Need Help!- CNC Machine

[danmcgee]

I need to make a CNC to cut thin aluminum .0197 thick or .5mm. table would need to be 76 inch long by 36 inch wide. I would want it to be very acurate and repeatable percison every time and does not need to be fast but need to be dead on every time.

I have the plans for the JGRO and the JOE 2006. I have the ability to make the frame out of steel or very thick 2024 alum. need to have good long lasting steppers or servos and able to import files from others with a simple as posible plug and play kind of format.

Anyone out there up to the challange to help me design this thing or have a set of plans that will support what I need so I can get to building the table. It will be used for making aircraft parts for my aircraft.

Any and all help would most appreciated.

Dan

[danmcgee]

Could this be accomplished by just increasing the table size to fit and the gantry size to fit the table with avaible parts sizes taken into account of course for gantry and cutting bed final sizes.

which one would be better suited for this kmodification the JGRO or the Joe 2006 any other design is also welcome. I really need to keep the flex to a very minimum as I am sure you all want to as well so perfection and reapeatability can be accomplished with out much problem.

any ideas? I would also want to know the best motors and and parts to use on the CNC as well as the softwear to get that will import DXF files from others so I can use it liike plug and play within reason of course.

Dan

[Zygoat]

ok, you are asking a lot of questions here. and none of them have a definitive answer. the answer to all of the above would be "which ever works best for you". so what you really need to do is, start reading all the info you can on these forums that pertain to your build. and then decided for yourself what is better. maybe ask a few very specific questions about each component after you get an idea about everything.

also you dont really give a numerical tolerance. are we talking .01mm .1mm 1mm? also really consider how tight the tolerances need to be. most of the time tolerance is .005" for general precision components. for example maybe a button or a switch on your instrument cluster. would it really need to be within .005" probably not. would it matter if it was .100" maybe, cosmetically, but probably not functionally.

now most metal work is done with a moving bed type system (you are in the wood working section by the way) but most people do both.

however, due to the size that you require i think a gantry system is the most practical. others might feel differently.

getting really tight precision on a gantry machine is tough. so we need to figure out how precise you really need to be.

you can check out my build here.

http://www.cnczone.com/forums/showthread.php?t=99824

read other builds as well. get ideas from them. you will need to spend considerable time researching everything. i hope you have planned for this.

the alternative would be to buy a machine that suits your needs. this is more expensive but will get you making plane parts much quicker.

[danmcgee]

Yep I guess I didn't it would have to be at least.005 inch thats not to bad almost all the holes will be matched drilled and the plans are also in a 1:1 so most of the parts can be cut and trued together for a perfect fit.

The CNC is so I can get a very clean cut with nice rounded edges and a cleaner finish than I could do by hand.

To be honest the JGRO cutting bed is 22x43.5 would cut most of the some 2000 parts for this aircraft, the skins could be cut by hand but would look beter if cut on the table. The rest of the framing parts will have to be cut by hand and then formed to fit in thier places.

I was just wanting to build the machine large enough to cut the skins and the rest of the parts on one single bed. the widest part is only 24" so a small increase in the bed size with wise could be done and make the bed 6' long. Now the JGRO is made out of MDF and may be strong enough as is or I could make the whole thing out of 2024 aluminum for even more stability.

I have a computer that I could make the controlor out of and can get the hardwear needed to make the machine, just need to know what the size difference would really nned to be as far as drive screws length and material type and I would go at it.

Ideas?

Dan

[Crevice Reamer]

That 6 foot axis will want at least a 3/4" screw--And probably a one inch would be even better.

I recommend these electronics for best precision and reliability:

http://crevicereamer.com/Page__57.html

CR.

[hemsworthlad]

Hi Dan,

There are loads of builds if you look that will easily do what you require.
Gary's machine would lend it's self perfect to a stretched version and strong and would be a relatively easy build if you can work with steel and Ali, look here.
http://www.cnczone.com/forums/showthread.php?t=95807

You could look at my build (which needs updating!!) that is a wider gantry style and easily holds the presion that you would need.
While not perfect for your needs it could be modified to do what you need and with a narrow machine cutting the thickness's you are talking a single central screw could be used making things a lot simpler, but to be honest I think Gary's machine would be perfect.
http://www.cnczone.com/forums/showth...t=92404&page=4

My advice would be look at lots of other builds and styles of machine and then ask advice and listen to those that have actually built a machine.!!
There are loads of great and experienced people on this site and usually very willing to help, unfortunatly there's also a lot of theorist's, number crunchers and gunner's who know the theory but not the practicality's and pitfalls of a actually building a machine.!!

Good luck and keep firing the questions untill your satisfied.

Dean.

[danmcgee]

That does look perfect Dean thank you. The table would just need to be just a bit longer is all. I sent Gary a PM about his machine you guys are great.

Dan

[skippy]

Firstly, you just said a cnc machine but I'd imagine you are talking about a cnc router?(the cheapest of type of cnc machine to make)
Me, personally, I wouldn't bother. If you really want to make a cnc router then by all means go ahead. However, let's look at your needs: (1) Materials: Principally machining 0.5mm aircraft grade aluminium which is not particularly easy to router due to it's thinness. (2) Quantity: you're planning on doing bits for your plane plus I'd imagine some other bits and pieces seeing as you'll have a router. That's really not a lot of work or cutting. The skins and most other parts of the majority of today's kit planes are cut by waterjet or laser and in the current market the cost of getting it done is quite cheap and doesn't justify the building of a router. However, as I say above, if you really want to make a cnc router then by all means go ahead. Good luck with whatever you decide and if you do decide to build a router, you've come to the right place to learn.
regards
Skippy

[DIYaholic]

danmcgee,
I agree with everyone, hemsworthlad, Crevice Reamer and Zygoat. Considering that I am one of those theorists (having not built a machine yet), you can take my advice with a grain of salt. You can even hit me with a chair, should I steer you in the wrong direction.

One of the first things you should consider is your budget. Your budget should include, but not limited to:
1) Funds available for the machine build (hardware, mechanicals, motors and drivers, etc.
2) Funds available for computer and software (cad, cam and controller software)
3) Consumables (endmills, router bits), repairs and upgrades
4) Your time & effort VS. Budget (purchased pre-assemblies VS. DIY solutions)
5) Time frame (research, design, constuction, tweaking of machine, learning new software)

I feel these are some of the things you must consider as you research (read) as many threads as possible.

It's kind of obvious that an all steel build should be more ridgid (accurate) than an all MDF build. With that being said, it is critical to have a great design followed by excellent construction techniques, to truely obtain a solid performing machine. The level (quality) of your machine performance is subjective. What works for you, may or may not work for someone else. You need to determine the performance level that you need, then design and build to that level of performance (all while keeping your budget in mind). Any and all design engineering is a series of compromises. It is your goal to maximize pro's (performance) and minimize the con's (funds & time).
Good luck with your research, design and build. Remember to have fun and post lots of pictures and video.
EDIT: skippy brings up some good points.

Randy,

[Crevice Reamer]

Hey Dan. Here's some basic CNC info that you might need:

http://crevicereamer.com/Page_2.html

BTW: Welcome to the Zone!

CR.

[Zygoat]

Originally Posted by Crevice Reamer Hey Dan. Here's some basic CNC info that you might need: http://crevicereamer.com/Page_2.html BTW: Welcome to the Zone! CR.

MGP: Manual Pulse Generator.

little ways down the page

should be

mpg just a heads up.

[Crevice Reamer]

Originally Posted by Zygoat MGP: Manual Pulse Generator. little ways down the page should be mpg just a heads up.

Thanks! Good catch.

CR.