Cam milling calculator

[nx06563]

I am thinking of starting the build for a Howell V-4 and thought I would try a couple of the hard pieces to see if I can do it.
I am trying to make the cams on a mill and need the Cam Calc program the motor boys put out several years ago. I got to the site and found the calculator but I cant get the program to work.
I like their method of advancing the cam 4 deg on a rotary table and adjusting the mill height to create the cam profile.

Does anyone have a version of the calculator that will work on windows 10 or excel?

This build may be the end of my model engine career.

Thanks,
Hogan

 

[rklopp]

See this thread: <http://www.modelenginemaker.com/index.php/topic,3547.45.html>

 

[nx06563]

The link for the excel spreadsheet version is gone. Has no luck with it. But thanks for the try
I wonder if its my computer

Thanks
Hogan

 

[rklopp]

The spreadsheet link gives me a 404 Page not found error, too, so it is not you computer. I even have a DropBox account.

 

[Jasonb]

It's available from Rod's (Tangler) Dropbox to download, see link in this thread, just opened for me without a problem. May have moved it about since that older MEM thread.

https://www.model-engineer.co.uk/forums/postings.asp?th=141935

 

[nx06563]

Thanks, I got it
Much easier than working it out on a cad program which I did out of desperation.

Thanks
Hogan

 

[tornitore45]

Defining a cam geometrically is one thing but machining the correct profile is a different thing. In a home shop with a manual mill the profile is approximated with a series of discrete cuts creating facets. Many cuts make the surface sufficiently smooth, that is not a problem.
There are two way to cut the cam on a vertical mill.
1) Cam axis parallel to the spindle axis. Boring head with the tool looking inward. A series of "moon crescents" are lobbed off reaching the base circle. Cutting continues around the blank for less than 360* leaving a protruding lobe untouched. This method present no problems.

2) Cam axis perpendicular to spindle. As the cam is indexed a few degrees at the time the end mill is raised or lowered according to a table until the full circle is completed.
This method is more versatile, it can produce any profile not just a series of arcs. However the profile approximation depend from the tool shape.
The tool is not cutting on the tangent to the profile curve. The cutting edge meets the cam profile on a sloped surface. The cutting tool will cut metal where is supposed to be and also on the up slope which happen to be higher than the tool profile.
The metal cut on the up-slope may or may not need to be cut, it may remove part of the metal that is not supposed to be removed in the next indexing.

A a small end mill is better than a large end mill and a small ball end mill is better than a small flat end mill.

The same result are achieved by using a regular end mill side cutting and changing the cam axis spindle axis relation 90*

The cam profile slope, the tool radius and the indexing angle all play in defining the "scalloped" cam surface.

One final observation. The ball end mill must be moved across the width of the cam. Using the end mill as a side cutting tool in the proper orientation the entire width (thickness) of the cam can be cut for each indexing position, however this method does not allow to cut multiple cams stacked along the camshaft.

 

[TSutrina]

Many years ago I designed a volute where the ID was a cone with the cam machined into the cone shaped OD to the ID. Since one revolution was needed, 360 deg. The contractor chose to machine it as you suggest from the top with the face of the cam produced by the end of the mill, an end mill. He wrote back saying he couldn't produce the part. I told him that the volute was designed to be machined with an end mill cutting with the face of the end mill producing the ID cone and the shank the cam surface. He had no problem producing the volute on a milling machine with a CNC rotating head with the axis set at the cone ID as horizontal. The angle of rotation corresponded to an X position adjusted for the face produced at the tangent point of the cam with the end mill diameter chosen. All surfaced were as machined on the final product from the mill. The exit port for the volute was machined separately.

 

[tornitore45]

TSutrina I can not visualize the part you describe but I get the idea of ofsetting the spindle axis. The result is that the tool edge cut at the proper height and the tool face spins above the previously cut surface. The offset is +R going uphill and -R going down hill. R = the tool radius. Since the cutting is done by a round tool edge the tool need to traverse the entire cam thickness.