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 ARCHIVED TOPIC: Rudy rod / co-rod hybrid


Please note this is an archived topic, so it is locked and unable to be replied to. You may, however, start a new topic and refer to this topic with a link: http://www.banjohangout.org/archive/350613

Ken LeVan - Posted - 01/27/2019:  14:03:44


Here’s a way to make a Rudy rod act more like the coordinator rods favored by bluegrass players while retaining the benefits of the Rudy rod.





I recently made two 14” six string banjos and realized I needed a bottom rod to offset the extra strain being exerted on the wide rim by the extra strings.  Meanwhile, I am making two bluegrass banjos and one of the customers requested the bottom rod they had seen on a post I made in the past.



Traditionally, openback banjos have had some kind of dowel arrangement, and bluegrass banjos have used the coordinator rod system developed by Gibson in the 1920s. Not that there is any physical reason for this, because there is no more stress on the neck of a bluegrass banjo than there is on an openback, but Gibson did a good job marketing it as being able to adjust the action, and it has become a kind of norm ever since - part of the grammar of bluegrass banjos much the same way as the dowel stick has become part of the grammar of openback banjos.



The problem with dowel sticks is that they are not adjustable, and very difficult to install.  Many vintage banjos were designed to have 1/2” bridges and as the trend towards higher bridges came about,  it was very difficult to change the bridge height on a dowel stick banjo without resetting the angle of the dowel - difficult to do.   Co-rods can be used to egg the rim, which is dangerous and in the wrong hands have caused delamination breaks in some old pre-war rims, but I guess the thought of easily adjusting the action has been too hard to resist



Around 1960 Vega abandoned the dowel stick system they had been using for at least 70 years and introduced a double rod system similar to the Gibson system, except with two aluminum rods, one of very large diameter, hearkening back to the dowel stick it was replacing, except this one could push to snug it inside the rim.  The rims for these were 7-ply hard maple with cross grain lamination, which allowed holes to be drilled and tapped so that 1/4-20 set screws could be threaded through the rim and  used to adjust the neck angle side-to-side and up and down.  The two rods were used to loosen and tighten the neck as the set screws were adjusted.  Complicated and reviled by many people who thought the neck had to have full contact against the pot.  I have one of these banjos and have made a semi-reproduction of the system on a longneck for a folk performer, and trust me, it works, but is complicated and requires a special rim.





The Rudy rod is a hybrid system consisting of a hollow wooden dowel with a threaded  metal tension rod inside - it’s very simple and works by means of tightening the tension rod - i.e. putting it in tension, which puts the wooden dowel into compression and makes an absolutely solid connection of the neck to the pot, more so that dowel sticks.  This system depends on having an anchor in the heel that the rod screws into allowing more tension to be applied than with  lag screws, which pull out of end grain.  A Rudy rod wouldn’t work for long if the tension rod was screwed into the end grain of the heel like the familiar lags used with co-rods.

Normally, when I make a Rudy rod, I install a washer plate and put a second bolt below the dowel, which allows a tighter connection, prevents rotation, and facilitates adjustment.



The bolt can be modified to accept a lower push-pull rod.





 



The key to this system is the bottom anchor bolt which has a 10-24 threaded end that  screws into the heel anchor and tightens the neck and a hollow front end threaded 1/4-20 which allows the push-pull rod to be installed ( or not installed as desired).



Here is how it’s installed:



(1) you start off with the anchor in the heel, and the standard Rudy rod.  The end of the tension rod can either be the tailpiece lug or tighten against an L bracket.



(2)  The bottom bolt is installed and both the bolt and tension rod tightened with a 7/16” wrench.  At this point you are good to go unless you want to install the optional bottom rod.



(3) If the push-pull rod is to be used, it is installed  through a second hole in the rim, and tightened into the bottom bolt with a special wrench.



(4) The pull bolt is installed on the outside of the pot, the push bolt, along with a nylon washer is inside.  Holding the rod with the little wrench, the bolts can be manipulated to push or pull.  You can “ tune” the rod, for those who are interested in that technique.



As I said earlier, this is overkill for openback banjos with properly made rims, but I did it on the 14” 6-string ones because of the extra stress and large diameter, and am doing this on the bluegrass ones I am currently making since the “co-rod” is a familiar idea in that genre, enhanced (I think) by the Rudy Rod, which is a superior neck mounting method all on its own.



I’ll add that I think this might be appropriate for thin rimmed 12” pots as well.



 

Dan Drabek - Posted - 01/27/2019:  15:32:47


Nice work Ken. Your industrial design genetics are showing. :->

I am sure your arrangement will warm the hearts of banjo tinkerers everywhere. The more nuts, screws, rods, bolts, and plates that can be manipulated the better. You've taken the best features of two systems and combined them into more than the sum of the parts.

I like the Rudy rod system for it's traditional look, and easy repair/modification features. But growing up with the co-rod system, ( which has aged into a traditional look of its own) I do occasionally tweak the top rod and don't mind having it. Plus, I think it helps add additional stiffness to the rim--which probably accounts for minor adjustments to the rod resulting in modification to the sound.

Interesting and informational stuff. Thanks for taking the trouble.

DD

Ken LeVan - Posted - 01/28/2019:  07:05:10


I think I may have established a new record for a subject nobody is interested in.

spoonfed - Posted - 01/28/2019:  08:14:22


truthfully Ken, I find all of your posts interesting I honestly do ! the only reason that I rarely comment is that I am not very clever and know very little about the technicalities of banjo building so, do not really have anything constructive to say, I do however value your contributions here and, usually learn something from them, please keep em coming .

jamesinkster - Posted - 01/28/2019:  09:25:52


Nice work. I personally prefer the aesthetics of just the rudy-dowel (I also use a second bolt on mine, for similar reasons as yourself...), but will keep this approach in mind if someone requests co-rods (which I don't love).

Curious -- what's the white (lexan??) on the end of your dowel and co-rod do? A bit of flex where it joins the pot or ?

thanks

Ken LeVan - Posted - 01/28/2019:  09:56:41


quote:

Originally posted by jamesinkster

Nice work. I personally prefer the aesthetics of just the rudy-dowel (I also use a second bolt on mine, for similar reasons as yourself...), but will keep this approach in mind if someone requests co-rods (which I don't love).



Curious -- what's the white (lexan??) on the end of your dowel and co-rod do? A bit of flex where it joins the pot or ?



thanks






It's UHMW - similar to teflon but much less expensive.  I buy it in sheets and use it for a number of different things.  It's very handy since it's easy to saw, drill, thread, etc. and nothing will stick to it, even epoxy resin.  I pin the little square onto the end of the dowel with a pin nailer.   It acts as a cushion where the wooden rod hits the inside of the rim.  I also use nylon washers on some nuts.

frisco slim - Posted - 01/28/2019:  10:38:24


Very interesting post, Ken, and beautifully presented as ususuaI.



I have long been curious about the Vega neck attachment with the Allen head adjustment screws. One question I had was whether the screws were threaded directly into the wood rim, which you have answered in the affirmative. The other question was what those screws pressed against in the neck? Was there a metal plate of some kind inset into the heel, or did the screws bear directly gainst the wood end grain? The latter possibility seems like it would be way too soft for the forces involved.


Edited by - frisco slim on 01/28/2019 10:38:47

Dan Drabek - Posted - 01/28/2019:  15:56:12


quote:

Originally posted by Ken LeVan

I think I may have established a new record for a subject nobody is interested in.






Sorry to see this Ken. Quality, labor intensive posts like this one represent a significant investment in time and effort. And to be fair, they ought to generate reasonable notice to inspire future contributions. There seems to be no lack of response to simple topics that have been asked and answered a thousand times, so I know the audience is not yet dead. 



DD



 

Ken LeVan - Posted - 01/28/2019:  17:32:13


quote:

Originally posted by Dan Drabek

quote:

Originally posted by Ken LeVan

I think I may have established a new record for a subject nobody is interested in.






Sorry to see this Ken. Quality, labor intensive posts like this one represent a significant investment in time and effort. And to be fair, they ought to generate reasonable notice to inspire future contributions. There seems to be no lack of response to simple topics that have been asked and answered a thousand times, so I know the audience is not yet dead. 



DD



 






Thanks, Dan,



I guess there are just some topics that are more universally interesting than others, and you never know - someone will get something out of it.  The pictures I used on this, and even the copy, are useful to me for several other things - website, records, etc. and I didn't just do them to post a thread, Many of the pictures I post in threads wind up on Google Images and Pinterest, which is why I put my name on them.  Plus this will be archived and dated on this site for future reference - one reason it's a good idea to name a thread something that tells what it's about.


Edited by - Ken LeVan on 01/28/2019 17:33:47

lab_dad - Posted - 01/28/2019:  18:14:20


Ken,
I wish you would put all this in a GIANT coffee table (text) book!
Complete with pictures of all of your damn sexy instruments.
Thanks for posting.
Martin.

Helix - Posted - 01/28/2019:  19:39:44


I've been away, then when I'm back I see you've been showing your light from under the bushel again.

It's real fine looking, keep it up.

C Flat Fred - Posted - 01/28/2019:  20:51:02


Ken,

I post very infrequently but I always look very carefully at your posts and really appreciate your illustrations and explanations of your work. My next banjo build will benefit from what you have shown us.  Unfortunately  I will be responsible for the quality of my work.



Fred

Leslie R - Posted - 01/29/2019:  03:57:28


I think it is a brilliantly thought out design. Incredible workmanship. I doubt I could achieve that if I lived to be 1,000.

Without a doubt, it will add stiffness to the pot.

I have never heard of "tuning the rod". What does that mean ?

Ken LeVan - Posted - 01/29/2019:  04:54:52


quote:

Originally posted by Leslie R

I think it is a brilliantly thought out design. Incredible workmanship. I doubt I could achieve that if I lived to be 1,000.



Without a doubt, it will add stiffness to the pot.



I have never heard of "tuning the rod". What does that mean ?






When you tighten up the rod, you can pluck on it and it makes a note like the note on a bass fiddle.  Since the rudy rod is tightly compressed on the inside of the pot and the screws go in to a heel anchor, what you are hearing is the entire instrument resonating.  Tightening or loosening the rod changes the pitch and you can determine the neutral note and "tune" this to a higher note as long as you are careful not to egg the pot.



I understand that some bluegrass banjo setup people do this with co-rods and have determined the notes they like. 



I have just used them to get the instruments to a happy state of tightness and neutrality by plucking as I turn them until I get a strong note.   For an example, on your two instruments, one makes (roughly) a G below middle C the other one makes an A below middle C.  I suspect these notes might be hard for some people to hear, like the note the head makes, although it sounds more like a string note than a tap note.

Ken LeVan - Posted - 01/29/2019:  06:26:19


quote:

Originally posted by frisco slim

Very interesting post, Ken, and beautifully presented as ususuaI.



I have long been curious about the Vega neck attachment with the Allen head adjustment screws. One question I had was whether the screws were threaded directly into the wood rim, which you have answered in the affirmative. The other question was what those screws pressed against in the neck? Was there a metal plate of some kind inset into the heel, or did the screws bear directly gainst the wood end grain? The latter possibility seems like it would be way too soft for the forces involved.






They had a metal plate that the set screws contacted.  The better way to do it, which I did when I made a banjo with that system, is to put wide-headed inserts, like cut-off nails or flat-headed screws into the heel where the set screws contact to act as a bearing.

Aradobanjo - Posted - 01/29/2019:  08:28:11


quote:

Originally posted  Ken Lebanon

When you tighten up the rod, you can pluck on it and it makes a note like the note on a bass fiddle.  Since the rudy rod is tightly compressed on the inside of the pot and the screws go in to a heel anchor, what you are hearing is the entire instrument resonating.  Tightening or loosening the rod changes the pitch and you can determine the neutral note and "tune" this to a higher note as long as you are careful not to egg the pot.



I understand that some bluegrass banjo setup people do this with co-rods and have determined the notes they like. 



I have just used them to get the instruments to a happy state of tightness and neutrality by plucking as I turn them until I get a strong note.   For an example, on your two instruments, one makes (roughly) a G below middle C the other one makes an A below middle C.  I suspect these notes might be hard for some people to hear, like the note the head makes, although it sounds more like a string note than a tap note.






Hello, 



Per Warren Yates video on bridge setup, Donny Little showed that the Co-Rods could be used to control sustain. “Open up”, is the description Donny Little used. What Bluegrass banjoists have pushed this notion?

Ken LeVan - Posted - 01/29/2019:  08:42:37


quote:

Originally posted by Aradobanjo

quote:

Originally posted  Ken Lebanon

When you tighten up the rod, you can pluck on it and it makes a note like the note on a bass fiddle.  Since the rudy rod is tightly compressed on the inside of the pot and the screws go in to a heel anchor, what you are hearing is the entire instrument resonating.  Tightening or loosening the rod changes the pitch and you can determine the neutral note and "tune" this to a higher note as long as you are careful not to egg the pot.



I understand that some bluegrass banjo setup people do this with co-rods and have determined the notes they like. 



I have just used them to get the instruments to a happy state of tightness and neutrality by plucking as I turn them until I get a strong note.   For an example, on your two instruments, one makes (roughly) a G below middle C the other one makes an A below middle C.  I suspect these notes might be hard for some people to hear, like the note the head makes, although it sounds more like a string note than a tap note.






Hello, 



Per Warren Yates video on bridge setup, Donny Little showed that the Co-Rods could be used to control sustain. “Open up”, is the description Donny Little used. What Bluegrass banjoists have pushed this notion?






I can't remember all the details about it, but it was on this forum, and was referred to as "tuning the rods".

ClayTech - Posted - 01/29/2019:  17:18:36


Don't worry about number of responses. Look at how many reads this thread has- almost 400! That's more than most of the threads on page 1 of the Building section. I, like many, really enjoy your posts like this. I don't generally say anything because it won't really add to the conversation, but please don't stop. Your posts about your builds are like a big coffee table book. Total eye candy!

fairlane64 - Posted - 01/29/2019:  20:54:23


Ken
Thank you for the post and all the information. I have only built 1 open back so far and have learned much from your posts. I used lag type coordinator rod on that banjo and the sound is loud and strong. On the next one I will use your illustrations to attach the neck. I enjoy building banjos and am now looking at doing some inlay work. Do you have a post that might help
thanks for all your help
don

Stephen45710 - Posted - 01/30/2019:  04:01:59


quote:

Originally posted by Ken LeVan

I think I may have established a new record for a subject nobody is interested in.






Thanks for taking the time to create this post and thank you even more for your willingness to share your knowledge and expertise! Your posts are a wealth of information and an asset to those of us still learning the craft of banjo building. 

Ken LeVan - Posted - 01/30/2019:  05:00:05


quote:

Originally posted by fairlane64

Ken

Thank you for the post and all the information. I have only built 1 open back so far and have learned much from your posts. I used lag type coordinator rod on that banjo and the sound is loud and strong. On the next one I will use your illustrations to attach the neck. I enjoy building banjos and am now looking at doing some inlay work. Do you have a post that might help

thanks for all your help

don






Don,



I have posted threads about inlay over the years - different kinds, and I have a bunch of pictures  there are SO many ways to do that, we all have our favorite methods and there are many threads about that that have been done.



If you give me an idea of what kinds of tools you have, what style of inlay you are contemplating, I can send you some pictures.

Joel Hooks - Posted - 01/30/2019:  06:30:04


quote:

Originally posted by Ken LeVan

quote:

Originally posted by frisco slim

Very interesting post, Ken, and beautifully presented as ususuaI.



I have long been curious about the Vega neck attachment with the Allen head adjustment screws. One question I had was whether the screws were threaded directly into the wood rim, which you have answered in the affirmative. The other question was what those screws pressed against in the neck? Was there a metal plate of some kind inset into the heel, or did the screws bear directly gainst the wood end grain? The latter possibility seems like it would be way too soft for the forces involved.






They had a metal plate that the set screws contacted.  The better way to do it, which I did when I made a banjo with that system, is to put wide-headed inserts, like cut-off nails or flat-headed screws into the heel where the set screws contact to act as a bearing.






Hi Ken, I also read your threads with interest but don't have much to add except that I think your designs are super cool.  



Vega: I have mentioned this several times before.  I have a friend who knew Bill Nelson when he was running Vega (after he inherited the business).  He would regularly visit and hang out in the Vega shop during the time when those banjos were being built.



Every single change from earlier designs were developed to cut costs.  Co-rods are less labor to install and require less skill.  Not fitting the heels properly to the rim also saves money.  The differently laminated rims were chosen because Nelson found a company that made wood tubing or pipe and he could just buy it and slice off pieces for the rims instead of making his own.  From the overall design, to the lousy two in one stain finish that wears off of the neck, it was all about making a higher margin. 



Bill Nelson (as I have been told) did not care about banjos-- they were just product.  According to my friend, Nelson said he could as well have been making washing machines or other home appliances, it was just product.



Luckily Nelson had people working for him like Pete Colby who did care.  While the materials were chosen for cost, and the fit and finish is lousy, the banjos Vega built in the 60s are pretty good (after you get past the ugly orange color and boring peghead shapes).



There is a story relayed to me from another friend who was close with Pete Colby.  When Colby was working at Vega they were using a machine that would shape the necks.  Now and then a nice piece of curly maple would make the machine chatter.  Nelson would pull it out of the machine and burn the blank in the wood stove.  Colby would tell him he could take those and work them into higher end necks but Nelson said he would rather burn them then pay for the time to hand shape a neck.

Ken LeVan - Posted - 01/30/2019:  06:42:27


Yes, Joel,



I remember you writing that, and I agree with it 100% having spent a career designing products for manufacturing companies driven by either manufacturing, marketing, or sales - never design.



Gibson did exactly the same thing, but 35 years earlier - co-rods are easier to do than dowel sticks (they mention that in their copy), tubes or cast flanges are easier to do than drilling shoe holes and bolting the shoes on or fabricating bracket bands, having one diameter and one hook spacing as a standard was easier than the multiple sizes Vega made, the double-cut peghead design is all done with spindles, very easy to do, but it looks complicated, casting and machining is easier to do than fabricating, their inlay methods were cheaper and easier than Vega's, their 3-ply rims were often very sloppily made/. Everything they did was designed to cut costs or give the marketing people a story to tell.


Edited by - Ken LeVan on 01/30/2019 06:43:00

fairlane64 - Posted - 01/30/2019:  20:47:41


Ken
I have some mother of pearl squares and some other parts. I have a Dermal with the plunge router base but have not bought the bits yet. I will also be looking at wood types to see what I like best. I like something simple but nice
any help would be appreciated
thanks Don

rudy - Posted - 01/31/2019:  05:58:34


quote:

Originally posted by fairlane64

Ken

I have some mother of pearl squares and some other parts. I have a Dermal with the plunge router base but have not bought the bits yet. I will also be looking at wood types to see what I like best. I like something simple but nice

any help would be appreciated

thanks Don






Don, Not to side-track Ken's discussion, but there are a bunch of archived topics on introductory inlay if you do a search.  I posted at least one of them, detailing a banjo accessories box to serve as a way for newbies to dip a toe in the waters.



Beginning inlay discussion



Sean Barry's posting for his "Pearl Technique" pdf

Ken LeVan - Posted - 01/31/2019:  10:53:06


quote:

Originally posted by fairlane64

Ken

I have some mother of pearl squares and some other parts. I have a Dermal with the plunge router base but have not bought the bits yet. I will also be looking at wood types to see what I like best. I like something simple but nice

any help would be appreciated

thanks Don






Don,



I looked through my "how-to" images from previous threads, and I wouldn't know where to start selecting images - it's too broad - you have making the patterns, marking the MOP, using the jeweler's saw marking the fingerboard, routing out the cavities, infill, etc. 



This isn't the thread for that.  I think you should start a thread asking specific "how to" questions, and you will get a lot of great help and ideas from this forum.



Ken

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