Building tuning keys

[aqualibguitars]

Hello friends.
here is new and different topic for discussion.
im in process of building own tuning keys for classical guitar and later on for acoustic guitar.
i have almost finalised 0.6 module worm gear with 18 teeth.
after discussion with a owner of workshop for teeth cutting of the gear the main topic was
how to engage the roller shaft in the gear.
in many keys its double D slot and in some it is broached in square form.
after checking some machine makers website. i saw that some use press fit joint to engage the roller.
i told this to the workshop owner and he said that tolerance for press fit is 0.1 mm
and after press fit it removes some material from the gear so the grip becomes little loose and may cause problem in future.
he told me to find how much torque is needed to tuning the keys
so i want to ask can anybody tell me how much torque is needed for both acoustic and classical guitar strings so that the roller shaft doesnt slip
and anybody have used the keys with press fit and have any problems o no.
thanks in advance

[PTC Bernie]

You might try posting this in the Build and Repair forum.

[aqualibguitars]

oops. sry sir.
can i move this post to build and repair forum?
or should i post it again?

[mirwa]

Its interesting the tolerances being mentioned.

Tolerances for interference fit, is under a thousand of an inch, .1mm would be almost impossible IMO to assemble

I make my own gears on occasion, I am a little lost where the issue is, the worm drive, the gear, the mounting for the worm, the mounting for the gear ??


Edit: after re-reading, I think I understand, what's a good mounting method for the gear to the string barrel, IMO press fit would be a bad idea, fraught with many ongoing issues, broaching would be best.

Steve

[Frank Ford]

Press fitting is a bad idea for a number of reasons. Yes, tolerances need to be close, but a small gear like that is typically made of brass, and in the past, press fit gears of that size are prone to cracking over time because of the stress.

No need to repeat the errors of the past:



Making your own worm-drive guitar tuners is a really complex machining process, and one particularly suited to high precision equipment set up for volume production. Best to buy them.

[aqualibguitars]

thanks friends for ur advice
im planning to make double D by using endmill.
its little easier to manage the nylon roller

[mirwa]

Originally Posted by Frank Ford

Making your own worm-drive guitar tuners is a really complex machining process, and one particularly suited to high precision equipment set up for volume production. Best to buy them.

I do not know where to even start in regards to making the worm gear itself. Definitely an ambitious project.




Steve

[aqualibguitars]

wooow mirwa nice pics.
which machine is this?
can i have ur Facebook account name if u dont mind to discuss further?

[mirwa]

https://www.facebook.com/MusicalInst...?ref=bookmarks

Moderators - if the link contradicts forum policy, please delete.

Steve

[aqualibguitars]

hello friends.
i m trying hard to find the material of the string rollers.
i showed to some shops but they are unable to identify.
can anyone tell me wat materials are used? pvc . delrin. nylon. abs or etc etc

[Frank Ford]

String rollers were originally bone, with brass shafts. Now, however, they are whatever material a manufacturer uses, based primarily on cost.

Delrin would be a reasonable second choice, as, I suppose, would nylon. I've used bone, because when making things by hand, cost of materials is usually not a factor.

Here's more on that:

MAKING A NEW BONE ROLLER

[Frank Ford]

And, if you're interested in tuner work, here's a little adventure in making string posts for a set of Waverly tuners. By the way, Waverly specifies machining tolerance of +/- .0005" for their tuner parts.

Special Waverly String Tuner Post

[aqualibguitars]

OH MY GOD !!!!!!!!!
Mr.Frank you are genius.
i wish i was there making these parts.
i know u will help me more in improvising my tuning machines if they are finished
may i know the weight of the bone roller of each piece u mad?
i too can try to make bone roller but afraid of cracking it.
i think sloane uses aluminium powder coated rollers but i see thru the hole
it has brass post. how is it?

[Frank Ford]

Here's a quick reminder that gears CAN be made strictly by hand, without the aid of lathe or other machine tools:



Not a task for the faint of heart or unsteady of hand . . .

[printer2]

Reminds me of an adjustable gun sight that I made once by hand. I am much more incline to buy ready made now, better use of time. Still, I appreciate the skill needed to do the work.