Let me first say that I have NOT yet performed this operation on rollers but the manner in which my lap steel nuts are formed gives me confidence in the expected results.

I'll try to describe that technique.

Beginning with flat 3/8in brass bar stock that has been cut to the appropriate height and length, the desired profile is hand filed. I built a jig to firmly hold the bar sitting on its bottom edge. The jig also is used to guide the file so the cutting strokes are straight and, initially, are parallel to the work surface. On the bridge side of the nut, the jig has a raised surface to hold the file at the finish height of the nut. On the key side, is another, lower, surface which provides a 'stop' so that, as the file is tipped during the cutting stroke, a consistant profile is achieved.

The first phase of the operation creates an even profile accross the entire length of the nut. Next, the nut is released, moved 3/8in (my string spacing) and resecured. HERE'S THE TRICK. Before re-clamping, a couple short pieces of string are placed under the nut so that it is raised by that amount from the previous filing. The jig keeps the file always in the same cutting pattern. The result is a 'graduated' profile on the nut conforming to the size of the individual strings. No fancy tools or machining skill required.

That works fine for lap steel nuts. A similar setup should work for cutting grooves in rollers. Presume we start with a roller properly mounted to some device which holds it in a fixed position while acurately spinning it. (Like a jeweler's lathe.) Next, presume a cutting tool mounted to a holding device that centers the cutter laterally to the roller but can be moved toward or away from the roller but not side to side. And finally, a movable 'stop' that can be secured between the cutter holder and roller holder.

With a CADD program I have determined that, using a 30 degree 'V', the depth of cut should be 1.5 times the diameter of a particular string. That would result in the top of the string to be flush with the edge of the roller.

First, using feeler gauges, select one that is 1.5 times a string diameter. Position the gauge and 'stop' between the cutter holder and roller. Move the assembly so the cutter point just touches the roller and secure the 'stop'. Removing the gauge will now allow the cutter to be advanced toward the roller and cut a groove of a depth equal to the feeler gauge. Start the roller spinning and do it.

If it is desired to have the top of the string(s) above the roller, simply subtract that amount when selecting the feeler gauge.

And, Carl, I totally agree with you about an adustable nut for each individual string. Even before reading your posts, I prototyped something quite similar to what you've described. So far, there's been no machine shop interested in producing such an item - even without pricing having been discussed. Making you a set has been in the back of my mind but coming up with a retrofit to your guitar would be problematic.

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"Stump" Reeves

If you put a straight edge across the tops of the strings at the nut and sight from the end of the key head you will see a huge curved gap. As Earnest says, it is not linear, it curves up steeply at the last few wound strings, especially on 12-strings, and that is the big problem. What is tolerable on a 10-string, becomes really bad on a 12-string. If you have a 12-string, put the straight edge only on the first 10-strings, then on all 12. The gap doubles.

That we pay thousands of dollars for these instruments and still have these kinds of problems seems ridiculous. But most pedal steels are made by players and machinists, and few if any have been rigorously designed by mechanical engineers. Also, the instrument has developed by adding on additional strings and pulling mechanisms, and the new additions have created problems that time has not yet solved (e.g., the extra strings on 12- and 14-string necks). After all, pianoes, horns and orchestral strings developed over hundreds of years.

Although some manufacturers may actually have individually graduated rollers, most (if they address the problem at all) simply have 2 or 3 different sized rollers. Emmons uses two (at least on my '80s P/P 12-string, don't know what the new LaGrandes use), and that seems to work well enough for 10-strings, at least for playing at the first fret, although that slide over the nut with the bar may still rattle. But two sizes doesn't work for 12-string, you need at least 3. Zum uses three sizes. Which may be good enough for a 12-string. We just need to get some measurements to see which brands of rollers can be switched easily. I took measurements of my Fessy and Emmons P/P, but left them at home. I remember they both had 1/8" width rollers, but the axles were different sizes. I would like to get the measurements for the Zum rollers and axles. Probably we can just mix and match without having to do any machining.

As far as machining goes, here are some thoughts. Simply changing the radius of the entire roller would seem to work. But the radius effects tone, as Bobbye Seymour will tell you about the changer. A single point of contact is best, but if grooves are needed (as they are for key heads) then the two point V is best. Grabbing the string with a U requires more precision than is found with string guage tolerances, and doesn't allow for small changes in string guages (which are common among steelers). Most roller grooves seem to be a U, but except for the smallest strings, the strings don't fit all the way in the groove and instead sit at the top of the U in a two-point contact. Applying a V formula to this situation would seem to be tricky, unless one machines the entire U into a V. Because the walls of the U are parallel, simply machining down the radius of the entire roller (as Larry suggested) would work, if radius is not important for tone or string breakage (most strings break at the changer, not the nut).

The formulas are nice, but most of us would have no way to implement the results of the formula with precision machinary. But just spinning the roller against a triangle file, as suggested by some, would probably be fairly simple. One could do this off the guitar and use the string to judge when it was right. You could just measure, or even eyeball, until by trial and error you get the string to the right height above the roller (or flush with the top if that is your goal).

Machining will be a last resort for me if I can't find some ready made rollers from one or more manufacturers that I can mix and match. Toward that end, we should all post the measurements of our rollers here. You need the roller width, diameter, groove width, and axle diameter - oh yeah, and the brand and approximate year for your guitar. I am particularly interested in the Zums, because they already have 3 groove sizes. Also, MSA and Sierra have long histories with 12-strings and already put guaged rollers on some of their models, so they are also of major interest for mixing and matching. If people who have these don't post measurements here, I suppose one of us could give the manufacturers a call.

Finally, a couple of other issues were brought up. Earnest pointed out that one manufacturer used guaged rollers to intentionally place the 3rd string (E9) higher than the 1st and 2nd strings (or rather to place the 1st and 2nd strings lower) in order to improve tone for the 3rd string with increased bar pressure. Now that Jagwire is making a 0.0115 string, that solution no longer seems needed. These strings balance the 3rd string tone with the others, and they last a little longer before breaking.

As far as individually adjustable string heights, this seems like overkill and would seem likely to adversely affect tone. Such adjustments are needed for fretted guitars to get the action just right. We don't need that for steel guitars. We just need to get all the strings on a linear plane. That's a one shot design correction for a manufacturer, and if it were done right then, we wouldn't need to ever adjust it again. If someone wanted to put on a radically different string guage, they might have to buy a new roller for that one string. Big deal. It's only a problem when different guaged rollers are not available because manufacturers skimped on this important design feature. If you're buying rollers by the hundreds or thousands, it would seem to be a really trivial additional expense to get them with several different sized grooves.

So for the simplest solution, let's all post our roller measurements.

[This message was edited by David Doggett on 10 March 2003 at 12:32 PM.]

You said,

"Wow, when I started this thread I had no idea this problem was bothering so many people."

And indeed you are correct. Having been in the design and troubleshooting business for most of my life, I can tell you that what you said is MORE the case than not.

RCA once proved that for every percentage point of complaints from their customers, there was a 57.8% factor that could easily be added to that complaint. Meaning that only a few notice and/or complain.

But it does NOT mean the others are all satisfied. Most simply live with a problem until it is solved. Also, some feel somehow it is a reflection on "their" judgement if they state that there is something wrong with a product they have purchased.

The good part is. It is the complainers that bring about improvements. If it were not for that, there is little likelyhood man would have advanced much past the stone age.

Thank God we don't still have "outhouses",

Emmons '80s P/P 12-string ext. E9:
roller width 1/8", roller diameter 5/16", string groove 1/32" (strings 1-10) and 1/16" (strings 11 and 12)), axle diameter 1/16"

Fessenden 2000 S12U:
roller width 1/8", roller diameter 5/16", string groove 3/64", axle diameter 3/32"

If others will post the roller measurements for their guitar(s) I'll put them all in a table so we can hopefully mix and match our own custom sets from ready made rollers from the various pedal steel manufacturers.

[This message was edited by David Doggett on 11 March 2003 at 07:47 AM.]

If someone wants the depth measurements, email me. However, the V groove cutting tool must be sharpened to a very sharp point, else the .011 string will rattle. I have the depths for any gauged string.

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If you play 'em, play 'em good!
If you build 'em, build 'em good!

In the meantime, we can probably greatly improve our problems with off-the-shelf guaged rollers that are already out there. Most rollers seem to be 1/8" width, and 5/16" diameter. But axles are of different sizes. My '80s Emmons P/P has a 1/16" axles, and my Fessy has a 3/32" axle. The grooves come in several different sizes, and that is the point. If we could just get a list of the roller dimensions from several psg manufacturers, we could just use these off-the-shelf rollers to put together a set better than what comes on some guitars (all the rollers with the same groove width).

Please take a minute and measure your guitar's rollers and post it here (steel tape measures usually have marks down to 1/32", which is adequate for this purpose). Many thanks.

[This message was edited by David Doggett on 17 March 2003 at 08:44 AM.]

A wonderfully worded and articulated post. Thank you dear friend for your giving us your expert thoughts on this issue. I agree with every single word you said.

The info about the angle that the strings leave the nut after passing over the roller was precisely what I was referring to ealier along with the U versus the V grooves.

These aspects may be thought insignificant by some, but they ARE very important in a given sound of any PSG or any guitar for that matter.

The reason is simple. It is the nut (and the changer) that touches the string last (excluding the bar and fingers). So it only stands to reason that a lot of research is needed in this area. Sadly, I believe this may not have been the case. Although I do not know it for sure.

In any event, thanks friend for taking the time to share this with us. Most informative post.

May Jesus richly bless you Bobby and all the rest of you,

David, I suspect you meant to say 1/16'th and 3/32'nd's, repspectively.

Let's say it's 2 or 3am in the morning. You're sitting at your wife's dining table, in your shop, at your desk, drawing table, etc. and you've got something between a #2 lead pencil, a ruler, a legal pad or other paper or maybe the most up to date computer drawing program or anything in between and an idea. You're tired, sleeply, hungry, constipated, aggrevated and desperately seeking "that miracle answer". I'll tell ya, one of the last concerns you have is what someone else has or is desiginning and whether or not your ideas will "meld" with another guitar. This may be taking it a little far, but I promise you, it don't miss the mark very far. Hence, we have the wide variences in the ways that a pedal steel is designed and produced. Personally speaking, I' really glad for and thankful to all those "crazy" guys that give so much of themselves and their lives to give us the most remarkable musical instrument in the world. And lest we forget, all the sacrifices and emotional pitfalls that their wives and families go through. Most of us have had more than our share of ups and downs because of our passion to build the "better wheel". Believe me, it makes no difference whether a particular guitar is good or bad, it and all the hundreds of parts, didn't just fall off of a steel guitar tree. Well, enough of that!

The roller nuts that I used on the "B" guitars and as well the Remington PSG's were .500" OD by .185" W. I used either a 3/32'nd or 1/8" axle. Somehow there was two sets of prints for the nut bar. One was milled for 3/32 and the other for 1/8. I personally liked the 3/32 better. I feel that it allowed the roller to roll with less resistence. The only other guitar that comes to mind that might innerchange with those rollers was the Mullin, and at that, it wasn't a really good fit without some additional work done to them.
Boys and girls, whether or not you have a perfect set of roller nuts, or for that matter, a near perfect overall guitar, is not the main issue,,,,,the main issue is the person sitting behind the machine and his/her personal commitment to learn what's there for you and to be able to execute to the point that you say something worthwhile when you play. At most levels and in most cases,,,,it's "not the car,,,,it's the driver"......!
Later,
BB

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If you play 'em, play 'em good!
If you build 'em, build 'em good!

I never noticed this problem on E9 (probably why some manufacturers haven't dealt with the problem), but on C6 and universals it is a problem because of that big ole 0.068 bottom string. If that thing doesn't have a bigger groove in the roller it sits up there a mile high.

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If you play 'em, play 'em good!
If you build 'em, build 'em good!

quote:

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most of the Sho-Bud rollers were a fair amount thinner (width) than most guitars

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