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Author Topic: Cutting Camshafts  (Read 4029 times)

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Cutting Camshafts
« on: October 13, 2007, 05:41:48 AM »
Hi
I have an idea to use my 4th axis to cut camshafts for model I C engines, but need help to go about writing G code.

Has anyone else cut a camshaft on a mill?

The easy route would be to cut indivedual lobes and thread them onto a shaft at appropreate angles, pinned and locktite.

Thanks

Mike  

Offline bowber

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Re: Cutting Camshafts
« Reply #1 on: October 13, 2007, 07:03:52 AM »
It depends on what cam software you have. I have meshcam for doing 3D work and this has a basic 4th axis setting so all you would do is make a 3D model in say Alibre Express and then export an STL file. You would then cut down to say half the depth of the blank and do it in four 90 degree sections, meshcam doesn't keep the 4th axis revolving it just steps it round the treats the job as a new surface profile to do stepover milling with a ball cutter, most likely long and tedious.

You may be able to get a program that can use a flat ended cutter and just revolve the 4th axis round while the Z goes up and down but I suspect this will be quite complicated to work out as the ramps on the cam lobe will not be cut by the centre of the cutter, it'll move to the side of the axis of rotation as the cam profile rotates, just the same as using a flat follower. You cutter would also need to be quite a bit bigger diameter than the cam profile, also the full cutter diameter will only be effective on the centre of the cut so you would end up with a scalloped cut on the ramps.

A better method is to hold the blank vertical in a chuck bolted to the table and use a special cutter that like a T slot cutter (effectively using a horizontal mill), you use a 21\2D CAM program then like lazycam to create the code from a normal cad drawing. Advantage with this method is you don't need the 4th axis :)

The real problem is creating the cam profile in the first place, you can use a spread sheet to drive the cad programs generation of the profile but I've never done this so I have to basicly draw points and use a spline to join them and create a smooth profile.

I'm in the process of making an Edwards radial 5 and the latter method is what I'm doing, I've got the profile and the blank done, I used sheetcam to create the gcode but I've not yet cut the cam, I may get it done this weekend, I'll take some pics if I do then you can see how I did it.

Steve
Re: Cutting Camshafts
« Reply #2 on: October 13, 2007, 08:54:32 PM »
If you want to know all you ever wanted to know about cam shafts, contact or read some of the posts by (NC cams) on CNCzone.com

Offline Ben

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Re: Cutting Camshafts
« Reply #3 on: October 13, 2007, 10:29:28 PM »
In the Nov/Dec 2004 issue of The Home Shop Machinist there is an article on "Building a Model Engine Camshaft Grinder". Hope this will help you with your project. Ben
Re: Cutting Camshafts
« Reply #4 on: October 14, 2007, 09:27:55 AM »
Steve

Thanks for advise, look forward to seeing pics of routine, also Dennis & Ben

Mike

Offline bowber

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Re: Cutting Camshafts
« Reply #5 on: October 14, 2007, 07:54:35 PM »
Hi

didn't get anything done on the radial this weekend, I did a bit of manual machining on a Stuart steam engine.
Times a little limited at the moment but I hope to get on again soon. A little drunk at the moment as well so hope it all makes sense :D

Steve