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

Need help making a camshaft

All Topics | Latest Posts

Search for:  in Thread Title in  
David K05/04/2019 17:44:24
258 forum posts
259 photos

Its for a four cylinder Gypsy engine, the plans show that the cam is built up from separate parts ie. the lobes and bearings are machined then Loctite onto the shaft.

Now I understand what a camshaft does and how it operates but I have little knowledge of making one. After some research I feel making the lobes on my mill using small flat cuts with the aid of a rotary table would be the best option for me.

So I need to come up with some figures for the machining process.

The plans show just one lobe as below


There is also a timing guide and some plans for a jig which I am not sure how its used but I assume it may be for a grinding machineimg_1297.jpg

David K05/04/2019 17:47:34
258 forum posts
259 photos

Looking at the timing it shows the crank moves 240 degrees for the inlet and 260 for exhaust so that would be

120 and 130 for the camshaft . On the dials for the jig it states 130 / 140 which confuses me .

Here is the whole plan , you will need to zoom in img_1302.jpg

Balljoint05/04/2019 18:46:41
37 forum posts
12 photos

Hi David

there is a web page with a program called camcalc at

I have never used it but a member of my club has recently produced a camshat using it

Hope this helps


JasonB05/04/2019 19:07:15
21284 forum posts
2416 photos
1 articles

As it is a flat flank cam you don't really need camcalc.

Just turn up blank with a 0.514 diameter but best not to part off so that you have something to hold.

Mount on the rotary table and zero it's handwheel, bring the cutter into contact with the 0.514" diameter and zero the axis. Put on a cut of 0.069" ( 0.257 - 0.375/2) lock the slide and make a cut. Rotate say 4 degrees and make another cut, rotarte another 4 degrees and cut.

carry on like this with the last cut being 230deg ( 360-130*) for the exhaust and the last cut being 240deg (360-120*) for the inlet.

You will get a flatter topped cam than shown on the drawing and the last job is to file the 0.093" radius and blend in the facets around the base radius


*The jig probably has a larger angle so that when the tappet clearance is taken into account the cam will have an actual effective rotation therefore opening of 130/120 so machine yours to the larger angle


Edited By JasonB on 05/04/2019 19:31:41

JasonB05/04/2019 19:23:15
21284 forum posts
2416 photos
1 articles

As there is not much to come off you could also do it with the blank sticking vertically up out of the rotary table

Again touch off on the 0.514" dia with the side of the cutter, right hand side of blank would be best, then move the work away from you and put on the 0.069 cut which would be a negative x axis move then wind the work back towards you and stopping when Y = zero. Now turn the table the required 230* or 240* degrees and lock it when you get to that position before feeding the work towards you again to cut the second flank.

If the 0.069" is too much you can do it in two or 3 passes


Edited By JasonB on 05/04/2019 19:32:14

David K05/04/2019 20:03:06
258 forum posts
259 photos

That's great Jason thanks , I presumed the flank had a slight radius, just curious but how do know

the flanks are flat.

JasonB05/04/2019 20:06:38
21284 forum posts
2416 photos
1 articles

As it does not give a radius on the drawing presume it is flat.

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
walker midge
Eccentric July 5 2018
rapid Direct
JD Metals
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