Forum member MW magnet repair tool set

Gardenstater

When gluing up already (radially) magnetized segments one could easily smash a finger if one wasn't careful and there had to be an aluminum pressure plate between the set screw and the radial segment so that it wouldn't be fractured. The adhesives were high end 3M epoxies or sometimes somthing else and were often supplied by the research lab that the assembly was going to. Trying to remember now what 3M one was used most often but it was super expensive.......

Gardenstater

Pretty sure it was 3M Scotchweld 2214 Structural adhesive. 1 part non metal filled epoxy heat cured at 250 to 350 deg F. Very strong stuff and bonded well to abraded non-plated steel and ground magnets but obviously unsuitable for our purposes. Also costs over $100 for a lil 6 oz. cartridge.

https://multimedia.3m.com/mws/media/1901645O/3m-scotch-weld-epoxy-adhesive-ec-2214.pdf

Tony M

100.00 for 6oz.

xschop

I'll stick with my $1.25 Store SG Gel.

Gardenstater

That's the stuff I used to repair my spider on one of the Silver Baskets I'm going to try to save. If I take it apart and find out the voice coil is rubbing on the frame piece, then it's toast.

xschop

As long as it ohms out, it can be saved.

Gardenstater

The Jig has landed over here! Sweet piece of machining for sure!

So far I don't see any problems with using it on my silver basket MW6500's. I started doing some measurements and it seems like the set screws are pretty well centered on the frame piece and the pole piece and they clear the magnet. I see now that the driver is resting on the dynamatted basket against the jig face. Doesn't appear that the magnet is touching the shoulder as I was imagining it would.

I'll start on the easier one tomorrow that isn't glued and hopefully doesn't require disassembly.

Thanks Rob and Tony!

xschop

Post dimensions of the 6500 magnet ID, OD, and thickness If you can.

Gardenstater

MW6500 (silver basket, 9/19/1979), Prior to disassembly:

Magnet O.D. = 3.336" max, 3.334" min
Magnet Ht. = 0.546" max, 0.540" min., varies, better measurement after disassembly to come
Pole Piece O.D. = 3.116" max, 3.113" min., varies, stamped
Pole Piece Ht. = 0.16" incl. label, better measurement after dissasembly to come.
Frame Piece O.D. = stamped, about same as pole piece, better measured after disassembly
Frame Piece Ht. = ".........."

Gardenstater

First Silver Basket mugshot photo. Pole piece/magnet alignment would appear to be a concentricity error of 0.025", ASSuming of course that they were each made concentrically in the first place.

Gardenstater

Gardenstater wrote: »

I see now that the driver is resting on the dynamatted basket against the jig face. Doesn't appear that the magnet is touching the shoulder as I was imagining it would.

I gotta correct this dude. Last night it appeared and felt like it was resting on the Dynamat when rotated back and forth on the jig. A 0.005" feeler blade could not be inserted between Dynamat and jig. This morning I put Dykem Blue on the shoulder where the magnet would be touching and lo and behold when I rotated driver back and forth it did rub some off, so magnet is touching. Dynamat is an irregular surface but there may only be 0.001" or 0.002" min. clearance. That works though, for me.

xschop

That area can be turned down to allow for thicker Dynamat. I left as much length as possible to allow the Pole-piece/magnet removal from above when flipped and placed in jig. And thats how you should dead-blow the pole-piece out of the magnet so the PP doesn't want to attract back to magnet.

Gardenstater

This is hopefully ready for knocking the pole piece out with the wooden dowel method, after I remove the dust cap. I figured with only 0.067" engagement between ferrite magnet and aluminum shoulder of jig I had better get it centered on the magnet as best I can to avoid chipping! A set of wire gages (preferably non-magnetic) would've been invaluable here but instead I had to calculated the exposed set screw lengths needed (sticking out from jig) in order to make the correction for the out of concentricity pole piece. I'm using jam nuts to keep the settings. Now off to HD for the dowel.

xschop

It goes the other way so the instep will center OD of magnet. You don't have to use the set screws either.....

Gardenstater

The issue I had with using that side is that there is still 0.039" radial slop or clearance all around my silver basket magnets and there are no set screws to retain it centered so that after every unsuccessful blow of the hammer I would have to re-center the magnet. I was going to try some pieces of wood with double sided tape to keep it centered.

I thought that is why you said to use the other side so that I could use the set screws to maintain the centeredness between hammer blows.

If the problem is not enough clearance below the pole piece, I will use my heavy duty workmate with the jaws opened up enough for clearance. No worries I'll make it work

xschop

You're pontificating unnecessarily. Just smack it as shown. I haven't broken a one. Just as long as the magnet perimeter is clean.

Gardenstater

I can use that side if you want. That was my original plan. I'll just wrap the magnet with 4 or 5 wraps of electrical tape and that will take up the slop I got some Oak dowel which should be up to the task and I'll try to include a piece in the box for Kryten if it will fit.

xschop

I see what you're talking about now. All my mags were @ 3.41". So the 6500 is an oddball magnet but still doable in the jig. Just wrap with electrical tape as you say and.smack away

Gardenstater

Thanks. We engineers are OCD but we ain't shtoopid ha ha. But really, super super nice job on the mfg. of this jig!!

Kryten

OCD? Maybe???? I'm physics and engineering trained and rabbit holes are always a possibility

xschop

I'm Southern Engineering trained. Didn't you see my original post where I used a roll of duct tape for magnet removal? lol

txcoastal1

Engineers are best trained to do their business on the paper

Gardenstater

Who do you want designing and overseeing the development of a B1 Bomber or a Commercial Airline Jet, a mechanic or an Aeronautical Engineer? I've always had most respect for hands on engineers....Sorry Larry if you are reading this (my roommate in college lol)

I hope the next time you fly, the plane wasn't designed by a Cocker Spaniel puppy lol.

This just reminded me of a great old movie called "The Flight Of The Phoenix".

https://www.youtube.com/watch?v=9bIUOPSzbVM

xschop

I saw that movie a while back. Rig it up and put 'er in the air.

I found a very large piece of ABS to revisit my first MW jig design that allows for magnet/pole-piece re-setting to baseplate without possibility of damage....

xschop

Gardenstater wrote: »

MW6500 (silver basket, 9/19/1979), Prior to disassembly:

Magnet O.D. = 3.336" max, 3.334" min
Magnet Ht. = 0.546" max, 0.540" min., varies, better measurement after disassembly to come
Pole Piece O.D. = 3.116" max, 3.113" min., varies, stamped
Pole Piece Ht. = 0.16" incl. label, better measurement after dissasembly to come.
Frame Piece O.D. = stamped, about same as pole piece, better measured after disassembly
Frame Piece Ht. = ".........."

So, for simplicity's sake, I'll see if I have a piece of alloy that I can turn down to 3.117 ID and it will only be needed on MW6500 rebuilds.

Just found that modded roll in the shop. Luckily It still has plenty left to do the job when the 6500 arrives (THANKS Tony M)!

BlueBirdMusic

This is a fast growing great thread. Rob, you created a .............!

xschop

xschop wrote: »

I saw that movie a while back. Rig it up and put 'er in the air.

I found a very large piece of ABS to revisit my first MW jig design that allows for magnet/pole-piece re-setting to baseplate without possibility of damage....

After looking at drawings, I've decided go with axially countersinking and thru-tapping the billet jig so it can be used to gradually and precisely lower mag/PP back onto baseplate, preventing any possibility of coil damage. Will require cone-point set screws...

Pontications

Gardenstater

xschop wrote: »

Gardenstater wrote: »

MW6500 (silver basket, 9/19/1979), Prior to disassembly:

Magnet O.D. = 3.336" max, 3.334" min
Magnet Ht. = 0.546" max, 0.540" min., varies, better measurement after disassembly to come
Pole Piece O.D. = 3.116" max, 3.113" min., varies, stamped
Pole Piece Ht. = 0.16" incl. label, better measurement after dissasembly to come.
Frame Piece O.D. = stamped, about same as pole piece, better measured after disassembly
Frame Piece Ht. = ".........."

So, for simplicity's sake, I'll see if I have a piece of alloy that I can turn down to 3.117 ID and it will only be needed on MW6500 rebuilds.

Just found that modded roll in the shop. Luckily It still has plenty left to do the job when the 6500 arrives (THANKS Tony M)!

In the meantime here I think I will get a short length of 3" (3.5" nom. O.D.) Sched. 40 or 80 PVC pipe and bore it to 3.118". If I part it off at 1" long, it can even be shipped with the jig without taking any more space, if the set screws are removed that is.

xschop

Ok. Are you saying the 1" length will fit inside the jig ID?

So I'll search for an alloy tube to make 3.50" OD × 3.12" ID and 1" long.

Gardenstater

Yep, that is what my thought was. It can nest inside for the smashing event and for the shipping event.