Manually milling non-circular curves

M

Maplehead

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Hi All
I have a rotary table and I’ve used it for milling circular curves, when I have a center hole to pivot around. So I get the concept and use.
However, I have designs with curves that are not circular. Can I manually mill these curves?
I imagine the answer is yes but I would have to plot out every single thousand’s of an inch movement of the X and Y dials.
Is that true and is that how the old timers did it? Right now CNC is not an option. $$$
 
Yes, it just takes a little practice. Usually when I make a mistake with the movement it is when I have paused to move in another direction. You just have to make it a point to think of the effects of your hand movements before you move them.
I call it etch-a-sketching.
I just made this for my wife for Christmas. All etch-a-sketch.
154579899583683ef1d3eb8586a430c833bdcab701d77a78501aa2b5a114a6c41bca7c69ec75875838915f74d8fda4...jpg
 
Thanks for the reply. That bone looks pretty good and the ends are similar to what I would be making.
So for a little more detail, I imagine the procedure would be something like, down 1 on Y, left 1 on X, for example.
Wouldn’t that create a bunch of little right angle cuts, like teeth or serations?
And plotting that from my CAD program seems like a nightmare.
 
Yes, very rough edges. I stayed outside the lines and finished it with a disk sander.
 
The larger dialmeter cutter you use, the smaller the jags will be. Yes, think Etch-a-sketch. That'll do it.
 
Also, you can make smooth curves by moving both x and y at the same time. I have heard of people that are amazing with this, but not me.
 
If you use a slow powerfeed on one axis you just need to constantly adjust the other axis by hand. Tom Lipton made a video as part of his wilton baby bullet build series where he explains how to use a template to create nice curves this way. Finding the link from my phone is too much hassle, sorry, but I think it was somewhere around part 15 of the series.

Sent from my SM-G930F using Tapatalk
 
Yeah, I imagined that if I could attempt both dials at the same time then the cut would be angled and eliminate the scalloped cusps. However, I’d have to operate with the accuracy of a machine to do that.
 
Doing it by X, Y, and cranking both at the same time or alternately can be a disaster unless you do a good amount of practice first, to get your hand and arm muscles and your brain on the same page without making any mistakes. I suppose that a good amount of practice on scrap would probably do that. I have had terrible luck trying to look at the line while my hands made the cut. It is just way too easy to make a mistake. It is not intuitive, it must be learned eye/muscle coordination. Doing it bit by bit carefully but off the cuff will probably lead to a glacial time frame for doing the cut, while also still being risky of making mistakes. Going slow is very hard on the cutter as well...

Consider other techniques to get you to the result you want as well, there are many ways to take a part to finished size, like roughing it with plunge cuts, followed by sanding and grinding it to final shape, just one option.
 
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