<div>I wasn't trying to be academic or argue over ounces/feet/pounds/inches/newtons/metres. Sorry if it came across that way. I just thought that as a group of roboticists we should be clear on something as fundamental as torque. I figured this list is about helping each other out, so I was trying to be helpful by correcting an error. </div>
<div><br></div><div>Good work finding the article, it looks like a useful technique. </div><div><br></div><div>Simon.</div><div><br></div><div><div><br><div class="gmail_quote">On Thu, Jul 7, 2011 at 3:12 PM, 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;">Simon<br>
If the authors terms spelling or otherwise offends or confuses you, then<br>
simply move on.<br>
<br>
If you are so keen on Foot pounds of torque then divide by 192.<br>
The actual method of checking is correct, which is what the article was<br>
about.<br>
<br>
The reason I presented it to the group, was it was a relatively easy<br>
means to check an otherwise unknown stepper motor.<br>
<br>
/While the academic amongst the group argue over the correctness of the<br>
written theory, the more practical will have done any checks and moved on./<br>
<br>
Mark<br>
<div class="im"><br>
<br>
On 7/07/11 14:26, Simon Knopp wrote:<br>
> Your quoted excerpt makes my point: torque is measured in *ounce<br>
> inches*, not ounces per inch. Torque = force x distance, not force /<br>
> distance.<br>
><br>
> Ounce(force) per inch would be a valid unit for stiffness, not for<br>
> torque.<br>
><br>
> Simon.<br>
><br>
><br>
> On Thu, Jul 7, 2011 at 2:12 PM, Simon Chester <<a href="mailto:simonches@gmail.com">simonches@gmail.com</a><br>
</div><div class="im">> <mailto:<a href="mailto:simonches@gmail.com">simonches@gmail.com</a>>> wrote:<br>
><br>
> It's not incorrect: <a href="http://en.wikipedia.org/wiki/Torque#Units" target="_blank">http://en.wikipedia.org/wiki/Torque#Units</a><br>
><br>
> In British unit, "pound-force-feet" (lbf x ft),<br>
> "foot-pounds-force", "inch-pounds-force", "ounce-force-inches"<br>
> (oz x in) are used, and other non-SI units of torque includes<br>
> "metre-kilograms-force". For all these units, the word "force"<br>
> is often left out, for example abbreviating "pound-force-foot"<br>
> to simply "pound-foot" (in this case, it would be implicit<br>
> that the "pound" is pound-force and not pound-mass).<br>
><br>
><br>
> On Thu, Jul 7, 2011 at 12:07 PM, Simon Knopp<br>
> <<a href="mailto:shrunken.apple.head@gmail.com">shrunken.apple.head@gmail.com</a><br>
</div><div class="im">> <mailto:<a href="mailto:shrunken.apple.head@gmail.com">shrunken.apple.head@gmail.com</a>>> wrote:<br>
><br>
> I stopped reading the first link when I saw "...torque is<br>
> usually measured in ounces per inch". A whole page about<br>
> measuring torque prefaced by an incorrect definition. Oops.<br>
><br>
> Simon.<br>
><br>
><br>
><br>
> On Thu, Jul 7, 2011 at 11:43 AM, Mark Beckett<br>
</div><div><div></div><div class="h5">> <<a href="mailto:m.beckett@amuri.net">m.beckett@amuri.net</a> <mailto:<a href="mailto:m.beckett@amuri.net">m.beckett@amuri.net</a>>> wrote:<br>
><br>
> 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<br>
> approach.<br>
> Also he is measuring the hold torque, which will be<br>
> 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<br>
> disregarded them as they are 1/4 chuck, rather than 1/8,<br>
> and a lot heavier than a dermal.<br>
> ><br>
> > After destroying 2 home made spindles, 1 after 10 hours<br>
> work cutting ali which I think was an air flow issue& the<br>
> next after 20 minutes because it was a cheap armature, I<br>
> may well look at the trim routers again.<br>
> ><br>
> > The extra weight puts higher demands on the Z axis,<br>
> which in my case is where I found out all about some<br>
> 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<br>
> another stepper but it has the same problem.<br>
> ><br>
> > There was a comment in this thread about speed control,<br>
> here's my experience.<br>
> > Most of these home made machines are routers rather than<br>
> mills& so cut with a very fine feed so you only need<br>
> enough speed rather than managing a speed feed<br>
> relationship of a mill where it produces chips.<br>
> ><br>
> > My approach is to do a test piece run and adjust the<br>
> depth of cut to keep chatter under control, almost<br>
> impossible with a plastic cased dermal.<br>
> > I then ramp the speed up until I here the spindle start<br>
> to load significantly, I can hear the speed drop, then set<br>
> 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<br>
> dermal knock off removed from it's case and ali blocks<br>
> for bearing mounts, I can cut 2mm deep at about<br>
> 150mm/minute feed.<br>
> ><br>
> > The secret to cutting ali is to keep it flooded with<br>
> coolant. In my case I use lots of CRC. I basically stand<br>
> there with a spray can& keep the grove full of CRC.<br>
> ><br>
> ><br>
> > For any one building a machine alignment of the feed<br>
> screws is the biggest issue. What worked for me is to<br>
> mount a bearing on the lead screw on the opposite end from<br>
> the motor& clamp the lead screw against for/aft movement<br>
> and at the motor end I use a piece of rubber fuel line as<br>
> a coupler. The modern reinforced fuel injection line has a<br>
> lot of reinforcing that prevents twist.<br>
> > For lead screws I use 8mm threaded rod, 1.25mm per<br>
> 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><br>
> <mailto:<a href="mailto:chchrobotics-bounces@lists.linuxnut.co.nz">chchrobotics-bounces@lists.linuxnut.co.nz</a>><br>
> [mailto:<a href="mailto:chchrobotics-bounces@lists.linuxnut.co.nz">chchrobotics-bounces@lists.linuxnut.co.nz</a><br>
> <mailto:<a href="mailto:chchrobotics-bounces@lists.linuxnut.co.nz">chchrobotics-bounces@lists.linuxnut.co.nz</a>>] On<br>
> 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<br>
> stepper motors<br>
> ><br>
> > 'Urro...<br>
> ><br>
> > Given a dremel new is $120-150 ish...<br>
> ><br>
> > Trim routers like these:<br>
> ><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,<br>
> no speed control<br>
> > inbuilt so you can use a closed loop speed control on it<br>
> for better<br>
> > cutting in soft stuff. It'll also have higher rotor<br>
> inertia and a<br>
> > better quality chuck.<br>
> ><br>
> > There are a few on the market. When I last looked there<br>
> were a few<br>
> > options on the shelf at Bunnings/Mitre10 that looked good.<br>
> ><br>
> > I was specifically thinking dremel replacements for<br>
> wood/plastic/alloy<br>
> > cutting. If you're looking for dedicated spindle ebay<br>
> is probably your<br>
> > friend..<br>
> ><br>
> > And, having said all that, my next project is going to<br>
> be swinging a<br>
> > water cooled VFD spindle. I am sooooo over the noise of<br>
> 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<br>
> wrote:<br>
> >><br>
> >>> There are some very reasonably priced options rather<br>
> than sticking with<br>
> >>> a dremel.<br>
> >> Can you elaborate?<br>
> >> And are these options for a dremel replacement or a CNC<br>
> spindle?<br>
> >><br>
> >> Thanks,<br>
> >><br>
> >> Volker<br>
> >><br>
> ><br>
> > _______________________________________________<br>
> > Chchrobotics mailing list<br>
> <a href="mailto:Chchrobotics@lists.linuxnut.co.nz">Chchrobotics@lists.linuxnut.co.nz</a><br>
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