Where to start

[jm82792]

I'd like to build a 12'' by 12'' CNC machine,
or something under 12'' X 16''.
I want to emphasize it being created from salvaged materials, sturdiness, being economical and easy to build. I'm limited on tools and I don't own a router.
I'm not knowledgeable when to comes to things related to CNC machines other then electronics.

I want some accuracy(1/16'') however, on the same token I want it to be economical, and in the end I want something to play with.......

Can I utilize the larger printer steppers that have 7.5 degrees per step?
Can I use stainless steel rods from printers,
with oilite bushings/bearings for my x and y axis?
Is that a decent way of making the(I don't know the correct definition) slide system for the x and y axis for a light duty machine?

Would polyethylene cutting boards work as a material to build with? I'd like to use cast acrylic(it's so easy to glue) however it's too hard to buy out here.
I'd like to bolt or screw the entire thing together...

For moving the axises around, I would like to use Acme threads however I'm not sure what to use for nuts.
I understand how it works but not what I need to make it do so. From what I can understand Acme thread is a particular pitch and there are numerous kinds of threads; acme being one that's commonly chosen.

For couplings that connect the screws to the steppers what should I use?
For the Z axis, is there simplistic design that works decently?

Finally for drivers, I'd like to keep it cheap,
however I don't want to create smoke.
What is an economical recommendation?

Thanks for the help,
Josh M.

[louieatienza]

Originally Posted by jm82792 I'd like to build a 12'' by 12'' CNC machine, or something under 12'' X 16''. I want to emphasize it being created from salvaged materials, sturdiness, being economical and easy to build. I'm limited on tools and I don't own a router. I'm not knowledgeable when to comes to things related to CNC machines other then electronics. I want some accuracy(1/16'') however, on the same token I want it to be economical, and in the end I want something to play with....... Can I utilize the larger printer steppers that have 7.5 degrees per step? Can I use stainless steel rods from printers, with oilite bushings/bearings for my x and y axis? Is that a decent way of making the(I don't know the correct definition) slide system for the x and y axis for a light duty machine? Would polyethylene cutting boards work as a material to build with? I'd like to use cast acrylic(it's so easy to glue) however it's too hard to buy out here. I'd like to bolt or screw the entire thing together... For moving the axises around, I would like to use Acme threads however I'm not sure what to use for nuts. I understand how it works but not what I need to make it do so. From what I can understand Acme thread is a particular pitch and there are numerous kinds of threads; acme being one that's commonly chosen. For couplings that connect the screws to the steppers what should I use? For the Z axis, is there simplistic design that works decently? Finally for drivers, I'd like to keep it cheap, however I don't want to create smoke. What is an economical recommendation? Thanks for the help, Josh M.

I would check out Solsylva.com for their plans. I used them and it is pretty straight forward. You can check out HobbyCNC or Xylotex for drivers/steppers; they both havev lots of users and therefore you may get better support...

[jm82792]

I could avoid a good amount of frustration and utilize a tested system, $10 sounds like a good investment.
Regarding the drivers, I have built a few microcontrollers from kits involving PCBs and parts, I've done through hole, SMD and understand electronics however it's more of how to follow a schematic not how to engineer anything.
I'd like to build the drivers from a kit or scratch if the complexity isn't high.
Although Hobby CNC's 3 axis driver is only $60 and it's more or less an idiot proof kit to assemble.
For steppers, I am tempted to use the ones I own(since they're free) and upgrade(I eventually will) because I'm assuming it's easy enough to swap them out.

From keeping a reef tank(coral, fish, etc) that I have 2k into(it's 4 years old), I know how you should go for quality and not skimping; however, I am trying to get my feet wet without breaking the bank.

[jm82792]

I purchased the 12X9 plans, they seem very concise and make sense.
I have a question and a possible issue though.
Things here warp badly since it's so humid out here and it swings wildly.
Can I use Ipe instead of pine for the frame?
Ipe is more stable since it's so dense and oily,
I'm thinking about using it....

[louieatienza]

Sure you could! In fact I used it when I built my solsylva 25 x 37 a couple years ago... There's a pic of it in the gallery section, all teh way at the bottom of the page.

[CarveOne]

I built the same Solsylva 25x37 machine that louieatienza did more like 3-1/2 years ago. I used red oak instead of pine lumber. It's glued with regular Titebond carpenters glue and where needed I used deck screws. Four coats of brushed-on polyurethane has sealed it enough that it hasn't had any warping issues. I wouldn't be afraid to build this machine using two layers of MDF glued together for the frame and gantry parts and sealed with polyurethane or oil based paint.

CarveOne

[jm82792]

Hmm I'll probably do Ipe then if I can get standard sizes of it, that should produce a beefier machine.
I was thinking about coating the frame in surf board resin
(I'd rather do Ipe or MDF.......)
I'm going to purchase the required parts soon,
I will start with cheap screws for the lead screws then I'll convert to acme.
I have a boat load of steppers, stainless steel rods and such.
Perhaps I can save money by utilizing them.

[stewi]

MDF and threaded rod work well. However, on a 20 pitch, you'll not get more than 12" per minute.

Low cost CNC - YouTube

Low cost CNC - YouTube

[jm82792]

The feedrate you get is slow with allthread(is that the screw pitch you are offering to?) however, I definitely am planning on upgrading to acme threaded screws once I see any form of results.

[stewi]

the thread is 1/4"-20 advancing 1" per 20 revolution.
Good idea, to get something going and improve later.
The printer steppers are too weak, the large step angle of 7.5 degree also contributes to low pull-in pull-out torque. Get something with 200 oz-inch holding torque.

[jm82792]

I will pursue some steppers on ebay or some other place on-line,
however I'll build the whole thing first and then get the steppers.
Thanks for telling me why the allthread is slow and the advice regarding the steppers.
I don't like figuring things out the "fun" way
(Usually resulting in smoking parts or some other interesting result)

[CarveOne]

If you feel that you must use all-thread rods to keep the cost low, consider using 1/2-13 all-thread rod. The lower number of threads per inch will give a faster speed rate for the same motor rpm. The rod has enough solid metal in it that it can be lathe turned down to 1/4" diameter on one end so it is the same diameter as your motor shaft. Coupling the motor to the rod can be done with hose clamps and neoprene hose, and other methods like Delrin or aluminum couplers.

Run the rod through a threading die to clean up the rough threads.

CarveOne