By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Forum House Ad Zone

Toolpost Grinding

All Topics | Latest Posts

Search for:  in Thread Title in  
Gray6227/01/2011 11:03:13
1058 forum posts
16 photos
I am in the process of designing and building a toolpost grinder and was wondering what the opinion is on the direction of rotation of workpiece to grinding wheel.
Some documentation I have found shows it as below however, others state that the work should rotate in the opposite direction to that shown

Billy Mills27/01/2011 11:24:23
377 forum posts
Perhaps a reversing switch might be handy!
 
Regards,
Alan.
JDEng27/01/2011 11:24:30
27 forum posts
There was some debate on this subject on this forum about two months or so ago. Opinion seemed to be divided.
 
When we were apprentices we were always told that the work and the wheel should rotate so that the point where the two met was going in opposite directions. IE. using the above diagram as a guide, for external grinding both should be going clockwise (or anti-clockwise); for internal grinding on the left hand edge of the job, the wheel should go clockwise and the job anti-clockwise.
 
I've never known exactly why but just accepted it however, after the previous debate, I've spoken to a one or two people who have done a lot of universal grinding. The consensus of opinion seemed to be that contra rotation prevents any potential backlash or slackness in drive belts or gears affecting the relative speeds which could mar the finish.
 
John.
 
 
 
Terryd27/01/2011 11:56:17
avatar
1946 forum posts
179 photos
Hi Coalburner,
 
A long time ago, in a toolroom far,far away I was taught the above method. As stated the work should rotate slowly, but the grinder should rotate at a relatively high speed, say 10,000rpm for such a small wheel. The speed of the rotating work and grinder should be added or subtracted depending on the relative rotation. So if your workpiece is rotating at say 250 rpm the relative speeds of the two will be either 10,250 or 9,750 rpm, not a great deal of difference really. Of course if you rotate the work at 50 rpm there is essentially no difference.
 
I would agree with John's last paragraph above, depending on the quality of your equipment.
 
By the way the instructions above are wrong I believe. For external work it shows the two shafts contra-rotating and claims that the speeds are thus added. It doesn't take a great intellectual exercise to show that in fact the speeds are subtracted in this mode. Think of a workpiece of the same diameter as the grindstone and imagine that you could increase the lathe to the same speed as that grinder. The two surfaces would simply roll together with no relative movement between the surfaces, so no grinding action. The same holds for their internal grinding assuming that you are grinding at the rear of the workpiece so that you can see what's happening.
 
Best regards
 
Terry

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

Sign up to our Newsletter

Sign up to our newsletter and get a free digital issue.

You can unsubscribe at anytime. View our privacy policy at www.mortons.co.uk/privacy

Latest Forum Posts
Support Our Partners
cowells
Sarik
MERIDIENNE EXHIBITIONS LTD
Shopping Partners
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

 

Donate

donate