Forum member MW magnet repair tool set

xschop

That unit is a forum Karma donation. Everyone share as needed.

xschop

Also if someone has a slipped tweeter magnet, just grind off 1/2 length of the threads, LEAVING THE SHAFT, to only 4ea screws. Don't grind off the tip as that is the sharp cup area that holds the plate.
I've reset a couple slipped tweeter magnets myself this way and the ground set screws do not affect woofer magnet reset operation either.....

Tony M

Well, it turned out I had some more time to search for those 3 tweeters that were bad in the free set of RTA12b's I got a year or two ago. I think I saved them, but I was doing A LOT of stuff then. Downsizing mostly, I think.

I spent a couple of hours or more and had looked at every possible box and space they might be. Nothing. I had given up. Seriously given up and thought I had tossed them for some reason or other.

I looked over the areas one last quick glance again to make sure I looked at everything. Then I was coming in to seal the Jig in its box.

WHOA! What's that? I found 2 6600 woofers, frozen but in great condition. I didn't study the top plates because dinner is ready in a minute. I took my wife out there to show her where they were and to take a couple of "find the woofers" pictures. My wife brought them in, and I locked up the cottage. I'll work on them tonight.

I took some pics to see if you guys can see where the woofers were. I will say, I had some things in front of them until later this afternoon. When I moved those things, I was concentrating on where I was moving them too and NOT what was behind them.

Where's the woofers?
Hints; only one can be seen. the other was behind it. They are not in a box or container. There is a fine working mid-woofer enveloped by cardboard for my SDA-SRS2's that was given to me by a member here on the Forum, Chris, when he came to visit about a year ago. Great guy, he is.

One picture doesn't have them in it. When you see it, you'll see why I didn't see them the other day. I had 2 rooms to search. I really looked hard in the front room the past couple of days, off and on, but there were a couple places and boxes I didn't search in the front room until starting today. I wanted to "all clear" the front room before the Tetris game began in the back room. What a weird story. I had given up. That happened to me on something else the past year. I was done looking for a tool maybe and couldn't find it. I turned to leave and there it was. Weird.

Just say if you spot the front one, don't give away its location just yet.

xschop

It's like Where's Waldo for woofers.

Gardenstater

I see it lol! I'm glad I was tough on you and made you look 😁

Tony M

After dinner, I went to see if I could free up those 2 woofers.

Easy Peasy.

It took me about 30 min. to fix 2 and glue up one of them completely. I also finished gluing the other woofer I fixed last night, inside of those 30 minutes.

I couldn't tell which direction I had to move the magnet or what. Both looked positioned fine. That was weird too. I just centered the pole plate in the Jig, locked down the Jig to the frame plate and that worked for both woofers. The freedom these woofers have now is like the ones in my SDA-SRS2's. You can push on any part of the cone gently, knowing / thinking it should rub, but they don't. I'm VERY PLEASED with this Jig's perfect design.

Outstanding engineering Rob.

So, I used the woofer's label as a guide to start with. "Readable"/ upright letters/numbers were my North.


The first one wouldn't move when did the "loosen 2 tighten 2" method. So, I turned it 180*. It just so happened to be the trick. Almost a "one step fix". I moved the magnet just another pinch to please my brain. Donig "STEP #8" like Rob says, the Jig comes right off, or the woofer lifts right out.


I couldn't see when the frame plate anchoring screws were out of the Jigs inner wall with any woofer, so I just took the 4 out completely. I measured a frame screw after I was done tonight at how far it has to be unscrewed to not have any part exposed on the inner wall. It was 7/8" of the screw outside to be safe.

I started with at the last stage, completely extracting the plate screws and I did the same tonight because I could handle / remove the Jig easier and to my liking.




I noticed some of my Gorilla superglue gel wicked into the woofer's magnet rims with the woofers I found tonight. They had a visible gap on all rims. I went back over in a couple of spots. I'll check them out again another day. I'll have to get 100.00 worth of Gorilla superglue Gel soon.

Tony M

xschop wrote: »

Nice job. Chances are, you'll send it out, then find your other woofers next day.

Didn't this almost come true!!!

Tony M

Hi Rob.

Were you thinking of making some more of these woofer Jigs for sale?

Tony M

Kryten wrote: »

Just for fun, start a note card for the number of trips and distance the jig travels and include it. The next guy can update it and send it along.

I put a one page lined list sheet with this Jig set. It has 15 lines, I think.

It has Rob sending it to me. Me sending it to @Gardenstater.( That will be Tues.)

I didn't put the miles, but I did put the Cities and states we live in.

This set truly is a well-engineered work of functional ART.

xschop

Are you just putting @ 1" length bead of glue at 4 places around perimeter?

xschop

That's what I did with the Super Glue Gel.
I was also cheating and used @VR3 thick felt anti-difraction ring when rotating the woofer to get to set screws quickly....

Tony M

xschop wrote: »

Are you just putting @ 1" length bead of glue at 4 places around perimeter?

Yes, about a 1 1/4" bead at 4 points.

I read about that method here on the forum not long ago.

Maybe you and F1nut mentioned that was all that's needed.

xschop

I believe so, although none were originally shifted, after glue dried, I purposefully knocked one of the 6516 drivers on the wood top bench and it didn't budge.

Glad you got all your MWs back up and running. They are becoming more scarce by the day.

Tony M

xschop wrote: »

That's what I did with the Super Glue Gel.
I was also cheating and used @VR3 thick felt anti-difraction ring when rotating the woofer to get to set screws quickly....

After setting the frame plate screws on the books, I would START the pushing sequence. If I got movement of the magnet, I'd flip it over so I could push down on the cone all while looking at it too.

Gardenstater

I'm guessing that the set screws are all pretty close in lengths? Well anyway, assuming they are, can you check how much length is sticking out with a dial indicator and sort of get a handle on the amount of concentricity difference and it's vector direction?

Another thought - Could the jig be modified to have a dial indicator that goes in between a couple of the frame plate set screws and then you could rotate the speaker in the jig and find the high and low spots?

xschop

You can cheat with a set of dial calipers or precision metal ruler when setting the base plate screws. But you still.have to play it by feel of the free-moving woofer when doing final pole-piece adjustment. This is all due to the non-concentricity of the stamped-steel base plate perimeter. Almost looks like it was plasma cut back in the day.

xschop

Tony M wrote: »

Hi Rob.

Were you thinking of making some more of these woofer Jigs for sale?

I checked my stash and thought I had a couple left. I had 4 and just mailed off another set, so 3 sets remain for sale. $115 shipped if anyone wants their own.

Gardenstater

xschop wrote: »

You can cheat with a set of dial calipers or precision metal ruler when setting the base plate screws. But you still.have to play it by feel of the free-moving woofer when doing final pole-piece adjustment. This is all due to the non-concentricity of the stamped-steel base plate perimeter. Almost looks like it was plasma cut back in the day.

What a shame as it would've made centering a piece of cake and one could know vector and distance of the misalignment before any trial and error.

So, the base plate has a lathe turned inner diameter for voice coil clearance BUT the outer diameter is not only not round but it is ALSO not concentric to the voice coil inner circle?

How bad is is it or are they all over the place? I can't measure roundness with my dial caliper since the jaws are not long enough. I know they must be pretty bad but just curious.

Are the pole pieces lathe turned on the cylindrical portion (part that goes inside voice coil) AND outer perimeter diameter or does a similar situation exist there?

It probably doesn't affect me too much because I will be cutting the dust caps off of mine anyways.

Next question would be is there a foolproof method of separating pole piece and magnet without any chance of damaging the voice coil? Can you insert sticks through the basket windows and have them push up on the cone and disengage the voice coil from the pole gap and then laterally break/push the magnet + pole piece off of the base plate?

xschop

From a MFG. perspective, the stamped steel baseplate was turned on a lathe to get perfect voice coil clearance, then riveted to basket.
The pole- piece was turned on a lathe using the 0.375" centering divet on the back (it's under paper sticker)

The Pole piece and magnet were probably aligned with shims before the dust cap was glued and the ferrite "donuts" we're magnetized by electron flow.

I've pulled the PP and magnet from baseplate many times. The danger to the VC comes when you have to set the PP/magnet combo back down on baseplate.

If you remove PP/magnet, definitely use the dowel tool to recenter them. Also adding the phase plug at this point will act as a guide, ensuring VC won't be damaged when PP/magnet are reinserted to VC.

Gardenstater

xschop wrote: »

I've pulled the PP and magnet from baseplate many times. The danger to the VC comes when you have to set the PP/magnet combo back down on baseplate.

If you remove PP/magnet, definitely use the dowel tool to recenter them. Also adding the phase plug at this point will act as a guide, ensuring VC won't be damaged when PP/magnet are reinserted to VC.

Thanks Rob. Should I use a sharpened edge putty knife to work around between the base plate ( or pole piece) and magnet and carefully pry them apart while inserting something like 1/8" or 3/32" birch ply pieces (or maybe brass shims?) in there until I can separate them by hand ? Just wondering about the mechanics of it since I know that magnets and steel can be very hard to pull apart when they are in contact (ask me about Samarium Cobalt ones sometime - yikes).

xschop

Grow some cajones and pull by hand lol. Hard at first, but it'll pop off. You could make a puller tool around magnet and hold basket lip with your shoes.
They are stuck together like Brandon and K-Schwab haha.

Gardenstater

LOL cojones rodger that! To tell the truth I was a little concerned that a putty knife, even being careful, would chip the brittle ferrite.

I will probably have to mount mine to a plate with standoffs and clamp that in a vice anyways, in order to keep it steady while I remove the Gorilla Max Strength Clear. I do not think that will be an easy job. I'll get an idea of how well it adhered after 2 yrs or so though.

xschop

Butane torch used temporarily to loosen the glue up?

The jig has an instep machined into it for PP/magnet removal. So just cut the dust cap off, then use a straight 3/4" dowel to hit the PP\magnet out/off the base plate. Saves the cajones.

Gardenstater

xschop wrote: »

Butane torch used temporarily to loosen the glue up?

The jig has an instep machined into it for PP/magnet removal. So just cut the dust cap off, then use a straight 3/4" dowel to hit the PP\magnet out/off the base plate. Saves the cajones.

I like those ideas. I'll try removal w/o heat first and see how it goes.

After I whack the pole piece out with the wooden dowel method, it will be a lot easier to pull the magnet off by hand without worrying about any possible voice coil damage 😉

xschop

True, but it is usually the magnet/base plate that is shifted, so the PP/magnet usually separates instantly from base plate when smacked via dowel.

Gardenstater

xschop wrote: »

True, but it is usually the magnet/base plate that is shifted, so the PP/magnet usually separates instantly from base plate when smacked via dowel.

I was assuming that there was clearance between the dynamatted basket and the top of the jig and that the whole thing rested in the jig such that the magnet was sitting on that shoulder just above the pole piece set screws. I figured that when you use the 3/4" wooden dowel and hammer to smack the pole piece, that it would separate the pole piece from the magnet since the magnet can't move.

I'll understand what I'm not understanding when I get it 🤣. Thanks so much for providing this.

xschop

Stop pontificating until it has landed.

xschop

Curious, since you've worked in mag manufacuring, do you (pontificate hehe) a dog-point 1/4-20 brass set screw would crack the ferrite magnet as long as it is already slipped from Pole-piece?

Gardenstater

Ha ha I was going to suggest the very same thing, or maybe even a nylon pointed one might be better. I'm not experienced with the amount of force involved (yet). I used to use the brass tipped ones for glue ups of unmagnetized samarium cobalt ring magnet segments but the pressure involved was at the discretion of the allen wrench operator.

P.M.

xschop

Nice. The jig can be tapped still for them. I'm taking R&D notes from everyone's posts/experiences.