Axles, bell cranks...

[Allan]

I went to one of our local markets the other day and (naturally) went into a place there where they sell all sorts of hardware, including what some would call junk. I came across a box containing axles. Obviously these had been made for something and were remaindered items. They are ten and one eighth inches long and three eighth of an inch in diameter. The last half inch (ish) at each end is reduced to a quarter inch. They seem to be made of chromed stainless steel. I bought them all (18) for six dollars. Now, I am considering using these as axles in a PSG build that I am messing with right now.

I have seen all sorts of arguments regarding 'square versus round' in this application but I feel that if I either use, 1) a set screw with a good cutting point on the end, 2) a slight flat made with a file edge, or, 3) a small drop of screw lock inside the bell crank, I may just get away with it.

Any comments or experiences would be most valuable.

Now, this is going to be simply a home based, hobby steel and for sure will never hit the road or the studio! The other thing I am considering is simply using nylon bushings for the axles to ride in. Comments on this?

I am starting on the CAD work in the next day or two and would appreciate knowing the centerline to centerline distance between the pedals on a typical PSG.

In the next day or two I am hoping to be able to post a drawing of the rather simplistic mechanism that I have come up with for the changer and I will be asking for comments on that also. (If I don't scrap it once I see it drawn up rather than just being in my head!)

Thanks for reading this, best regards, Allan.....

[Bent]

Allan, I spaced my pedals 2 3/4" o/c
I Measured on a ShoBud Superpro and there the spacing was 2 5/8". Can't explain why I gave it another 1/8" ...not that it matters much.
With that spacing, I wouldn't make my pedals any less than an inch wide.
Yes, you can use nylon bushings for the cross rods. However, I found them to vary slightly in hole size. I bought the size 'W' drill bit to make the holes uniform and just slightly bigger than the 3/8" round that I turned on the square shafts.
As for fastening a bell crank to a round shaft securely:
Jerry Blanton did this on his Blanton Steels, take a look: http://music.mikeester.com/for_sale.html where he made the crank open in the back and used a set screw up top.
I want to say that Blanton was way ahead of his time. Just study the ingenious way of tuning the pedals. No tuners at the end plate. It was al done on the slot screw on the bell crank. Simply shorten or lengthen the throw of the crank on the pull rod.

Allan, according to this, no loctite needed!

[Allan]

Thanks for that reply Bent, very instructive as usual.

That system in your link is very interesting indeed. It's remarkably like something I have been playing with using some Mecano parts to experiment. It is a step ahead of what I have come up with so far so I can stop wasting my time with it. Nice!
I am fairly sure I can see how it works but I also see a way to (I think) improve it. The question is, does it need improving? I need to do a few drawings and a whole lot of trig. to get some real numbers to check on that. Ah! I feel a spread sheet coming on - but not today! As I said in the original post, I am going to get started on the CAD for the guitar and I don't need to settle on a method for that aspect at this stage. My drawings do tend to be just one or two steps ahead of the construction when I build stuff.

Thanks again for the information, regards, Allan.....

[Eldon]

Allan, It's great to hook up with another scrounger on a forum or oterwise. Another suggestion for crossrods though you might have things under control are 10-12 inch spikes. They are less than $1.00 a piece, not stainless steel and they fit bang on into a vehicle door bushing made of some kind of brass. I'm going to try this combination when I make mine.

Warmest Regards, Eldon

[Bent]

Allan
Some of us discussed this system earlier on the SGF. I think the 3 factors needed are Tuning the pedals, Timing the pedals and adjusting the Throw of the pedals(pedal length of travel). I believe(could be mistaken) that the problem with the Blanton system is that it will do the Tuning and timing but not the length of travel.
I believe that Georg had some interesting things to say about it? Georg?
Another problem some had was that they had to reach up under with a screwdriver to tune the pedals. This could be partly overcome by using knurled brass head screws instead of slots.
At the same time I also heard that this system hardly ever needed pedal tuning, only when changing strings.
Allan, also note that you are not getting an accurate impression of the angle of the mounting hole in the crank. From that angle in the pic it appears straight when in fact it is on quite an upward slant. So in a way, when you put the crank on the shaft you have to stick it in from underneath a bit if you know what I mean. There was one picture that shows this angle perfectly. I will be sure to post it if I can locate it.

[Allan]

OK, first off, I have a rotten cold so there will be a delay in posting any CAD work for a while. To be completely gross, I am not willing to scrape the grot off my screens and I am sneezing explosively right now. Get the picture?

Just a quick come back to Eldon here though - I hereby remove myself from all association with the word 'scrounger'! I am an opportunist! LOL...

Bent, thinking about that alternative system that you linked for me, I am starting to wonder if it is a better system or just a different system. If it is simply different without being better I may not go that way. Needs more study and, as I said before, a bit of trig. and some engineering physics to look at the relative mechanical advantage. We will see - I will still do some work on it.

Thanks both, I love the responses.

Regards, Allan.....

[Bent]

Allan, I hesitate to say whether a system is better or not. I think every system certainly has its advantages, and maybe also its drawbacks? Compare for example the all-pull and the pull-release. Both are great, proven systems but they both have their own drawbacks if one wants to look at it with a critical eye.
The thing about the Blanton System is that Jerry Blanton invented a system so totally off the beaten path and he deserves accolades for that. I wish that I were that forward-thinking. With Blanton we have the advantages I listed. Then we have what might be called a disadvantage where the pull rods aren't able to pass through bell cranks ahead of its own bell crank. This creates a problem with having to bend rods to go around the obstruction, or even resort to angled pulls. It's at least a 35 yr old system. Maybe someone could do a revamp to make it conform to today's technology?

[Georg]

As you said about the Blanton System, Bent, although there's really only two parameters to deal with in a PSG: Tuning and Timing. Throw is part, or result, of both.

The Blanton System, as it is shown on the pictures at least, allows for Tuning-adjustment or Timing-adjustment, not both, so one parameter has to be fixed perfectly at building-time - which is next to impossible really. So, making for example the A pedal "Tune" and "Time" string 5 and 10 perfectly in sync, would be really hard unless there's also a way to adjust the length of those rods built into the system.

There's also the problem with "space" you mention, as the Blanton bellcranks occupy too much of it. Bended rods will always be slightly unprecise, and how one should be able to add rods and bellcranks for splits, compensators and/or extra pulls, is beyond me.

May be more hidden in there than shows up on the pictures, so the Blanton System may not have as many weaknesses as it appears. Just can't say from those pictures alone.

[Allan]

What I am really learning from this thread is how much I still have to get my head around!

Just one small thing at this time then if I may...

When you say 'timing' I am taking that to mean that when more than one string is adjusted with a pedal or knee lever they need to arrive at the target note together. Is that correct?

Georg, thanks for joining in on my education, I really appreciate your input also.

Regards, Allan.....

[Georg]

"Timing" means how two or more strings on the same pedal raise, or lower, in sync along the entire pedal/lever-travel. "Tuning" is that they end up on correct note at full pedal/lever-travel.

Not all strings on a pedal are necessarily Timed the same, so while string 5 and 10 ideally should be Timed in sync when pedal A is activated slowly since those string are the same note, string 1 and 7 often use different Timing and Tuning so string 7 can be used as (part of) a half-stop for string 1.

In both cases good, and separate, control of Timing and Tuning helps make the change sound good, but most constructions only have precision-control over Tuning of the end-note and "a rough balance" of Timing. This works well because we usually don't "glide" pedals so slowly that Timing-errors can be clearly heard.

Hope that helps.