Forum's Ugliest Winder. . . Almost complete

[David King]

Jim,

I was wrong before, you want the diameter of your unspooling dowel to be 2x the bobbin height.
For example: the distance between your bobbin top and bottom plates is 1/2". You'll want your circumference to be twice that or 1". Your diameter is C/pi or 1/3.14159 which =.3183.
We'll just call it 5/16" or 8mm.
Take a sheet of paper and make a mark in the center.
Take 5/16"/8mm drill/dowel/ (or Bic pen with some layers of tape on it to make it .318").
Tape the end of your string to the bottom of the dowel.
Wrap the string around the dowel a few times and tie the other end of the string to a pen or pencil.
Wind the rest of the string up around your dowel so that all the string is near the base of the dowel and close to the point of your writing implement.
Now stand the dowel and pen upright on your mark on the paper and hold the dowel firmly in place.
(I would glue or thumbtack the dowel to the paper.)
Pull the string taught and start scribing a circle around the dowel while simultaneously letting the string unwind from the dowel.
With each time around you circumscribe the dowel you will be 1" further out from your last line (forming an ever wider spiral).
When you reach the desired diameter for your cam you can stop circling/ unwinding string.
Fold the paper in half making sure your fold line transects the center of the dowel's center mark.
Cut along the outermost scribed line on one side of the paper with a pair of scissors -cutting through BOTH layers of paper.
Unfold your paper and stick it down to the material you want to cut your cam from.
Cut out the cam following the edge of the paper.
Drill through the center.
Stick the cam onto your winder traverse cam shaft.
You are done.

[kayakerca]

Jim,

I was wrong before, you want the diameter of your unspooling dowel to be 2x the bobbin height.
For example: the distance between your bobbin top and bottom plates is 1/2". You'll want your circumference to be twice that or 1". Your diameter is C/pi or 1/3.14159 which =.3183.
We'll just call it 5/16" or 8mm.
Take a sheet of paper and make a mark in the center.
Take 5/16"/8mm drill/dowel/ (or Bic pen with some layers of tape on it to make it .318").
Tape the end of your string to the bottom of the dowel.
Wrap the string around the dowel a few times and tie the other end of the string to a pen or pencil.
Wind the rest of the string up around your dowel so that all the string is near the base of the dowel and close to the point of your writing implement.
Now stand the dowel and pen upright on your mark on the paper and hold the dowel firmly in place.
(I would glue or thumbtack the dowel to the paper.)
Pull the string taught and start scribing a circle around the dowel while simultaneously letting the string unwind from the dowel.
With each time around you circumscribe the dowel you will be 1" further out from your last line (forming an ever wider spiral).
When you reach the desired diameter for your cam you can stop circling/ unwinding string.
Fold the paper in half making sure your fold line transects the center of the dowel's center mark.
Cut along the outermost scribed line on one side of the paper with a pair of scissors -cutting through BOTH layers of paper.
Unfold your paper and stick it down to the material you want to cut your cam from.
Cut out the cam following the edge of the paper.
Drill through the center.
Stick the cam onto your winder traverse cam shaft.
You are done.

Thanks David. That is an excellent description. I will be at it tomorrow!

[David King]

Well I hope I'm right, I just made it up on the spur of the moment but I've never tested it, it seemed like it should do the job. I don't think the overall size of the cam matters but you could start bigger and keep cutting it down to see if anything changes along the way. If it works we could make a little excel spreadsheet that spits out the stick dia when given the bobbin height. It sure beats doing a bunch of math I never understood.

[kayakerca]

Well I hope I'm right, I just made it up on the spur of the moment but I've never tested it, it seemed like it should do the job. I don't think the overall size of the cam matters but you could start bigger and keep cutting it down to see if anything changes along the way. If it works we could make a little excel spreadsheet that spits out the stick dia when given the bobbin height. It sure beats doing a bunch of math I never understood.

My last CAM (post 28 above) design was created on a similar technique. I took a basic heart shaped CAM and bisected it into 16 equal sections (8 per half). Then I took a piece of graph paper and divided the height of the bobbin into 8 sections (8 dots). I lined up the top (curved in section) point of the heart shaped CAM with the first dot. I then pinned the centre of the CAM shape in place. I rotated the CAM on the pin and lined up each bisect line with the sequential dot on the bobbin height segment set of dots and marked the intersection on the CAM. After the 8 intersections were marked on the CAM, I manually "connected the dots" in as smooth/progressive arc as I could by hand, cut along the outer edge of the marked half, folded it in half and cut out the other half. The CAM came out pretty close (again, pictures in post 28 above), but unfortunately, the amount of slop in the markings and pin holding the CAM while it rotated didn't allow for a very accurate set of markings on the CAM and therefore the shape was off. Lying in bed last night going over your 2 X r / Pi formula and the progressive and smooth arc you unwinding technique I think you are right on the money! The progressive expansion of the arc at a constant rpm of the traverser motor should provide a perfect linear transition across the bobbin. Now, that assumes I can make the setup to mark the arc perfectly. String won't do as it is thick and stretches. Braided fishing line on the other hand is extremely thin with zero stretch. I'll setup the sketching part using the milling machine to control the drill bit I'll use as the dowel base for the CAM size I want. Oh ya, did up that little spreadsheet last night before bed! A 7/16" bobbin height requires a .2785" (7.074mm) dowel. :-)

I'll let you know how things turn out. I have to put together some bobbins and lacquer them up, so even if I get the new CAM done today, I won't be able to really test it out until tomorrow. But I think you may have solved the mystery David. Well, at least the mystery I was unable to solve for myself.

.......... edit ............

If the technique works, I'll upload the dowel size calculator I made. Since it is hard to get a dowel the size needed, I created a calculator that gives the closest drill size to the required dowel size in decimal, fraction, number size, letter size or metric, which ever is closest.

[kayakerca]

And the answer to the dowel spiral CAM designer question is. . . .

No perfect CAM out of the box and I was as meticulous as possible in the manual construction process. It produces a CAM that is slow at the inward "V" end and fast at the pointed "V" end and accelerates throughout the entire transition.

That said, I would say the technique provides and excellent base shape for "crafting" a CAM that can be tweaked (which I will).

The p/u below has 7,700 winds and I don't think you could get that or much more with bobbins that are flipped to wind in the other direction where it would then be loading the winding more at the top.

I am adding the Excel spreadsheet (and David King's notes from his post above) that I used created from David's comments. Hard to say if it really matters what size dowel you use to create the spiral when you will end up modifying it signicantly. While the CAM here was crafted with a 7/16" bobbin height in the formula for dowel size, I believe mounting the CAM in the centre would be difficult as you would want to be bang on to the thou'. I think using slots that allow you to fine tune the traverse distance is a better approach.

[ReWind]

In my (somewhat limited) experience with heart shaped cams, you can't move the cam off center to change the traverse throw distance without also distorting the coil shape.

[kayakerca]

In my (somewhat limited) experience with heart shaped cams, you can't move the cam off center to change the traverse throw distance without also distorting the coil shape.

I would agree where the distance of the change is significant relative to the size of the CAM, but if you are adjusting a Strat bobbin height maybe 10 - 20 thou' and the CAM is on the large side, I don't believe it would make a perceivable difference compared with the other irregularities in the bobbin. This current CAM version is ~ 2 1/2" end to end. I'm probably wrong though.

[David King]

It would be interesting to make a series of cams for different traverse widths and see how they compare when overlayed. An adjustable throw cam would be just the ticket if it were a simple matter of widening it side to side with two overlapping sides or a hinge at the pointed end and a jackscrew arrangement to push the lobes in and out. I bet there are patents covering all of that and going back a hundred years.

[kayakerca]

I would be interesting to make a series of cams for different traverse widths and see how they compare when overlayed. An adjustable throw cam would be just the ticket if it were a simple matter of widening it side to side with two overlapping sides or a hinge at the pointed end and a jackscrew arrangement to push the lobes in and out. I bet there are patents covering all of that and going back a hundred years.

That would be interesting, but I think you would want to perfect the drawing, cutting and shaping cleanup to have get a valid comparison.

Here is the Strat p/u wind with the dowel/spiral CAM construction. I think I am happy with this one.

This is as level a wind as I have had with the CAM.

[Eastbville]

Kayakerca, your latest wind looks good. Nice job. I have several major manufacturer's pickups in stock that look similar.

[David King]

WOW! Kayakerca that looks totally great. Thanks for proofing out my totally off-the-cuff, pulled-it-out-of-my-bunghole concept. Maybe we just got lucky?

[kayakerca]

WOW! Kayakerca that looks totally great. Thanks for proofing out my totally off-the-cuff, pulled-it-out-of-my-bunghole concept. Maybe we just got lucky?

Hi David:

As I was saying earlier after the first one I wound with the dowel/spiral CAM, it is an excellent starting point, but definitely needed tweaking to get from the pyramid shapes wind to this smoother one. Great way to produce a start point for a heart shaped CAM traverser though! I am happy with the results from this CAM. Thanks for the idea!

[RedHouse]

... I was wrong before...

Still "less than perfectly correct" David.

...It produces a CAM that is slow at the inward "V" end and fast at the pointed "V" end and accelerates throughout the entire transition.

That said, I would say the technique provides and excellent base shape for "crafting" a CAM that can be tweaked (which I will). ...

That's because that's not the way to design a cam profile. If you want to design a cam profile you have to have a couple things in mind, the base circle, the displacement (travel) and what type of "profile" you're after.



In our case, you are after "Uniform Motion" (see Fig-a), then, to lay out your profile is actually easy, just get out a ruler or your favorite drawing software and follow the procedures in the second picture attached (sorry it's so pixellated)



First decide how many sections (degrees) you want to use, in the atached pic I chose 15° intervals, then decide on your displacement (travel) which is represented by the top and bottom lines in the horizontal scale (Fig A)

Draw your profile across the horizontal graph (Fig B), this represents 1/2 the diameter but never mind that right now. Then draw your base circle and conect the intersections of the horizontal graph to the circles in the cam degree graph (Fig C,D,E).

Then plot a location (ie; a dot) at each intersection there the circles intersect with the degree divisions in the cam degree graph (Fig F) , then conect the dots (Fig G)... it's really as simple as that. Then you can cut out the profile in whatever material you are using.

In my old Lollar based winder (v2.0)



when I got tired of hand-guiding the traverse I made this heart shaped cam which worked great;

http://www.classicamplification.net/...mMotionCam.MPG

and IMHO made some nice coils:



(the wire is actually nice and even and in a slight arc, the pic was taken with a close-up lens which skew's the look of it)

...Here is the Strat p/u wind with the dowel/spiral CAM construction. I think I am happy with this one.

This is as level a wind as I have had with the CAM.

And that is a nice looking coil BTW.

[David King]

Brad,
Thanks for the explanation and the beautiful graphics however I don't see any significant difference between your time graph and my string unwinding trick. I can certainly live with still being wrong but I'd love to know why.

[kayakerca]

First decide how many sections (degrees) you want to use, in the atached pic I chose 15° intervals, then decide on your displacement (travel) which is represented by the top and bottom lines in the horizontal scale (Fig A)

Draw your profile across the horizontal graph (Fig B), this represents 1/2 the diameter but never mind that right now. Then draw your base circle and conect the intersections of the horizontal graph to the circles in the cam degree graph (Fig C,D,E).

Then plot a location (ie; a dot) at each intersection there the circles intersect with the degree divisions in the cam degree graph (Fig F) , then conect the dots (Fig G)... it's really as simple as that. Then you can cut out the profile in whatever material you are using.


(the wire is actually nice and even and in a slight arc, the pic was taken with a close-up lens which skew's the look of it)

Brad:

That is the same technique I tried in my CAM #4 (see post 34 in this thread) but mine was all by hand and "really" a crude attempt. That said, same principle. Time to upgrade my SketchUp skills and take a run at your technique for creating the layout for the CAM.

Thanks!