Changer Finger Design

[dgalloway]

I am a newbie and this is my first attempt at trying to make a changer or any steel guitar part as far as that goes. I am going to attempt to post some pics of my layout. I am using 6061 alum for the string cam and 16 gauge weld steel for the raise and lower fingers. The axle size is 1/2 inch stainless and the top of strings to the top of the body will be 1 1/2 inches with the top being full 3/4 inch walnut which will leave 2 3/4 inches hanging below the top. I have a total width of 10/32" and hope to use a 1/32" nylon spacer between the fingers to give me 11/32" string spacing. My pull rod holes will be 5/32" spaced 5/16" using 3/32" stainless rod, tripple raise and lower. Would like some feed back if anyone feels this design will work or what improvements I should make. I only have a small drill press and 1 inch belt sander and various hand tools so I really don't won't to make 10 fingers that don't stand a chance of working. All comments are appreciated. Thanks.
Dave Galloway
Overland Park, KS

img008 (640x489).jpg (187.31 KiB) Viewed 3375 times

img009 (374x500).jpg (65 KiB) Viewed 3375 times

img010 (234x400).jpg (47.28 KiB) Viewed 3375 times

[Bent]

Dave, That looks pretty durn good for the first time!
I would like to suggest a couple of things: Instead of the large radius you have on the string finger, I suggest you just make it a straight slant...from widest at top to narrowest at bottom. I believe this give you just a touch more finger throw where you need it the most - on the lower.

donefings.jpg (49.67 KiB) Viewed 3372 times

This next one is me and my distaste for plastic in a steel guitar. Then especially in the changer where the tone originates. I suggest you buy some 1/2"ID galvanized spacer washers for this. They can be had from a fastener supply company.

Keep us posted on this exciting project!

[dgalloway]

Thanks for the Pic and the info. I have followed your posts on the forum and have seen the pictures of your guitars, very impressive! Wish I was closer to Canada, would love to see your shop and see your production. You build a beautiful guitar. I decided to make the changer first because it appears to me, the most difficult piece and that everything else depends on it. I will make the mods and re-post. Off subject, do many of the builders go to International Steel Guitar Convention in St.Louis?
Thanks Again

Dave G

[dgalloway]

Bent, here are some pics of the what I hope are the changes you suggested. Let me know what you think and if I am on the right track? I moved the bearing on the lowering finger to the left and straightened the string arm angle. Tried to picture the fingers engaged to show the travel. Do you or does anyone know what the maximum degrees of rotation are required for a whole note raise and a whole note lower, i.e., smallest string to the largest string diameter?
Thanks again for any input.
Dave G

IMGP1498 (800x600).jpg (148.74 KiB) Viewed 3278 times

IMGP1499 (800x600).jpg (146.75 KiB) Viewed 3278 times

IMGP1501 (800x600).jpg (149.12 KiB) Viewed 3278 times

[Bent]

Dave, that is a great workable solution. As to the throw..I had it figured out once upon a time but can't remember the figures. However, you will be surprised at how short a throw you really need ... for a raise it is hardly visible. For one of the most difficult lowers - string 6 g# to f# it takes a long throw, but not as long as the changer is capable of.

[dgalloway]

Appreciate the response, I will give it a go and see how it works out. Needless to say it will be sometime before I am able to post back with the results, but look forward to the journey, and I am sure I will have plenty more questions for the forum as I go along. Now it is off to try and replicate 9 more! Thanks again for the info.

[burt]

I have calculated the amount of changer finger rotation (in degrees) in this post:

viewtopic.php?f=4&t=513

[dgalloway]

Burt that is good information. After having thought about it I believe the only variables that have effect would be the finger diameter and the scale length for the general degree angle. I believe you mention 3/4" dia. and 24" scale. If a 24.25" scale is used then a slightly smaller finger diameter would be needed to maintain the same degree angles? Math is not my strong suit, my days were spent trying to figure out how to get another yard on a football field or another foot with a discuss or inch with a shot putt. My whole thought has been of the design is what if it doesn't lower or raise a string enough or it raises and lowers way too much. Knowing the angles gives me a picture of whats needed for movement. Thanks for the input.

Dave

[bluesteel]

Dave, I'm looking into this also. I offer 3 thoughts:

1. You might want to reconsider how far down the back of the cam you have that cutout for the string end. It looks as though it may be really tricky changing strings once the guitar is assembled.

2. Bent uses brass fingers. His guitars get rave reviews for clarity and sustain. My old Curnow has aluminum fingers, and it doesn't hae great tone or sustain above about fret 15. I think it's because of the aluminum.

3. It's interesting to see your finger return spring operates on the lower - most guitars I've seen seem to have it on the raise. Your raise finger is shorter as it doesn't need to go all the way down to the bottom, for the spring to attach to. I've no idea what effect the difference makes, if any. I just noticed it, is all.

Good luck!

Will

[dgalloway]

Blusteel, good points. I may yet use brass instead of aluminum, do you know if 360 or 385 alloy will work? I agree that I probably need to move the string notch a little more up for easier access. Years ago I used to work on large mechanical accounting machines with a ton of moving parts and springs and got pretty used to hooking springs and cables down in some pretty tight places so didn't think much about it. Guess I should make it a little more user friendly. On the spring, I am hoping that when all the lowers are pulled to the stop plate, the raise fingers will be pulled to their neutral stop screws by string tension and pivot action of the finger. Thanks for the input and I like what you say about the brass.

Dave G