[chbot] building CNC router - was Free stepper motors

[HARTLEY, ROBIN (ROBIN)]

Hi,
I've built a semi-successful CNC router/mill.
I haven't used it to do PBCs but have routered up to 6mm Ali

To do PCBs the best approach seems to be using a floating engraving head.
This follows any contours in the board and so gives consistent cut width.
Otherwise it's necessary to keep the board very flat during routing.

The biggest issue has been with using a dermal as the spindle & lack of rigidity. I've made my own spindle but have blown it up twice now & so it's on the "to do" shelf for a while.

Good drive electronics are important. I started with discreet chips & dropping resistors but have moved to a commercial 5 axis board that uses PWM current limit & micro step. The complete board was cheaper that the list price for 5 of the chips. The boards are listed on trademe but I go mine direct from China for about 2/3 the price all up.

Caution some types of unipolar steppers don't like being driven as bipolar & others don't like PWM current limit.


I'm happy to answer any questions & tell you what didn't work for me.


Regards, 
Robin 

 

 

-----Original Message-----
From: chchrobotics-bounces at lists.linuxnut.co.nz [mailto:chchrobotics-bounces at lists.linuxnut.co.nz] On Behalf Of Cass Jones
Sent: Friday, 1 July 2011 9:53 a.m.
To: Christchurch Robotics
Subject: Re: [chbot] Free stepper motors

Thanks, having a look through now, any chance of earmarking  a set or
should I just get there early? has anyone here made a pcb mill or done
any cnc stuff before?

On Friday, July 1, 2011, Chris Hellyar <chris at trash.co.nz> wrote:
> Hi,
>
> They're all 200 step nema 17's.
>
>  From memory there were no matched sets of 3, but Richard can confirm.
>
> There would be some pairs for X&Y though.
>
> If you're keen on making anything cnc-ish check out the forums on
> www.cnczone.com it's an awesome resource.
>
> Cheers, Me.
>
> On 30/06/11 22:23, Cass Jones wrote:
>> Is there a set of 3 or 3 similar 200 step motors in there by any
>> chance? I'm planning on making a circuit board mill as my next
>> project.
>>
>> On Thu, Jun 30, 2011 at 9:42 PM, Richard Jones<rjtp at ihug.co.nz>  wrote:
>>> In reply to Mark Becket I have appended photos of the stepper motors to our
>>> last meeting pics located here:
>>> ChchRobotics2011June20 | 113134050398543502524 <https://picasaweb.google.com/113134050398543502524/ChchRobotics2011June20?authkey=Gv1sRgCLH0yquZjd6hVA&feat=directlink>
>>> The motors were kindly donated by Chris Hellyar when he was tidying up
>>> around last February.
>>> I also have a few NiMH AA cells if people want those for robots. I'll bring
>>> these items to our next meeting on Monday 20th July 2011.
>>>
>>> Richard
>>>
>>