Repairs to my Mos roller Bridge. Advice please.

ElectronK
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Repairs to my Mos roller Bridge. Advice please.

Postby ElectronK » Sat Aug 28, 2010 10:45 pm

I took my bridge off about a month ago. I tried to clean and get the roller bridge working properly. I have not had much luck so far. Only one of the rollers has broke lose. I soaked it for a month in a half in Marvel Mystery Oil. I'm probably going to have to take it appart further. I think there a thread about that around here somewhere.

ANYWAY, that is not what the thread is about (though if you want to say something about breaking the rollers free, go ahead)

If you look at the attached picture (click to enlarge), the rollers look funny. I think someone has previously disassembled the bridge and put the rollers back in the wrong order.

Does anyone have a reference picture for what the correct order is?

Thanks

Image

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Sarah93003
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Re: Repairs to my Mos roller Bridge. Advice please.

Postby Sarah93003 » Sat Aug 28, 2010 10:58 pm

All of the good pictures I have happen to have strings in them so it's difficult to see the detail. I can tell you that the ones in your picture are out of order. Basically the saddle with the pulley that has the widest "slot" is for your low E string. Then just put the saddles in order from "fattest" to "skinniest". The saddle that has the pulley with the smallest slot is for the high E string. Does that make sense? I'll try to explain better if it does not.
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1965 Mosrite Celebrity Prototype with Vibramute
1972 Mosrite Celebrity-III
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1994 Gretsch Streamliner G3155 Custom
2005 Gibson Les Paul Standard Plus
2006 Jude Les Paul 12 String

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Veenture
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Re: Repairs to my Mos roller Bridge. Advice please.

Postby Veenture » Sun Aug 29, 2010 3:04 am

I'm with Sarah and upon following her advice, the strings could be allocated as follows:

Image

(In one or two cases the rollers seem to share the same measurements)

In further trying to free the rollers you could try using a piece of string, wind it round the roller and then tugg the string to and fro until you get some movement. You'd need to secure the bridge onto something first. I've never tried it but perhaps and old Round Wound guitar string (smallest guage, most likely) could be used instead -to provide better traction :?

BTW, is this the bridge from your 'Halloween Mosrite'?

[edit] do all of the "pillars" housing the rollers have the same height? If not, (which is what I'm thinking) the sequence would possibly have to be adjusted but let's wait for the experts to chime in ;)

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Sarah93003
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Re: Repairs to my Mos roller Bridge. Advice please.

Postby Sarah93003 » Sun Aug 29, 2010 7:33 am

Excellent illustration Paul! :D I think you have it spot on. Another method I would try to break them loose is to take a rubber band, cut it with scissors, secure the bridge base in a vise and put the rubber band in the slot and applying pressure see if you can it them to move.

If that doesn't work then I'm guessing that they are rusted and may need some light sanding on the mating surfaces. You can disassemble these in the same manner that they were made. Basically these little pulleys were turned from a round piece of stock that had a hole in the center. The center hole is the same size on all six of the pulleys. Once they parted these little pulleys on a lathe they would have sanded both sides to take off any burr left behind in the parting operation.

The saddles I believe are all the same height and they also have the same size hole drilled through. To make the assembly they had to take a small piece of wire and push it through the saddle, with the pulley in place, to the other side and then file the ends flat. This created the tiny axle that the pulley spins freely on. Eddy Elliott, a forum member, used to make these bridges when he worked for Mosrite.

To disassemble you need to reverse the process. The most difficult part is going to be finding something with a smaller diameter than the axle and yet strong enough to push through the saddle. If you can do that, you will be able to remove the saddle and clean the mating surfaces and then reassemble.

I do not think that these are a "pressed fit" in machinist terms. The first method I would try would be the following:

1. Remove one of the saddles from the bridge
2. If you have a vise I would close the gap so it is small enough to allow the saddle to lay on top with enough room for the axle to push down without hitting anything and getting bent.
3. Take a standard pin, such as used in sewing cloth, and cut it with wire cutters to about 1/2" long. If there is a burr left from cutting it, sand that off. The pin will be pretty strong and have a head that you can push on.
4. Hold the pin with a pair of needle nosed pliers and center it on the axle. With your free hand place something flat on top of the pin head and apply pressure to see if you can get the axle to move. If it were me, I would use a butter knife because it's nice and flat and you can rest your thumb on it without getting hurt.
5. If the axle moves I would push it through until you can remove the pulley. I don't think I would push it all the way out though.
6. Once the pulley is free I would use a very fine grit wet/dry sand paper on all of the surfaces, such as 600 or 1000 grit.

On the first attempt, if it does not work, I would try from the opposite direction, just in case. If it does work, be very careful not to lose any of these tiny pieces. I have seen bridge for sale on eBay with missing pulleys and you can't buy these at the hardware store.

If you are not able to exert enough pressure to push the axle through AND you haven't bent your pin, then you could use a small drill press as an arbor press and push it through that way.

If the pin isn't strong enough then it's going to be tough to find something with a diameter that small that is stronger. One thing that comes to mind is a small nail set that could be ground down to a smaller diameter.

Jeez, I wish I had one of these bridges in my possession I would give it a go.
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1965 Mosrite Celebrity Prototype with Vibramute
1972 Mosrite Celebrity-III
1977 Gibson MK-53
1982 Fender Bullet
1994 Gretsch Streamliner G3155 Custom
2005 Gibson Les Paul Standard Plus
2006 Jude Les Paul 12 String

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olrocknroller
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Re: Repairs to my Mos roller Bridge. Advice please.

Postby olrocknroller » Sun Aug 29, 2010 9:12 am

If running a string back and forth won't break the rollers loose, put it in the oven at 300 degrees for a while...like ten minutes, then while it's hot, repeat the attempt to get them rolling. If you want, you can also try reheating, and dropping the hot piece into the loosening oil...heavy parts will cool more slowly than the smaller ones, which gives the oil a chance to creep in.

My experience with set pins is that they usually end up Murphied if you try driving them out, then you are faced with trying to replace the wire with the correct gauge for a friction-fit. My loosening oil of choice is plain old diesel... :ugeek:

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ElectronK
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Re: Repairs to my Mos roller Bridge. Advice please.

Postby ElectronK » Sun Aug 29, 2010 4:46 pm

Veenture wrote:
BTW, is this the bridge from your 'Halloween Mosrite'?



yeah, this is from the Monsterite.

I'm trying the oven trick right now.

left it in the oven for 10 minutes. Sprayed it with WD40

no go

Now I'm soaking it in marvel mistery oil

ElectronK
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Re: Repairs to my Mos roller Bridge. Advice please.

Postby ElectronK » Sun Aug 29, 2010 5:29 pm

Gave each one and good twist with a fine tipped pair of needle nose, and they all came free.

They probably haven't been cleaned since the thing was produced. Lots of little specs of rust and dirt coming out on the sides.

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Re: Repairs to my Mos roller Bridge. Advice please.

Postby GattonFan » Sun Aug 29, 2010 5:34 pm

Yeah - they are a pain. I would probably take them out and replace them with some of the Hallmarks - Keep the originals, in case you ever want to sell it, but get some functional string rollers on there ... Not a huge expense, and a world of difference.

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So many guitars; So little time ..

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olrocknroller
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Re: Repairs to my Mos roller Bridge. Advice please.

Postby olrocknroller » Sun Aug 29, 2010 5:37 pm

Congratulations!

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Sarah93003
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Re: Repairs to my Mos roller Bridge. Advice please.

Postby Sarah93003 » Sun Aug 29, 2010 7:49 pm

Victory!
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1965 Mosrite Celebrity Prototype with Vibramute
1972 Mosrite Celebrity-III
1977 Gibson MK-53
1982 Fender Bullet
1994 Gretsch Streamliner G3155 Custom
2005 Gibson Les Paul Standard Plus
2006 Jude Les Paul 12 String


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