Thanks, John,
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Yes, measuring how much torque it actually takes is a good idea!
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I think the lowest speed on the Stark mill, which doesn¡¯t have a back gear, is around 200rpm, so a 20-tooth gear would have to turn 10rpm to keep up and with the 40:1 DH the stepper has to go 400rpm? According to the chart on the page I linked before the 111oz-in stepper torque¡¯s about 70% stall, or 80% max running torque at that speed - does that seem right?
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But I think a bigger worm gear would be better for that - this dividing head¡¯s the smallest one I have!
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Cutting cams like it shows here is another intriguing use of a DH, and would use its tilting capability, but at this point that¡¯s probably better done with cnc.
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On Wed, Feb 5, 2020 at 08:12 AM, Richard wrote:
If you just need the stepper to rotate the D head the you can easily
check and see what actual torque is needed some sort of arm with a
weight on the end keep increasing the radius until it rotates the
calculate the oz in or Nm. If you intend rotating whilst cutting that
will obviously require more torque.
Hobbing on the mill is possible but not with your existing dividing
head. You will need to rotate the component much faster. Just think
about what speed you would like to run the cutter at then divide by the
gear ratio you are hobbing. Your stepper would be really spinning when
the component is driven at 40 to 1.
The 3" is not a problem I would have thought, just jack it up on
spacers. I have hobbed using Linux CNC and also built an interface to
allow hobbing without the computer just using an Arduino Mega and
putting an encoder on the spindle. Best option if you need to make a
worm and wheel.
To hob you? obviously need to be able to tilt the head!
Richard
On 05/02/2020 11:36, Clark Panaccione via Groups.Io wrote:
Thanks, John - was that on the rotary table, or on your belt drive one?
This is the highest rated Nema 17 I found, 2.3a should work with the
little TB6560 driver recommended in the ¡°Arduino rotary table for
dummies¡± thread on homemodelenginemachinist.com:
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Any insight on the control interface? It looks like yours had
pushbuttons arranged kind of joystick-like - is that for setting up as
well as operating? I thought maybe just a couple big buttons for left
and right, in addition to a keypad and display, would make it a little
simpler for me to run.
It would be interesting to rig up something like the RELS on my little
antique horizontal universal mill for hobbing but I think the 3¡± swing
on my dividing head is too small to worry about powering it for that.
Don¡¯t know how many true axes that would be, with the table running at
funny angles ; )
On Mon, Feb 3, 2020 at 10:38 PM, John Lindo wrote:
I used a Nema 17 for many years, it worked vert well, changed to
Nema 23 during the full mill conversion to CNC , thus making it a
true 4th axis machine,
--
John
