Hello Everyone

[Robrant]

Hello all,

I’m from East Devon and been dabbling in this and that for years, I work in IT so also need to get out a bit more.

Sorry to ask a question straight off, and if this isn’t the right place let me know.

Am starting to get some parts together to make a simple CNC Mill, by small I mean A4 size cutting area.
Trawled through hundreds of threads, got confused, excited then more confused and am now spending some money on it.

I bought a used System 3 board from DIY CNC and am looking at some cheap stepper motors from eBay, I’m not sure of what voltage I should be looking at or how this is set on the System3 board yet.
Spindle wise I’m thinking TR10x2D Trapezoidal may be overkill and I’ll try some B&Q threaded bar, I’ll make my own Delrin nuts.

The whole project is more experimenting and learning than wanting to produce anything.

Any pointers greatly appreciated.

Regards
Rob

[irving2008]

Hello all,

I’m from East Devon and been dabbling in this and that for years, I work in IT so also need to get out a bit more.

Sorry to ask a question straight off, and if this isn’t the right place let me know.

Am starting to get some parts together to make a simple CNC Mill, by small I mean A4 size cutting area.
Trawled through hundreds of threads, got confused, excited then more confused and am now spending some money on it.

I bought a used System 3 board from DIY CNC and am looking at some cheap stepper motors from eBay, I’m not sure of what voltage I should be looking at or how this is set on the System3 board yet.
Spindle wise I’m thinking TR10x2D Trapezoidal may be overkill and I’ll try some B&Q threaded bar, I’ll make my own Delrin nuts.

The whole project is more experimenting and learning than wanting to produce anything.

Any pointers greatly appreciated.

Regards
Rob

Hi Rob,

Well B&Q threaded rod will work just, but dont expect any great speed or accuracy. Stainless threaded rod is better, but TR10x2D is better still.

Cheap steppers wont be very torquey, so while it might work, with the high friction from the threaded rod the results are going to be dissappointing in terms of cutting speed and achievable depth of cut. But then if this is purely a learning exercise maybe thats acceptable. Depends what your goal is... just dont expect to be munging lumps of alloy any time soon; balsa wood and small MDF workpieces are more achievable.

With that set-up PCB milling is also a possibility, although you won't be doing those 0.2mm traces between SMD pads.

A4 size workarea (200 x 300 say) means a machine footprint of around 500mm square depending on design and components.

Have you decided on rails and cutting power yet?

Good luck and don't forget to keep a build log!

[Robrant]

Thanks Irving,

I'll order some TR10x2D today.

For rails I like the idea of bearings and angled alloy running on some steel bars I have (from old printers).

I want to get the steppers and drivers hooked up to the PC and get my head around that first.
The stepper motors are what I'm stuck on, some are 3v, 5v or even 24v and I don't know how to set this on the driver.
Was looking at these:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=170386297979&ssPageName=STRK:MEWAX:IT
Or even something like this:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=170381507797&ssPageName=STRK:MEWAX:IT

Or am I way off?

PCB Milling is something I'd like to do, nothing too strenuous though.
I'll certainly keep a log.

All the best
Regards
Rob

[irving2008]

Thanks Irving,

I'll order some TR10x2D today.

For rails I like the idea of bearings and angled alloy running on some steel bars I have (from old printers).

I want to get the steppers and drivers hooked up to the PC and get my head around that first.
The stepper motors are what I'm stuck on, some are 3v, 5v or even 24v and I don't know how to set this on the driver.
Was looking at these:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=170386297979&ssPageName=STRK:MEWAX:IT
Or even something like this:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=170381507797&ssPageName=STRK:MEWAX:IT

Or am I way off?

PCB Milling is something I'd like to do, nothing too strenuous though.
I'll certainly keep a log.

All the best
Regards
Rob

Ignore stepper voltage, what matters is phase current. The stepper driver can be set to provide a constant current to the coils. For the sort of size you are refering to, with the frictional loads you need to be looking at motors with 1 - 1.5Nm of holding torque. The size 16's you list are 0.7Nm which is probably marginal. Size 23 motors, 1.8deg step (200steps/rev) are what you need, the board you have will drive up to 2.5A bipolar parallel wired motors (8 or 4 wire, not 6-wire). A typical motor would be this (http://cgi.ebay.co.uk/Powermax-II-1-8-Stepper-motor-73W-2-3A-Bipolar-Series_W0QQitemZ270461349097)

[Robrant]

Thanks again Irving,

It's a big learning curve for me, just got my head around Mach3 last night using a little stepper, it got too hot to hold so that'll be the phase current.

I'll watch those motors or get something more appropriate as you suggest.

Regards
Rob