| Author |
Topic: Changer Fingers |
Todd Brown
From:
W. Columbia , South Carolina
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Posted 3 Mar 2012 10:04 pm |
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| From what I gather, the consensus is using Aluminum for changer fingers. I know several different grades have/are being used. It seems the T6061 aluminum is most commonly used today. I know compared to the grade of aluminum that Sho-Bud used on their early '70's fingers, the T6061 is harder, but by how much. We all know about having to sand grooves out of Sho-Bud and many other brands of Aluminum fingers. Just wondering if the T6061 is as susceptible to getting grooves as bad... |
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Richard Sinkler
From:
aka: Rusty Strings -- Missoula, Montana
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Posted 4 Mar 2012 1:02 am
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Not sure about the hardness as far as it's Rockwell number, but I have seen grooves in every guitar I have had that had aluminum fingers. I just got done sanding one down on my Carter a couple of days ago.
_________________
Carter D10 8p/8k, Dekley S10 3p/4k C6 setup,Regal RD40 Dobro, Recording King Professional Dobro, NV400, NV112,Ibanez Gio guitar, Epiphone SG Special (open D slide guitar) . Playing for 55 years and still counting. |
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Bent Romnes
From:
London,Ontario, Canada
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Posted 4 Mar 2012 5:25 am
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Todd, I believe 6061T6 aluminum grooves as bad as the next type. I have seen grooving in guitars as new as 6 months old. Also, I have removed grooves in fingers on a 1992 steel with light buffing.
To eliminate the problem, have your fingers anodized.
_________________
BenRom Pedal Steel Guitars
https://www.facebook.com/groups/212050572323614/ |
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Todd Brown
From:
W. Columbia , South Carolina
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Posted 4 Mar 2012 8:35 am
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| Mullen are the only ones making anodized fingers, right? Why not more builders? I've heard that before, that the Mullen anodized fingers were so hard that they won't get grooves worn into them. I think the only other brand I've heard about that has fingers that don't groove are ZB's. I believe they used a Stainless cap on top or solid Stainless Steel fingers. Maybe BMI still uses something close to what the ZB's used? |
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Storm Rosson
From:
Silver City, NM. USA
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Posted 4 Mar 2012 9:16 am
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 The ultimate in MHO would be nitrided for hardness and less friction,,,,Stormy  |
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Richard Sinkler
From:
aka: Rusty Strings -- Missoula, Montana
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Posted 4 Mar 2012 10:58 am
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| Quote: |
| Mullen are the only ones making anodized fingers, right? Why not more builders? I've heard that before, that the Mullen anodized fingers were so hard that they won't get grooves worn into them. |
Todd, that is a great question.
_________________
Carter D10 8p/8k, Dekley S10 3p/4k C6 setup,Regal RD40 Dobro, Recording King Professional Dobro, NV400, NV112,Ibanez Gio guitar, Epiphone SG Special (open D slide guitar) . Playing for 55 years and still counting. |
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Todd Brown
From:
W. Columbia , South Carolina
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Michael Yahl
From:
Troy, Texas!
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Posted 4 Mar 2012 12:06 pm
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There are two basic types of anodic coatings for aluminum and aluminum alloy products.
Type I is used primarily as a substrate for subsequent painting as it improves adhesion or it is used alone for appearance and corrosion resistance as it takes a rainbow of colors quite easily. The thickness of this converted substrate is also quite thin and in the range of .00002" to .0007". It can be damaged quite easily.
Types II and III can be much heavier and therefore harder. These range from .0002" to .001" for Type II and up to .006" for Type III and is considered 'Hard' anodize and can reach a hardness of 62 Rockwell C Scale. This is the same hardness as tool steels that are hardened and ground to cutting edge tools.
There are several reasons that many avoid the hard anodizing process. Although many improvements have been made in the processes in order for them to accept a wider variety of dyes, traditionally the coloring is a pale to dark olive color.
The biggest reason that it is avoided is that in the anodic process, the thickness specified penetrates the material 50% and builds the material 50%. This means that any dimensions that are tolerance critical, such as the finger bore to axel shaft clearance, must be held to tight tolerances and the anodizer must be reliable at holding his tolerances.
A .0002" (2 ten-thousands of an inch)miscalulation or size difference can render the components scrap. Once hard anodize is completed, you cannot simply polish the parts to fit as they are hard as rock. It would require a secondary honing operation at a shop that has the appropriate equipment.
This is all added cost and often the risk of scrap does not warrant the process.
There is usually a minimum 'Lot'($80-100)charge and EPA fees in addition to being charged by the pound for the process.
The smaller builders simply cannot afford this added cost for such a minimal improvement in a design characteristic verses the time and effort required to achieve it.
I believe that Mullen has high enough production that they can justify doing this. Additionally, they have CNC equipment that will hold those tolerances. In the end, the consumer pays for this additional quality just like any other product.
_________________
"Don't fergit to kiss yer horse!"
'72 Sho-Bud Professional D10, (in pieces .....), '78 MSA Classic XL D10, '69 Emmons PP, Fender 2000
Peavey Session 500 BW, Crate Digital Modeling Amp
PSG PARTS
http://www.psgparts.com/ |
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Todd Brown
From:
W. Columbia , South Carolina
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Posted 4 Mar 2012 12:17 pm
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| And that folks, is our answer right there. Thanks, Michael. I know that your replacement Sho'Bud fingers are machined from T6061 aluminum. What are the differences from that grade to what ShoBud used on their Professional fingers? I just hate that it seems so many brands have changer fingers that easily groove and have to be sanded and polished out somewhat frequently. I guess we gotta live with it... |
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Richard Sinkler
From:
aka: Rusty Strings -- Missoula, Montana
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Posted 4 Mar 2012 1:08 pm
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The cost is the main factor.
Michael said:
| Quote: |
The biggest reason that it is avoided is that in the anodic process, the thickness specified penetrates the material 50% and builds the material 50%. This means that any dimensions that are tolerance critical, such as the finger bore to axel shaft clearance, must be held to tight tolerances and the anodizer must be reliable at holding his tolerances.
A .0002" (2 ten-thousands of an inch)miscalulation or size difference can render the components scrap. Once hard anodize is completed, you cannot simply polish the parts to fit as they are hard as rock. It would require a secondary honing operation at a shop that has the appropriate equipment. |
While this is true, parts can be masked prior to the anodizing process. I used to supervise a metal finishing plant in Oakland, and we often had really tight tolerance parts for anodizing as well as plating. On a finger, it would be possible to place a plug in the hole where the axle goes and that surface would not get anodized or etched in the prep phase. The sides of the finger can also be masked, although with proper planning, the finger could be machined under size enough to compensate for the buildup of hard anodizing on the surface. Seen this a million times. The anodizing process can control how much build up the coating would be. But, the cost to have a person sit and mask parts would be prohibitive to the small builder. And as Michael stated, the color of hard anodizing is really ugly, sort of pale grey to faded brick red depending on alloy and thickness. You could (at that time) only dye the hard anodizing in dark colors such as black, dark blue, dark brown, etc... Even then, color was never guaranteed. The anodizing could also have teflon impregnated during the sealing process. Don't know how much it would affect the string sliding off the top of the finger, but it would be great lubrication for the sides of the fingers, especially if the mounting for the changer also was teflon sealed. No having to put oil in the fingers, except the lower part (scissor type).
_________________
Carter D10 8p/8k, Dekley S10 3p/4k C6 setup,Regal RD40 Dobro, Recording King Professional Dobro, NV400, NV112,Ibanez Gio guitar, Epiphone SG Special (open D slide guitar) . Playing for 55 years and still counting. |
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Michael Yahl
From:
Troy, Texas!
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Posted 4 Mar 2012 1:23 pm
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Without a chemical analysis it's hard to say what the exact alloy/hardness of the original fingers were. If they are 6XXX series they may have been 6061-T0 as they were punched from solid and the -T0 indicates dead soft and they may have been something like 5052. This is more ductile and also softer but can be heat treated to a harder condition. The shear marks on the sides bear witness to the process and it's unlikely that Sho-Bud performed a secondary heat treat operation. This would also explain the reason that these fingers wear faster than those machined from a -T6511 treated material.
These days most everything is 6061-T6511 which is cold drawn, tempered and annealed. It is the most readily available type of 6061 in this alloy and the most stable with a high machinability factor.
Many of the 'shapes', angle, box, channel are of 6065 alloy.
_________________
"Don't fergit to kiss yer horse!"
'72 Sho-Bud Professional D10, (in pieces .....), '78 MSA Classic XL D10, '69 Emmons PP, Fender 2000
Peavey Session 500 BW, Crate Digital Modeling Amp
PSG PARTS
http://www.psgparts.com/ |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 4 Mar 2012 1:50 pm
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Type 6061, in either T4 or T6 condition is what I believe most builders use. It's fairly hard (compared to the old cast parts), and it's cheap and easy to procure and machine. A better choice might be 7075, but it's expensive and hard to get, since Boeing buys most of what's made for airframe structures. Type 2024 is probably the hardest common grade, but it corrodes fairly easily unless plated. As with anything in life, every alternative has a down-side. While hard anodizing may substantially reduce the grooving, when it does groove, you're stuck with buying a new finger, since there's no suitable repair, and any attempt at smoothing would only remove more of the protective coating.
Th best thing is to take reasonable care of the instrument, make sure the case fits properly (that the weight of the guitar never rests on the rollers or fingers) and polish the finger-tops only when absolutely necessary (when damage affects the sound).
I'm really surprised that a lot of builders don't make the pillow blocks (axle mounts) a good deal higher than the tops of the fingers, as this simple change would eliminate a lot of the damage we see. |
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James Morehead
From:
Prague, Oklahoma, USA - R.I.P.
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Posted 5 Mar 2012 7:22 am
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I play an old shobud--play the heck out of it. It is nearly 50 years old. I have done nothing to the fingers, except change strings.(to busy to refurb my own guitar!) Finger grooving is hardly noticable visually. It sure does not effect my tone or the guitar's playability. I have many 40 year old 'buds come through my shop, and have yet to see one with even one finger unplayable. A little buffing, and they are good for the next 40 years. (Now, what I just said has nothing to do with the newer pot metal fingers of the late 70's and '80's--that's a different topic.)
My conclusion: play more and obsess less.
But if you are curious, here is a good read on aluminum grades, etc. Enjoy! 
http://www.aircraftspruce.com/catalog/mepages/aluminfo.php
_________________
"Good judgement comes from experience, and a lot of that comes from bad judgement"~old cowboy proverb.
shobud@windstream.net |
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