I'm getting really interested in changer design. It seems you can't buy one from anyone, and there's a genuine achievement in building your own, so I have been doing some thinking about how I might build one. Or more than one....
Here's a 3x full scale model showing neutral, raise and lower, to try some ideas out. I want to get to a point where I get the same amount of raise and lower for the same amount of movement. Not easy, as raise requires less travel than lower. I've been looking at different profiles on the changer finger itself: curves, and straights at different angles. The jury's still out, although I think a convex profile may give me the effect I'm looking for if I have the right angle and radius.
I'd really appreciate any thoughts here, guys.
Will C
Changer design
Changer design
- Attachments
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- Changer_raise.JPG (28.13 KiB) Viewed 2398 times
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- Changer_lower.JPG (29.09 KiB) Viewed 2398 times
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- Changer_neutral.JPG (29.98 KiB) Viewed 2398 times
Re: Changer design
Good ideas Will, and they should all work.
Say..are these pics about 1:1 scale? (example: from top of string finger to tip of spring hookup on lower bar is 4 3/4" on my screen). So they appear to be a bit too big. If so, then you would want to have a longer distance between spring hookup and the end of the lower bar to make sure the spring don't rub.
Also, It looks like the o/c pivot points are a bit too close. This would make for a hard pedal/knee lever operation. As for achieving a difficult(long) lower, I have found that a straight angle is the best - refer to finger to the left in pic one. Quite a goal you have set for yourself, trying to make the same amount of raise and lower for the same amount of movement. Make sure you let us know what you come up with in that department!
If you have more pics at a later date, it would be helpful if you placed a straight ruler alongside the model.
Great ideas Will!
Say..are these pics about 1:1 scale? (example: from top of string finger to tip of spring hookup on lower bar is 4 3/4" on my screen). So they appear to be a bit too big. If so, then you would want to have a longer distance between spring hookup and the end of the lower bar to make sure the spring don't rub.
Also, It looks like the o/c pivot points are a bit too close. This would make for a hard pedal/knee lever operation. As for achieving a difficult(long) lower, I have found that a straight angle is the best - refer to finger to the left in pic one. Quite a goal you have set for yourself, trying to make the same amount of raise and lower for the same amount of movement. Make sure you let us know what you come up with in that department!
If you have more pics at a later date, it would be helpful if you placed a straight ruler alongside the model.
Great ideas Will!
http://benrom.com/
21 BenRom pedal steel guitars, a Nash 112 and a 1967 TOS Milling machine with many cutters making one hell of a mess on the floor.
21 BenRom pedal steel guitars, a Nash 112 and a 1967 TOS Milling machine with many cutters making one hell of a mess on the floor.
Re: Changer design
Hi Bent, thanks for chipping in. The scale on-screen is something I have no control over. But the model itself is built 3 times full size, and the long finger from the changer finger pivot down to the stop underneath is from memory 100mm - measured from my existing Curnow steel to give me a starting point. That's about 1 inch above the deck, a bit less than 3 inches below it and of course the thickness of the top deck.
I'll try to remember to put something in to give it scal in future. Doh...
I'll try to remember to put something in to give it scal in future. Doh...
Re: Changer design
**scale**
Bent, what do you mean when you say the o/c pivot points are a bit too close? What are the o/c pivot points? What are they too close to?
I think the best for "equal action for equal movement" would be a changer finger profiled with a short radius arc. But I've no idea if it would be possible to get "equal effort" as well. I'd trade that for short, crisp knee lever movement. And a shorter C pedal travel!
Will C
Bent, what do you mean when you say the o/c pivot points are a bit too close? What are the o/c pivot points? What are they too close to?
I think the best for "equal action for equal movement" would be a changer finger profiled with a short radius arc. But I've no idea if it would be possible to get "equal effort" as well. I'd trade that for short, crisp knee lever movement. And a shorter C pedal travel!
Will C
Re: Changer design
Hi Bluesteel:
I am not a pro, so what do I know! However I suggest trimming finger corners where a lower might distort return-spring action.
I am not a pro, so what do I know! However I suggest trimming finger corners where a lower might distort return-spring action.
Conceive, believe, achieve!
Re: Changer design
Will what I meant with o/c pivot points was the "on center" of the screws you have for the finger and the lower bar - the distance between the two appeared to be too close. And then yo also have the distance from the lower-bar screw to where the lower bar touches the finger. The closer they are, the faster the action but the harder the pull
http://benrom.com/
21 BenRom pedal steel guitars, a Nash 112 and a 1967 TOS Milling machine with many cutters making one hell of a mess on the floor.
21 BenRom pedal steel guitars, a Nash 112 and a 1967 TOS Milling machine with many cutters making one hell of a mess on the floor.
Re: Changer design
Bent, thanks for that input.
Dave, I think you are probably referring to the corner where the lower finger abuts against the return stop? The length of the lug that the return spring attaches to is not really to scale - it would be further below the bottom edge of the lower finger than seems in this model. I just got lazy when I did that bit.
So I don't think there would actually be a problem in real life - I mean, everybody's changer seems to have that squared off bottom corner, so it's up to me to make sure the lug is long enough to get the run of the return spring out there in clear air below the bottom of the lower finger, so there's no interference. Or I could have it come away from the stop on a gentle angle toward the lug. But again, thanks for the thought.
What's interesting is, nobody has chipped in yet to say "You're way off beam here" - I take that as tacit encouragement.
Will C
Dave, I think you are probably referring to the corner where the lower finger abuts against the return stop? The length of the lug that the return spring attaches to is not really to scale - it would be further below the bottom edge of the lower finger than seems in this model. I just got lazy when I did that bit.
So I don't think there would actually be a problem in real life - I mean, everybody's changer seems to have that squared off bottom corner, so it's up to me to make sure the lug is long enough to get the run of the return spring out there in clear air below the bottom of the lower finger, so there's no interference. Or I could have it come away from the stop on a gentle angle toward the lug. But again, thanks for the thought.
What's interesting is, nobody has chipped in yet to say "You're way off beam here" - I take that as tacit encouragement.
Will C
Re: Changer design
Will
Keep going as you are and you will have no problem building your own changer. You have it well studied out.
Below are shots of a changer I fitted to my steel a few years back and it works just perfectly.
Stu
Keep going as you are and you will have no problem building your own changer. You have it well studied out.
Below are shots of a changer I fitted to my steel a few years back and it works just perfectly.
- Single Changer finger lowering.jpg (32.58 KiB) Viewed 2306 times
- Single Changer finger raising.jpg (34.6 KiB) Viewed 2306 times
Re: Changer design
Stu, thanks for the encouragement. Your design is simple and elegant. Less is more! Sorry I didn't spot this till now. Been spending time out in the (cold!) workshop putting digital readout on the mill. 
Will
Will