Introducing my build - the ScrapHeap CNC machine (or 'The Poor Man's CNC')

[HankMcSpank]

Inspired by the well documented 'easy cnc mill' ...I've finally got around to building my own CNC (which was meant to emultae the easy CNC mill, but I got carried away & it's now nothing like it!). I thought I'd post my progress here for a bit of fun & moral support (it's a lonely old path to walk alone!)

Because I'm such a cheapskate (I turn the electric grill off when I'm turning over my beefburgers), I wanted to spend as little as possible on this.

Ingredients..

6 x Dot Matrix printers - kindly donated from work (they were about to be trhown out) ....excellent for hardened steel rail & the bearings that ride ontem...also stepper motoers (albeit weak ones) & switches.

Steel pipe (was formerly used as handrail)...this is for the frame

4mm Aluminium plate (used to be blanking plates to fill in the gaps on the front of computer cabinters). This has proved to be excellent for keeping everything fairly level.

Bought items...

Stepper driver card (I couldn't be bothered to make my own)

Linear rail mounts (a godsend ...the linear rails out the dot matrix printer were 11.94mm...a bit of ebaying found a product called 'sk12' mounts (for 12mm rails) ....these held my rail perfectly! All 12 for about £20 delivered (I'm a Brit)

M8 threaded rod - remember ...I'm cheap.

Roller Skate bearings.

Delrin (to make my own anti backlash nuts)

Some screws/bolts.

I'll be powering from a fairly powerful bench PSU I already have.


Ok, I've only just started the build (two days in), but here you can see the dot matrix printer transport after I'd stripped it out of it's casing (you can make the photos larger by clicking on the main photo within the page that opens).....



These are the linear rail mounts (money well spent)....



Here's an early shot which outlines the basics of the steel frame (lossely based on the easy CNC mill design - the steel frame will be all welded once everything is finally built & 'lined up').




& here's where I'm up to as of today...





(note, the little bit of wood you see at the end of the threaded rod , was just an experiment to try & get the threaded rod level. Also the bright green thing with a red top isn't a sex toy...it's a carton from one of my kids ice lollies, I've got some enamelled copper wrapped around it for a home pickup project - another day!).

yes, I know the stepper is going to be too weak...initially, I'll only be cutting thin acrylic & we'll see where this takes me (I'm using a dremel as a spindle but have my eye on that sexy wolfgang spindle!)

Still to do...

mount the motors (I'm still trying to figure out the way to do this cheaply!)

Align the threaded rods with the motors. I found some round bits of rubber with threaded metal inserts in the worksjhop at work...I will try & fashion these into a flexible connector to joing the motor to the thresded rod (you can just make them out in the main photo)

Further updates to follow....

Comments welcome (but not about me being cheap!) ...bear in mind this is my first build (& no plans to follow...making it up as I go along) , I'm not really the mechanical engineering type (more the electronics sort)

[Drools]

Your design looks very simple and clean looking. What is the final milling area you end up with?
This is the original approach I took then I quickly decided "in for a penny in for a pound" so I upgraded to 1" rods so I can have a large milling area. It will take more time and of course money but I think the added functionality will benefit my plans in the long run.

[HankMcSpank]

Thanks for your comments

Well, for all it's size (the frame meaure about 50cm x 40cm), the cutting area is only about 15cm x 12cm ...ample enough for me at this stage though!

[FandZ]

I'm not too sure how well that sheet metal will hold up but regardless, you get an A+ for style. I think that is a great cnc design for a first build. Kinda like training wheels for the next bigger and stronger one. I kinda wish I would have went that route for my first one.

A suggestion, looks to me you have some room to add a little reinforcement. You could probably stiffen that sheet metal with some aluminum angle easy enough.

I'm sure you are going to have a blast. I'll be checking back for updates. Nice job.

[HankMcSpank]

Thank you for your kind words of support.

I agree that the aluminium plate sounds/looks to thin, but the X plane is reinforced a little via 1/2" ply I've installed underneath the 4mm plate (there's not much in the way of flex). The Y plane linear rod mounts sit almost immediately on top of the linear rails they run on....therefore again, not much flex. These plates were absolutely essential to helping me align everything (being precut professionally, the plate edge were incredibly straight & at peercet right angles)

I know these CNC machines take a life of their own & often the first build is the precursor to an obsessive path to incredibly tight tolerances, but I'm hoping this one will meet my modest needs with only a small amount of modd'ing/tweaking. (like I say, I don't want to spend much on this - it's only cost me about £100 in total ...mainly for the stepper motor driver board)

thanks once again...I'll post another update with pics once I get the motors fitted (likely to be in about one weeks time)

[FandZ]

Originally Posted by HankMcSpank often the first build is the precursor to an obsessive path to incredibly tight tolerances,

Haha... You're right on that one. I'm close to being done with my first build and I've pretty much have my second build sketched out. And what's worse is my mind is already thinking about a third build.

Reading over your post, you said you are looking for a cheap way to mount the motors. Again, I'd suggest aluminum angle and some nuts and bolts. I can sketchup up an idea or two if you need some suggestions but I'm sure you have enough creative juice to pull it off. Here's a picture Y axis mount to give you an idea of bolting it in.

[HankMcSpank]

Thanks for the ideas about motor mounting.

Last night, I connected up my dot matrix printer 'rescued' steppers just to get a handle on how they'll 'fit' into the puzzle....my GOD, the noise (ie when when I rest them on the steel/alumunium frame base - like seriously loud. When I jog in the software app, it's not disimilar to the sound a hammer drill makes when drilling masonary (ok, a bit quieter thah that - but not much -the sound is still reminiscent).

Anything can be done here?

Is it likely to be ...

1. The old type of motor (didn'y have much operational life, but we're talking a good twenty years old...has stepper technology progressed on the quietness front?)

2. The way I'm mounting?

3. The voltage I'm using to my driver board ...(24V) .....the motor says 3V(!), not sure I'm understanding this bit.

Something else?!!

[Drools]

I would try to lower the voltage as the first step.
I too have some recycled NEMA 23 steppers that I obtained form old dot matrix printers. I tried them at over 20VDC and they did move but became very hot and missed steps so I ran them off of 12VDC and that fixed everything. Now I intend to purchase new Nema 23 motors but for the time being I want to use the recycled ones just to get an idea of the torque I'm going to need.