Machining cam lobes

[StyxParticipant @styx]

I want to machine some cam lobes on the milling machine and I seem to remember a program that gave a list of co-ordinates in the z axis relative to a radial movement. This gave a stepped profile which needed a light dressing with a file. Can anyone shed any light on this or any other way of producing a cam lobe.

Thanks for any help.

Steve….

[StyxParticipant @styx]

[David Clark 13Participant @davidclark13]

Hi There

Draw the cam shape out in a cad package.

Offset the outline by the radius of a ball nose cutter.

Plot the co-ordinates at say every .5mm or 20 thou vertically.

You can then machine the entire top half of the cam then rotate the job 180 degrees and machine all of the bottom.

Sketch to follow after lunch.

regards David

 

[JasonBModerator @jasonb]

Thats a long lunch David

 

There are a couple of calculators on Model engine news site, just turn the blank in a rotary table, adjust z feed mill and repeat.

 

http://www.modelenginenews.org/design/index.html

 

J

[David Clark 13Participant @davidclark13]

Hi There

Rough sketch but the principle should be clear.

The Z height is stepped at say 0.5mm the Y is where the 0.5 intersects with the path of

the 8mm ball nose.
If you move the cutter to these co-ordinates and take a cut, you will generate the cam.

You can start at the top or bottom of the cam, does not matter which.

The path is for the centre of the ball, if working manually the Z will be 4mm lower.

If using CNC, allow the 4mm in length compensation.

.

Edited By David Clark 1 on 30/06/2011 19:33:06

Edited By David Clark 1 on 30/06/2011 22:16:40

[Roderick JenkinsParticipant @roderickjenkins93242]

Steve,

 

As Jason B says, visit Ron’s site from the link -use the mk2 version. I wrote the original SIC article and program, first in GW-basic and then in Q-basic both of which are DOS programs. The Qbasic version still runs under Windows XP, though in a rather small window. I have converted the programs into an Excel spreadsheet. PM me if you would like a copy.

 

If you have CAD then you can draw the cam and then draw a series of lines radially from the base circle centre at 3 degree intervals (using a polar array). You can then read off the co-ordinates of the intersection of the radial lines with the cam profile. This will give you the Z setting for the mill against the rotation from a dividing head

 

cheers,

 

Rod

[StyxParticipant @styx]

Rod, Dave and Jason,

Thanks for all the tips, plenty for me to think about.

 

Steve….

[GaspodeParticipant @gaspode]

I met a guy at one of the shows a few years ago who had made a kind of pantograph type arrangement for tracing the outline of a full-size cam and moving the scale cam against the cutter in the same shape.

 

<pause for a quick bit of googling>

 

The guy’s name is Invar Dahlberg, the model was a Mercer Raceabout, and the tool was used against a grinder – see http://www.craftsmanshipmuseum.com/dahlberg.htm

 

HTH

[GaspodeParticipant @gaspode]

I met a guy at one of the shows a few years ago who had made a kind of pantograph type arrangement for tracing the outline of a full-size cam and moving the scale cam against the cutter in the same shape.

 

<pause for a quick bit of googling>

 

The guy’s name is Invar Dahlberg, the model was a Mercer Raceabout, and the tool was used against a grinder – see http://www.craftsmanshipmuseum.com/dahlberg.htm

 

HTH

[JasonBModerator @jasonb]

This is one I did the other week using the mill method, bit of an odd shape as it needs to work an ignitor as well as the exhaust valve.

 

 

Model Engien Builder mag has been running a series with a cam grinding jig that has a follower that runs on a master or template and then produces the actual cam from that. Basic 3D image here

J

Edited By JasonB on 19/08/2011 17:08:01

[FlywheelParticipant @flywheel]

Hi Steve

Google CamCalc then type in your known figures for your cam, press calculate and the program will work it all out for you

 

regards

[JasonBModerator @jasonb]

Joseph, the link I posted back in June takes you to Camcalc and the newer Mk 2 version

 

J

[WindyParticipant @windy30762]

Hello Steve

 

This link Software for People Who Build Things!
There is a program on cams also many other interesting ones that might be of use to model engineers.

 

Windy

Edited By Windy on 19/08/2011 19:45:56

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