Steel Builders - roller groove calculator

Karlis Abolins · Post by **Karlis Abolins** » 18 Jan 2005 7:00 am

It took me a while to figure out how to calculate the depth of a groove for a set of gauged rollers but I did it with the help of my 15 year old son. This formula assumes that you are using a 60 degree thread cutting lathe tool. The formula is in the form of an Excel spreadsheet. The example is for Chuck Campbell's 12 string Sacred Steel tuning. You can change the string gauges and the exposed amount for each string. In my example, I am using an exposed amount of .010 inch. The exposed amount can be the same for all strings or you can graduate the exposed amount.
http://home.comcast.net/~k.abolins/groove.xls

Karlis

David Parker · Post by **David Parker** » 18 Jan 2005 11:07 pm

Karlis it is very simple to machine gauged rollers. The point of the 60 degree threading tool cuts into the roller to the depth of the diameter of the string and on the lathe use a dial indicator to read the travel of the tool. Dave

Karlis Abolins · Post by **Karlis Abolins** » 20 Jan 2005 10:21 am

Dave, It took me a little while to investigate your recommendation. I think it is important to understand the purpose or purposes of gauged rollers. Your recommendation will result in a set of rollers that will hold the strings in the grooves. However if you put a straight-edge (like a bar) across the strings at the nut, you will find that strings 3 through 8 will have measurable gaps. That in itself is not a problem as most people don't slide to the open position very often. The gaps will diminish as you slide up the neck with the help of bar pressure.

I have charted out a standard E9 set of strings to show this. If you groove the roller with a 60 degree tool to the depth of the string diameter, you end up with an exposed string height ( height above the plane of the roller tops) equal to half the diameter of the string. I have mathematically placed a stright-edge across the tops of the strings and mesaured the distance above or below the straight-edge. The results show that string 2 is very slightly above the straight-edge while strings 3 through 9 are below.

A=string
B=string gauge (diameter in thousands of an inch)
C=exposed string height
D=groove depth
E=distance of the exposed string top above or below the plane of the string tops (bar)

groove depth = string diameter
<pre>
A B C D E
F# .012 .0060 .0120 .0000
D# .015 .0075 .0150 .0001
G# .011 .0055 .0110 -.0034
E .014 .0070 .0140 -.0033
B .018 .0090 .0180 -.0028
G# .022 .0110 .0220 -.0022
F# .026 .0130 .0260 -.0017
E .030 .0150 .0300 -.0011
D .034 .0170 .0340 -.0006
B .038 .0190 .0380 .0000
</pre>

To a perfectionist like me, the above reults are a compromise. To me the purpose of gauged rollers goes beyond holding the strings in place. I want the gauged rollers to result in a string top plane which has no gaps for individual strings. The spreadsheet above goes beyond that requirement and results in a string-top plane that is parallel to the plane of the roller-top plane. It makes all of the strings stand above the rollers by the same amount. I experimented with a variation that gives similar readings to your straight-forward process but adjusts for the gaps,

To compensate for the gaps and to ensure that each string is resting in the groove, I adjusted each groove depth relative to the plane of the string tops. I increased the depth of each groove by .001" to make sure that the 3rd string rests completely in the groove.
<pre>
groove depth graduated to give a flat plane across the top of the strings
A B C D E
F# .012 .0050 .0130 .0000
D# .015 .0064 .0161 .0000
G# .011 .0079 .0086 .0000
E .014 .0093 .0117 .0000
B .018 .0108 .0162 .0000
G# .022 .0122 .0208 .0000
F# .026 .0137 .0253 .0000
E .030 .0151 .0299 .0000
D .034 .0166 .0344 .0000
B .038 .0180 .0390 .0000
</pre>
I am not sure that anyone but me (or perhaps Carl Dixon) is concerned about this issue but I wanted to make this available to everyone. If anyone wants my second spreadsheet, please e-mail me.

Karlis[This message was edited by Karlis Abolins on 20 January 2005 at 10:23 AM.]

David Parker · Post by **David Parker** » 20 Jan 2005 11:30 pm

Karlis I don't understand what your "C" dim. is. Height above what ? It appears to be half the dia of the string. Dave

Per Berner · Post by **Per Berner** » 21 Jan 2005 2:38 am

Carl D is by no means alone in hating 1st fret buzz. But to get a perfect result with gauged rollers would take a lot of luck if you don't have access to extreme precision machining. And what happens if you decide to change string gauges?

On the steel I am building right now, I intend to solve the problem by mounting each roller in individually height adjustable saddles.

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Emmons Legrande II D10 8+5, Sho-Bud Pro III Custom SD10 4+5, Goodrich 120, Peavey Nashville 1000

Farris Currie · Post by **Farris Currie** » 21 Jan 2005 3:27 am

Per,i'll say one thing,that will cull the men out from the boys!!and i am a precision machinist!!gosh how do you drill hole thru,that and keep it straight??
farris

Per Berner · Post by **Per Berner** » 21 Jan 2005 4:10 am

Farris, I haven't tried it outside the cyber world yet!

But it could work equally well using slightly modified off-the shelf Strat-style roller saddles - just not as purdy...

I'll post some pics when it's done, which could take some time.

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Emmons Legrande II D10 8+5, Sho-Bud Pro III Custom SD10 4+5, Goodrich 120, Peavey Nashville 1000

Farris Currie · Post by **Farris Currie** » 21 Jan 2005 5:09 am

AND they wonder why i hate engineers?? haha!
nothing to it!!!!!!!!!!!!!!!!!!!
farris

Peter · Post by **Peter** » 21 Jan 2005 5:17 am

Per, you don't have to drill a long hole for the long axle.
It might be better to use the fulcrum point idea like the Stat tremolo unit.
The fulcrum point could be on the right hand side and the adjustment screws on the left side, near the tuning keys.
The string pressure will push the little blocks into the fulcrum point.

Just a thought...maybe it works.

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Peter den Hartogh
1970 Emmons D10 P/P; 1977 Sho-Bud D10 ProIII Custom;
1975 Fender Artist S10; Remington U12; 1947 Gibson BR4;
Internationally Accredited 3D Animation Academy

Per Berner · Post by **Per Berner** » 21 Jan 2005 6:01 am

Good thinking, Peter. I'll try that if the original idea doesn't work out. I think I can afford to scrap a few pieces of aluminum trying.
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Emmons Legrande II D10 8+5, Sho-Bud Pro III Custom SD10 4+5, Goodrich 120, Peavey Nashville 1000

Karlis Abolins · Post by **Karlis Abolins** » 21 Jan 2005 7:30 am

Dave, A picture is worth a thousand words.

Dimension C. is half of the string diameter and half of the groove depth. It works for a 60 degree angle.

Karlis

Karlis Abolins · Post by **Karlis Abolins** » 21 Jan 2005 9:32 am

Per, Your comments about precision are valid. It is fairly easy to get precision to .001" and a little more difficult to get precision to .0001" but you can get very close.
To your comment about changing string diameter, it would be fairly easy to have rollers that are gauged to string diameter with a constant exposed string amount. You can then change the roller when you change the string. If you follow Dave's example with my adjustments, you can do the same thing unless you change the end strings.

Per, You might want to consider using a wedge arrangement rather than a screw and pivot arrangement to get better contact between the parts.

Karlis

Peter · Post by **Peter** » 21 Jan 2005 1:11 pm

Here is a thought:

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Peter den Hartogh
1970 Emmons D10 P/P; 1977 Sho-Bud D10 ProIII Custom;
1975 Fender Artist S10; Remington U12; 1947 Gibson BR4;
Internationally Accredited 3D Animation Academy
[This message was edited by Peter on 21 January 2005 at 01:26 PM.]

Curt Langston · Post by **Curt Langston** » 21 Jan 2005 4:09 pm

Looks great Peter. I am concerned that too much free space around the bottom and edges may compromise sustain.....Just a thought.

Peter · Post by **Peter** » 22 Jan 2005 12:18 am

Curt, the block containing the roller could be made much higher, like the inertia block on a Strat.

Per Berner · Post by **Per Berner** » 22 Jan 2005 1:41 am

Peter, I think your knife-edge idea looks like a very interesting improvement on my design. It might lessen the risk of sustain loss, while also being much easier to manufacture. The saddles would of course come loose when you're changing strings, but that would be a very minor problem.

And by the way, your 3-D renderings are absolutely fantastic!

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Emmons Legrande II D10 8+5, Sho-Bud Pro III Custom SD10 4+5, Goodrich 120, Peavey Nashville 1000

Peter · Post by **Peter** » 22 Jan 2005 4:06 am

Thanks, Per.
This should keep the saddles in place AND increase the sustain.

Or even better, with a hard-metal fulcrum plate across the guitar. The plate will lock all saddles in place and you need only 3 screws to hold it. (Per, tell me when to stop)

Karlis, my apologies for the topic drift.

[This message was edited by Peter on 22 January 2005 at 11:25 AM.]

Jim Palenscar · Post by **Jim Palenscar** » 22 Jan 2005 5:37 am

..or, as a number of folks have advocated (ie. Ed Packard for one), simply use the same gauges
with the hole drilled off center by a titch and rotate to bring each string in plane. Yes - it would result in string lengths being unequal (for perfectionists), but I'm doubting that it would be a problem given the success of the fore/aft movement of the changer fingers of the Anapeg and the Excel.

Per Berner · Post by **Per Berner** » 22 Jan 2005 6:33 am

Jim, that is indeed an ingeniously simple, no-cost solution. But wouldn't it be very fiddly, involving hundreds of attempts to get it right, taking great care not to move the adjacent rollers, only to have the settings ruined when the strings come off?

Also, I suspect the rollers would move around a bit from the strings' back and forth movements . Even the tiniest difference in resistance between the two directions would eventually result in the roller rotating away from the perfect position. I'm just guessing here, though.

But most importantly, in my not-so-humble opinion, the combined efforts of Peter and myself look way cooler

...

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Emmons Legrande II D10 8+5, Sho-Bud Pro III Custom SD10 4+5, Goodrich 120, Peavey Nashville 1000[This message was edited by Per Berner on 22 January 2005 at 06:34 AM.][This message was edited by Per Berner on 22 January 2005 at 06:34 AM.]

Karlis Abolins · Post by **Karlis Abolins** » 22 Jan 2005 7:52 am

Peter, I think that this is very much on topic. We are talking about solving a problem that is common to all of our guitars. There are many ways to solve the problem from Ed Packard's low-tech solution, to gauged roller grooves to adjustable roller blocks. Herb Brasher, a Seattle-area steeler, has built a very elegant adjustable nut for his lap steel. As I mentioned earlier, an adjustable roller block using a wedge would be another way to solve the problem.

Karlis

Curt Langston · Post by **Curt Langston** » 22 Jan 2005 8:58 am

Peter, your animations are nothing short of sheer excellence! I believe that a patent is in order. Spectacular!.......This Forum is an amazing source of information......

Jim Palenscar · Post by **Jim Palenscar** » 22 Jan 2005 8:59 am

About 20 years ago there was a guy who made an adjustable roller arrangement/nut whereby each roller was suspended in its own cylinder and was adjusted from the underside of the guitar with a screw.

Farris Currie · Post by **Farris Currie** » 22 Jan 2005 9:55 am

Just wondering,how many of you could actually build these parts yourself.i have a good friend who is a engineer,who is so jelous of me,he can design it on cad ect.but says he couldn't build it no way.
farris

Peter · Post by **Peter** » 22 Jan 2005 10:06 am

Jim, I love the idea of the off-center holes in a non-gauged set of rollers.
I believe Ron Lashley SR made the first sets, but because some guitars with these sets changed hands at some time, the information about the off-center holes got lost and the new owners thought they had a bad guitar.
I would have made the roller edges knurled, so that it would be clear what you are supposed to do. Does Ed P. make these sets and sell these sets for other brands?[This message was edited by Peter on 22 January 2005 at 10:27 AM.]

Bobby Lee · Post by **Bobby Lee** » 22 Jan 2005 10:30 am

About 20 years ago there was a guy who made an adjustable roller arrangement/nut whereby each roller was suspended in its own cylinder and was adjusted from the underside of the guitar with a screw.

I like that idea a lot better than having the screw visible on top. It's the sort of thing you'd want to tinker with maybe every 5 years or so, if you decided to switch string gauges.

This thread is great - you guys are amazing with your drawings and computer renderings. Thanks!

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<img align=right src="http://b0b.com/Hotb0b.gif" width="96 height="96">Bobby Lee - email: quasar@b0b.com - gigs - CDs, Open Hearts
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