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Re: Secondary coil forms and winding jigs
Hi Bart, all:
Bart wrote:
Also, I've partially built a winding jig using a variable dc motor. A dc
motor should work excellent for tension. Applying 5v to say a 24v motor will
begin it rotating, but slight tension will load it by slowing or stopping as
the torque is very low at this voltage. Once the coil form is mounted and
the winding spool is set, the tension and speed can be set via the voltage
to the motor. Additionally, the winding spool itself will need a variable
drag built it to final set the tension and speed. I still haven't used it as
I'm in "think mode" for the coil form attachments, but the rest is finished
and the idea should work well and allow proper tensioning.
If I read you correctly, your are pondering on how to attach your coil form to
the winding jig? Well, how about (I did it this way) using a threaded rod
(about 20" longer than your coil form length). Now you take two pieces of wood
and make a cross (which fits rather tightly inside your form) out of them.
Make two sets of these (front and rear of coil). For very big coil forms I
would go for a total of three sets (one in the middle). Place the crosses
inside your coil form and prevent them from slipping around with two nuts on
each side (allowing you to interlock the nuts and the crosses to the threaded
rod). This centers your coil form around the rod. Now take two more pieces of
wood and place them on the threaded rod (secure with two nuts, too). This will
provide more than enough clamping force to rotate your coil form via a motor.
If you plan on building lots of coils I would go for a set of ball bearings
(to let the rod spin easily) on the end bearings. Otherwise (as in my case) a
piece of wood (1" by 2") provides more than enough bearing surface. After
about 6000 revolutions (just a guess, could be plus / minus 500 revs) my
"wooden bearings" didnīt show much wear, even though the threaded rod was
running directly on the wood surface. (you could slightly see the thread
pattern in the wood, but it was not as deep as the full thread heigth.
Winding jig greets from Germany,
Reinhard