Merlin V12

[JRR]

Hi Terry
I see that you are going to start on the camshafts . Might I suggest that you mill a hexagon on the end of each shaft ,it will make it easier to set the timing as you need to rotate the shaft before you lock up the screws on the sprockets.
John

 

[mayhugh1]

Great idea John. Thank you.
I'm trying to decide whether to make the cams from single pieces of steel or to build them up. I was thinking about making 'spools' that would consist of an intake lobe and an exhaust lobe on either side of a bearing. Six spools would be needed for each camshaft and they would be bored to slip over a central rod and be Loctited. I'm still trying to figure a way to insure I get the phasing between the spools done quickly and accurately during assembly before the Loctite sets up which will happen almost immediately. I might be able to delay the curing by chilling the Loctite before use. The lobes on the spools would be easy to machine on the mill, but I would also introduce another thousandth or so run out in the bearings with the build-up. But the result might be better than trying to make them from single lengths of steel. What to you think? - By the way, it's OK to post your comments or recommendations in my thread if you like. - Terry

 

[JRR]

Great idea John. Thank you.
I'm trying to decide whether to make the cams from single pieces of steel or to build them up. I was thinking about making 'spools' that would consist of an intake lobe and an exhaust lobe on either side of a bearing. Six spools would be needed for each camshaft and they would be bored to slip over a central rod and be Loctited. I'm still trying to figure a way to insure I get the phasing between the spools done quickly and accurately during assembly before the Loctite sets up which will happen almost immediately. I might be able to delay the curing by chilling the Loctite before use. The lobes on the spools would be easy to machine on the mill, but I would also introduce another thousandth or so run out in the bearings with the build-up. But the result might be better than trying to make them from single lengths of steel. What to you think? - By the way, it's OK to post your comments or recommendations in my thread if you like. - Terry

Hi Terry
I am pleased you liked the hex on the camshaft, you won't regret doing it . Just make it a little bit longer.
As for the camshafts, I think you should make them in one piece, although I can understand your reluctance to milling them on a conventional dividing head as the chances of a stuff up are very high. I have a dividing head on which I am able to index individual degrees which makes it a lot safer. When you have all the degrees worked out for each and all the cams it was quite straight forward. I did a test run first on some free cutting mild steel,when I was happy with that I carried on with drill rod and left it soft as it has roller followers.
Silly question, how do I post to your threads?
John

 

[JRR]

Great idea John. Thank you.
I'm trying to decide whether to make the cams from single pieces of steel or to build them up. I was thinking about making 'spools' that would consist of an intake lobe and an exhaust lobe on either side of a bearing. Six spools would be needed for each camshaft and they would be bored to slip over a central rod and be Loctited. I'm still trying to figure a way to insure I get the phasing between the spools done quickly and accurately during assembly before the Loctite sets up which will happen almost immediately. I might be able to delay the curing by chilling the Loctite before use. The lobes on the spools would be easy to machine on the mill, but I would also introduce another thousandth or so run out in the bearings with the build-up. But the result might be better than trying to make them from single lengths of steel. What to you think? - By the way, it's OK to post your comments or recommendations in my thread if you like. - Terry

Hi Terry
I am pleased you liked the hex on the camshaft, you won't regret doing it . Just make it a little bit longer.
As for the camshafts, I think you should make them in one piece, although I can understand your reluctance to milling them on a conventional dividing head as the chances of a stuff up are very high. I have a dividing head on which I am able to index individual degrees which makes it a lot safer. When you have all the degrees worked out for each and all the cams it was quite straight forward. I did a test run first on some free cutting mild steel,when I was happy with that I carried on with drill rod and left it soft as it has roller followers.
Silly question, how do I post to your threads?
John

 

[mayhugh1]

John,
Thanks for the reply. I'm still trying to make up my mind, but I highly value your input. I've just completed a successful cam blank turned from a single piece of steel, and so I feel more comfortable now.
You can post in my thread in exactly the same way that you post in your own thread. The forum is set up so that you can post comments or questions in anyone's thread. Just use the reply button at the bottom of the last post in any thread that you want to comment on and then type in your comment just as you have been doing in your own thread. - Again, thanks - Terry

 

[mayhugh1]

John,
Can you tell me what you did for valve springs. I don't find anything in my documentation about them.

Best Regards,
Terry

 

[JRR]

Hi Terry You are quite right I have no details of the valve springs , so I wound mine up out of .035 dia wire with a pitch of .1 & a length .625, it worked for me.
That was a challenge making the timing change cover ,even more so when you come to thread in the chain with a length of string!
You might like to consider fitting ball bearings to the magnetos as it will solve a lubrication problem an remove any load on the gears.
Kind regards John

 

[mayhugh1]

John,
Thanks once more for you insight and invaluable help. Don't be shy if you think of anything else. - Terry