I saw some stuff at my local RC/hobby shop a couple of days ago, kind of like an ABS/UPVC plastic in sheets of varying thickness. I believe you can use a router on this stuff. I'll pick some up next time I'm in the area and find out what it's called. I could make a really nice form with that, with beveled edges and such. The coil wire should slip on there really easy too for a nice tight wind.
It also comes in different colours if you want to get real fancy
More to come - I've got the form almost finished, but the camera battery went dead
Posted on: September 28, 2011, 08:44:06 PM
Once your 3 pieces are cut, sandwich the smaller one between the two larger. Line them up so that there's a nice even channel all the way around. Clamp them in place and drill the 3 holes for your bolts. Put a bolt through each time you drill a hole to help against slippage.
I've used 1/4" nylon bolts + nuts (home depot has them). If you're building a TGSL and are figuring out how many turns you need by matching the frequency (because you don't have an inductance meter), you'll be able to measure with the coil still on the form if you don't use any metal parts to build your winder.
Next, cut a piece of wood dowel (I used 3/8" dowel), find the center of your form and drill the hole for the dowel.
I've cut about a 9" length, but that's probably going to change. I'm building as I go, so I'll take measurements and post them at the end.
Don't glue the dowel into the form yet. It will only be glued to the center plate of the form, so that you can remove the bolts and take the sides off to remove your coil.
Posted on: September 28, 2011, 09:15:40 PM
Now is probably a good time to cut slots (thanks to Golddigger for that suggestion - worked out really well). Put the form together and tighten the bolts (shouldn't need much more than finger tight). You can leave the doweling out for now. Cut the slots about 1/2 to 3/4" apart all around the edge of the form. You'll need to cut a couple of millimeters into the middle D so that you'll be able to push a needle through underneath your coil once it's wound.
Please be careful by the way. Remember - diamond earrings, gold nuggets and all that other stuff you guys like to find are very difficult to pick up without the proper amount of fingers. I'd hate for anyone to end up in the hospital while following my post!
Gonna go start on the frame now.
Posted on: September 28, 2011, 09:53:56 PM
Oh yeah, the V you see cut in the bottom of the form in the picture is to hang the tail end of the wire through when you start winding. You can wrap the tail around the doweling a couple of times to keep it in place.
Posted on: September 28, 2011, 10:01:32 PM
OK, I have a base board that is 18" x 19" from 3/4" ply, and two uprights 13" tall by 4" wide from 1/2" ply. The base board is much bigger than is needed (10" x 10" would probably do fine) but I think I'm going to try and add an electric motor a bit later on and will need the extra support on one side. 13" is probably higher than necessary too, but I'm trying to keep the sawing down so that my neighbour doesn't implode (it's getting a bit late). 8 or 10" would be fine for the height. At 8" you'd be able to fit a form for about a 14" coil
Clamp the two uprights together lining up a nice square end on each (they will be glued to the base board, so the squarer they are the straighter it will stand up). Drill a hole through both for your doweling, at the opposite end to your square end.
Now on one of the uprights, put your drill through the hole you just made, run the drill, then pull your drill down at and angle, so that you're making a tapered 30-40 degree hole instead of a straight one. You'll need this to be able to remove your form in order to take it apart once you need to remove the coil from it. You'll pull the dowel + form out of one side, angle it up then pull it from the other side.
Hmm, that probably sounds a bit confusing. I'll take a pic so you can see what I mean.
Next, glue your two uprights in place. Put the doweling through while you're gluing the uprights to help keep them in line.
I'm just going to epoxy my uprights and leave it overnight. If you're using wood glue make sure you clamp it in place.
That's enough for me for one night, I'll try and get this finished up tomorrow.
Paul.
Posted on: September 28, 2011, 11:16:57 PM
Ok, where was I at?
I now have a base with two uprights with holes drilled for the doweling, as well as the 3 piece form.
Time to glue the form in place on the dowel. Remove the two side panels from the form - only the middle (smaller) D will be glued to the dowel.
Mount the dowel in the frame along with the middle panel of the form. You'll want to have the dowel sticking out on one side of the frame, but not the other. This is where your winder handle will be, so if you're right handed leave the dowel sticking out the right.
The form needs to be glued pretty straight, or it will wiggle as you turn. A neat trick I just came up with is to use the biggest 3/8" drive socket you can find to hold it square (assuming you have 3/8" dowel like I do).
Get everything set up before you glue with your dowel for the handle sticking out one side, and the form panel equidistant between the uprights (see pic). Slide the socket up to the form plate and squeeze them together. Glue the panel to the dowel on one side. Once it's set, slide the socket out the way and glue the other side.
I used thin CA glue for this, with a spray accelerator. It makes it a nice quick job, and there aren't any globs of glue. If you do get globs you'll need to remove them somehow or your outer panels won't sit flush, you'll end up with a gap between the panels, and your coil wire will get stuck down it as you wind.
Once that's glued and dried you can remove it from the frame and install the outer panels (hopefully you understood the part about beveling the hole on one of the uprights at 30-40 degrees, or you won't be able to remove your form at this point).
That's about it for that part. You can now mount your form back on the frame and give it a spin. Hopefully it's reasonably straight and doesn't wiggle too much.
You'll need a winder handle. I haven't figured out a particularly good way to do that yet. I just have a length of thin ply (or a piece of an old wooden ruler, or one of those paint stirrer sticks) with a 3/8" hole at one end to mount on the dowel, and a hole at the other end with a bolt through it. A self tapping screw holds the handle to the dowel.
Lastly, you need somewhere to put your roll of coil wire. I cut a square of 3/4" ply roughly 3" x 3", drilled a hole and glued in a 3" length of doweling, then glued it to the base board. Line it up so that the roll of wire will sit in line with your form. If you're going to end up with any sort of angle on your dowel, make sure it's tilted a little up. If it's tilted down any the roll of wire will keep creeping down and falling off as you wind.
As you can see from the last picture it is far from perfect, but it works ok. The wire snags a little on the rough edges. I could either sand it smooth or carefully wrap the form panels with masking tape to take care of the problem, but I'm going to try and build the form out of plastic as soon as I get time.
I have another plan in the works to mount an electric drill instead of the winder handle. The drill chuck will directly hold the dowel, and I'll regulate speed with a dimmer switch and a footswitch. If I'm going to go to all that trouble I should probably add a digital counter too.
I'll keep you all posted on how that goes.
Thanks for reading. I'm glad there are people were interested in my project. And for those of you who aren't interested - my apologies for spamming the 'new posts' list for the past couple of days
Paul.
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