roller nut rollers?

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Tim Toberer
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roller nut rollers?

Post by Tim Toberer »

Anyone have any tips for making these? My first attempts have been a bit frustrating. My most successful attempt was hand turning the grooves after boring and facing 1/4" brass rod. Then parting off. Getting them the right thickness has been a bit tricky. Basically I left them a little oversize then painstakingly filed them so the fit with the right amount of play. My lathe is old and inaccurate, kind of like me. I delicately tried to cut the grooves to keep string height equal, but they could be better.

I'm considering starting with 1/8" X 1/4" rectangle bar boring 1/8" hole then cutting off little rectangles and turning them round on a mandrel. That way they are an even thickness. This seems like it will bring its own troubles. I keep thinking there has to be an easier way. I looked for a while, but can't find anything off the shelf.
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Karlis Abolins
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Post by Karlis Abolins »

Here is my procedure for making rollers.
Step 1 is getting the bar stock to the proper diameter. It helps to start with stock that is the correct diameter to begin with.
Step 2 is boring the axle hole deep enough to make 2 or 3 rollers.
Step 3 is to chuck the stock so that only the width of one roller is exposed. This is done because bar stock this thin will bend and deflect if there is too much difference between diameter and exposed length.
Step 4 is to use a 60 degree tool to make the groove. Position the tool in the correct location. Slowly advance the tool toward the stock until you slightly score it. Zero the tool indicator. Advance the tool to the the correct number. You now have a groove that is the correct depth.
Step 5 is parting the roller from the stock.
Repeat steps 2 through 5 until you have all of the rollers that you need.

The 60 degree tool which is the tool used for cutting threads is ideal for this process because the math for calculating groove depth is special for a equilateral triangle.

The formula I use to calculate the groove depth is: (string diameter times the square root of 3) times ((the square root of 3) divided by 2). Decrease the result by the amount of string that you want above the surface. I have found that .005 inch exposed amount is adequate.

Karlis
Tim Toberer
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Post by Tim Toberer »

Ok thanks. I'm not far off I just need to improve my machining skills.
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John Sims
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Post by John Sims »

Jim Palenscar may be able to give some advice. He made a set for me recently for my U12
Regards,

John

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Chris Lucker
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Post by Chris Lucker »

Start with diameter of round rod you wish
Collet holding the material
Live center supporting
Sixty degree thread cutting tool 90 degrees to material
Decide how deep you want each string slot
Slim cutoff tool
Lap to precise width
Coolant
Chris Lucker
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Bill Hatcher
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Post by Bill Hatcher »

go to amazon and look up stainless spacer beads....bet you can find something there that you can use or modify.

https://www.amazon.com/s?k=v+groove+sta ... nb_sb_noss
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Andy DePaule
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Better than Amazon

Post by Andy DePaule »

Hi Tim,
Better than Amazon and the only work is opening a plastic bag! :lol:
https://bb.steelguitarforum.com/viewtopic.php?t=378498
Andy :D
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Tim Toberer
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Post by Tim Toberer »

go to amazon and look up stainless spacer beads

Those look promising, and they are cheap! I don't know why but it drives me crazy having to make little parts like this. I pored over the McMaster Carr catalog and just couldn't find anything.
Chris Lucker
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Post by Chris Lucker »

Tim, what is the axle diameter, width and depth of each of your roller slots?
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Tim Toberer
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Post by Tim Toberer »

what is the axle diameter, width and depth of each of your roller slots?
I've been trying different dimensions. 1/8 axle and 3/16 width. I just happen to have these end mills. I just cut the grooves to give clearance. Jobs that require math and accuracy are not my strong point. :oops: I even made one comb by hand using a file. Aluminum seems to be the materiel of choice. Hardwood just doesn't cut it. I try to make everything possible out of wood. I have a nice assortment of dense exotics, but this calls for metal.
The formula I use to calculate the groove depth is: (string diameter times the square root of 3) times ((the square root of 3) divided by 2). Decrease the result by the amount of string that you want above the surface. I have found that .005 inch exposed amount is adequate.
If I'm doing this correctly my answer for a .05 string is a depth of .07 (.0699)? Sorry I suck at math. I have a set of aluminum rollers I'm working on, I figured I'd give this a shot.
Chris Lucker
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Post by Chris Lucker »

Decide how much you want the strings to be above the roller.

For example, assuming you have machined 60 degree slots in your rollers and you want a 0.070" Ralph Mooney-sized string to have 0.024" above the roller, use this equation:
1.5 x 0.070" = 0.105"
Subtract the amount of string you want above the roller (0.024")
Sixty degree groove depth should be 0.081"
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Karlis Abolins
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Post by Karlis Abolins »

Tim, Use Chris' formula. It gives you the same answer as mine without dealing with square roots. My formula simplified, by squaring the square root of 3, is string diameter times 3 divided by 2. It can be simplified even further by dividing the 3 by 2 giving string diameter times 1.5.

Thank you, Chris, for straightening this out and making what looks like a complex task easy. I will go back and update my spreadsheet with your version of the formula. :D

Karlis
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Karlis Abolins
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Post by Karlis Abolins »

Chris, Subtracting .024 from the depth works for a .070 string. It doesn't work for some of the thinner gauge strings. That is why I suggest .005. This of course assumes that I want all of my strings to be at the same height above the nut rollers.

Karlis
Chris Lucker
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Post by Chris Lucker »

Karlis, yes I agree, you are correct. But I never make gauged rollers for the thin strings -- only the fat ones.
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Tim Toberer
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Post by Tim Toberer »

Well I'm realizing the limits I have. Machining aluminum is a bit different than other materials I've worked with. I fouled up the rollers pretty good to start. This turned into my whole day. The 60 degree thread tool was not up to the task. Probably not sharpened correctly. It would not cut the aluminum cleanly, left it very gummy and rough. I'm gonna have to do a little research into machining aluminum for any future projects. I had trouble getting a good finish. I ended up saving them with a combination of filing and sanding. They are for an experimental project so no biggie. I will definitely be using your tips for any future rollers and probably switch back to free cutting brass. Thanks for the info! I really need to up my game a bit. It's pretty amazing to see what some of the other folks are building here.
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Sonny Jenkins
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Post by Sonny Jenkins »

Tim there are many different aluminum malloys,,,some much more machinable than other. I think the only kind you would want to use for rollers would be the kind MSA uses,,,I forget the number. They use that for 3-4 strings and then stainless for the others,,,I think.
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Post by Chris Lucker »

Tim, what cutting fluid were you using? I cannot recall the brand name, but if I accidentally use the fluid made for steel (black and gold can) on aluminum I know immediately I made a mistake. The same happens if I use the green can aluminum machining fluid on steel. Raggedy cuts and bad smell.
You may want to try nickel silver rod. It is easy to machine. You treat it like brass. You generally can get it with 12% or 18% nickel with the rest being copper and zinc. I have the rod around because I machine ferrules and other components for bamboo fly rods, but I also use it to make Telecaster bridge saddles. Hey, if nickel silver is good for frets.
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Tim Toberer
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Post by Tim Toberer »

what cutting fluid were you using?
Don't laugh, but I think its just Wesson oil. Hee Hee. Like I said I gotta up my game a bit.
there are many different aluminum malloys,,,some much more machinable than other.
It's from Menards so probably not ideal.

I like the nickel silver idea. I have never tried to machine it, but it files well and shines up nice. I have used it on some bagpipe parts.
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Sonny Jenkins
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Post by Sonny Jenkins »

That hardware store aluminum is much too soft. For rollers or machining. 6061 or 7073. The 70s series much preferred,,,I think that is what MSA uses
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Post by Jim Palenscar »

I generally use 2024 and only drill out 1 at a time as I don't trust the center not to wander when making custom gauges. If the center hole isn't perfect making a gauged set is pointless as the variation throws the depth off. I use a computer program made for me by a friend and vary the slope so that I deal in .0005" or more round numbers- probably that is even optimistic but it works for me. I attempt to leave a full shoulder on each string and obviously cutting a .090" deep groove in a .125" wide roller won't work and I like to use a .020" minimum groove for the thinner strings so varying the slope allows me to make a set that gives me a planar top as they come off the roller nut. This still isn't perfect as larger strings come over the top at a more obtuse angle than thinner strings so it's still necessary to push the fat guys down a bit on the neck side. I would suggest if starting from scratch using a .0625" axle as the axle is partially responsible for hysteresis IMHO.
Tim Toberer
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Post by Tim Toberer »

so that I deal in .0005"
You make some very good points! I'm not trying to be contrary (I definitely admire anyone who is striving towards this), but at what level is this just pointless. More power to you if you can work within these tolerances, and I think its not a bad thing to aim for. But does it matter?? I'll be the first to admit I need to get more accurate in my work, but this is just beyond the level that seems necessary.
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Post by Jim Palenscar »

More vibrato
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