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rolland
04-23-2017, 02:52 AM
http://i291.photobucket.com/albums/ll291/rgh25/cam_zpsyhradatc.jpg
I am needing help setting up to make this cam, I have made cams in the past but not with this dwell. Normally I can use an off set in the four jaw chuck and get by but not in this case. I was thinking (not always good) in using the R/T in the mill but not sure there either. So any help would be greatly appreciated. I do tend to over think things from time to time and that may be true this time. It is for an Webster IC engine.

David Powell
04-23-2017, 04:15 AM
http://i291.photobucket.com/albums/ll291/rgh25/cam_zpsyhradatc.jpg
I am needing help setting up to make this cam, I have made cams in the past but not with this dwell. Normally I can use an off set in the four jaw chuck and get by but not in this case. I was thinking (not always good) in using the R/T in the mill but not sure there either. So any help would be greatly appreciated. I do tend to over think things from time to time and that may be true this time. It is for an Webster IC engine.
If you use a Rotary table on a milling machine you could make this cam quite simply. Take a piece of graph paper, draw the cam to scale as large as you can get on the paper, buy a clear plastic angle gauge ( as found in basic draughtsmans sets or better), set the gauge centre over the centre of the shaft and measure to the edge of the cam in the drawing with vernier calipers every 5 degrees. Scale that dimension down to full size, make a list, work out tool offset, ie if you use a 1/4" cutter add 1/8 " to every dimension. Make another list, Set up, cut blank and then file to smooth. IF you need better accuracy in the cam than you get this way don't ask me ! My cams worked for packaging machines. Regards David Powell.

Peter.
04-23-2017, 04:17 AM
Turn some 3/4" stock down to .712 in the lathe and bore the centre hole. Part off 1.5" long or so. Put it in the rotary table chuck on the mill, cut the two flats .281 from the centre and 62.4 degrees apart then mill the base circle. Back in the lathe to part off.

David Powell
04-23-2017, 04:27 AM
For the round part of the cam you can, of course simply cut that by turning the rotary table while the cutter contacts the work, for the non round part you just come in to the dimension you worked out and then take the cutter away before moving the rotary table and then return to the NEXT dimension. Hope this helps David Powell.

chipmaker4130
04-23-2017, 10:38 AM
Brian Rupnow has a great method for using the RT and mill to make cams. Any slope/dwell you want, even different on each side of the lobe. Maybe he'll fill you in...

rolland
04-23-2017, 07:48 PM
It seems that the little things will cause you the most problems, I could not figure out why I could not get the stock to index correctly. Well it seems that I let the chuck on the R/T slip out off center I could not see the forest for the trees. Once everything was centered it all worked out right. Doing machine work is going to drive me around the bend one day. :p

tom_d
04-23-2017, 11:20 PM
Turn some 3/4" stock down to .712 in the lathe and bore the centre hole. Part off 1.5" long or so. Put it in the rotary table chuck on the mill, cut the two flats .281 from the centre and 62.4 degrees apart then mill the base circle. Back in the lathe to part off.

I'm curious how you calculated the 62.4 degrees.

Peter.
04-24-2017, 02:00 PM
I'm curious how you calculated the 62.4 degrees.

I drew it in CAD and used the measuring tool. Draftsight is free and quite easy to use to a basic standard.

jdunmyer
04-24-2017, 06:52 PM
I have another method that's much better if you need more than one cam:
Use a spin indexer in the vertical mill. You'll have a nice "handle" to hold the work instead of a wimpy clamp screw and you make it an appropriate length, then part off the cams. This works especially well when the cam is a quarter the size of the one shown.

Obviously, you need a mill, spin indexer, and 5C collets.

tom_d
04-24-2017, 10:09 PM
I drew it in CAD and used the measuring tool. Draftsight is free and quite easy to use to a basic standard.

Thanks for the tip. I will have to explore Draftsight. My reason for asking about the angle is that I tried crunching the numbers on paper and came up with 58.8 degrees rotation each direction from the part as drawn to make the flat surfaces. I might have transposed some numbers somewhere along the way.

boslab
04-25-2017, 07:15 AM
Perhaps irrelavent but a method I was showed is as follows, turn 2 buttons to minor dia, drill clearance hole for a screw, and harden, turn stock to major dia, then clamp the disk between the two minor dia buttons by means of a through bolt, file down the cam shape, works for one or two, old fashioned I know
Mark