Build Tread - Millbox - open source mill

[fuper]

Hey all -

Thought I would share my little personal project Millbox

I'm detailing a small desktop mill/router build I'm doing from scratch. Everything is opensource.

I'm calling it the Millbox. It's made with, as much as possible, aluminum stock. I want it to be an easy and inexpensive build.

My "long term" plan is to design or adapt aspects of the reprap project to allow it to do 3d printing.

The only tools i'm using so far is a Taig mill, manual, a 10" drill press and a hacksaw. I'm in an apartment so space is tight!

I believe this is the correct forum as I see build threads.

Regards,
Shane

[fuper]

Okay - I'm building everything on top of a base slab of aluminum. It's 12" x 12" and 3/8" thick. I was going originally for 1/4" thick but 3/8" was what was avalable on ebay so I went with that. Here is a pic, it's Mic-6 cast plate:



This will eventually be drilled and tapped so I can attach a vise etc.

[fuper]

there will be 4 y axis posts, screwed to the base in each corner. To these I will attach precision shafts and the acme screw and steppers. I'm going with a tormach style so each side will have a screw and stepper.



Here is the drawing:



The posts are extruded stock, 2.5" wide by 0.5" thick. I got a 48" length from ebay. Ya it really is cheaper for me buying on ebay rather then driving 10 miles and going to the metal supermarket!

[fuper]

I wanted something to drive the stepper that didn't use exotic or hard to get parts. I have family [wife side] in India and my Wife's cousin expressed an interested in this project to use around the village. He can get regular old logic chips easily. Thankfully I found a design, tested it and it works "fine" for my needs.



The original page is: Stepper Motor Controller

I've done a PCB layout and when I get back from a trip to Chicago this weekend I'll probably get a batch of these done at batchpcb.com



As this is open source if you want the Eagle files etc: Fuper

This driver is a full step, nothing fancy. It uses a quad xor chip and a dual flip flop. With these two chips it generate the correct sequence to drive 4 transistors to power the stepper. It's a unipolar driver.

[fuper]

I put together all the parts I've machined so far. Thought I would share pictures:



Here is the inside of the y-axis post. The shaft fits comfortably through. I may need to machine a pocket for the acme screw coupler.



The bottom of the baseplate: I will eventually counter sink and use low profile screws here. I don't want this thing resting entirely on screw heads.



Kinda excited overall!

[RomanLini]

Looks cool!

Do you have an "overview" drawing showing what the machine will look like? I'm guessing a moving gantry (as you have dual drive motors)?

[fuper]

Looks cool!

Do you have an "overview" drawing showing what the machine will look like? I'm guessing a moving gantry (as you have dual drive motors)?

Thanks RomanLini!

You are correct it's a moving gantry design.

I'm working on a sketch of the final thing. I have drafted all the individual pieces giver or take of the final design. It's all flat bar stock with the cast plate.

I originally wanted Millbox to be 2' x 2' or at a minimum 18" x 18" but went with the 1' x 1' because:

A) I'm not a professional machinist!
B) This is a prototype
C) The cast plate was available on ebay in 1' x 1' !

I am trying to keep costs as low as possible while still having the Millbox made out of metal.

Thanks for the kind words!

Shane

[fuper]

I figured I would screw something up:



I got these thinking I might need shaft mis alignment compensation. I figured these couplers would be really stiff. Nope super springy.

I thought about filling in the cracks with resin. Anyone tried that? Couplers are kind of expensive [in my mind for what you get], it would be nice to salvage them.

Otherwise I'll go to look at the remnants shelf for some aluminum rod and attempt to drill them out myself.

I don't have a boring head for my Taig and I'm not sure how well the drill press will work on this.

[cornbinder23]

Those couplers are supposed to be flexible to side loads like that, have you tried to "un coil" them to see how stiff the are axially?
You can always get those in S.S. , but another option that is fairly inexpensive to buy and even easier to make is the Oldham coupling.
Nice build by the way looks like it will be a nice and tidy package when you are done

JTCUSTOMS

[fuper]

Those couplers are supposed to be flexible to side loads like that, have you tried to "un coil" them to see how stiff the are axially?
You can always get those in S.S. , but another option that is fairly inexpensive to buy and even easier to make is the Oldham coupling.
Nice build by the way looks like it will be a nice and tidy package when you are done

JTCUSTOMS

I follow I think! They are hard to "un coil" by hand. I have to try pretty hard to get them to move that way [at all], which is good given the stepper is turning and applying a force.

Thanks so much for pointing this out!

The Oldham coupling is pretty neat. If this coupler set doesn't work out I'll attempt to make one and see how that goes. Does the oldham coupler allow for side loads or shaft alignment issues?

Thanks for the kind words on the build!

[fuper]

I cut and machined the x-axis pieces. There are 3 pieces total. Two vertical pieces of the 2.5" x .5" stock that will be vertical and attach to the acme screw and linear shaft that comprise the y axis. These two pieces will be cross braced with an additional piece of stock and screwed together using #10-32 screws.





Basically it's the same piece as the y-axis but 9.5" tall instead of 4" tall. Additionally there are two holes to mount the cross beam. I removed the two holes that the prior piece used to mount to the baseplate.

You can download the cad files at the bottom of this post:

More cad files | Fuper

[cornbinder23]

This should explain the "http://www.youtube.com/watch?v=utEKKox2WHA"]Oldhams

JTCUSTOMS