Since it's been raining here so darn much lately, I can't work on my foreground interior project. Today, while cleaning the basement a bit, I came across the remnants of my factory seat bracket. I noticed some acme threaded rod, some gear block mechanism that turns the acme rod, and a carriage that rides along the spinning rod.
Also, I've been tearing down a few printers and found a couple of "stepper" motors.

This, gave me a crazy idea to make a DIY CNC.
it's going to be my "rainy day" project.
A small CNC would definitely help with a lot of my interior project plans.
and could even be modified slightly to make a 3d printer or laser engraver (I saved lasers from the printers)

I've been doing a little research and with an arduino and a couple motor control boards, along with some free programs, it's possible to control steppers for each of the x,y,and z axes independently.

Does anyone know what type of motors the seat bracket uses ?
If they are steppers, they'd be more ideal than the 24v ones from the printers.

This is just another of my crazy ideas...
It'd be great for those strut tower brace brackets I never got around to.
Maybe make aluminum door handles or oh sh*t handle(s)

 

Certainly sounds like an interesting project!! Do the CNC's run off CAD based programs?

 

Thanks!

This CNC would run on g-code. From what I've been researching, you'd design in a CAD program, like freeCAD; then convert to g-code with a CAM program (pyCAM) . Next you'd use something like EMC2 or (GRBL and gcodesender together) to send the code to the CNC itself. (I'm a fan of open source, as such most of the programs I listed are OS).

This all has steep learning curves, but the results seem well worth it.

 

Whoa! Cool! You're talking a whole new level of DIY Scott! Did anyone understand what Scott just said?

 

This is a different level of DIY.
I recall my son did some CNC stuff during middle and High school.
Then back in 06 I worked for a CNC shop as a Sales Rep. but I could not convince the owner how to market his products.
Once you have the design you want.
How or what are you using to make the item you want to create?
Keep this info on going this is really interesting stuff.

 

Like always, my projects are budget oriented.
The decent CNCs use ball screws or acme thread for their drives, a lot of budget DIY CNCs use cold rolled threaded rod. It's not as accurate though.
Ball screw is way outta my price budget. Acme thread is do-able, but I wanted to finder cheaper sources.

I found that C-clamps and apparently seat brackets use acme threaded rod. I thought to myself: Self, I can get seat brackets pretty darn cheap from the JY. It has two 2ft lengths and one about 4 in. I'm going to have the x and y axis be approx 2 ft and the y axis be either 8in or 6in using c-clamp thread.

I have to do some investigating of the motors in the seat. They are magnetic, which makes me think they are steppers, but to me it wouldn't make sense to use steppers instead of regular DC motors for a simple seat bracket. We all know GM does things that don't make sense though...

I may have to tear one of the motors open to see... Like I said, I'd much rather use a computer 12v power supply that I have on hand than to have to buy a 24v one to power the printer motors I scavenged. It's much easier to control a stepper motor with programs than a dc motor. Each "step" of a stepper motor moves the drive shaft a certain number of degrees. A normal DC motor isn't nearly as easy to control precisely.

I'll tear into things and report back

I'm thinking of building a semi-small one, then using it to help build a larger one, if I get a lot of use of it.

 

I sort of understood most of what he said. Scott email me please...I have a little project I may collaborate on with you if you are interested. modp343 at gmail is my email

 

Will do Barbara.

I didn't get to work on it yet, was busy cleaning. I let it go too long.

I have to do some brake work for mom tomorrow, then I'll get to looking at all the possibilities to get this thing built.

I did some research, the seat motors have two wires, most stepper motors use atleast 4 wires, though it's possible to run them with 2 wires with fancy controllers. I'm not holding my breath at them being steppers, until I take one of them apart. Might have to keep them around for another idea I have up my sleeve. I have too many ideas in my head. I must be crazy...

If they're not, I gotta figure if I want to buy 12v steppers or a reliable 24v power supply. probably cheaper to get the motors. Gotta hit ebay.

I also gotta design a smooth movement for the axes. I think I'm going to use bearings on either a metal angle or u channel, with metal rod being another option. Not sure if I want to use steel or aluminum. Both have their merits... but I'm cheap, I may try to re-purpose old bed frame rails... I'm known for overbuilding things, kinda a running joke in the family.

For the table I want something dead flat. At the least some MDF or laminated particle board may work; probably with a sacrificial luan over it, so the mill can make full cuts without making me sad

Btw, I don't have an engineering degree or computer science degree, just a lot of heart. My degree couldn't be further from my hobbies haha.
I'm discovering that there are many ways to do the same thing,mechanically, I just gotta pick the right one, which ever that is

PS, I finally took a pic of the cherry today.

 

Got to looking at both the acme thread and the seat motors today.

The acme thread from the seat bracket is slightly shorter than I previously thought. I want my design to have at least 24in of travel in both the x and y directions. I eyeballed the acme thread at roughly 16 in.
The seat motors are permanent magnet, brushed DC motors, not steppers.

Both of these aspects set my design back, unless I want to scale down my design, which I'm not sure I want to. I may look into using regular threaded rod for the x and y, with acme on the z.

I have a lot to reconsider with this project. I'm definitely going to take my time designing it. I want everything to go well.

If I gotta buy acme thread, I'll likely build a 3x3 model, as 3ft rod doesn't cost significantly more than 2ft. even a 3x4 if I'm going to commit the space.

There are other drive mechanisms to consider as well: rack & pinion or belt driven. I'm considering building a belt driven system, then upgrading with time to screw driven. Decisions, decisions.

I've been looking into designing an extruder and "hot end" for a 3d print head. I think I thought up a decent design.

There are a couple of monte things I'd love to be able to print. Think engine bay cover, custom spoiler, heck even roof rails. Possibilities are endless... Actually, I'd just like to just reprint more durable speaker covers.

Next I have to look into designing a laser attachment and what I'd use for the CNC function (probably a flexible shaft driven by rotary tool.

Hard to believe I'm not an engineer. I couldn't handle having to design things for a "boss". I like to have free creative flow.

 

This project won't die! Like I said, I'm going to keep everyone updated I did some deeper looking into the power transmission aspect of this project. Feasibly, I keep coming back to two likely options: screw driven and belt driven. I don't see rack and pinion being a feasible option, for ME. Many professional units use both R&P and screw driven movements.

Of these tow options, I see screw driven being better for ME personally. Belts like to do weird things when accuracy matters.

I found two inexpensive options for lead screws. Classic threaded rod (in 1/2 -13 thread) or acme (trapezoidal) threaded rod (in 1/2-10 thread).

I might just go with the classic threaded rod for my first machine, as a proof of concept. The acme thread on ebay and enco is cheap enough, however the shipping kills it.

Today, I did some calculations. In theory, the normal threaded rod has a higher resolution. However, acme thread was designed to have more efficient transmission of power.

my calculation for 1/2-13
13 revolutions/min * 200 steps / revolution = 2600 step per inch
1 step = 0.000385 inch

(theoretically, slower with higher resolution)


my calculations for 1/2-10 acme thread
10 revolutions/min * 200 step/rev = 2000 step/inch
1 step = 0.0005 revolution

(theoretically, faster movement with lower resolution)

I say theoretically because most stepper motors can be micro stepped to increase the resolution.

For giggles, I calculated the percent difference @ 26% difference, not something to be balked at. If I find the transmission of power of threaded rod to be sufficient, I'd be satisfied with a slower system with higher resolution.

Estimated rod length needed ( for a 3x3)

3x 3ft threaded rod for x and y axis.
have sufficient rod for z axis.

4.71x3 @HD = 14 and change
8.57 @ lowes for 10ft electrical support (1/2threaded rod @ 10 feet)

acme
40+ for 3ft @ fastenal locally
3x (8.80 + 9ship) = approx 60; alot compared to normal threaded rod.


I'm looking ahead and considering a moving gantry instead of a moving table system for a variety of reasons.
For one, you can work with pieces longer than your table as long as you put a reference in the design. This would be used to align things after the piece is moved.
A moving gantry design doesn't need as large of a foot print as a moving table.
The major drawback is that it's easier to lose square with a gantry than table design.

I have much more thinking and designing to do before building this thing ;