Changer axle

[azureskys]

just install a stainless steel changer shaft , im sure you ll be glad you did. A half inch or whatever size it is you need , you can speculate from now till whenever change the shaft and see where you are at that point then if it still isnt right you know its something else because the shaft will not flex the sheer strength of a bar that size is probly way up in the tens of thousands of pounds.

[sheffield steel]

Hi Guys,

I would agree with Georg, that it is not just one aspect on a psg that will cause detuning but a multitude of minute, shall we say defects, that will add up and cause specific problem/s. I do however hold the same theory (upto a point) that there can be more cabinet drop on C6th where the pedals are pressed more in the centre of the body. As we all know there are many forces & stresses imposed on a psg that are happening at the same time or individualy this is why we suffer from this problem, we can only try to minimize these effects on our beloved instrument. As I said in an earlier thread my guitar only has 1 or 2 cents on the meter on strings 5 & 6, which by the way is not detectable with the human ear, so are we chasing the holy grail of psg's here? I would think that a good solid construction/build with quality components can only minimize these multi effect problems that are accociated with the psg and to put more gizmo's on, will only serve to complicate even more what is already a complicated instrument as well as adding MORE weight. Cutting down the thickness of the body ect is IMHO a bad move, the old Fender 1000's apparently had little or no cabinet drop (so I've been told) if this is true, can this be attributed to the bodies being 2" thick and surrounded by a metal frame! Damn HEAVY THOUGH!
Bent, I think that you said that you made a body that was thicker wood and you had very low cabinet drop, nuff said.
Any one got a computer program and that's a wiz kid with them, maybe the stresses can be worked out, just a thought.

Dave.

[Georg]

Any one got a computer program and that's a wiz kid with them, maybe the stresses can be worked out, just a thought.

You mean; to work out stress points for a "model PSG"? Might work if someone draws up that "model PSG" with measurements.


For our PSGs such a program will only provide us with rough indications, as although PSGs tend to look very much alike they are not all constructed the same way using the exact same materials. So, a "model PSG" range to cover most "normal" and some "abnormal" deviations in construction would be needed for such a program to output really useful info and not just theory.

For instance: my main PSG (and never mind that it doesn't have detuning problems) would require a completely different set of data/measurements input to begin with, as the string-tension/-forces are only loaded onto the body at one end - it is an "abnormal" semi-floating neck/changer construction. A couple of other factors also set it apart from the average "model PSG", such as a more linear uptake of string tension, and a designed-in partial counterforce system with no extra parts.

I averaged all these, and other, factors in my head (and added in a little computer analyzes and other methods for fun and good measure) before redesigning, and hit close enough for comfort at first attempt. If all designers/builders were that lucky (or clever ), we would never have these discussions neither here or on the Steel Guitar Forum. Would be nice, but maybe a bit boring...

[12string]

Folks,

I finally located and ordered a 1/2" HSS round bar today and hope to find time to disassemble my guitar in the not too distant future and swap the existing one.
Also today I did a little experiment in my workshop regarding changer axles.
I found a 2 foot length of 7/16" stainless steel rod I bought for another job and never used, and thought I'll see how much force it takes to bend it.
I know this is slightly less than the 1/2 inch discussed but it is what I had to work with.
Looking at the diagram below, I took a piece of steel bar 3 1/2 inches long and nipped it tightly in my vice. This gave me a gap to bridge, the same length as my changer axle. I then laid the axle rod over the gap central and 6 inches away. Using a piece of strong 1 1/2" flat spring steel bar, I passed it over the axle and under the fixed spacer, with a 5kg weight tied at a mechanical advantage of 6:1. This should give a total of 38kg(including weight of bar, across the central 1 1/2 inches of the axle rod.

axle.jpg (12.2 KiB) Viewed 950 times

What do you think happened???
I hear folks saying" nothing", " can't possibly bend it" " could park my car on it", " pull my car with it, without it bending"
Wrong, wrong, wrong, wrong. The ends reached for the sky and it bent like a banana
It was possible to see this due to the length of the rod, if it had been 4 inch I doubt if it would have been visible.
This shows all is not what it seems as 38kg is nothing, my guitar will have 150 kg pressure all told, although evenly spaced, but my guess is now a 1/2 inch stainless steel axle will bend some, as to whether this increases cab drop, I don't know but I guess I will have some idea soon,

Stuart

[mac639]

I'm a little confused....which piece bent, the red one or the blue one. I just put a 3-1/2" piece of steel rod in my vise. I couldn't bend it at all with my 30" wrecking bar in the center of it. I ain't too strong, but I pushed down with quite a lot of force. I expected it to pop out of the vise but it didn't. Anyway, isn't it the blue piece you were trying to bend?

Mac

[Georg]

The ends reached for the sky and it bent like a banana

As expected...

All involved parts in a PSG bend and/or give some under varying string-tension, no matter what anyone thinks or says. Reducing, or compensating for, the resulting detuning is all we can do.

[12string]

Mac

It is the red piece we are looking at, the blue piece is an inch thick and just a spacer to give a 3 1/2 inch gap and something to lean on.
The red piece is the axle. Being 2 foot long amplifies any bend and makes it real easy to see bow,

Stuart

[mac639]

gotcha!
Mac

[Bent]

Great experiment Stuart! Now lets try the same thing with a 1/2" drill bit - It's been hardened...will it bend or break or stay put?

[Pat Comeau]

I really think that if the peice would of been around 4" long and 1/2" diameter it wouldn't bend that easy, try that same expirience with the same peice but 4" long, cause anything being shorther is always harder to bend in my opinion. , but the peice in a wise and try to bend it with a pipe a little larger than the shaft.

Pat C.