First Timmer Staring with 20'X10'X6' 5 Axis! Needing Guidence. :)

[EvanZ]

Hello folks! Glad to be here. First off My name is Evan, I'm in Kansas, I'm a CNC nut. (I feel like I'm at an AA meeting, "HIGH EVAN").

Anyway. I'm currently in the prosses of building a large 5 aixs CNC. I have seen a LOT of "LARGE" cnc projects on here but none yet this big. My frame will be X=20', Y=10', Z=6'. I'm planing to use rack and pinion for the X and screw for the Y and Z. Havn't pick out motors yet. Could use some help here. I'm having issues with what rails/guieds I want to use, as well as where the best deal for the rack pinion are. Do I rack up and drive both sides of the X? Was thinking bar/pipe with "C" Linier type barings, 2 per side. My gantry will be 2'X2'X10 trussed box frame.


Speed is not very important as of yet, but will want somthing that's not SO slow it takes days to run my cuts. I'm making this machine for prototyping faom block, wood, plastics, etc. I don't need a ton of torque. Some motor size help here would be nice. Looking for .01 resolution. So again, no need to go overboard.

It has to be built cheap, and fast. (how many times have you heard that?) When I get his one plus it's project down. I will move on to making a slew of CNC equipment I need, including, pipe cutting, metal working, Laser cutting, plasma, and someday a waterjet.

All help is thanked, and needed.

Evan

[jdell42]

Define cheap for a 20'X10'X6'... 20K?

Accuracy becomes a big deal at lengths that large so you cant skimp on the components.

And when you say speed is not important.. think about how long it will take to traverse 20' at even 300ipm...

Sounds like a very interesting and challenging project.

[andy_ck87028]

cheap 20' * 10' * 6" 5 axis?

It sounds like you want an all singing all dancing dream of one solution to every problem and I think that is impractical.

I would focus on what your cutting needs are and you may end up with 2 machines that will be cheaper than one machine.

For example.... do you really need high precision for 20' * 10" wood / foam sheets or is the high precision really needed for small aluminium using the 5 axes?


Andy

[EvanZ]

I'm sorry my idea is so far out there, none the less, this is what I need to do. I'm not looking to be told not to, or that im nuts. I'm looking for this great pool of engineering brain power to help me do it. Not trying to be rude, but figured you guys would like a challenge.

For the record, this is one of the smaller machines I need in this type. No, the way im building it 2 machines will not be cheaper. Yes, I need .01 Res at 20'.

I'm looking at parts and have started ordering already.

Currently I would like some guidence in motor selection. I will be driving my 20' X from both rails. IE 2 tracks. Still trying to pic rails, I like the 1" bar welded to a flat bar with open Linear Bearing pillow blocks, but am still open to ideas. The gantry will not be super heavy, still waiting on a number from cad. Finishing things up as far as my Z design still.

Any help on motor speed calculations would be great to.

Right now I'm thinking this for the X axis 20'
http://stepper3.com/shop/product_inf...products_id/92

This for the Y and Zaxis 10'
http://stepper3.com/shop/product_inf...products_id/90


Any guidence would be great. I'm hear because I respect all you guy for your amazing abilities and ideas.

Thank you again,
Evan

[jdell42]

Your 10 ft y axis gantry with a 6 ft stroke will need to be very strong and consequently heavy to prevent both deflection and to resist the cutting forces at full stroke. This adds the challenges of overcoming both friction and intertia of such a heavy gantry.

IMO 630oz motors aint going to cut it you will probably need triple the size for this machine to have it cut at any respectible speed. I have not done any calculations but this is just from my own observations.

I think this objective is very ambitious and I don't want to fall in the "nay sayer" category but this is probably stretching the practical limits of a home built machine.

[dannystooblue]

Looks like a challenge to me, I would be interested in following this thread. I think that 0.010 resolution over 20' may be a little bit more that you will get. Have you designed the base of this machine yet? how do you plan to get the linear motion components straight and in the same plane over the 20'?

Motors, well I would consider something large and servo. I had bought 5 axis's of servo dynamics drive boards and 4 large servo's (43flt lbs of torque I think) for somewhere in the neighbor hood of $1k. I think something along these lines would probably motivate your machine at a reasonable rate of speed and resolution. The accuracy will really be up to you. I would expect that you will have to use several pieces of racks end to end at least on the 20' axis. If you plan to buy all new stuff to build this I do not think cheap is at all possible. Lets see some sketches of your concept!

Danny

[BobF]

We used to have one about that size at work. Much like the one in this picture.

http://www.beaconind.com/Cinci.html

Good luck.

[mxtras]

I agree with the comment about the size of your chosen steppers. I think you are going to need a little more butt in your drive system.

I will see if I can dig up a link for you. EDIT - - here ya go:

http://homeshopcnc.com/page6.html

Scott

[andy_ck87028]

Originally Posted by EvanZ I'm sorry my idea is so far out there, none the less, this is what I need to do. I'm not looking to be told not to, or that im nuts. I'm looking for this great pool of engineering brain power to help me do it. Not trying to be rude, but figured you guys would like a challenge. Evan

Go for it, after all its your adventure

Originally Posted by EvanZ a large 5 aixs CNC.

Originally Posted by EvanZ It has to be built cheap, and fast.

I'll be fascinated to see how you achieve your four goals.

Good luck

Andy

[Geof]

Find JerryFlyGuy in the member index and then find his threads and posts. He built a machine pretty close to the same size that you are planning; I think the only real difference is he has a shorter Z axis.

His was a ridiculously ambitious project, your's is too, but he completed it so obviously it is do-able. I think it only took him two or three times as long as he planned and a lot more hair tearing than he expected.

Don't worry about being told you are nuts that is a relatively polite term. Anyway it is the nutty people who make the biggest advances I think. But do read and think about what the naysayers write because sometimes a bit of caution can prevent a lot of grief.

[ger21]

Originally Posted by Geof Find JerryFlyGuy in the member index and then find his threads and posts. He built a machine pretty close to the same size that you are planning; I think the only real difference is he has a shorter Z axis. His was a ridiculously ambitious project, your's is too, but he completed it so obviously it is do-able. I think it only took him two or three times as long as he planned and a lot more hair tearing than he expected.

I was also going to point you to those threads, but there isn't actually a build thread for that machine. But it did have a good size budget if i recall correctly.

[Geof]

Originally Posted by ger21 I was also going to point you to those threads, but there isn't actually a build thread for that machine. But it did have a good size budget if i recall correctly.

It would be an ambitious project just to pull all JFG's posts and collate them together. And I think the budget at the end was much larger than planned at the beginning; funny how these things work out.