Advice please on case hardening camshaft

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Basil

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I've done quite a bit of research on case hardening and understand the process but having never tackled it before can anyone please give some pointers. My biggest worry I think is distorting the shaft severely and having a none usable component. The Kasenit has been on my shelf for 20 plus years. Can it go off?
Thanks
 

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You probably won't need to harden the shaft. With the 10lb or less springs there wont be alot of pressure pushing on it. With the minimal time we actually run these engines it will probably last 50 years. My peewee is 11 years old and the cam is still camming like the day it was made. As long as it gets lubrication it will last many many years.
 
Thanks Steve, it’s definitely something I’ve been thinking about. In the bigger engines I build I now use a 10 wt synthetic oil that has proved to be far superior to to anything else I’ve ran as far as wear is concerned. Worth a try. The lifters are hardened and I took advice from other builders of the Seal major and enlarged the lifter heads so the cam does not ride up the side.
 
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With hardened lifters you might have to. I make my cams with O1 tool steel/drill rod and the lifters from 12L14 leaded steel. The idea being the cam is harder than the lifters so the lifters wear more. In your case the lifters are harder than the cam so I would either harden the cam or make new, softer lifters. I could be wrong but that's how my brain works. Its easier to make new lifters than a new cam.
 
I tried it once and once only.......took evey precaution but still came out banana shaped.

What I tend to do these days is machine up all the cam blanks in pairs from drill rod (silver steel) , pin all with roll pins to the shaft I will be using (about 5mm diameter) , grind the cam lobes, remove the pins and harden just each cam pair, replace on the shaft, polish , finished.
 
There is a lot of good advice from seasoned engine builders here - but if you MUST harden the cam perhaps read up on Eric Whittles build of his 10cc air cooled aero V8, he hardened and tempered the cam which was made in one piece from silver steel (drill rod) - I reproduce the cam hardening procedure here - as it is only a very small percentage of the complete magazine series I believe fair use rule applies.

Heat treatment

Hardening and tempering of the camshaft was left until the engine was completed and run for half an hour or so to help smooth the cam profiles, particularly the lobes. Whether there was any advantage in this is difficult to say for sure.

The camshafts of my two Cirrus engines were left unhardened. The cams are much wider than those of the V8, and the contact area of the followers much greater so the wear was virtually non existent and I considered hardening to be unnecessary. In the event, due to the narrower width of die V8 cams and despite the risk of distortion, I decided to harden and temper and, to my surprise the shaft did not distort at all.

The shaft was brought to red heat with the propane torch and plunged vertically into a quart sized plastic container of cold water. The three journals were polished with fine emery to steel brightness and the shaft tried in the bearings. It was a perfect fit and rotated with no binding at all. Tempering was accomplished with very low heat, playing a gentle flame from end to end until the three journals turned a light straw colour. The shaft was then plunged into cold water.

The 18 tooth crankshaft gear is case hardened.
 
Thanks Peter. Unfortunately now junk. I'm not sure what went wrong. I followed the instructions on the can. Did a couple of carbon soaks then a water quench. Maybe it was in the oven too long?? Has pits and bumps on it and has also shrunk some. Only very slight warpage. Not doing that again! Need to regroup, thinking of EN24T. Machine and grind. This cam was machined only and out of mild steel. Building a Seal Major 30cc for marine use.
 

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The shaft was brought to red heat with the propane torch and plunged vertically into a quart sized plastic container of cold water.

I even made a jig to hold the cam exactly vertical for the drop and it still came out like a banana.
What isn't mentioned is that even the heating process can have a bending effect.
 
Thanks Peter. Unfortunately now junk.
Oh bummer, sorry to hear that. Do you think it was the mild steel that stress relived more-so than a tool steel? Even so, as others have indicated, I've read mixed results with liquid quenching varying from OK to not good. Probably the devil is in the details. I have seen some successful built-up cams from pre hardened lobe components attached to common unhardened shaft. Not the purest way I suppose, but OTOH they ran so maybe its one of those choose your poison type deals. I've also wondered about using air hardening tool steels but I haven't heard much about that for whatever reason.
 
Going to order up some EN 24T and see how it holds up as is. What is the opinion on making the lobes pretty much as wide as the full lifter head? As mentioned the spring pressure is very light and with the oversized lifter heads the cam ramps are less stressed. Maybe a high zinc oil also.
thanks for the input everyone. Learning lots👍
 
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Hi Basil I'm building the Sealion and in ETW's writings he stated case hardening the cam and that if you were worried about distortion get it hard chrome plated. I was like you very weary of the distortion so I looked at hard chrome plating but you get a change in dimensions as you are adding material.
I took my cam to a specialist hardening company to get their views on it and they agreed that distortion was a possible outcome. But the good news was they did Tufftriding which was stated by them to be a better alternative to hard chrome plating and because it is done in a salt bath at around 650c as opposed to case hardening at around 950c the risk of distortion was a lot lower and no change in dimensions.
So that's the way I went and the cam slid straight in the bearings and rotated just the same prior to being treated'
The rockers I case hardened
Paul
Cam3r.jpg
 
Picture from a UK builder of the Whittle V8 camshaft still to have the lobes finished as referred to above.
 

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Hi Basil I'm building the Sealion and in ETW's writings he stated case hardening the cam and that if you were worried about distortion get it hard chrome plated. I was like you very weary of the distortion so I looked at hard chrome plating but you get a change in dimensions as you are adding material.
I took my cam to a specialist hardening company to get their views on it and they agreed that distortion was a possible outcome. But the good news was they did Tufftriding which was stated by them to be a better alternative to hard chrome plating and because it is done in a salt bath at around 650c as opposed to case hardening at around 950c the risk of distortion was a lot lower and no change in dimensions.
So that's the way I went and the cam slid straight in the bearings and rotated just the same prior to being treated'
The rockers I case hardened
PaulView attachment 127463
What material did you make your cam from?
 
Hauck Heat Treatment - Tufftride QPQ (hauckht.co.uk)
This is the company I used
Also check the web for hardness for hard chrome plating steel
Then check the web for hardness for Tufftrided steel

Paul
They had no problems with a small order like this? If you don't mind what was the cost? I was thinking of machining the next one out of something hardened and tempered to a machinable state and see how it holds up. Thanks
 
Has anybody used pre-hardened stress proof material? Around 30 on the Rockwell hardness scale, so should wear much longer than mild steel, but not so hard that it cannot be machined (and quite beautifully) with HSS tooling (or carbide, of course). I've never used stress proof for a cam, but have used it a time or two on other products - it really does machine beautifully.
 
Just make one out of silver steel and make the lifters out of leaded steel and call it a day.
I hear what your saying Steve. I was hoping not to have to throw the lifters away too. Thought I made a nice job of them!
I have a friend that uses Stressproof for 2 stroke high performance liners and they work excellent even though they look like swiss cheese with the massive ports.
Putting away in a box for a week. Not quite retired yet and work is building up. Thanks for the help guys.
 

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