Gathering mechanical steel guitar data for an invention

Hans Holzherr · Post by **Hans Holzherr** » 1 Jul 2013 3:27 am

I have made an invention for the pedal steel which I would like to market. It is a mechanical switch that provides a second set of changes to any pedal or knee lever, without the necessity to do invasive changes to the guitar such as drilling holes in the body, or adding or exchanging crossrods etc. The actual operating switch of the whole assembly toggles between these two sets of changes and is mounted to the crossrod of the respective pedal or lever. That means the switch has to be operated without eye control, but with everything else with playing this instrument, muscle memory takes care of that, with the switch sticking out of the array of bellcranks a little to aid switching.

My current concern is to determine and maximize cross-brand compatibility while keeping the number of parts as low as possible. To that end I have posted online an Excel Sheet at https://docs.google.com/spreadsheet/ccc ... sp=sharing , listing some relevant mechanical data of brands of pedal steels. It is an interactive sheet that anyone can help fill in. Currently, the sheet is still fairly empty, but I'd very thankful if Forum members helped with gathering as much data as possible.

So far, I have installed the prototypes in a Carter (square crossrod 3/8") for tests. Installation in two different models of Mullen (hexagonal crossrods of different diameters) and a Fessenden (square 5/16) will follow shortly. The most important data are exact diameter of crossrod, minimal distance between crossrods, minimal clearing under crossrod. The measurements should be taken with a slide gauge if possible in order to determine maximum deviations from nominal diameters such as 3/8, or 5/16. My aim is also to maximize pullrod compatibility, but diameter measurements make only sense with pullrods that have a 90-degree bend at the end because that is the type of pullrod the switch uses.

When mechanical compatibility with a certain brand/model of guitar is given, the only mechanical limitation I see is the number of vacant holes in the changer fingers. On the other hand, most 3-raise/3-lower changers and standard setups should be able to accommodate an additional change on a single lever or pedal.

Currently, there are four brands/models of steels that are grayed out on the Excel Sheet, which means they are definitely not compatible with the switch: BMI, Moyo, and push-pull guitars. Furthermore, the compatibility of round crossrods is as yet questionable as long as diameters are unknown (to me).

The idea to ask the manufacturers for the data has crossed my mind, but I think they are busy enough with building.... But of course, if they read this, their entries are most welcome.

I would also like to thank Forum member Carl Dixon for his generosity in sharing his thoughts and pictures relating to his mechanical solution of the 'switch problem' a few years ago. However, I would like to point out that my solution bears no resemblance at all to Carl's switch.

Thank you very much for your contribution or input!

Lane Gray · Post by **Lane Gray** » 1 Jul 2013 3:48 am

MSA rounds are 3/8" round. Don't know the metric equivalent. Not sure how much folks would want to add weight to an MSA D-10

Hans Holzherr · Post by **Hans Holzherr** » 1 Jul 2013 3:51 am

Thanks anyway.

Frank Montmarquet · Post by **Frank Montmarquet** » 1 Jul 2013 8:33 am

The newer Sierra's have square cross rods, also, the pull rods are straight, threaded on each end for adjustment nut on changer end and threaded plastic pivot in bell crank slot.

Keith Davidson · Post by **Keith Davidson** » 1 Jul 2013 2:06 pm

3/8" would be approx 10mm

Hans Holzherr · Post by **Hans Holzherr** » 2 Jul 2013 12:03 am

Keith, 3/8" is exactly 9.525 mm, but that's not what my post and the Excel is all about, at all.....

Peter den Hartogh · Post by **Peter den Hartogh** » 2 Jul 2013 3:06 am

ETS in mm

Code: Select all

SQUARE...Crossrod type
9.54.....Nominal Crossrod diam.
11.5.....Minimal distance between crossrods
9.5......Minimal clearance under crossrods
60.......Minimal clearance above crossrods
90 deg...Pullrod end
2.35.....Pullrod diam.
3/32"....Thread 3/32"
25.......Hex nut length

Hans Holzherr · Post by **Hans Holzherr** » 2 Jul 2013 3:19 am

Thanks, Peter! Data entered.

Peter den Hartogh · Post by **Peter den Hartogh** » 2 Jul 2013 12:28 pm

The hardest thing to measure was the minimum clearance under the crossrod. First of all, when a square rod rotates it reduces the clearance even more. Second, not all crossrods are rotated equally at rest. The measurements were made with the assumption that "under" means between the rod and the body.
Hope this helps.

Hans Holzherr · Post by **Hans Holzherr** » 3 Jul 2013 7:24 am

Peter, that's all correct. The crossrods on my Carter are not parallel to the body top but at an angle. With minimal clearance I mean the clearance when the crossrods are parallel to the top. In order for the switch assembly to do a maximum 20-degree turn from an upright position it needs at least a 4 mm clearance, but if the starting position is not upright, it could do with less. So, any clearance of 4 mm or more is not critical. On the other hand, I have a Mullen G2 at home that belongs to a friend, where the clearing is only 3.5 mm AND the crossrods are parallel to the top. This means the crossrod that has the switch will only be able to rotate 15 degrees or even less before it hits the wood. I have yet to find out if that's enough for a 1.5-tone change, for instance.

admin · Post by **b0b** » 3 Jul 2013 7:32 am

I've been waiting for this invention for a long time. I'd like to be able to change the function of a few pedals and knee levers, and leave the others unchanged. Can several pedals/levers be changed with a single switch?

At this point, what brands are definitely compatible with the invention?

Hans Holzherr · Post by **Hans Holzherr** » 3 Jul 2013 7:53 am

Every single part of the switch assembly is mounted to the crossrod of the pedal or lever to which you want to add one or more alternative changes. Everything else is left as it is. So, it works individually, not 'globally'. The downside of it is that there is currently no way to flip more than one switch at once - if you use one hand.

The general answer to your second question is, every brand that has square 3/8 crossrods with a clearance of at least 4 mm to the underside of the top. And basically, 5/16 square rods, too, but the critical clearance there starts at 4.5 or 5 mm. 5/16 hex rods with 5 mm clearance or more shouldn't be a problem either, but I need to test the Mullen G2's 3/8 hex rod.

Hans Holzherr · Post by **Hans Holzherr** » 3 Jul 2013 11:01 pm

I have to add that the minimal distance between crossrods is also very critical as in some brands this distance is only a little more than the width of the crossrod itself. The overall width of the switch assembly (measured along the length of the guitar body) is about 23 mm or 0.9", so in cases with a small distance the switch may interfere with an adjacent bellcrank base if the width of the latter is similar. To keep interference at a minimum, the switch bellcranks are tapered, and the switch itself can be installed at a position on the crossrod where it doesn't interfere with a bellcrank on an adjacent crossrod.

The upshot is that at this point, with the lack of data, the question of compatibility cannot be answered reliably for possibly critical cases as described.

Hans Holzherr · Post by **Hans Holzherr** » 7 Jul 2013 6:21 am

bump ttt

Hans Holzherr · Post by **Hans Holzherr** » 9 Jul 2013 3:10 am

Almost 800 views and one (1) data contribution. Turns out that this is a very poor method of gathering data. I guess I'll have to ask the manufacturers.

I'm thinking of launching a poll to see if there's enough interest in such a device, at all. That's crucial, of course, as in order to offer the switch I'd have to have hundreds of parts made to keep the price-per-piece low, which means an investment of thousands of dollars, legal costs for protecting the invention not included.

admin · Post by **b0b** » 9 Jul 2013 11:45 am

I want one for the vertical knee lever on my Desert Rose. Problem is, the guitar is not a standard model. Adding my data to your spreadsheet would probably not be helpful. The clearance does appear to be within your limits.

Also, I don't understand the terminology on the spreadsheet. For example, what does "nominal Ã˜" mean?

Hans Holzherr · Post by **Hans Holzherr** » 9 Jul 2013 10:49 pm

b0b, 'nominal dia.' acts like a name like in '3/8 crossrod', but this dia. has a tolerance, so it actually varies between maybe 0.37" and 0.38", depending on the manufacturer of the rod. Still, both of these examples would be called '3/8 crossrod'. The aim of these columns on the Excel Sheet is to see if there are any 3/8 crossrods whose diameter is greater than 9.7 mm because that's what the switch parts can accommodate at the most. Thanks for asking.

In what way is your Desert Rose not standard?

admin · Post by **b0b** » 10 Jul 2013 8:29 am

My Desert Rose is a single 8. It's a smaller cabinet. Since it was a custom job, I'm not sure that the measurements would be the same as the standard model.

So, the "Ã˜" symbol means "diameter"?

Hans Holzherr · Post by **Hans Holzherr** » 10 Jul 2013 9:25 am

b0b, yes.

Richard Sinkler · Post by **Richard Sinkler** » 8 Sep 2013 9:41 am

Sounds great to me. But my Carter is loaded up (9p, 9k) and I'm not sure there would be room for anything else. I would love to be able to add different changes at will to my right knee levers, and also my left center (C6) levers for certain songs.