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Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
jpsmith123 wrote ...
Well I'm leaning toward the idea of trying to make some kind of a box, but I think if I do I'll make it out of 1/8" CPVC sheet, since I can get it fairly inexpensively from McMaster-Carr, and since I have a little bit of experience with that stuff.
I just have to figure out how to go about doing it...
It would probably be easier if I had a milling machine, but all I have is a sloppy Ryobi drill press and a sloppy cross-slide vise.
I only ever use a vise for very small components. I usually rest the workpiece on a piece of ply or MDF (or that vinyl coated MDF if I don't want to risk 'any' marks on it. I generally use a fairly slow drill speedand just hold the workpiece still with a gloved hand. This works fine for fairly small flat pieces. At higher speeds or high torque applications I use clamps to hold the workpiece onto the MDF/table, with more MDF spacers between the clamps and workpiece. One of those 'wood boring bits' might be suitable for drilling holes in PVC, but I've not tried it. If you clamp the top and bottom of the box together before drilling the holes will be 'in line'. I imagine it should be possible the 'centre pop' the PVC sheet. Just take it slow.
the other way to cut the holes is to mark out the holes, then drill loads of small holes around the inside edge, as close together as possible, then chisel between the holes and finish off to size with a file/dremmel/whatever.
Registered Member #1321
Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843
I finally got around to testing the two epoxy encapsulated coils (under low power) to see if the epoxy had any significant effect on the frequency response, and it looks like it didn't. It may have have had a very slight effect on the layer wound coil, but no discernable effect on the segmented coil.
Anyway, while in the process of swapping out coils, I accidently bumped the ferrite (one piece hit the other piece), taking a chunk out of one of my ferroxcube u100/57/25-3c90 "U" pieces. Rats. I hardly bumped it at all...there was hardly any mechanical energy involved in this little accident, and yet the damage was significant.
So I'm once again reminded of just how ridiculously fragile ferrite really is. And it makes me want to not put the transformer in any kind of an open frame, where someone might look at it the wrong way and thereby smash it to smithereens, but to put the whole transformer into some kind of protective enclosure, where nothing can come in contact with it.
Registered Member #1321
Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843
I finally got around to start the construction of experimental transformer #3.
I ended up using a 1.5" hole saw from a kit that was on sale at Harbor Freight for $5. (And this cheap kit has proven once again -if any more proof was necessary - that you only get what you pay for). The runout was pretty bad. And if it wasn't chucked in the drill press just so, it was really, really bad.
And before even getting to that point, I had to replace the chuck on my Ryobi drill press with a good one. The chuck that came on the drill press was very lousy (about 0.018" runout as per a dial indicator). Luckily I was able to get a massive, very well-made precision chuck on amazon for $22.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
you might need a larger vacuum chamber for other projects in the future, so maybe its time to build it now. dont lose a good idea due to poor lead termination.
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A New Idea For Ferrite HVHF Transformer Construction
