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

Jacobs Gear Hobber

All Topics | Latest Posts

Search for:  in Thread Title in  
Bazyle21/05/2013 12:14:52
5125 forum posts
199 photos

Further to Joey's earlier question re calculations this site might help. It is not clear if Duncan ever finished his hobber but he has a nifty program for calculating gear ratios for it. (thanks Duncan if you ever read this).

This program is also useful if you have a universal dividing head but not the gears listed in Machinery Handbook for differential indexing. Just calculate the ratio given by the listed gears and then use the program to find the combination using the gears you do have.

I wonder if it wouldn't be easier to adapt a very small horizontal milling machine. The simple production ones even smaller than a centec come up on ebay but get little interest. Probably end up as scrap but they would provide the necessary X & Z axes plus spindle leaving only a blank rotator and gear drive to make.

Found my copy of MEW 108. Somewhat hard to understand the explanation but found a much better description by JS on another forum.

david lockwood09/04/2019 14:01:13
41 forum posts

Does anyone know what rpm I should be running the Jacobs hobber at ?

I am just about to machine up the belt drive and I have to work the ratios out

many thanks to anyone who can help


Pete Rimmer09/04/2019 19:07:31
676 forum posts
39 photos

The manual for my hobber (which uses 32mm diameter hobs) says the hob speed is 300rpm for steel and 980rpm for brass.

david lockwood10/04/2019 18:38:31
41 forum posts

Thank you Pete

Mark Rand10/04/2019 23:02:59
873 forum posts
3 photos

That speed gives about 100 feet per minute for steel, which is the accepted cutting speed for HSS cutters on mild steel blanks.

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

Latest Forum Posts
Support Our Partners
Allendale Electronics
Eccentric July 5 2018
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