Heart shaped cams

[BillScheltema]

Hi all,

I am upgrading my winder and thought I may look into a manual traverse.
So, instead of a motor driving the cam I will do it myself thereby leaving in the human nuances.

Have any of you guys played around with the heart shaped cams? Wheres a good place to start.
I vaguely remember reading an online article with Jason Lollar and there were some photos of some, but can't seem to find the article now.

Bill

[Bruce Johnson]

Bill, your question is confusing....If you're going to disable the automatic feed, then you won't need any cam at all.

The automatic feed system in a winder can be operated by a motor-driven cam, or by some kind of a leadscrew. The cam type systems are the most common because they're usually simpler to build. If the cam is a simple eccentric (that is, a circle mounted off-center), you'll get a back and forth feed motion, but that motion is non-linear across the width of the bobbin. The feed arm spends more time at either end, and moves quickly across the center. So, the wire buildup will be uneven, too thick on either end.

There are different ways to compensate for that non-linearity in the cam and the linkage. A common way is to redesign the cam to change the rate of acceleration and decceleration at either end of the travel. The result usually ends up being heart-shaped. So, that's what a heart shaped cam is for, to flatten out or reshape the inherent non-lnearity of a cam driven automatic feed mechanism.

Designing a cam like this takes some serious math and geometry. There are whole books written about how to design simple cams. The actual shape depends heavily on the geometry of the linkage and the cam follower. Realistically, you work by trial and error, taking guesses, making up cams, and trying them out. You may not ever get the feed perfectly linear, but you can probably get close. But then, you may not want the feed to be precisely linear. You may want the wire to build up slightly in the corners. Reworking the cam shape from a simple eccentric, you can change the feed motion profile to whatever you want.

But, that's all about fine-tuning automatic feed winding, not hand-winding. Which do you want to do?