I stopped reading the first link when I saw "...torque is usually measured in ounces per inch". A whole page about measuring torque prefaced by an incorrect definition. Oops. <div><br></div><div>Simon.<br><div><br>
<div><br><div class="gmail_quote">On Thu, Jul 7, 2011 at 11:43 AM, Mark Beckett <span dir="ltr"><<a href="mailto:m.beckett@amuri.net">m.beckett@amuri.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Since there is a dgree of interest around steppers<br>
I found this while searching for something else.<br>
<br>
<a href="http://www.romanblack.com/stepper.htm" target="_blank">http://www.romanblack.com/stepper.htm</a><br>
<br>
I'm sure the members could improve on the glue it down approach.<br>
Also he is measuring the hold torque, which will be different to the<br>
rotating torque.<br>
<br>
<br>
For Robin<br>
He has a very interesting section on one wire<br>
<a href="http://www.romanblack.com/blacknet/blacknet.htm" target="_blank">http://www.romanblack.com/blacknet/blacknet.htm</a><br>
<br>
For those folowing the CNC he has this<br>
<a href="http://www.romanblack.com/cnc_good.htm" target="_blank">http://www.romanblack.com/cnc_good.htm</a><br>
<br>
Mark<br>
<br>
<br>
On 4/07/11 16:43, HARTLEY, ROBIN (ROBIN) wrote:<br>
> Hi,<br>
> I've looked at the trim routers and initially disregarded them as they are 1/4 chuck, rather than 1/8, and a lot heavier than a dermal.<br>
><br>
> After destroying 2 home made spindles, 1 after 10 hours work cutting ali which I think was an air flow issue& the next after 20 minutes because it was a cheap armature, I may well look at the trim routers again.<br>
><br>
> The extra weight puts higher demands on the Z axis, which in my case is where I found out all about some uni-polar steppers not liking bi-polar drive with PWM.<br>
><br>
> Due to my design I'm a bit limited on space& I got another stepper but it has the same problem.<br>
><br>
> There was a comment in this thread about speed control, here's my experience.<br>
> Most of these home made machines are routers rather than mills& so cut with a very fine feed so you only need enough speed rather than managing a speed feed relationship of a mill where it produces chips.<br>
><br>
> My approach is to do a test piece run and adjust the depth of cut to keep chatter under control, almost impossible with a plastic cased dermal.<br>
> I then ramp the speed up until I here the spindle start to load significantly, I can hear the speed drop, then set my G code to run up to about 50% of that feed rate.<br>
><br>
><br>
> With a home made spindle, which is basically a cheap dermal knock off removed from it's case and ali blocks for bearing mounts, I can cut 2mm deep at about 150mm/minute feed.<br>
><br>
> The secret to cutting ali is to keep it flooded with coolant. In my case I use lots of CRC. I basically stand there with a spray can& keep the grove full of CRC.<br>
><br>
><br>
> For any one building a machine alignment of the feed screws is the biggest issue. What worked for me is to mount a bearing on the lead screw on the opposite end from the motor& clamp the lead screw against for/aft movement and at the motor end I use a piece of rubber fuel line as a coupler. The modern reinforced fuel injection line has a lot of reinforcing that prevents twist.<br>
> For lead screws I use 8mm threaded rod, 1.25mm per turn,& for the nuts I use a piece of plastic chopping board.<br>
><br>
><br>
><br>
><br>
><br>
><br>
> Regards,<br>
> Robin<br>
><br>
><br>
><br>
><br>
><br>
><br>
> -----Original Message-----<br>
> From: <a href="mailto:chchrobotics-bounces@lists.linuxnut.co.nz">chchrobotics-bounces@lists.linuxnut.co.nz</a> [mailto:<a href="mailto:chchrobotics-bounces@lists.linuxnut.co.nz">chchrobotics-bounces@lists.linuxnut.co.nz</a>] On Behalf Of Chris Hellyar<br>
> Sent: Saturday, 2 July 2011 11:03 a.m.<br>
> To: Christchurch Robotics<br>
> Subject: Re: [chbot] building CNC router - was Free stepper motors<br>
><br>
> 'Urro...<br>
><br>
> Given a dremel new is $120-150 ish...<br>
><br>
> Trim routers like these:<br>
><br>
> <a href="http://www.powertoolshop.co.nz/product_info.php/cPath/20_96/products_id/20" target="_blank">http://www.powertoolshop.co.nz/product_info.php/cPath/20_96/products_id/20</a><br>
><br>
> For $119 with a full alloy body are a better bet.<br>
><br>
> As I see it, it's cylindrical so it's easier to mount, no speed control<br>
> inbuilt so you can use a closed loop speed control on it for better<br>
> cutting in soft stuff. It'll also have higher rotor inertia and a<br>
> better quality chuck.<br>
><br>
> There are a few on the market. When I last looked there were a few<br>
> options on the shelf at Bunnings/Mitre10 that looked good.<br>
><br>
> I was specifically thinking dremel replacements for wood/plastic/alloy<br>
> cutting. If you're looking for dedicated spindle ebay is probably your<br>
> friend..<br>
><br>
> And, having said all that, my next project is going to be swinging a<br>
> water cooled VFD spindle. I am sooooo over the noise of brushed routers!!!<br>
><br>
> Cheers, Me.<br>
><br>
> On 02/07/11 10:17, Volker Kuhlmann wrote:<br>
>> On Sat 02 Jul 2011 02:06:20 NZST +1200, Chris Hellyar wrote:<br>
>><br>
>>> There are some very reasonably priced options rather than sticking with<br>
>>> a dremel.<br>
>> Can you elaborate?<br>
>> And are these options for a dremel replacement or a CNC spindle?<br>
>><br>
>> Thanks,<br>
>><br>
>> Volker<br>
>><br>
><br>
> _______________________________________________<br>
> Chchrobotics mailing list <a href="mailto:Chchrobotics@lists.linuxnut.co.nz">Chchrobotics@lists.linuxnut.co.nz</a><br>
> <a href="http://lists.ourshack.com/mailman/listinfo/chchrobotics" target="_blank">http://lists.ourshack.com/mailman/listinfo/chchrobotics</a><br>
> Mail Archives: <a href="http://lists.ourshack.com/pipermail/chchrobotics/" target="_blank">http://lists.ourshack.com/pipermail/chchrobotics/</a><br>
> Web site: <a href="http://kiwibots.org" target="_blank">http://kiwibots.org</a><br>
> Meeting Time and Location uncertain while Science Alive is out of action.<br>
><br>
> When replying, please edit your Subject line to reflect new content.<br>
><br>
> _______________________________________________<br>
> Chchrobotics mailing list <a href="mailto:Chchrobotics@lists.linuxnut.co.nz">Chchrobotics@lists.linuxnut.co.nz</a><br>
> <a href="http://lists.ourshack.com/mailman/listinfo/chchrobotics" target="_blank">http://lists.ourshack.com/mailman/listinfo/chchrobotics</a><br>
> Mail Archives: <a href="http://lists.ourshack.com/pipermail/chchrobotics/" target="_blank">http://lists.ourshack.com/pipermail/chchrobotics/</a><br>
> Web site: <a href="http://kiwibots.org" target="_blank">http://kiwibots.org</a><br>
> Meeting Time and Location uncertain while Science Alive is out of action.<br>
><br>
> When replying, please edit your Subject line to reflect new content.<br>
><br>
<br>
_______________________________________________<br>
Chchrobotics mailing list <a href="mailto:Chchrobotics@lists.linuxnut.co.nz">Chchrobotics@lists.linuxnut.co.nz</a><br>
<a href="http://lists.ourshack.com/mailman/listinfo/chchrobotics" target="_blank">http://lists.ourshack.com/mailman/listinfo/chchrobotics</a><br>
Mail Archives: <a href="http://lists.ourshack.com/pipermail/chchrobotics/" target="_blank">http://lists.ourshack.com/pipermail/chchrobotics/</a><br>
Web site: <a href="http://kiwibots.org" target="_blank">http://kiwibots.org</a><br>
Meeting Time and Location uncertain while Science Alive is out of action.<br>
<br>
When replying, please edit your Subject line to reflect new content.<br>
</blockquote></div><br></div></div></div>