Box Cams

I am preparing to machine my Box Cam. I would like to do this using a 4th Axis on my CNC Mill but since this would cost a Bazillion Dollars to add, it looks like it needs to be done using Neanderthal methods or almost.

Using what I got, I was thinking about setting up the blank up on a Spin Indexer with the OD finish turned to fit the Casing and the ID at 2.450\". I would then mill the 1/2\" slot and plunge cut the Cam Track using a .200\" end mill .200\" deep by advancing the Cam 1 degree on the indexer and repositioing the X axis usng a G81 canned cycle. The Cam Track would not be cut completely through the ID. After the Box Cam is mounted and secured in the Casing I would setup the assembly back in the lathe and final bore the ID. This would open the bottom of the blind Cam Track.

This is a tedious way of doing the operation but I think that it will work and that the error will be small. Has anyone attemped this and if so what were the results?

Is there a better approach other than the paper template and hacksaw approach?

Does anyone have an EXCEL Spreadsheet that would calculate the Cam Track Points?

Thanks

nitewatchman

I could draw it in Mastercam and Email it to you as a .mc9 or a .dxf file and/or post it as a generic g code file. I would have to have a much clearer understanding as to what you want as far as data is concerned. I just bought a CNC indexer and I was thinking along the same lines. It\'s a YUASA UDNC-100 . Cutting the total depth in one pass (in steel) would be a pretty hard cut for a .2 endmill. And if you don\'t cut all the way through, the bottom of the endmill is plung cutting all the way around and you know it\'s hard on a endmill to plung cut. It\'s not a easy job either way you go. As for me, :?  I can\'t make up my mind which way to go!
R-R

If you have the material to use you could do it in two halves. For doing it in a manual indexer, I would think that you could program your mill to come in and using a longer endmill, cut a line at the angle desired, rotate and do the other angle. This would be done with it roughed out, or work it out in your passes. Another idea is if your cnc is 3 axis, use a ball endmill and do the angles in the z axis.

I did mine on a 4th, but as somebody says, if you make both halves separately, you could then clamp them track-side-up in a vise and mill the contour on a 3-axis machine.

Thanks for the feedback and assistance!

[quote name=\"R-R\"]I could draw it in Mastercam and Email it to you as a .mc9 or a .dxf file and/or post it as a generic g code file. I would have to have a much clearer understanding as to what you want as far as data is concerned. I just bought a CNC indexer and I was thinking along the same lines. It\'s a YUASA UDNC-100 . Cutting the total depth in one pass (in steel) would be a pretty hard cut for a .2 endmill. And if you don\'t cut all the way through, the bottom of the endmill is plung cutting all the way around and you know it\'s hard on a endmill to plung cut. It\'s not a easy job either way you go. As for me, :?  I can\'t make up my mind which way to go!
R-R[/quote]

I was thinking that if the plunge was started in the 1/2\" slot that it would only have to cut on the lead edge of the end mill and the center would not have to cut. The depth of each cut is about 0.025\" on the lead side of the hole. Since the bottom of the groove rotates away from the cutter on each index there is clearance generated for the end of the cutter. Cutting a blind groove would also allow the Cam to be mounted in the Casing before cutting it apart.

I lean this way since the critical part of the Cam is done or the blank is scrapped before a lot of the less critical work is done. Requires some thought.

I also considered contouring the Cam Track using a ballnose end mill. I used this approach to machine the ears for the Crank Shaft on the Side Rails to wrap around the Casing. The programing can be done in Smart Cam and I think it would work but I think that I will try the indexer approach first.

nitewatchman

nitewatchman
I plan on doing mine on a bridgeport using an indexer. I have a file a programmer wrote for me to use on my manual machine. I could send it to you if you are interested.

Mike

Thanks for the offer Mike, I would be very interested!

nitewatchman

Nightwatchman: What I was talking about is if you are milling with a flat bottom endmill (not a ball) and rotate the work under it, the leading half of the bottom of the endmill is plung cutting some. Not much, but it does plung cut a little. I\'ve done several job like that and it wears the tool. Many times you done have any choise.. I guess I\'m splitting hairs....
R-R

[quote name=\"R-R\"]Nightwatchman: What I was talking about is if you are milling with a flat bottom endmill (not a ball) and rotate the work under it, the leading half of the bottom of the endmill is plung cutting some. Not much, but it does plung cut a little. I\'ve done several job like that and it wears the tool. Many times you done have any choise.. I guess I\'m splitting hairs....
R-R[/quote]


You\'re correct there will always be some degree of plunge cutting. Best to avoid if possible.

nitewatchman

Nitewatchman: What do you think about putting the cambox on a arbor with some tiny toe clamps about four on each end. Then you can use a 3/16 ball mill (I have a couple of them)and mill down the middle of the slot. Measure the heigth and make a adjustments as neccessary to get it right. .00625 in each direction. Again, I\'m spliting hairs. Don\'t forget the pictures.. Lots of pictures...

Thanks
R-R

Nitewatchman
Machined my box cam today using the layout I sent you. It worked great except that TDC is actually BDC.

Mike

Great,

I am setting up to do mine now, plan on using the same approach.