Camshaft Steels

[GWRdriver]

I have a friend in the UK who is building a "Seal" engine (photo) and he has asked me for a recommendation for a steel for the camshaft which would not required heat treating. He's reluctant to case-harden the cam for fear of distortion and in skimming over the Craftsmanship Museum Seal build web page I see where several of the builders experienced bowing when case-hardening their cams. I have virtually no IC experience so I don't have a recommendation but I would like to help him if I can. So my question is, is there a steel he can use for a camshaft which would not need case-hardening but still wear reasonably well?

 

[Swifty]

There certainly is, a lot of tool steels are fairly hard in there as supplied state, although you will have to purchase from a tool steel supplier. Other members with cam experience will surely have other suggestions.

Paul.

 

[deverett]

In the UK, probably silver steel in its unhardened state wold be first choice if making the camshaft from one piece.

It is readily available from most model engineering suppliers in 13" lengths and relatively easy to machine.

Dave
The Emerald Isle

 

[gbritnell]

I use drill rod/silver steel (W-1 grade here) for my cams. I don't harden them but do harden the tappets. I don't know about this particular engine but one of the old procedures was to make the lobes separately, harden and then pin them to the shaft. I have never tried this method as I thought it would be too much of a pain to indicate and locate each lobe.
gbritnell

 

[Woodster]

UK spec EN24T should be ok, or S155 if you can get it. I make full size cam blanks for a living (Lotus, Cosworth, KentCams, Williams, McLaren, Red Bull etc) and most are S155, but not all.
EN24T can be a pig to machine. S155 machines a treat, but can be hard on tooling due to the high chrome content.
Other specs that MAY be ok are EN16/16T or EN3B. EN3B is suited to case hardening but can be a real pig to get a good finish, EN16 is a general purpose tool steel that machines nice and bright, but may not last as long as an EN24T cam.

 

[MachineTom]

Do remember that model engine are use is measured in minutes per year. With that kind of duty cycle Most anything called steel would work. On mass produced cars and motorcycles the cams are not hardened, but the followers are hardened and ground.

Motorcycles with overhead camshafts have followers that use very hard shims. The shims are used to set the valve clearance, some of the shims have a small OD and could be used as a running surface with a soft follower rather than HT to the follower. Just a thought.

 

[stevehuckss396]

O-1 drill rod is my cam steel of choice.

Don't know what method he will use to cut the cam. If he goes with the offset turning method in the lathe, I have a chart for the seal.

 

[GWRdriver]

Thanks for everyone's suggestions. I've forwarded the information along.

 

[Mechanicboy]

On mass produced cars and motorcycles the cams are not hardened, but the followers are hardened and ground.

Not all, the cam in Peugeot to example has 2 difference cam shaft: The whole shaft made of cast iron with hardened cam running on the lifter of hardened steel or hardened sintered steel cam crimped on hardened holowed (due oil canal) steel shaft running on steel roller mounted on rocker arm.

In my model engine i used cam made of drill rod (silversteel) running on the lifter of cast iron, no problem due the load is less than big brother of these automotive engines.