Due to the high cost of switch machines here in Canada, I have started to make my own and wonder if anyone else has done so. I can do it for about 10% of the cost of a manufactured one. Here is what my twin coil units look like. The movement also moves a DPDT swith so panel indications can be powered as well as signals. Will come in handy for wiring reverse loops. I drive these switch machines with this dandy littl snap unit which provides a high energy pulse which really makes the switch machine jump. The current is of such short duration that the coils don't burn out. This is what it looks like. It has a couple of diodes and resistors on the back. If any of you are making your own I would like to know how you do yours.
Interesting project Rob! I have never tried to build a twin-coil switch machine. I bought a case of them many years ago and still have not used all that I have. But, I have been dabbling with making my own slow motion switch machine, which as far as I can see can be made with printed circuit board and a few other components at about a third of what it costs to buy one at retail. Do you power your frogs thru your machine also?
Hey Robin, did you wind your own coils, or are they available somewhere? Back when dad worked for Moore Brothers Electric, he had some of the enamel wire they would re-wind auto and truck starters and stuff with. He would sometimes wind some with very fine wire, but I often wondered how he knew how many winds to put on. I'm dumb that way. He did have one they had experimented with that worked slowly. They fastened an air cylinder on one end of the armature, and had an adjustable needle valve on the exhaust outlet so they could get a slow pull, but the coil will begin to heat up if it takes too long. Maybe you could use one of those plastic screen door shock absorbers?
Hi Watash, I wind my own coils. There must be a way to calculate how many windings but I just guessed and wind till the holder is full. I get rolls of copper wire from Radio Shack but have an old pinball machine with lots of relays so will use the wire from that for future coils as Radio Shack is really going away from electronic parts. They are forgetting their roots. I don't dampend them at all, just let the snap do its thing
Can you give a little more detail? What did you use for spools, rod inside the spools, # windings, etc.? A few more photos from different angles would be nice too. Switch machines are expensive here, that's for sure. I do have a few homemade ones that my father made a few years ago, but we ran out of the bits we were making them with. A few of them were too stiff to use. I'd sure like to find a reliable inexpensive method to make them.
Let me voice a passing thought. What about the coils in a door bell? They are low voltage, and seem to be strong enough to shift a turnout momentarily. I have seen several in junk shops and second hand stores. You might even hook them up to a wall plug-in power supply with a switch to cut power when not running. Scott, some I have seen have a flanged nylon sleeve with a flange on one end and what looked like a plastic washer glued to the other end, with the winding in between. It looked like it may have been hot glued at the flanges to mount to the base. The armature is always dead soft iron rod or shaft. The stroke would depend on the length of winding, and length of armature rod. A brass wire would have to be used to connect to turnout points. For momentary use, hot glue seems ok, but any solenoid builds up heat, so would not work for constant duty like to hold rail points in position. They can get extremely hot (fire hazard) if voltage ir too high along with amps, so experiment awhile with scrap turnout. Maybe a light over-center spring to hold points in place both ways? Might be worth a look?
To answer some questions! Bill I will be powering frogs because steam locos stall without it. Diesels do OK especially two or more, but steam is a whole different story. Scott, this picture shows some varying stages of my production. I use brass tube that has an outside diameter of 1/4 inch. I cut them into three inch lengths, file half way through the tube at its centre. The slot is 1/2 inch long. Next I cut 6inch nails into 2 inch lengths. The diameter of the nails is such that they fit smoothly inside the tube. About 3/16 of an inch. I file a flat spot in the centre of the nail and drill a 1/16 hole into it. I place it in the tube and solder a piece of 1/16 wire that is cut to 5/8ths length into the hole so that it protrudes through the slot in the tube. Next I solder on four washers. The outside ones are 1/4 inch in from the end and the centre ones are soldered at the ends of the slot. I wind the coils with whatever copper wire I have on hand. I think you can see how the parts are assembled in the picture of the finished switch. When I run out of brass tubing I will be changing to plastic. Plumbing supply stores sell ridgid piping for connecting taps or toilet tanks to the water supply. The internal diameter is around 3/16 of an inch and should do the job. I will just be able to glue fibre washers onto it instead of soldering. Thanks for your tips and suggestions Watash. Those old door bells will provide the copper wire needed. A fun project but I find I have to get in a production line mode to make them because it does take time but the price is right.
Quite a production line you've got going there Switch machines are not expensive here and I would not feel the need to make them, so they must be way overpriced in Canada Anyway, I have all the ones I need
Robin, Go over to the DCC or HO forum and look up a post from Corey Lynch. Send him an email, I gotta feeling he could tell you how many turns you will need. And he could probably tell you how much current it will draw so you don't burn the house down. It's been 50 yrs since I played with coils and I remember there was a formula, but lord knows, with all those wonderful pharmacuticals of the '60's I'm lucky to remember my name some days.
Robin,, Like Chris it has been over 40 years since I repaired TV's and had to wind coils and make modules. I used to have a book that had the formula for coil winding and wire size. I spent the last 2 days looking for it but it must have gotten lost in all the moves we have made.
Thanks for the info Robin. I'll look through some junk bins and try to build a few this weekend. If anyone knows an appropriate # of turns so I don't burn down my house I'd appreciate it. The rest of the house doesn't matter much, but I'd sure hate to lose my layout!!
I went digging back through some of my files and found that to have a reliable hard working switch machine 1850 turns of #32 wire for each coil will power HO and N switches fine. It seems a lot but it just nicely fills the space between the washers. The brass and metal washers must be taped to prevent shorts.
