Ok I see that you have some problems which you have dealt with in your
own way.
As far as I am concerned the only way I can guarantee a correct
relationship between spindle position and encoder position is with a
timing belt.
Our attitudes obviously differ lets leave it at that.
Keep safe
Richard
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On 20/04/2020 15:47, alexphredorg wrote:
The gear teeth are cut directly into the spindle.? The spindle is also
larger at the left end, where the drive pulley mounts. There is a
photo here:
<>
and this shows the whole arrangement:
The orange belt is sitting at the edge where the spindle diameter
increases from 40mm to 44mm.
There is a difference between ideal and "there is no way".? I'm still
trying to understand why you think a timing belt is required.
alex
------------------------------------------------------------------------
*From:* [email protected] <[email protected]> on
behalf of Richard via groups.io <edelec@...>
*Sent:* Monday, April 20, 2020 1:42 AM
*To:* [email protected] <[email protected]>
*Subject:* Re: [digitalhobbyist] #MISC Pulleys?
You say a timing belt is ideal, so you recognise the advantages. I am
surprised that you cannot fit a timing pulley on your spindle, can you
not just replace the original gear driving the change wheels?
Richard
On 19/04/2020 19:14, alexphredorg wrote:
How does a toothed belt provide higher accuracy than a round belt
between the encoder and spindle? ?Assume high quality bearings and
essentially zero friction at the encoder side.
A timing belt is ideal, but in my case it wasn¡¯t a good option and the
round belt has been working well including with thread cutting. ?A
timing belt for me either would have added the lash and noise of a
gear train or would require making a custom two part pulley that
clamped around the narrow part of my spindle ¡ª that would potentially
also add inaccuracies.
alex
------------------------------------------------------------------------
*From:* [email protected] <[email protected]> on
behalf of Richard via groups.io <edelec@...>
*Sent:* Sunday, April 19, 2020 10:03:03 AM
*To:* [email protected] <[email protected]>
*Subject:* Re: [digitalhobbyist] #MISC Pulleys?
There is no way I would ever use a flat or round belt to drive an
encoder if I wanted an accurate pulse train that matched the rotation
being sensed.
Torque has nothing to do with it, we are solely interested in the
accuracy of the drive ratio be it 1:1 10:1 3:1 or whatever. A flat or
Vee belt cannot provide that accuracy.
Richard
On 19/04/2020 17:00, alexphredorg wrote:
Check Amazon and eBay for HTD pulleys with 3mm pitch.
Remember that you have a lathe, so you can bore out a 12mm or 15mm
pulley to 3/4¡± pretty easily. ?For my Emco lathe (8mm stepper, 19 or
20mm leadscrew) I found a stock set that worked without any
modifications.
19mm is extremely close to 3/4¡± too, so keep an eye out for that size.
The stepper drive needs a toothed timing belt so that it won¡¯t slip.
?The very low torque encoder can be done with a flat, V or round belt.
alex
------------------------------------------------------------------------
*From:* [email protected] <[email protected]> on
behalf of Richard via groups.io <edelec@...>
*Sent:* Sunday, April 19, 2020 7:50:55 AM
*To:* [email protected] <[email protected]>
*Subject:* Re: [digitalhobbyist] #MISC Pulleys?
The lead-screw on my lathe is about 20mm diameter and 3mm pitch so
very
close to yours.
I run a 3Nm stepper on my system with a 2:1 drive. A 40 tooth HTD
pulley
on the screw and a 20 tooth on the motor using a 5mm pitch 15mm wide
HTD belt.
Belt and pulleys should be easily available from a good stockist,
though
in fact I made my 20 tooth pulley.
Do not even consider using round belting to drive a lead-screw if the
ultimate aim is some sort of ELS.
Richard
On 19/04/2020 15:37, Ralph Hulslander wrote:
Looking?for pulley and belt suggestions.
I have 3.10Nm stepper with a 8mm shaft.
My leadscrew is 3/4 - 8tpi.
The stepper has been criticised as to small for that leadscrew and
suggestion to use pulleys.
So where do I find a pulley with a 3/4 bore and a matching (smaller)
8mm bore?
Most 3/4 bore pulleys use a 4L V belt.
I wonder if I could use some round urethane belting? A 5-6 mm round
belt might run in a 4L grove.
Ralph
--
Clausing 8520, Craftsman 12x36 Lathe, 4x12 mini lathe, 14" Delta
drill
press, 40 watt laser, Consew brushless DC motors and a non
working 3D
printer
