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RK-75 Teardown and Setup

Posted by FlyinEagle on Friday, April 20, 2018

Since I bought my RK-75 I had constantly wondered about the tone-ring fit after reading that they are often tight after a month or so in a shipping container crossing the Pacific.  I was previously hesitant to tear it down because I had it professionally set up when I bought it, I liked the tone and action, and I wasn’t confident in my abilities to set it back up.  After an additional year of education I was confident I could it, so I finally took the plunge and tore it down when I last changed the strings.

 

What I found was surprising.  Not only was the tone ring fit not tight, but it was downright sloppy loose.  It easily had 1/8” of movement in one direction, which means it had at least 1/16” of play all around. I did this in February, and my basement where I keep the banjo had a relative humidity of 10-15% all winter, so I am aware that the rim was the smallest it would be all year.  I followed Warren Yate’s method of building up some of the diameter of the rim using masking tape. I built it up so that there was about 1/32 or maybe a little less of clearance all around.  I will be very tempted to tear it down again in August after the rim has been acclimated to the 40-50% RH I keep the basement at all summer.

 

This was not the only issue I discovered.  At the heel, there were 2 globs of hardened lacquer, one on each side of the neck, and that is what was making contact with the pot at the tone ring skirt.  I wish I took photos of that it, because it is clearly something that should have been addressed at factory assembly. Anyway, I sanded the lacquer off and re-assembled.  The loss of the globs must have changed the neck to pot fit, and I started to get a 4th string buzz.  I gave the truss rod a ¼ turn to give a little more relief and that cleared up the buzz after a couple days of settling in.  I made sure the co-rod nuts were set almost neutral, just a hair beyond finger tight.

 

The result?  A marked improvement in volume and tone, and especially variability in tone.  It definitely enhanced the tone while picking up near the neck (y position), and it also enhanced the tone in the 7th to 14th fret range.  Much easier to get that up-the-neck lonesome howl when you want it.  I think this has more to do with the globs of lacquer than the tone ring fit, since I still left the fit loose.

 

I’ve had a Cunningham bridge on this banjo since the fall.  That bridge also brought with it a greater variability in tone (although it wasn’t lacking before with the Scorpion bridge I previously had on it. I kept the stock RK Presto on there for now, but I am thinking about trying something else, just to get the experience of learning how different tailpieces affect the tone.  I set the presto about ¼” up, and just about parallel with the head.

 

I guess the moral is, these RK banjos are simply unbeatable at their price.  I never hesitate to recommend them, but being a factory assembled instrument, it might take just a little bit more setup for these banjos to reach their full potential.  

 

Happy pickin!

-Jeff

 



1 comment on “RK-75 Teardown and Setup”

teletodd Says:
Friday, April 20, 2018 @9:17:18 AM

I have an RK75 and I have yet to completely tear it down, although I did check the co-rods which were fine. I've watched the Johnny Button video series and a couple others and it seems like they do all that tear down work and then do nothing to the rim to change the fit. as such, so far I've just experimented with various bridges, string gauges and head tension.

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