Cutting cam for Farmboy

[Boot]

How do I go about cutting the cam for the Farmboy engine? The article in home shop magazine is way above my understanding. I was thinking of offsetting the cam in my 4 jaw chuck but don't understand how far off center it needs to be. Anyone cut any cams for one of these Farmboys lately?

 

[stevehuckss396]

I can't help you with the farmboy as I am not fimilar with that engine but here is the formula to find the offset

Offset = Flank radius – half the base circle

 

[kuhncw]

Hello Boot,

I've not cut the Farm boy cam, but I have the prints

I am guessing the article you mention is Graham Meek's cam article in the newest issue of Home Shop Machinist? His article applies to cam lobes with a radius on the flanks. The Farm boy cam has flat flanks which are much simpler to cut, assuming you have a rotary table. The cam nose radius is 0.335 inches, so start with a cam blank that is 0.670 dia. The base circle is 0.500 inches dia. Layout the cam outline on the blank. The flanks will be straight cuts, made at the appropriate angles and the base circle will be cut by rotating the part 220 deg as shown on the print. That is a rough outline of the process and I hope it makes sense.

The rotary table can be flat on mill table or perpendicular to the table depending on how you want to set it up.

If you have more questions, just ask. A lot of the HMEM members have cut flat flank cams and can help.

Regards,

Chuck

 

[Boot]

Thanks Chuck ; That will help me and yes it was Graham Meeks article. You have simplified the operation for me. When I cut them I will probably have more questions. That may be closer to Spring time here in PA.