Webster engine cam question

[cruiser1]

newbie building Webster engine- using plans from this site- page 8 of 21
shows cam to be machined- I have a lathe, mill and a rotary table- what is the proper sequence to machine this part
especially in leaving the .254 on the lobe- is something missing on the print or was I asleep in school?- Thanks in advance

 

[bmac2]

Hi Cruiser
I’m just starting my Webster ( my first IC) so I’m nowhere near doing the cam but being anal retentive I have a plan. :noidea:
Starting with a piece of ¾ stock. To get the lobe on the cam If I measure down .02 (0.021740 on the cad) and scribe a line across it works out to 0.254” wide.

 

[bmac2]

In the lathe drill / ream the .375 hole in the center.
Mount the rotary table centered on the mill, put the piece in a small 3-jaw and set the rotary table to 18 degrees.

 

[bmac2]

Then with an end mill take off .094 rotating the table between 18 degrees and 162 degrees. This should give me something that looks like this leaving the .562 small diameter (not sure what it’s called).

 

[bmac2]

I figure I should be able to finish it off by rotating the table a couple of degrees at a time and running the Y axis in and out until the cut intersects the 0.254” scribe line.

 

[bmac2]

Then just part it off in the lathe. I know a lot of times what makes sense to me can be total gibberish to the rest of the word. I don’t know if this will work in the real world but I hope this helps

 

[Cogsy]

Here's an excellent video by Chuck Fellows showing how to make a single lobe cam with a boring head and rotary table. I've followed this method and not only is it easy, it gives a great result as well.

[ame]https://www.youtube.com/watch?v=ohqO0GIdoLU[/ame]