Hi again magno_grail:
It sounds like you've convinced yourself you want to try to make this work.
If that is true, you will need to adapt the carriage to allow you to mount the toolpost grinder on a linear bearing slide or a swingarm you can tie to a lobe template that rotates with the spindle as you've alluded to.
That part is pretty straightforward.
Be aware though, that on a cam grinder the workhead is the one that swings; not the wheelhead.
That allows a really stiff mounting for the wheelhead, so the wheel can't move even with high wheel forces.
Here's a link to a Youtube video:
CB Performance - Cam Grinder - YouTube
Fortunately though, a BSA motorcycle camshaft is not very long and it is comparatively stout, so you will likely get away nicely with suspending it between a collet and a live center, and won't need steadies.
Developing the proper cam profiles I assume you know how to do, and finding a way to index the cam blank properly so you get the four cam lobes in the proper radial orientation, I assume you also have a plan for.
Do you know how accurate these features need to be?
As I commented before, dedicated cam grinders have big wheelheads, big wheels and what sounds like hard wheels, running in a very rigid setup with a lot of flood coolant to keep the heat down.
The grinding forces are very high compared to normal cylindrical or surface grinding because the entire width of the lobe face is ground at once, and the radial infeed is what controls the force.
Anyone who's ever done plunge grinding on a surface or cylindrical grinder knows that the loads on the wheel go up hugely as the DOC increases or as the WOC increases...with a 1/2" wide wheel in full contact your DOC on a wimpy grinder like a Boyar Schultz or Harig cannot be very deep...of the order of tenths per pass if you want to keep the spindle loads down enough to avoid bogging down the wheel.
The best reasonably sized toolpost grinder is no match for even a Boyar Schultz surface grinder spindle for rigidity, and mounted on a swingarm on a wimpy lathe carriage, I expect it to bounce a bit, just from the slack in the setup.
So you may have to use a very narrow wheel and step it over several times to keep the loads down enough to be successful.
If you don't get the blends perfect from all the stepovers, your lifters will ride on the ridges.
As I said before I don't know automotive machining at all, but I have spent quality time around grinders.
I may be full of shit, and you may be able to ignore all I've said and showcase a brilliant job you can display with pride.
But these are the areas I'd be mentally preparing to overcome if I was contemplating tackling a project like this.
I'd love to hear michiganbuck and eKretz weigh in on this...both have lots of grinder time under their belts too.
Another detail worth considering; from what I've seen of BSA camshafts, the lobes are crowded right together with only a very narrow space between them.
That means your wheel has to run right up to the lobe next to the one you're grinding.
If the setup is even a little bit off, or you get careless, you're going to smack that neighbour lobe into your wheel and the result will be ugly.
Here's a link to a picture:
BSA Replacement Camshafts - SRM / Hepolite - A50 / A65 / A7 / A10
So lots to watch out for and lots to anticipate when you try this.
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