I want to do some IF transformer winding and I can't seem to find a machine (for under $200) that will do what I need. Most will only take a core that will slip over a 7/16" threaded spindle. The simple type with a drill chuck don't have a wire follower that can manipulate the wire back and forth to create "pie" windings of a specified length. Anybody have ideas? I am fine with a hand crank machine as I am not planning on a production run, but because I want to use standard 1/4" cores, it seems the chuck version is all that is out there--and then I would need to make my own mechanical follower.

Norm

Hi Norm,

Seems a simple-enough undertaking.

You should be able to get anything you need from McMaster-Carr Supply Co.
http://www.mcmaster.com

No minimum order and they only charge actual shipping cost.

- Leigh

Thanks, Leigh. I buy a lot of things from them. I already gave up on finding the right IF transformers and coils (looked at 100's) which gave rise to my thoughts of just making my own. Looks like I will have to give up on finding a machine that will do "pie" winding and just make that as well. Unfortunately, as the cost of the parts adds up, a person quickly hits $600 at which point, the CNC computer controlled machine makes better sense. Another way to go is use the less expensive winder and re-fit its coil holder to take smaller diameter forms--if that winder does "pie" winding. I have a question in to one of the sellers now.

Norm

You looking for a machine that has a rapid traverse mechanism.

Since it seems to be a hobbyist type of machine your looking for how about a MoReCo also known as a Morris coil winder?

viewtopic.php?t=164864

Of Morris winders they are all essentially alike. There are early machines with cast iron bases and late machines cast aluminum base. There are eccentric cams that move a spring loaded cam follower/wire guide. The ratio of gears can be changed that drive the spindle. The spindle clamp is very crude but it works and one can clamp whatever they want for a spindle so long as it is centered. Built in counter.

In of itself the Morris depends on wire preparation and user skills to create a good coil.

I have made spider web coils and lumped inductances of 1" wide and 275 turns, universal wind.

They are all over ebay, etc. They once sold for at the end for $29. A letter and a few $ would get different cams and an alternate wire guide. What is hard to find is the cast mount for the spiderweb former. The pressed sheet aluminum former is more often found. The former holds the pins to create the spider web. Cams are relatively simple to make from sheet steel and a screwed bushing......

FWIW there is a China machine the NZ-2 that does a slow traverse. I do not know if the gearing can support rapid traverse 1/2 cycle/1 spindle turn. These have a variety of prices but none I have seen less than about $195. There are YouTube vids of the machine but only ones are of slow traverse. The China machine can be power driven. A guess says the China machine is all metric fitted, retro US gearing could be problematic unless some machinist work done.

YMMV

Chas

I didn't find any Coil Master machines on EBay. One big problem with most machines is they can't do smaller than a 1/2" dia. core. I really want to use the 1/4" dia. core so I can fit standard slugs into them. This means that I am looking at the simple hand crank machines with a chuck where I can use 1/4 all-thread to hold my cores. Leigh's suggestion to buy gears from McMaster may be my best solution. Nylon gears are easy to work with, of sufficient durability for Litz wire coils, and cheap--$30 gets me a couple angle motion transfer gears and two gears to get me the weave look I am after--I think. I figure a 80 tooth to a 56 tooth will give me weave look for my pies. That would be a little less than one-and-a-half times the wire moves from side to side on my form so that it doesn't stack on top of itself. But maybe I should use slightly more or less than 2.5 times side to side. I can see where this might get expensive buying gears at $10 a pop. What I will probably do is buy the winder and then hand wind a little to see how to stack the wire before buying gears.

As far as what the coil will need to look like--there is really good information here:

http://www.pa2mrx.nl/UK/PA2MRX-UK.htm?c ... ing_uk.htm

and the best information I have found is here:

http://frank.yueksel.org/other/RCA/Radi ... uctors.pdf

Norm

I built this one a few years ago for under fifty dollars. Works well. Have yet to try to wind a Univi Coil, like those used in IF transformers.

That's awesome. Any thoughts on number of times the wire should travel side to side for each turn? From what I have read: the coil pie or stack should be roughly square in cross section and the weave keeps capacitance lower. For many turns, several pies are better than one. For transformers where the coils are wound the same direction, the plate lead would be from the start (or finish) and the grid from the opposite on the secondary. Litz wire of more strands is needed for higher Q. Pad capacitors are to be kept on opposite sides of the base. No solder blobs or metal parts (terminal posts, etc.) near the coils. The shield as far as possible from the coils. Thermite cores are the highest Q.

I will probably wind my coils first on sleeves that can be slid on the form to see what works best for spacing apart from each other. What would be really interesting would be to have the spacing between windings be adjustable from the front panel like the Hammarlund SB 400.

Norm

Hi Norm,

One important point regarding gears...

All gears are made to a specific Pressure Angle (PA).
The two common PA values are 14 1/2 degrees and 20 degrees.

The difference in performance is slight, and of no consequence in your application.

HOWEVER, all gears that mate MUST have the same pressure angle.
Mixing PAs yields pairs that work very poorly, or not all.

- Leigh

Information on gear ratios for the guide cam is given in Radiotron Designer's Handbook 4th edition, page 458. Here is a link to the relevant pages:
http://electronbunker.ca/DLpublic/RDH4_ ... 56_459.pdf

Here's a book by Dave Gingery that shows how to make a Morris clone:
https://gingerybookstore.com/CoilWindingMachine.html
John

Thanks, Bob. I read that section last night. It suggests that some experimentation is needed even with the formula. I was not planning on the cam method, but instead using a pin in the second gear to drive the guide back and forth using a linkage. Setting the guide pivot point and where the coupling link connection is in relation to that pivot point will determine how long the winding will be. The number of times the guide moves from side to side per turn is determined by the gear ratio between the drive gear and the gear with the pin and link to the guide. This method may be flawed in that I am restricted by what gears I can purchase, however, I don't see any other choice.

Leigh, you are quite correct and fortunately, McMaster-Carr tells a person looking to buy gears this information--because I did no know about any of these things.

I have ordered the simple winder from an EBay vender. When it comes, I can experiment a bit by hand to see what works best in terms of the lay of the wire before buying gears and setting up a mechanical jig for winding the transformers.

As far as the tube coil forms. The only thing I found was Mason bee tubes and cores. They are 5/16" ID so are not ideal. The paper cores might be closer to what I want--however--probably not and I don't want to spend $20 bucks to find out. There are probably plastic tubes out there that would work. What would work is making my own tubes. A foam paint roller, brown craft paper, and a 1/4" dowel would be all I need to roll my own coil tubes.

Next up--cans and deciding if I should use nut holders and 6/32 thread with solid ferrite core or just threaded hollow ferrite cores that operate inside the form.

Norm

Very reasonable price for that book--so I ordered it. I am not sure how much it will help, but it should provide at least its value.

Norm

Norm,

McMaster-Carr has Garolite tubes with IDs from 3/16" to 3".

Search for "Easy-to-Machine Electrical-Insulating Garolite Tubes"
The 1/4" ID size is about $10 for 40 inches.

These are brown fiberglass, which should be suitable.

- Leigh

Just a backyard mechanic here, Norm, but I needed to wind a coil for a regen I built awhile back, and threw this little gizmo together. The supply reel is underneath. The take up shaft can be any diameter screw. The handle is composed of PVC fittings.
Maybe it can give you some ideas.

Would there be an advantage over Phenolic tubes? I see the Garolite can be bought with a 1/32" wall thickness, whereas the phenolic is only available with a 1/16" wall thickness. Garolite 40" is $9.49 and Phenolic 36" (US Plastics) is $4.55. I kind of like the idea of the thinner wall which was my original thought for rolling my own, but the Garolite tubes would be much more consistent and durable. Paper tubes are subject to humidity concerns as well. Maybe Garolite is the same as Phenolic and they are both just trade names.

Norm

Hi Norm,

When you search for phenolic on the McMaster site, it returns Garolite.
Garolite is the fiberglass material commonly referred to as G-10 when used for PC boards,.

It's quite rugged, rather impervious to damage, and dimensionally stable with temperature.
It's not even slightly hygroscopic, so no moisture absorption.

- Leigh

I am now searching for the cans. I have pretty much settled on 1.5" round tube-- 1/16" wall in aluminum. Square tube is also available but the end caps are problematic. Round tube can be fitted with either a push on cap ($2.53 steel, $5.26 aluminum) or a hole plug (steel 25 for $10.15). Next is how to attach the can to the chassis. I couldn't find any cheap rivet-on studs. McMaster has some spring attachment studs, but the holes are too small for rivets and they are expensive-$2.93 each in black oxide. They really aren't the right application.

Norm

The Gingery book that John cited upstream is a superb resource for anyone with the basic mechanical and fabricating skills to build their own winder. A great companion reference is William Querfurth, "Coil Winding: A Description of Coil Winding Procedures, Winding Machines and Associated Equipment" (Chicago: Geo. Stevens Mfg. Co., 1954). It is available to members at Scribd.

Thanks, Dale. I will get a copy of that book as well.

Norm

That is the book I used to make mine. I used tooth gears instead of the friction drive. I made off set cams for moving the winder arm for Unvi coils. Now that winter is here, I may get a chance to play around winding a couple. Since the photo was taken, I changed out the Click counter to a Digital one for smoother winding.