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Mar 13, 2018 - 6:22:50 PM
17 posts since 3/5/2015

I have been trying to improve the tone on my first open back banjo. It had some non harmonic sympathetic resonance or like an echo. I tried several bridges and tailpieces and other things with not much change, so I thought the head tightness might be the issue. I wasn't sure what was the correct tightness so I checked out some forums and youtube videos on the topic and there was a good deal of info on tap tuning to G# and assessment of head sag (thickness of a quarter) under string tension. There were some recommendations for drum dials and torque specs as well. I found a torque screwdriver from CDI (model 151SM) with a ideal range of 3 to 15 inch pounds (approx 3.5 to 17 CM KG or .3 to 1.7 NM). This tool allowed me to very evenly and accurately tighten the hooks and nuts and also try a lot of different tensions. I think being able to uniformly tighten the nuts eliminated the acoustic problem. I worked my way up from 3 to 9 inch pounds. I found that around 8 inch pounds (9.2 CM KG or .9 Nm) seemed to be a good tension for the 11" open back banjo with a renaissance head that I was working on. I would say the best range was in the 7 to 9 inch pound range), although I didn't go higher than 9 inch pounds. 8 inch pounds is getting pretty tight with not much light showing between head and 6 " ruler (gap around .025"). The tap tone at this tension seemed to be around B, significantly higher than the G# recommended by many. The G# tap tone was achieved at around 5.4 to 5.6 Inch pounds and it sounded OK at this tension. Would like to hear from others about their experiences. I am going to try and calibrate the adjustable Evans torque key with the TDI torque screwdriver. The evans torque key ($20) is a lot less expensive than this $100 plus torque screwdriver from TDI and looks pretty nice. I will let you know what I find out. But the TDI product is very nice indeed. I am glad I have it and I really think it helped me to improve the tone of this banjo.

Mar 13, 2018 - 7:21:44 PM
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882 posts since 2/9/2007

Yes indeed. Whatever overall tension you like best, you'll get a more musical sound if it's even.

How well torquing the nuts works, though, all depends on how slick your hooks, nuts, shoes, etc. are. On a banjo with nice clean, ever-so-lightly-lubed hardware and everything fitted well, I can do it by feel with a t-wrench and wind up pretty close to equal all around on the Drum Dial. That is not at all the case on instruments of lesser quality and/or which bear the scars of age and hard use, where I'd think that using a torque wrench could just create more confusion...

Mar 14, 2018 - 4:41:59 AM

2300 posts since 12/4/2009

Hello,

Banjo head tension is a critical setup component. Using a torque wrench is one attempt to address this component. When you (like me) are frustrated by the process, just remember that this site has other methods less frustrating.

Learning how to care for a banjo is one aspect that I enjoyed. It also drove me to ensure that playing for others is a good experience the last setup I did.

Mar 14, 2018 - 9:07:02 AM

311 posts since 8/7/2017

As Dan said, the torque reading is highly dependent on the condition of the threads (lube, corrosion, accuracy in machining, etc.) . So, posting your readings is nice, but may not work for banjos in better or worse condition than your own. Also, in aviation work, torque wrenches must be calibrated to a standard every 6 months.

I found the following while adjusting my Cedar Mt "Brainjo" (thin rim) to solve the same problems you mentioned:

1) It was hard for me to tell what pitch the head was at. Snark tuner was not dialing in reliably, for instance. I think it takes more experience than I have to match the tone to a string :-) The best I could hear was "higher than before" and "lower than before".

2) Tap tuning was my best bet. I marked a "drumstick" (3/16" dowel) 1" from the end with a pencil. I then used the pencil mark to achieve a standard distance from the rim for tapping the head with the dowel. This worked pretty well in determining which brackets were tighter than others. As a hand drummer (doembek) I knew that head tone/pitch is very dependent on how far from the rim you hit the head.

3) My best sounding banjo head tension was at a higher tension, measured by the dime/6" ruler method, than other folk's reports. Patrick Costello has written that he tunes his banjo head quite tight for best tone (tone is entirely subjective, of course). Patrick tries to remove the dimples that the bridge puts in the head. I have not gone quite that far, but the dimples are pretty miniscule. My Cedar Mt banjo arrived with a fiberskyn head; my other 2 banjos have a frosted top mylar head, and never had a problem with bad harmonics/echos (and bridge dimples exist).

4) I wove a piece of cloth (bluejean belt loop) in between the strings between bridge and tailpiece. I don't know how much that helps, but it looks cool :-) The only problem is that now my jeans tend to sag unless I tune my belt up to a pretty high pitch.....grin.

5) I sanded the legs of the compensated bridge (Deering) to reduce it's height 1/16". This improved intonation. I replaced the GHS stainless steel strings with D'Addario carbon steel strings (did not like the tone of the GHS)

6) This was a useful site for me:

http://www.banjowizard.com/setup.htm

Hope this helps.

Edited by - BrooksMT on 03/14/2018 09:21:44

Mar 14, 2018 - 9:20:45 AM
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17 posts since 3/4/2018

I have never used a torque screwdriver or wrench on my banjo's. I was told by a pretty good builder that the torque method had a lot of variables as to different friction levels between nuts and hooks due to corrosion, bent, etc...  I tried the tap method and it didn't work for me at all.

I have since use a drum dial which measures deflection of the head itself and this works great for me...This has made changing heads and setting up banjos so much easier and accurate for me.  I found the one I have on ebay and it was used.  It has been one of the best tools I have bought regarding banjo's.

Edited by - BanjoOnMyKnee101 on 03/14/2018 09:25:10

Mar 14, 2018 - 10:11:41 AM

17 posts since 3/5/2015

The banjo hardware was new Balsum Banjo Works. I think some of the hooks could benefit from a little lubrication and I am going to try this. But overall I think the torque screwdriver worked accurately and has .2 inch pound incremental settings between 1 & 15 inch pounds, which offers a lot of options. As I increased the tension on the head I also measured the space between a 6" ruler and the head and also did the tap tone test. I found that the space between the 6" ruler and the head got smaller (.030" at 7 inch ponds; .028" at 8 in lb; and .025" at 9 in lb) and the tap tone got higher ( A# to B# or C) as I increased the tension on the head. After 8 inch pounds the 1st string seemed to get a little thin or tinny to my ear, So I am staying with 8 for the time, but lower tensions down to around 5 in lbs. sounded pretty good. But the tool also helped to get the tension even on all the nuts and around the head which may be the most important variable for improving the tone. I am going to get a drum dial as well and see how even the head tightness is using that tool.

Mar 14, 2018 - 11:57:29 AM

Parker135 Players Union Member

USA

289 posts since 2/19/2012

Something has always puzzled me about this whole process. With no strings and bridge, I can understand working to get even tension across the head with a good chance of success. Beyond that, I think it's a best-effort thing. For one, many banjos have a greater hook spacing across the neck and sometimes the tailpiece. Those hooks have to be a little tighter to get uniform readings (with a Drum Dial) across the neck area. Then, with strings tuned to pitch, the bridge sinks into the head a little. How uniform is the tension then? It may be symmetrical across the path of the strings, but I seriously doubt that it's still uniform everywhere on the head. Of course the Drum Dial is a little wonky in this area because it measures deflection under the indicator, not tension, and there is always some sinking in the vicinity of the bridge unless tightened to near bursting. Most of my experience has been with skin heads where Drum Dials can be a little misleading anyway, but I do use one to look for general zones of tension distribution and symmetry across the head. After going through this a time or two for initial head tightening without strings, I use a 10" straightedge at the end of the bridge for day-to-day maintenance. I don't think I can realistically do much more than that to really improve the situation.

Mar 14, 2018 - 12:39:53 PM
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66671 posts since 5/9/2007

I keep an even tension by starting with a tension hoop showing the same amount of reveal(distance from top of the hoop to the head) and with all hook nuts touching the flange.
The first set of nut tightenings(heel to heel,consecutively) are 1/2 turns.
All subsequent tightenings are 1/4 turns.

After completing each set I eye the evenness of the hoop reveal making up for any unevenness during the next circuit of tightening,not taking a full 1/4 on low places while taking a pinch over 1/4 on high spots.
I stop at G# or in other words a dime under a 6" ruler.

Mar 15, 2018 - 11:00:50 AM

597 posts since 11/7/2003

"I found that the space between the 6" ruler and the head got smaller (.030" at 7 inch ponds; .028" at 8 in lb; and .025" at 9 in lb)"

The amount of tension, and even tension is important but for your banjo that seems REALLY tight to me.  Do you use any stuffing?  Everybody hears differently but I've never played an openback that to my ears didn't sound better with some sort of stuffing.

Mar 15, 2018 - 11:57:21 AM

Dubb

USA

20 posts since 9/13/2017

I like tools and being hard of hearing " just cause I have hearing aids doesn't mean I can hear" I bought a drum dial for $45.00 shipped to my door. That satisfied my search for head uniformity both mine and the banjos.
Dubb

Mar 16, 2018 - 5:06:59 AM
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pickin_fool

Canada

1689 posts since 6/30/2017

you cant really use torque to get the correct tension on a head..there are too many variables associated with torque

Mar 16, 2018 - 5:56:44 PM

4442 posts since 6/3/2011

quote:
Originally posted by pickin_fool

you cant really use torque to get the correct tension on a head..there are too many variables associated with torque


You can use torque to get you in the "Ball Park".  Then use a Drum Dial to even the head tension.  How tight? Until it sounds like you want it to.

Mar 16, 2018 - 8:37:32 PM
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rudy Players Union Member

USA

12311 posts since 3/27/2004

Many of us use torque for initially snugging the head down.  It's just a matter of semantics that the torque is registered not in inch-pounds but tactile feedback of resistance to turning force by way of the fingertips.  It's just another name to call it by.

After the initial tightening phase I switch to snugging the nuts in rotational sequence, watching the flats of the nuts so they can be advanced one flat (one sixth of a turn) for each round.  Using a wrench and calling each adjustment a "quarter turn" or "half-turn" is easy to get off track, as if your next wrench placement slips to one less or one more flat of the nut then it's off.

The necessity of setting precise tension on the head at all points is overrated.  It's really about the sound.  Mechanical methods of determining head tension, be they simple visual observation of how much  the bridge feet sink in, drum dials, or other tension reading methods like the straightedge / coin method that's been demonstrated on the StewMac website for a few years are all fine to use, but a lot of players eventually settle on using feel and a well-developed ear to tell when it's right.

As far as that "perfect tension" on the head, on the vast majority of banjos it isn't.  There is visual proof of that in some of the laser interferometry photos that have been displayed here in the past.  The unequal distribution of hooks around the rim assure that the nodal response of the head isn't the same over the head surface, as well as the pressure deviation cased by the bridge.  I've went to odd-numbers of hooks and perfect even spacing to eliminate that variable in my own banjo designs.

If someone feels the need for a mechanical method to assist them in arriving at an acceptable head tension there's certainly nothing particularly wrong with that.

Mar 16, 2018 - 9:36:15 PM

Helix Players Union Member

USA

11031 posts since 8/30/2006

I suggest using two nut drivers to complete the task, the one across from the other which allows me to "feel" any differences now, like when one is loosened by tightening the others.

I also use 1/6 of a turn to bring it into spec.

I tune my heads to allow voicing with the wood in the rim, there is quite a range available and quite a few different opinions about that: as many as there are players, I suppose. Snappy isn't always the best feeling from the rig. People set up for the PA , so that masks a lot of inept set up. It also masks possible audio limitations of a banjo or rim combination.

Mar 16, 2018 - 11:08:09 PM

28 posts since 8/18/2017

I home built a drum dial with a Chinese dial indicator for 5 total dollars. Ppl say .009 deflection is a g# well maby if everbody spring inside the indicator is exact! Chinese dial indicator is soft. So I like almost A... That's about .003 with mine. Anyway it's simply to even out the tension .001 extra by the feet ends seems normal from what I've seen.

Mar 17, 2018 - 9:16:13 AM

311 posts since 8/7/2017

Jeff, would you post photos or drawings of your design? I have dial indicators, and thought about making a drum dial. But if you have already figured out a method, it'd be nice to see it. Thanks

When I worked quality control for a while at a machine shop, we had precisely machined metal blocks that allowed us to test our indicators (indicator reading vs the known dimensions of the block). This is one way a user could account for differences in springs or other parts of an indicator. You'd not need the expensive blocks, but could make your own out of whatever was available. Then, by recording the dial indicator's readings on the blocks, you could see if the readings drifted with the age of the indicator.

One thing important with the machine shop testing was to be sure that the surface the indicator sat on was perfectly clean. It's pretty easy for gunk to build up on the measuring table, enough to affect the indicator reading but not enough to be easily seen or felt. I used a lot of clean rags and alcohol cleaning the table during a day's work.

I'm not sure how gunk would affect the Drum Dial or similar indicators. Banjo heads certainly build up gunk from the thumb or fingers dragging across the head. The frosting on the head also wears off, so that would affect the readings too, I think (if the indicator spanned a bare spot, the probe would move farther down than if the indicator was over a perfectly level surface).

Mar 17, 2018 - 10:08:22 AM

rudy Players Union Member

USA

12311 posts since 3/27/2004

quote:
Originally posted by BrooksMT

Jeff, would you post photos or drawings of your design? I have dial indicators, and thought about making a drum dial. But if you have already figured out a method, it'd be nice to see it. Thanks

When I worked quality control for a while at a machine shop, we had precisely machined metal blocks that allowed us to test our indicators (indicator reading vs the known dimensions of the block). This is one way a user could account for differences in springs or other parts of an indicator. You'd not need the expensive blocks, but could make your own out of whatever was available. Then, by recording the dial indicator's readings on the blocks, you could see if the readings drifted with the age of the indicator.

One thing important with the machine shop testing was to be sure that the surface the indicator sat on was perfectly clean. It's pretty easy for gunk to build up on the measuring table, enough to affect the indicator reading but not enough to be easily seen or felt. I used a lot of clean rags and alcohol cleaning the table during a day's work.

I'm not sure how gunk would affect the Drum Dial or similar indicators. Banjo heads certainly build up gunk from the thumb or fingers dragging across the head. The frosting on the head also wears off, so that would affect the readings too, I think (if the indicator spanned a bare spot, the probe would move farther down than if the indicator was over a perfectly level surface).


Brooks,

You can find the original directions I posted here for making your own "Drum Dial" type gauge at the web archive of my website:

http://web.archive.org/web/20160328210325/http://www.bluestemstrings.com/pageBanjoTG.html

The photos aren't archived on the page, but I have the source diagrams and photos.  I think they are in my home page photos here on the Hangout but they are impossible for me to find since Eric re-did this website.

There are several archived discussions for home brew tension gauges (and the problems associated with making them)  if you do a search.


 

Mar 17, 2018 - 3:40:47 PM

pickin_fool

Canada

1689 posts since 6/30/2017

I wonder what earl did..oh yeah..tightened it to just below breaking point then backed off a 1/6 of a turn

Mar 17, 2018 - 3:59:37 PM

311 posts since 8/7/2017

Thanks, Rudy. The picture you posted here, plus the text on your website, should be enough to get going :-)

Edited by - BrooksMT on 03/17/2018 16:00:55

Mar 17, 2018 - 6:09:08 PM

4591 posts since 5/8/2014

quote:
Originally posted by BrooksMT

 . . .

When I worked quality control for a while at a machine shop, we had precisely machined metal blocks that allowed us to test our indicators (indicator reading vs the known dimensions of the block).   . . .

 . . .


Aren’t those called “Jo blocks” or “Johansson blocks”?

Like Rudy and Helix, once the head and nuts start to snug down, I tighten/loosen by sixths of a turn, using the flats of the nuts for reference.

Mar 18, 2018 - 3:06:33 AM

pickin_fool

Canada

1689 posts since 6/30/2017

jo blocks=gauge blocks...precision ground and hardened...they are a tad too accurate for anything banjo related

Mar 18, 2018 - 8:51:11 AM

66671 posts since 5/9/2007

I like tightening to a certain note.
I described an 11" bluegrass tension,earlier.
A 12" would probably be more like a half dollar under a 12" ruler.

Mar 18, 2018 - 2:02:07 PM

Parker135 Players Union Member

USA

289 posts since 2/19/2012

That would be fun to check out if I had a 12" banjo. I wonder what happens to the process of tuning to a certain note (what would that be?) vs drum dial vs rulers and coins. Someone step up in the interest of science! With no evidence at all, I bet the 10" ruler and quarter would still be about right since that deals with the local area around the bridge, with the extra inch of surface area around the perimeter not changing the result all that much, but just transferring the tension in a little further from the edge.

Mar 18, 2018 - 3:31:46 PM

rudy Players Union Member

USA

12311 posts since 3/27/2004

quote:
Originally posted by Parker135

That would be fun to check out if I had a 12" banjo. I wonder what happens to the process of tuning to a certain note (what would that be?) vs drum dial vs rulers and coins. Someone step up in the interest of science! With no evidence at all, I bet the 10" ruler and quarter would still be about right since that deals with the local area around the bridge, with the extra inch of surface area around the perimeter not changing the result all that much, but just transferring the tension in a little further from the edge.


Going from a 11" to a 12" head makes a difference of 15% more total surface area, which is a lot IMHO.  If the hook tension is identical the head tension will be considerably less.

When I go from 11" to 11-1/2" diameter heads the effect in both tension and resultant tone is very noticeable, and much moreso when going to a 12" head.

Mar 18, 2018 - 4:08:24 PM

Parker135 Players Union Member

USA

289 posts since 2/19/2012

I'm sure there are differences. I'd just like to see how the ruler/coin trick works out.

Mar 18, 2018 - 4:38:25 PM

rudy Players Union Member

USA

12311 posts since 3/27/2004

quote:
Originally posted by Parker135

I'm sure there are differences. I'd just like to see how the ruler/coin trick works out.


I do remember there was postings about 11" and 12" stick and coin tensioning in the past.

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