First I'd like to say howdy to everyone, and thanks for making all this information available.. I have learned so much and haven’t even touched the welder or soldering iron yet...
Oh, and please let me apologize for the monster post... but it's my first, so I have lots of stuff to cover...
Now, in all my reading I remember seeing something said that I should start off smaller and then work up. This just isn’t an option for me as 1) I'm impatient, 2) I just don’t have the resources to do something twice, and 3) I really don’t see that big of a difference in a small machine vs. a large one, everything is just bigger... ok, so at this point I think I have the perfect recipe for disaster... perfect, time to push forward...
So as the title says, I'm a total nooooobie to cnc. I work around cnc machines at work all day, but never have the chance to "crawl inside" to see what makes one tick. I have been doing lots of research, and for what I want (a 4' x 8' usable cutting area) I think I have decided to go with bipolar steppers and drives... I think that this will fall in my budget, and I feel confident that I can make it work for the accuracy I need.
Goals of my cnc machine:
1)Be able to cut and contour in 3d a full 4x8 sheet of mdf/ply for signs, speaker boxes, cabinets, and anything else I can dream up
2)Convert the machine from a router to a plasma table and have the ability to cut at most 1/2" mild plate steel for some prefab kits in designing
3)Have the ability in the future to add a 4th axis for doing all that nifty stuff, chess pieces, baseball bats, table legs, and so on...
4)Do it on the cheap, and I mean on the super cheap, I’m talking maybe $500 to $750 give or take to get the 3 axis running...
What I see that I need
1)A legal full copy of mach 3
2)The parts to build the driver circuits
3)Stepper motors
4)Steel for the table
5)Linear drive components
6)Steel
7)Bearings, linear slides, bolts wire, and a bunch of other little stuff….
What I don’t have and wish I did
1)Milling machine for making the parts to get my cnc going
2)More money
What I have at this point:
1)A large shop (2400sq-ft) to build, test, and run the machine
2)Computers, that will run mach 3 with no problems
3)Electronics background in design, and prototyping
4)Mig welders
5)A plasma cutter than can more than handle the 1/2" plate
6)A steel yard about 4 miles away from my shop
7)The ability (knowledge) in structural design to build pretty much anything that I can dream up given enough time
8)2 metal working lathes, one a mini 7x12 with 3 jaw chuck, an the other a 100 year old 10x24 lathe with 3 jaw chuck and independent 4 jaw
9)The demo version of mach 3
10)Rhino version 2
11)Some crazy ideas
12)Someone that just might pay for the mach3 for me
13)A boss (at my regular job) that is into this and wants to help (and is cool too!!) yea I know that’s a first
14)Someone that can mechanically or photo etch the driver boards for me for nothing more than the cost of materials
15)A design for the driver boards and sources for the parts that I don’t already have in house (I’m planning to use the l297/l298 design)
16)A 3/4 hp router and some bits
17)Lots of empty spaces in my breaker box, and the knowledge and ability to add more circuits as needed, and a “proper” amount of fear!
18)An austron 35amp 13.8v supply in a 24 space cabinet on wheels with 2 17Ah gell cell batteris for backup and momentary current draws over the 35amps..(im planning to put the drivers, computer and any other electronics in this cabinet as well)
My plan
1)Learn a bunch more
2)Finalize the design I want to use
3)Get the motors that I’m going to use
4)Build the driver circuits
5)Test the drivers and motors on the desk with mach3
6)Begin building the table
7)Assemble
8)Troubleshoot, troubleshoot, repair, redesign, build, troubleshoot, repair
9)Use the machine and giggle like a schoolgirl when it finally works
10)Upgrade the stereo in the shop so that it’s loud enough to be heard over the router. (and really annoy the neighbors at 3am) TURNABOUT IS FAIR PLAY!!!
My current design and thoughts:
Build the table pretty much like the one that I saw on
http://www.inshorepowerboats.com/cnc.../CNCROUTER.htm
With a few changes… I like the y and z-axis setups, so I will probably replicate this. But the x-axis is using rack and pinions and that’s a little outside my budget, so here’s my thought. I have some and can easily get more #40 drive chain. My thought was to either lay the chain along the top rail of the table frame and have the gears ride in that (still need to investigate this and how much slop there would be) and use that like a rack and pinion. The other idea I had was to suspend the chain along the insides of the rails, and have the x-axis drive gears interface the chain there. The chain would be pulled taught and would make an upside down “U” where the drive gear would be at the top, and then 2 idlers would make the other bends, this way the chain is around 180deg of the pinion gear. Either system would be replicated on both sides with a connecting shaft between, so there would be no chance of the gantry racking diagonally… then use one of the 500oz*in motors I found on the net geared 10:1… figuring 300rpm max (I have no idea what this should be, I just picked a # outta the air) on the motor and a 1” diameter gear for the pinion, my math says that I should get a max speed of about 90ipm. So, if ya’ll will, please rip this design to shreds and show me what I’m missing…
Project5k