Hello, I am new here and pretty new to the cnc world. I am looking to either bulid or buy a cnc machine for a specific application and am just hoping yall can help me out.

The application consists of cutting 4x8 sheets of 1/4'' thick lexan and the occasional piece of 3/4'' mdf or plywood. The cuts need to be straight and square to within about a 1/32 of an inch, which I know, is very sloppy in terms of machining. I will never need more accuracy than that. It doesn't have to be very fast, either. 100ipm is plenty.

I would just buy a cheaper machine such as a shopbot or a dynacnc, but even those are more accurate than what I need. I am not opposed to spending 15k on a machine, but the fact is that its much more machine than I will ever use. So, does anyone have any ideas on something that will fit this bill?

Thanks,
Cole Easterling

Come on people...22 views and no comments??

I don't quite understand what your asking. A shopbot is better than you need, but you're willing to spend more??

Are you looking plans to build your own?

Have you looked at the table top router tables being sold by DynaCNC? They would be way under your budget and I hear the customers are getting great accurate cuts from them. Just a suggestion.

I am not opposed to spending more, if I were going to use it all. It is just that I won't ever use a shopbot it to its potential. It would be a huge waste of money in my opinion. I am just wondering if there are other alternatives that are (gasp) actually a little less accurate, not as fast, and maybe not as finished. Because, if there are, then that means I get a machine that is perfect for what I need and is a heck of alot less money.

I looked at dyna cnc stuff, but I have to be able to do a full 4x8 sheet, so that throws them out.

a used machine with more precision that you need :) speaking from experience, i passed up this specific machine becasue it was out of my price range- but looking back, the time i have spent and am 'still' trying to finish mine- could have paid for the price difference.

what part of the country are you in?? this machine has the capablity of cutting MDF to those tolerences at 4x8ft cap. it's has rack and pinion drive, made with Al extrusion, with linear bearing on precision rod . it might be a good solution for you. the machine is in las vegas. if buying a used machine is not what your looking for, then i'll get you details on the plans for this one. let me know

I am just wondering if there are other alternatives that are (gasp) actually a little less accurate, not as fast, and maybe not as finished. Because, if there are, then that means I get a machine that is perfect for what I need and is a heck of alot less money.

If I wanted a fast build, economical, great machine, I'd buy a full kit from Joe2000che. For 1/4 sheet wood working, I don't see how you could beat it.

I have no doubt he would ship it to you pre-assembled and painted, for a price.... if you need that level of completion.

joe2000che eh? A forum member on here? Does he have a website?

He has a thread, here. (http://www.cnczone.com/forums/attachment.php?attachmentid=12256&d=1132911833)

He has a design that looks like this:

http://www.cnczone.com/forums/attachment.php?attachmentid=13104&d=1135286733


He has a kit that looks like this:

http://www.cnczone.com/forums/attachment.php?attachmentid=16337&d=1144023547


The machine looks like this (almost finished but bed not yet painted):

http://www.cnczone.com/forums/attachment.php?attachmentid=13415&d=1136163253


He can be reached by PM.

Well after looking at Joe's plans, I am wondering how scalable it is...As in can it be reliably scaled up to a 4x8 machine?

Well after looking at Joe's plans, I am wondering how scalable it is...As in can it be reliably scaled up to a 4x8 machine?

I wouldn't.

He's working on a 4x8 design right now.

If you need a 4x8 machine that is pre-built, perhaps you should consider a ShopBot.

Its certainly been considered. Just looking to you all for some more opinions:)

It doesn't have to be pre-built though. I have access to a very nice shop and considerable experience, so plans are definately an option.

I am certain DynaCNC can get you into a 4x8 table for less than 15K. Mine was less than that. Just my opinion, but it seems that it would do the trick. I'm not sure what you are after if you can get the table for under the 15K and it is accurate enough what else? There are several other machines out there that would also fit the bill for under 15K pre-built.

I don't need and won't ever use something that has a resolution down to .001 and lower or that cuts over 100ipm. If there's not anything worth having that's cheaper, then I'll plop down 10-15k on one of the nicer machines without hesitation.

BUT...If there is a cheaper option that satisfies my needs and will be a reliable solution, then there isn't a reason to spend that much. Hope that makes sense.

You will probably not find a "sloppy" cheaper machine. There is just no market for them. The problems is that the electronics and power components (motors, drivers rack and pinion, etc) are the same for a sloppy machine VS a one with tighter tolerance. There is very little cost savings to be had in those components. Your only real cost savings will be in the linear motion components (rails, bearings, etc) and so the price differential will be a lot less than would seem logical at first.

Your challenge is that you want to cut thicker material in one pass at fairly aggressive cut rates. If you need to make multiple passes you will have to have the tighter tolerances or the cuts will look like crap. Your choices are:

1. Buy a more accurate machine that has the power and working space you want.
2. Build your own machine out of hardware store parts on the cheap and get the tolerances and speed you want and invest your time.


Also have a look at the machines from EZ-Router. They are built to last (steel tables, heavy duty gantry, big motors) and GREAT electronics (Mine (:-))

Tom Caudle
www.CandCNC.com

if you have the facility, i would just build it to suit your needs, it'll be way cheaper, and you'll have exactly what you need... my one suggestion is that if you do build the rig yourself, and since money isnt too big of a problem, go ahead and get the good stuff, get real ball screws in whatever pitch you feel necessary for your needs, they will (or at least to my understanding) out perform and outlast a leadscrew/plastic nut combo... what you spin the screws with is up to you, but since your not looking to rip a hole in the space time continum with the gantry, a nece stepper system geco or others...should serve you well for many years... the way i see it, if you build it, then if it breaks you know it well enough to fix it, if you decide to change it for higher resolution, then you know where you are and how to get where your going...

just my 2 cents worth...

Thanks guys, All this stuff is great. Does anyone have a suggestion on some plans that are particularly good? If not, I'll probably end up designing my own on solidworks.

thats what im doing, only in rhino...i havent seen any plans, so i cant speak on them, but for me the bottom line is i just dont wanna pay someone else for something that i can do...

Getting off topic a bit...How do you like rhino compared with parametric programs? I have used the demo for a few years, but never have gotten the workflow down correctly, especially for skins and such.

well actually i was first introduced to cad through rhino, so its all i know, and i love it... it is true that it takes some getting used to, but considering how powerfull it is, i cant imagine trying to use anything else... i can draw anything i can imagine... modify it, manipulate it, just go in any direction... my biggest complaint about it is its price...

check out www.jpcustomcrafts.com/shopmachines.htm to see what i have drawn up so far for my plans....

Thats awesome man. Do you it with your mouse and stuff or command line? In my experience with it, command line seemed easier.

I love the drive idea for the x-axis by the way. Also love that A&M business card holder.(I'm Aggie class of '09 :) )

hehe yea, a buddy of mine ordered thoes custom from me for gifts... aggie huh? GIG 'EM AGGS!!! are you in colege station?

i do about 75% mouse, and 25% command line, things like copy, paste, rotate, array, join, group are all easier to type than to navigate the menus for...