Old BMI questions and introduction

Patrick Timmins · From: Seattle

Hi.
New to the forum and pedal steel. I have wanted one for about 25 years, just never had the money at the right time. Purchased a D11 ZB (SN 027) from a super nice forum member. I was immediately hooked. I just purchased an early BMI SD 12 (SN 073) from another member as a project who was also super helpful.
The ZB is so cool and so smooth, Eric did a great job setting it up and the shipping damage was minimal and easily repaired with a little help from Eric over the phone.

The BMI was purchased as a non-pedal S12 with all pedal parts included. Dennis was super honest about the purchase.

I got the pedals and everything back together in 2 evenings after work and have spent a couple of evenings fine tuning it. There a couple of issues I could use some help on.

A: the pickup is crazy microphonic but sounds good. I have heard people say the ZBs are triple coil, but as a former pro audio tech, I assume they mean it is a single coil and has 3 coil taps.
Is that correct? The ZB has some extra pins/pole pieces above and below the main center pole pieces. I guess it could be triple coil.
The BMI has what appears to be a 3 coil tap switch as well. I really like the sound, but if I shout into the pickup, my voice totally comes through the amp.
Should I just pot it in wax with a vacuum pot?
Are there other pickups out there that have 3 coil taps?

B: On the BMI, pulling up a full step isn't a problem, but dropping a full step is. It has the older 2 raise, 2 lower fingers. Estimated it was built 1973ish. It has kind of a crazy RKR reversing mechanism. If I take the spring off the finger, it goes down a full step plus. With the spring on, it goes from not quite reaching the full down step to going back up in pitch (over tuning). Does anybody have a recommendation for a spring without so much tension? There are a bunch of wood screws that are drilled into the aluminum base to hold the springs, has anyone added an adjustable spring tension bar on these guitars? Guitar currently set up as extended E9 with 3p & 5K.

I tried to talk to Don at BMI, but I really couldn't understand what he said and it seemed like he wanted me to write him a letter to purchase spares . No disrespect to Don ,I just couldn't understand what he was saying over the phone. I was also on my cell phone which doesn't help. I would like to get a period correct foot pedal to add as a fourth.

I'm pretty comfortable doing most things myself, I just don't have much pedal steel experience. I grew up mostly working as a musician, recording studio rat, and pro audio equipment repair tech. When I wasn't doing that, I was usually working IATSE, machine shops, fab shops, working as a carpenter and did my stint in the Navy. Finally went to college when I was 30 and have a couple of engineering degrees now.

I'm in West Seattle and have a full machine and fab shop if anyone needs anything in the northwest. I can weld just about any alloy and have a 4 axis CNC milling machine, manuals, and a lot of sheet metal equipment. If any pedal steel guys in the neighborhood need a quick fix, or want to grab a beer, hit me up. it'd be great to meet some other members in the area.

Apologies for the long post; just wanted to introduce myself along with the questions. Any advice is appreciated.

Thanks,
Patrick.
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Patrick Timmins · From: Seattle

I was about to go to bed and realized I had made an assumption in my post about 3 coil pickups. I used a Gauss meter and measured the fields over the ZB pickup. Moving the transducer over the pickup from the changer towards the tuners, i saw the magnetic field change from south to north to south. The ZB at least appears to function as a triple coil. the BMI only showed one magnetic field and shows South.

Please correct me if I am mistaken.

Thanks,
Patrick.
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Ian Worley · From: Sacramento, CA

Welcome to the forum Patrick.

What string(s) are you having issues with? Is it the string 2 lower to C#? If the pull is on RKR, the crossbar is fairly close to the changer there, sometimes the angle of the pull rod between the bell crank and the changer scissor can cause issues, binding and just applying pressure to the scissor at an odd angle. You can test this by just removing the pull rod and pushing the scissor from the end plate window with a philips screwdriver to see if the change works correctly without anything else there to affect it

What hole are you using in the changer finger scissor? The geometry on the BMI fingers is a little odd, the pivots on the scissor are very close together. A too-tight return spring will definitely cause the issue you're describing on a lower. At a certain point in the pull, the nut on the pull rod becomes the fulcrum and the spring starts pulling the finger the opposite direction as the rod continues to pull the scissor inward. Using the lowest scissor hole in the changer (nearest the spring) gives you the greatest mechanical advantage to overcome this.

Smaller diameter strings require a longer pull for the same tension, which just exacerbates the resulting problem, but most guitars will lower 2 a whole step without a problem (assuming that's your issue). I rebuilt an S10 BMI similar to yours a while back, it had no trouble with that change.

Perhaps the springs were replaced at some point with stiffer ones. They need not be much tighter than is required to hold the scissor firmly against the stop bar for the longest raise on any given string. Beyond that they're just making the lowers stiffer to engage. If the spring is just way too tight you can probably relax it a little just by stretching it with a couple of pairs of pliers.

Jon Light (deceased) · From: Saugerties, NY

Sounds like you've got a good idea of what you are looking at and dealing with. My BMI was my first guitar and it had a very modest setup with no full step lowers so I have no experience with testing its limits.

The only thing I'll add is that after your observations, if you feel that you have the chops to devise spring tension adjustment hardware, (having already discovered that this will solve the problem, as you have) it would be a huge asset. But otherwise, yes, relax the spring and get there that way.

Generally speaking, there are some strings whose tensions push the physics to the limit when it comes to lowering. Many steels max out their capabilities to accommodate this. What string are you working on?

Consider any of the springs on strings that do not have any lowers as backups in case you screw it up. You would just pull one of them and replace it by binding the changer with any sort of wire, making it stationary (no lower, no need for any movement of the lower finger) and steal the spring.

Alternately, you could fabricate some added length via a very small ring or a hook that would anchor on the screw and provide a hooking point for the spring, as per the photo.
Trial and error re: length. Just remember that it can be a fine line between allowing enough movement vs. having enough tension. The finger must return all the way and hold in place.

There are a number of us who can and will be happy to shoot any photos you may need of any view of a BMI.

Patrick Timmins · From: Seattle

Thanks Ian and John.

Yes, it is the second string and is attached to the RKR lever with the goofy reverse action. I can easily get it to over travel. I aligned the pull rods so it is a straight shot. No rubbing or binding.

I tried both lowering positions on the finger. The lower of the two seemed a little better as Ian mentioned, probably because it has a little more leverage against the moment of the spring, but still won't let me get there.

I have ordered a couple of stock extension springs from McMaster Carr and should be able to find one that will work. The kind that you cut to length and shape yourself.

I ordered .313 diameter spring stock with Min load rates of (what appears to be on the guitar now) 2.88 lbs,
then 1.78 lbs,
and .96 lbs.

There wasn't much available in between for that spring diameter.

The action on the BMI feels very good through the pedals and the knees, but definitely takes a bit more effort than the ZB Custom D11 from 1969. It would be nice if I can get the BMI as easy to pedal as the ZB. Unfortunately, that is all I have to compare it to.

Has anyone else designed an adjustable spring tension block for a BMI or similar setup? Don't want to reinvent the wheel if someone has all ready gone through the process.

I also ordered a bag of those tiny hair pins if anyone needs some extras. It was $10 for 100.
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Larry Dering · From: Missouri, USA

Patrick, welcome to the Forum. You are a glutton for punishment for sure. I have 2 BMI S10S, one is on the bench for rebuild. My take is the mechanical action of these are limited by the leverage due to design. The linkage belcrank is short and the guitar body shallow so I don't see a way to improve the action. I work harder to press pedals and levers than some of the other steels I own. They have a great tone and when all parts are in good shape it plays very well. I like mine and will continue to use it as a gigging guitar. I admire your talent in taking on a project like this with no previous experience. You will certainly know how it's done after that. Forum member Paul Redmond is a machinist and has done about all that could be done to his BMI. Maybe he will chime in.

Patrick Timmins · From: Seattle

Thanks Larry.
It's felt a lot more like fun than punishment. I think it's just down to getting some more springs to experiment with on the second string drop.

I took a few rings off the springs as was suggested and it works much better for strings that were barely reaching +pitch.

The reversing mechanism on RKR is a bit wallered out as it uses a thread to pivot on. Will probably have to make a new one and use a shoulder screw for consistent action.

I would like to know if anyone else makes a 3 tap single coil pickup like the BMI has. Didn't see pickups on the BMI website. I like the tone selection it has, just really microphonic.

Any recommendations for a replacement pickup for the 12 string BMI?

Thanks for helping a newbie out!
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Lee Dassow · From: Jefferson, Georgia USA

Patrick, You can try a Wallace truetone single coil
pickup. I have one on my 12 string BMI extended E9th.
Jerry's in New Mexico and excellent to deal with.
Tennessee Lee.
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Patrick Timmins · From: Seattle

Thanks Lee.

Are the coils taped for multiple outputs? Even if they are not, sounds like they may be a good sub. The string spacing is a bit narrower than my ZB D11.

Did string spacing change on BMI guitars since the early 70's? My BMI 12 measures at 3.63" from string 1 to 12.

Is there anyone that does a triple coil as the ZB Custom pickups appear to be?
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Ian Worley · From: Sacramento, CA

Perhaps you could post a picture of the pickup including the lead wires? Is there a brand name or any other info on it?

That odd reverser mechanism is standard issue on BMIs. If you're a machinist it would be simple to re-engineer it with something more stable. Lots of better ways to skin that particular cat

Eric Dahlhoff · From: Point Arena, California

Patrick,
If the pickup is micro-phonic you could send it to Tom Brantley & have him rewind it or pot it in wax. He's great.

http://tombrantleyrewinds.com/
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Patrick Timmins · From: Seattle

I realized that it may be picking up everything partially because it is mounted very rigidly on what looks like fuel hose around the screws. Think I may try mounting it on foam instead. Attached is a photo of the coil tap switch.

First position reads 15.19 K ohm.
Second position reads 23.04 K ohm.
3rd position reads 31.24 K ohm.

I can only read one magnetic pole from the top of the BMI pickup.

On my ZB Custom pickup, I can read 3 distinct magnetic poles which would indicate to me that it is a triple coil pickup.

I realize the cowhide on the wrist pad is a bit tacky, but it's all I had to recover the wrist pad after a few beers.
Action on all the pedals and levers is smooth and balanced now (except the RKR).

The previous owner removed the BMI silk screen (I think) from the front when he did the vinyl wrap. I just put a sticker from my microphone company where the logo should be.

I think all I have left to do is make a new RKR lever setup and figure out the pickup situation.
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Ian Worley · From: Sacramento, CA

That's a mystery pickup, doesn't look any standard production model, but maybe someone will recognize it. Very likely just a one-off custom job though. If it doesn't sound good, just replace it.

Is that just a Strat-style switch in the back apron?

BTW, Don Fritsche sells the front apron logo stickers for $5

Patrick Timmins · From: Seattle

It sounds good, just microphonic. I'm afraid if I pot it, I will loose some of the top end.

The switch is just a 3 way blade switch. I've looked for coil taped single coil pickups, but haven't found much. The string spacing is too different from the old ZB's.

Can anyone tell me if there is a standard string spacing for 10 and 12 string? The BMI is at 3.63" from 1 to 12.
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Ian Worley · From: Sacramento, CA

Patrick Timmins · From: Seattle

Thanks for the string spacing info Ian.
The guitar is all back together. I remounted the pickup on some foam and the body noise coming through the pickup is gone. Re worked the RKR and it is smooth now with a feel stop at the half note drop. Had to make a new spring from spring stock I got from McMaster Carr.

I think all it needs now is a sticker from BMI. I just spent about an hour playing it and still having a hard time with the string spacing.

I don't see many extended E9 12 strings. Is the Zane Beck copedant being used by many people. Like a U12 but only 4 floor pedals and 5 knees.
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tom anderson · From: leawood, ks., usa

Oh had a ZB once that I put his cooedient on. It was very hard to play because of how many pulls were on each ppedal. I later learned that the copedient worked smoothly on the guitars he made with the raises on one side and lowers on the other.

Patrick Timmins · From: Seattle

Here's what I have on the BMI SD12 right now. Everything feels pretty smooth.

At first, I was hoping to get the BMI as smooth as the ZB. Now it is even smoother than the ZB. Just bummed about the string spacing being so close.

I have no idea what a 1973 BMI SD 12 3&5 is worth, but kind of thinking; if it's not worth much, I may just mill out the back plate (since it has individual holes for the nylon tuner nuts to poke through), make a new 10 string pillow block to space out the strings and make a new 10 string roller nut bridge. It all just bolts in.

Good idea, or bad?
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Landon Johnson · From: Washington, USA

I have some issues with mine as well - nothing major. I just posted about my 3rd string issue..,.

I live in Lewis County; 75 miles south of Seattle. We oughtta meet up and compare BMIs!

Patrick Timmins · From: Seattle

Sold the BMI SD12 to a fellow down in Oregon who wanted to get an extended E9 and is really happy with it. Technically, my wife sold it while I was working down in San Diego. Had a chance to stop by Steel Guitars of North County. What a cool place. Flew home with a (early 90s?) Sierra Session SD10. The captain even let me put it in the overhead knowing it weighed about 65lbs in the case. Happy ending for everyone in this story.

Very Happy

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