Modified Sine Question for John Summers or other Cam Specialist

[mayday]

I quoted a very large Cam plate that is 4" thick. it has a 4.02 wide cam track that has to be flame hardened to 60 rc. the roller is 4". I would like to use a smaller cutter to finish this if possible but will I still get the true curve by doing this? If I verify and save as an STL file will that give me a good model to use to toolpath?

[Harryman]

What is the format of the info that you have?

 

Can you get the math that was used (if any) to develop the shape?

[mayday]

Harry, I use the Mod sine post that John wrote to generate the curve centerline of the cam roller. Generally I try and use the same size cutter as is the cam roller to get the best edge profile. using a 4" shell cutter is not the way I want to do this so I am wondering what effect that will have on the edge profile of the cam path using a small cutter

[Harryman]

If you have math can you use Fplot and just create an outer and inner contour?

 

Is this a (sort of) circular cam track? Or in one end of plate and out the other?

[mayday]

in and out. with a dwell and start angle,end angle for the modified sine. I have tried the fplot without luck. the posts John wrote work great. for either barrrel or plate cams. they have the formula's built in and the post draws the cam path in MC

[Roger Peterson]

Mayday, since you have an accurate centerline path for your cutter, how about doing a contour toolpath with an 4" diameter endmill using cutter comp in control to left, then again to the right. Then backplot saving as geometry, which would give you the walls of your cam profile. There may be more to it than that, just a thought.

 

 

[mayday]

That was my original that Roger, then thinking why not an STL to surface to solids thru verify.

just for looks

[LNDCAD]

Once you have the centerline path of the 4" diameter cutter, you could create a solid of your cam blank and then use the centerline path to sweep the cam track surfaces. Now you have an inside and outside face of the cam track generated by the 4" dia. cutter, and you can run any tool diameter to finish the track. The trick is to not try to generate the original cam track from a tool that is smaller than the roller, or you could create undercut areas that the larger roller cannot follow. Is sounds like you have a good post to create the modified sine geometry. I have never used the post that you referred to, but I have several other programs that can create cam geometry if you have any trouble generating the initial path. E-mail me if I can be of any help. I have been on the receiving end of much help on this forum and would be happy to repay some.

[mayday]

Thanks all

Lndcad, I am always interested in cam path generation software. I seem to run into these jobs at a pace where I have to my brains to remember how I did it the last time

[Harryman]

What is the original root for the geometry? Is it several intermediate points that need to be smoothly connected? Is a true mathematical sine curve sought?

 

Please forgive my overactive curiosity gland. I really dig machining math based stuff.

 

I like the sweep solid idea.

[mayday]

Harry, email me, I reenabled my email. I'll return the cam posts to you to play with

[mayday]

should be some samples in it Harry, Im blasten outta here. talk to ya later

[Harryman]

Thanks, and Happy Labor Day!

[John Summers]

The easiest way to deal with a cutter which is smaller than the follower might be to offset the follower CL geometry to the actual cam contour (OFS CTOUR), then use that contour as drive geometry with any size cutter. This is NOT the same as building the cam at the plate dimension.

Harry, harmonic motion IS a sine wave, but cams use MODIFIED HARMONIC, which modifies the first 1/8 and last 1/8 of the sine wave. This is to ease into the acceleration, which minimizes 'jerk'.

FYI for everybody -- CAM.MPK has been updated recently. There appeared to be a glitch in barrel cams.

[mayday]

quote:

---

CAM.MPK has been updated recently. There appeared to be a glitch in barrel cams.

---

is it on the ftp site John? if not could you email the udate to me? no big hurry, im set with the plate cam post

 

 

Thanks

[John Summers]

The plate cam was OK. There was a little glitch if you selected LINEAR cam, which is used for barrel cams. The programs are all on the FTP site MISC...

In my previous post, it might have been clearer if I said "offset follower CL by the follower radius, then use that contour with the smaller cutter."