand, I plan to overbuild this thing as much as possible. Rapid movement back and forth is not the goal, the goal is to cut larger materials. That said, I think this is the right way to go. Current gantry is 6x8". It will weigh a lot. And I plan for it not to flex. Weight is my friend in this case. V-Carving a 16" sign back and forth will probably not work as fluid on this machine as my current one. Although I put in a V-carve g-code into Rons machine and it buzzed right along. Those 1500oz steppers will make it move.

Have not run any formal calculations yet. Based on Ron's performance I think I will probably max out at 800IPM. There are faster machines out there for sure, but I doubt they would be able to cut at the depth that this one will.

Plus 800 rapids are pretty quick anyways. Jogging from one corner of the table to the other would at max take 15 seconds.

Here is the latest .skp model. If anyone wants this let me know. I will definitely share. Once I get some more accurate measurements of my components I should be able to make this a bit more accurate. The height of the rails, width of the pillow blocks, ect is just an estimation for now.

Doing the sketchup model really helps me find out exactly where things land. For example I found out that I could get an extra 6 inches of Y space by making the wood top and supports bigger. Thought I needed the room for something else, but did not. It really helps visualizing things. I am going to try to keep the model updated thru the entire project.

[wendtmk]

That's one hell of a nice looking billiards table...

Mark

[lgalla]

Alex with the longer Y axis and 12"carriage you could run 2 Z axis.2 routers or router plus drill.I have new HSR-20's also for the Y but only have 3 44" rails.Waiting for one more from E-bay to get started.
Larry