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Adjust coordinator rods vs. taller bridge?

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Apr 25, 2019 - 8:49:23 AM
37 posts since 10/4/2003

I have just got back into banjo playing after several years off. I purchased a decent Morgan Monroe MNB-2 which plays nice but the action is way too low. I am not a set-up expert but the shop I used to use for that has closed so I guess it is no better time than the present to learn. The existing bridge is 1/2" so I am assuming a taller bridge would be the best bet to raise the action, then use the coordinator rods to fine tune the action. Is this correct?

I did notice the rim was misaligned with more hoop showing above the head towards the neck and less showing towards the bridge. I threw caution to the wind, disassembled the entire 'jo and discovered the bottom edge of the aluminum ring of the head was pressed firmly against the neck cutout and not allowing the hoop to be adjusted tighter near the neck. After some very, very careful filing of that shoulder in the cut out, I was able to get the pot reinstalled after assembling with equal tension all the way around while off the neck.

Apr 25, 2019 - 9:09:54 AM
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Players Union Member

rudy

USA

13913 posts since 3/27/2004

quote:
Originally posted by mn2deep

I have just got back into banjo playing after several years off. I purchased a decent Morgan Monroe MNB-2 which plays nice but the action is way too low. I am not a set-up expert but the shop I used to use for that has closed so I guess it is no better time than the present to learn. The existing bridge is 1/2" so I am assuming a taller bridge would be the best bet to raise the action, then use the coordinator rods to fine tune the action. Is this correct?

I did notice the rim was misaligned with more hoop showing above the head towards the neck and less showing towards the bridge. I threw caution to the wind, disassembled the entire 'jo and discovered the bottom edge of the aluminum ring of the head was pressed firmly against the neck cutout and not allowing the hoop to be adjusted tighter near the neck. After some very, very careful filing of that shoulder in the cut out, I was able to get the pot reinstalled after assembling with equal tension all the way around while off the neck.


A 5/8" bridge height is pretty much standard, I'm not sure why yours came with 1/2" bridge.

The "rim misalignment" is more likely to be a tension band that was not tightened down evenly.  If the head bead was bottoming out in the neck notch that could be a pretty good tip off.  (that premised on the correct head being installed on the banjo, of course.)

If you're faced with a possibly uneven tension band then the best thing to do is slack it totally, lay the rim flat against a table surface and measure up to the top of the band to make sure it is the same height as you start re-tensioning it.

Once the head is in place and the tension band slightly tightened against it then you can proceed with tightening each nut BY THE SAME AMOUNT as the head is tensioned. I usually move nuts 1/6 of a turn for each go around.  It's super easy to simply move each nut so you advance 1 flat at a time.

Tighten your head by using the coin / straightedge method if you don't have a good feel for head tension:


Edited by - rudy on 04/25/2019 09:12:04

Apr 25, 2019 - 12:13:09 PM

730 posts since 6/3/2013

1/2 inch bridges were common in the 50's and 60's. I have a 64 Vega Earl Scruggs model that had one. When the neck warped, I had a new neck made and went with a 5/8ths. Many now are going with .656 and 3/4 bridges. I have a .656 on a Huber. Your picks will hit the head when you try to play close to the neck with a 1/2 in. and 9/16th. and some say taller bridges produce better tone. Your best bet is to have the neck recut, for a .656 or 3/4 bridge, and have everything set up by somebody who specializes in banjos. Shouldn't be anymore than $70. Morgan Monroes also have wide necks. So make sure your new bridge has the same spacing. You may even want to go wider. 1 7/8th. bridge spacing would be good for that wide neck.

Edited by - dupreejan on 04/25/2019 12:15:01

Apr 25, 2019 - 12:17:32 PM
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2092 posts since 1/16/2013

For me, co-rod adjustment for action is a "last resort". I know there is tolerance for action adjustment but not much. Too much pressure will begin to change the tone of the banjo and put pressure in other areas that shoudn't have it. As Rudy said, a 5/8 is the most used but some prefer other heights. I know its not easy for every one to get a heel re-cut to to fix the action but that is the best. Then your co-rods can be neutral and the minor adjustments can be made with the truss rod.
-Jim

Apr 25, 2019 - 12:37:09 PM

730 posts since 6/3/2013

I agree with 9470. If your current action is super low, you could go with a 9/16ths. bridge and back down the action 1/32nd. and it would be about right, which is tolerable and wouldn't affect the banjo structurally. But usually lowering action a full 16ths. of inch you start to change and stress things. You could get by with the 9/16ths. bridge if you have no other option.

Apr 25, 2019 - 1:12:11 PM
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37 posts since 10/4/2003

Thanks for all the info everyone. When I reassembled the pot I assembled head down on the table and started adding parts. The tension ring looks really even now and the banjo sounds much, much better.

Apr 26, 2019 - 4:44:57 AM

37 posts since 10/4/2003

Well, Ii measured the bridge last night and it measures .550" so it is over a 1/16" short. I'm going to buy a new 5/8" bridge and then fine tune the action with the rods from there. Now, which of the miracle bridges to buy?? So many to choose from.

Apr 26, 2019 - 10:12:32 AM
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730 posts since 6/3/2013

I've used Purcell and Snuffy Smith. They will custom space it for you. Don't lower the action any more than 1/8th above the 12th fret, maybe even a hair higher if it feels OK to you. You can always use heavy gauge strings to make up the difference.

Apr 26, 2019 - 10:59:12 AM

3765 posts since 9/21/2009

The Sullivan Roasted Maple bridge is great and wont break the bank. $10.00 I think. I have them on all my banjos and love them.

Apr 26, 2019 - 8:41:08 PM

4585 posts since 9/5/2006

scorpion

Apr 27, 2019 - 10:01:51 AM

68984 posts since 5/9/2007

A tight tension hoop/low bridge seems to be asking for the neck to lay back slightly.
Check the roundness of the rim in line with the co rods and 90degrees to them.
You may find the co rod line to be longer than its cross-line.

Apr 27, 2019 - 10:52:58 AM

1605 posts since 9/13/2018

Rudy is correct. The coin/straightedge method had been around for ever. It’ll get you close. Thanks Rudy

Bruce

Apr 27, 2019 - 5:24:32 PM

68984 posts since 5/9/2007

If the bridge is still happy at 1/2 inch the rim may be adjusted for 9/16 or 5/8 bridge height.

Apr 28, 2019 - 6:05:31 AM

37 posts since 10/4/2003

I have a Gary Sosebee 5/8" on order. I am not going to worry about rim roundness at this point. I just really need to get this action up a bit as it measures between 1/6 and 3/32 at the 12th fret. When playing I am getting weird noises from everywhere it seems. My plan is install the 5/8" bridge, make certain I have no loose tension nuts, measure head tension with a straight dowel and a quarter. If necessary I will use the co-rods to raise the action a bit if necessary, but if it requires more than a tad, I'm going to shim with a strip or two of maple veneer.

Apr 28, 2019 - 8:32 AM

68984 posts since 5/9/2007

Measuring the roundness of the rim is a good test for the necessity of a shim or simply a tweak of the co rod nuts.

Apr 29, 2019 - 10:50:21 AM

37 posts since 10/4/2003

Thanks Steve, next time I have reso off I'll definitely check.

Apr 30, 2019 - 6:25:15 PM

9676 posts since 6/2/2008

quote:
Originally posted by mn2deep

Well, Ii measured the bridge last night and it measures .550" so it is over a 1/16" short. I'm going to buy a new 5/8" bridge and then fine tune the action with the rods from there. Now, which of the miracle bridges to buy?? So many to choose from.


That little difference in bridge height can make a surprisingly big difference in action. So bumping up to 5/8 could be all you need to do. if not, you could always go to .656".

The amount of co-rod adjustment you'll need (if any) after changing the bridge should be very little.

May 1, 2019 - 5:02:09 AM
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37 posts since 10/4/2003

Thanks Ken, that is exactly what I am hoping. I have been playing the banjo, but I am really ready for it to sound normal again. I believe when I reassembled the banjo with no tension the co-rods I actually lowered the action further. I will say, this has been fun.

May 5, 2019 - 6:30:47 AM
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37 posts since 10/4/2003

I received my new bridge Friday and installed it immediately, got things tuned back up and intonation set. Wow, what a difference.. The action is now just a smidge over 1/8" at the 12th fret, all signs of buzz are completely gone and the banjo sounds so much better. I now have almost 3 hours of playing on the new bridge and I have to say, my fingers are sore, but the banjo is so much easier to play with less finger placement goofs. I love it!!

Thanks to everyone for all your advise.

Edited by - mn2deep on 05/05/2019 06:31:21

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