Need 4 ft by 30 ft cutting area

[nowforge]

Does anyone have experience in building a CNC router that can cut large wood flat panels. We would like cut 4 foot by 30 foot by 1/2" wood panels in one load. Z-axis is limited to drilling.

Can a lower cost Shop-Bot type CNC system give sufficient X-Y accuracy at these dimensions?

I look forward to your comments.

Thanks,
Ed Porter
eporter@dowco.com

[New2CNCPaul]

30' is pretty long but I don't think it will be that hard to do with a R&P (Rack & Pinion system)

The only problem I can see is with loading. Would you want a full 30' in front of the bed or would 4' be ok?


Paul

[joe aiello]

We have a steel fabricator(Flametec) here in Lawrence,Mass who has upgraded his torch machine (has rack pinon)with steppers and some cam software;I think it goes to 50' . About five years ago we took a tour of Ted Benson's shop in NH;he had machine from Germany that routed and bore holes in beams(he does post and beam buildings),probably 50' -70'. ....joe

[nowforge]

Hi Paul,

I'm not quite sure what you mean by "Would you want a full 30' in front of the bed or would 4' be ok". What should we know about loading?

The router has to have repeatable accuracy while cutting 1/2" to 3/4" wood panels over the 30 foot distance. I agree that an R&P system will work the best (no ball screw lash, stretched cables, etc).

I like the open source commitment of Shop Bot but I do not know how accurate their systems are.

What companies would you recommend for hardware that could be interfaced to "in-house" software? There are many companies advertising some very robust machinery (I would love to be able to afford the systems!) but my feelings are that they will be overkill for our application.

I appreciate your help and look forward to your comments. Thanks!

Ed Porter

[amplexus]

How accurate does it have to be? Rack and pinion is not very accurate but a 30' ball screw big enough not to whip will bankrupt you. Getting 30' rails straight and level will be interesting (lasers or a 30' surface plate). If you build the gantry first you can use it for sideways spacing but it will not help with the height, nothing to run a dial indicator on. If the gantry is not too heavy 600 oz in or so nema 34 steppers and a gecko vampire drive should work. Keeling has some good motors for a little over a hundred bucks each. If you need more power a pid servo is the way to go. For software I like solidworks and mastercam, but the linux tools are also nice.
Amplexus

[JerryFlyGuy]

I guess I'd have to despute the comment that R&P aren't very accurate. Atlanta gear http://www.atlantadrives.com/racks.htm has some spec's I'm sure would be accurate enough for 90% of the users on here..

Fwiw I've built a 10 x 20 [ft] router in my garage. A few things I learned along the way..

1- Pay the extra cost to do things right..

-If I did it again I'd build the side rails/frames and have them heat treated and then machined properly.. you can search the archives and follow some of the more tedious ways I went about building my machine [it wasn't as simple as weld, heat treat and machine..]

2- Buy good mechanical equipment.
-Precision Planetary reducers, High preload linear rail systems, precisions [Helical] R&P.

3-Buy the proper drive system.

If I did it again, I'd go straight to Automationdirect.com and buy their AC servo motors [and most likely their drives.. however this is still in debate {in my head} as I also really like my GraniteDevices drives which do run AC servos] Forget stepper motors on something like this.

4- Built it twice as heavy as you think you'll need & use twice the motor size you think is 'good enough'.

I'm preparing for my second motor swap from MCG33004's to Fanuc Yellow Caps.[250 oz-in Cont to 800++ oz-in cont torque]

5-Invest time in a proper 3D design & design it to the last detail. This will save many head aches as the project progresses. Building a precise and accurate machine which is both maintainable and buildable, w/ a workable "Build-Flow" is not possible w/out having accurate details on where you plan on ending up.

6- Lastly, go look at some commerical machines [of commercial companies still in operation/production, some of these companies went out of business because of stupid design's yet some of their machines live on...] Do some in-depth research to see what you like and don't and what works and doesn't, you'll be glad you did.

Hth

J

[nowforge]

Hi Jerry,

I appreciate your comments ...... nothing works like experience! What type of budget should I be considering (including software). I tend to agree with you that everything should be done correctly.

When you built your system, what type of table construction did you use?

I would like to thank everyone for their comments, thanks for the help!

Sincerely,
Ed Porter

[JerryFlyGuy]

Originally Posted by nowforge Hi Jerry, I appreciate your comments ...... nothing works like experience! What type of budget should I be considering (including software).

For a 30ft table w/ steel, heat treating and welding [supplying your own labour] I'd think you could build this table for somewhere around $100-125k. [Sounds crazy I know, but when you realize I've spent even more than that on my smaller table [due to not doing it right the first time] your getting a steal of a deal compared to something that is commercially priced]

Originally Posted by nowforge I tend to agree with you that everything should be done correctly. When you built your system, what type of table construction did you use? I would like to thank everyone for their comments, thanks for the help! Sincerely, Ed Porter

It's been my experiance that if one takes the time to do things the right way the first time things just go better and take less time and in the end, cost less. Plus you have something which you can believe and have faith in vs something that you think will work.. some of the time and the rest of the time your not sure.

My machine is basically two side rails mounted on the floor [wouldn't do that again] w/ cross members tieing the two side rails and also forming the base for the bed. If I was to do it again I'd make the two side rails and the cross members more integrated so they form one single structure. I'd make sure the entire bed was supported via the side rails and that the entire machine rested on no more than 4 points. Much simpler to level and maintain level.
Also I'd build a dedicated floor [concrete] under the machine so as to limit movement due to having a floor not designed for the machine sitting on it [garage floor is a good example of the incorrect type of floor].

My machine was constructed entirely of steel [welded]. In the near future I'm going to be changing out specific components to cast iron [machined] components to correct some of the poorer choices made during the original design.

Hth

J