By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Allendale Jan 24th

Pulley design

All Topics | Latest Posts

Search for:  in Thread Title in  
Martin Dowing17/02/2021 08:24:18
avatar
350 forum posts
8 photos

I need to make rather large pulleys (140-200mm) for standard 10 mm V-belt.

Grove is to be 9.7mm wide on the top and 11mm deep as theory and published projects are saying.

What are correct grove angles?

What I have found that tor a small pulley (up to ~3 inches) correct grove angle is 32 deg and for larger pulleys it is 38 deg.

I understand it, as it seems logical that due to larger contact area of big pulley frictional force per unit of contact area does not need to be so high because total contact area is larger.

I am aware that many people are making pulleys with 30 deg angle, regardless of size.

So what is correct angle for large pulleys?

38 deg or perhaps less?

Phil P17/02/2021 08:45:33
768 forum posts
194 photos

Page 2 on this PDF should give you the dimensions you require.

http://www.bearing.net.au/wp-content/uploads/2014/07/SKF-Pulley-Catalogue.pdf

Phil

gerry madden17/02/2021 09:33:29
167 forum posts
67 photos

I'm not sure the angle is to do with pulley contact area. I think its to do with the distortion of the cross-section of the belt as it bent. The tighter the bend the more the distortion.

I got so confused by data on the net so when I made some pulleys I bent the belt into the working radius of the pulley and measured the resulting 'v' angle on cross-section. My measurements seemed to agree with some of the internet guidance and after making them they seemed to work too!

Gerry

Mike Poole17/02/2021 09:43:24
avatar
Moderator
2936 forum posts
70 photos

It probably isn’t too critical in a hobby workshop application. Belt slip is unlikely and premature wear of the belt or pulley is also unlikely to be serious. If you want to transmit full load 24/7 then the belt manufacturers recommended specifications would be best adhered to but as long as you are in the right area it will be satisfactory.

Mike

Bo'sun17/02/2021 11:27:57
390 forum posts

For hobby use, I'd go along with Gerry. Just make sure the belt doesn't bottom out in the groove.

Martin Dowing17/02/2021 15:03:21
avatar
350 forum posts
8 photos

Thanks for all your comments. I will go for 36 deg., not exactly what industrial art calls for larger diameters (38 deg) but more than usually modellers are doing (30 - 32deg).

Reasoning is that pulley will be used quite a lot but because it is going to be made of aluminium, then this angle will be a little bit steeper to accomodate for wear.

Martin

Howard Lewis17/02/2021 16:29:42
4662 forum posts
10 photos

According to Kempe's Engineers Year Book, section E9//5 Z, A , B and C section belts have angle beteen 34 and 38, so 36 looks about right.

Howard

oldvelo17/02/2021 19:30:11
269 forum posts
54 photos

Hi Martin

Have you considered using "Poly Vee Belts" for much better performance than "Vee Belts" as an alternative. Much easier to fabricate with the ability to use much smaller driver pulleys. Classic example is Wood working hand held power planers.

Eric

P.S. Poly Vee Belt Drive lives at my house

Martin Dowing17/02/2021 20:57:08
avatar
350 forum posts
8 photos

@oldvelo,

System will be used for motor speed reduction, so sizes of pulleys have to stay as designed.

Smaller pulleys are already rather small and further size reduction would only bring unnecessary strain..

But yes, I do use poly-v belts because they perform so much better.

Martin

Martin Dowing17/02/2021 23:02:28
avatar
350 forum posts
8 photos

@oldvelo,

I think, I misunderstood you.

Do you mean belts like those used for example in washing machines?

oldvelo18/02/2021 00:42:57
269 forum posts
54 photos

`Hi Martin

Yes washing machines, motor cars, and almost all modern machines use Poly Bee Belts

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Support Our Partners
ChesterUK
emcomachinetools
Warco
Eccentric July 5 2018
JD Metals
cowells
Eccentric Engineering
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest