¿ªÔÆÌåÓýHow 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 > > > > > > > |
