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Jan 20, 2021 - 2:19:13 PM
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26 posts since 10/8/2020

Seems like drum dials have been discussed a whole bunch recently so I hope the forum doesn’t mind another question.

When using a drum dial to establish uniform head tension, should the banjo be in normal tune, should the strings be loosened, or does it matter?

In other words, does the string pressure on the bridge matter in terms of adjusting the head for uniform tension.

Thanks

Jan 20, 2021 - 3:09:27 PM

11479 posts since 6/2/2008

I do it with strings tuned to pitch. It may not matter. Demonstration video on DrumDial website even shows it being used on the underside of the head.

Jan 20, 2021 - 3:44:17 PM

26 posts since 10/8/2020

Yep, watched that video and it makes sense. Thx

Jan 20, 2021 - 3:47:39 PM

124 posts since 1/7/2019

It doesn't actually seem to matter. I had mine all set to an even value with the strings up to pitch, loosened the strings (a lot) and the value was still the same all the way around.

Jeff

Jan 20, 2021 - 4:20:59 PM

6763 posts since 12/5/2007

I wouldn't advise that you try to get your head evenly tensioned with a bridge in place and strings up to tension. The bridge deflects the head and it is no longer flat. My approach has always been to adjust head tension without strings or a bridge in place. I try to get the head evenly tensioned to get a reading (for bluegrass) around 90. After I've done that, installing the bridge & strings and bringing the banjo up to pitch, I check the tension near the neck and it is usually around 91 with the added downward pressure because of the bridge. Measurements behind the bridge will be lower because the bridge depression won't let the dial sit flat on the surface of the head.

I've never tried it but, my best guess is that if you tried, using a Drum Dial, to get the dial to read this much tension behind the bridge, you will break the head or it will be unevenly tensioned.

Jan 21, 2021 - 7:28:56 AM

ChunoTheDog

Canada

581 posts since 8/9/2019
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Everyone I've seen does it with bridge on and strings tuned up.

Jan 21, 2021 - 7:35:06 AM

6763 posts since 12/5/2007

quote:
Originally posted by ChunoTheDog

Everyone I've seen does it with bridge on and strings tuned up.


No way to get an accurate reading that way.  Head deflection from the bridge pressure will not allow the base of the Drum Dial to touch the head all the way around.

Jan 21, 2021 - 8:00:47 AM
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ChunoTheDog

Canada

581 posts since 8/9/2019
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quote:
Originally posted by xnavyguy
quote:
Originally posted by ChunoTheDog

Everyone I've seen does it with bridge on and strings tuned up.


No way to get an accurate reading that way.  Head deflection from the bridge pressure will not allow the base of the Drum Dial to touch the head all the way around.


Here's my (basic and limited) take on it. Tensioning the head without bridge/strings gets you an even head tension when no external stresses are placed on the head via string tension/bridge. So once you set the bridge and tune it up, you now have an uneven head tension.

I could be wrong and I look forward to hearing varying takes on this (perhaps there's even a physicist or structural engineer among us who can tell us all the science behind it).

Edited by - ChunoTheDog on 01/21/2021 08:01:13

Jan 21, 2021 - 8:06:49 AM

ChunoTheDog

Canada

581 posts since 8/9/2019
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quote:
Originally posted by Gixxer340

It doesn't actually seem to matter. I had mine all set to an even value with the strings up to pitch, loosened the strings (a lot) and the value was still the same all the way around.

Jeff


This from my experience is also true. Last time I removed strings/bridge, even tailpiece from my banjo and checked the head tension, it hadn't moved.

Which makes me think my reasoning in my post above is not correct. 

Jan 21, 2021 - 8:48:38 AM

6763 posts since 12/5/2007

I must not be making myself clear here. With the bridge in place, under string pressure, and tuned up to pitch, you cannot accurately measure the head tension all around the head with a Drum Dial because it will not sit flat on its base rendering any measurement inaccurate, except near the neck, away from the dent that the bridge makes in the head.

Jan 21, 2021 - 9:22:06 AM

124 posts since 1/7/2019

quote:
Originally posted by xnavyguy

I must not be making myself clear here. With the bridge in place, under string pressure, and tuned up to pitch, you cannot accurately measure the head tension all around the head with a Drum Dial because it will not sit flat on its base rendering any measurement inaccurate, except near the neck, away from the dent that the bridge makes in the head.


I understand your contention but that has not been my experience. If I use the edge guide to reference the gauge off the tension hoop, I have seen no difference in the readings whether there is no bridge and strings on the banjo or whether the bridge is installed and the strings are up to tune. 

Just my experience YMMV

Jeff 

Jan 24, 2021 - 10:42:12 AM

18 posts since 6/5/2006

The drum dial base is 2" in diameter but the little roller point on the plugger is only about 3/16" wide. In my experience, it has no trouble accurately reading head tension 2" from the rim whether the strings are tuned up or not.

Jan 24, 2021 - 12:18:09 PM

505 posts since 1/28/2011

I just tried this on one of my banjos. The drum dial reading was the same, bare head, or with strings tuned up normal tension.

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