Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: Clare Snyder <clare@snyder.on.ca>
Newsgroups: rec.crafts.metalworking
Subject: Re: Timing belt drives
Date: Tue, 03 Sep 2024 00:57:18 -0400
Organization: A noiseless patient Spider
Lines: 60
Message-ID: <lq1ddjdl9e0os80un5893ank95st1ig5v8@4ax.com>
References: <90c5djpacm2j9ob6qjt6dhthcnvqab1e87@4ax.com> <vb4sh6$2uaie$1@dont-email.me> <vb4tis$2u7qn$1@dont-email.me>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Injection-Date: Tue, 03 Sep 2024 06:57:23 +0200 (CEST)
Injection-Info: dont-email.me; posting-host="a99fe6a07876c7f4caef3fc6886ea9a7";
	logging-data="3397904"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1+bQrMzVrOA0BednDagKLNx"
User-Agent: ForteAgent/8.00.32.1272
Cancel-Lock: sha1:Jm2Br1DF6jCn7YHzEyIV57bJTxM=
Bytes: 3736

On Mon, 2 Sep 2024 10:45:01 -0700, Bob La Londe <none@none.com99>
wrote:

>On 9/2/2024 10:27 AM, James Waldby wrote:
>> Clare Snyder <clare@snyder.on.ca> wrote:
>>>
>>> Any of you guys have experience with timing belt drives? I need as
>>> compact as possible 1 1/2:1 reduction from a 600 rpm  2.5HP engine
>>> (3600 crankshaft RPM with 6:1 reduction) then another 1 1/2:1 after
>>> that (so lower speed higher torque) ( total reduction 13.5:1).This
>>> will be driving a 20 inch diameter 2 inch wide tire/wheel.
>>>
>>> How wide and how large do I need the small sprocket? For simplicity I
>>> would likely like both stages identical. This simplifies everything
>>> including tensioning
>> 
>> I've seen some timing belt power transmission calculators online,
>> which account for RPM, small pulley diameter, required torque, etc,
>> but haven't done a design.  The `AI Overview` from a google search for
>> `timing belt drive power sizing` has about 6 bullet points, each with
>> a link, that get to some design webpages or calculators.
>> 
>> I think an auto engine timing belt handles 15 to 25 HP, which you
>> could scale down from or get parts from.  Depending on what your app
>> is maybe one stage of planetary gear reduction as in drill motors
>> would work; and there are some inexpensive electric bike clutches that
>> look like 4"-diameter planetary drives but might be irrelevant -
>> https://www.amazon.com/AMLESO-Electric-Planetary-Clutch-Motor/dp/B09XVL1NV7
>> - besides having nylon gears.
>> 
>>> Small sprocket on output shaft  driving large sprocket on jackshaft
>>> turning small sprocket driving large sprocket spinning on output shaft
>>> of the engine/gearbox  with wheel attached to that sprocket. Distance
>>> from center of small sprocket to outside of large sprocket cannot
>>> excede 7 inches.
>>>
>>> Is this possible/feasible???
>
>
>I didn't read all of that, but my problem with timing belts relates to 
>CNC motor drives.  If I didn't get the tension perfect they would either 
>exhibit backlash or they would sap power from the system at a much 
>higher than expected rate.
>
>That being said I have seen a cog belt with cog pulleys used on a fairly 
>powerful pulley with good effect.  The 5hp motor on my Hurco mill uses a 
>1:1 cog belt to drive the spindle... and Hurco rated the mill at 4HP. 
>LOL.
>
>I don't have the experience with them, but everything I've read 
>indicates a harmonic drive is the magic sauce for some applications.
>
>
>-- 
>Bob La Londe
>CNC Molds N Stuff
 I've decided to just try a bigger engine - - - 

Engine has 6:1 reduction - direct driving a 20 inch wheel to move 300
to 350 lb. New enginr is 2 9/16 bore and 2 7/16 stroke