Acoustic machines

[ef37a]

On a whim passing a charity shop I bought a very cheap nylon strung classical style guitar (I need the wide neck ) .

The label says it is a Viva and it seems ok but for the machine heads, they are tight as ****!

Had one side off and the mechanism itself is ok but when back in the head the large diameter white plastic spindles bind at certain points in the revolution, so much so I fear the plastic turn grips will strip.

I have looked on Zon and cannot believe how cheap machine heads are! There are sets under 4 quid! So, my question is. Are all the machines on the same pitch or would I have to file out the holes to fit them? If the latter I might as well just do that to the existing headstock (tho' I would like some better mechs; on it anyway) . What sort of money is something decent?

Do I actually need the ~ 8mm diameter string spindles or can I fit a set of better, individual enclosed machines?

Dave.

[zenguitar]

There are no standards whatsoever for cheap classical machine heads. It's pot luck. Most workshops keep a supply of old classical machine heads for the parts. When one of the machines in a set is broken it's often easier to find a combination of old parts that fits than it is to identify a replacement set that will fit.

However, as the machines do appear too be working OK I would look at the holes where they are binding. I would get some needle files and sandpaper and remove some wood at the binding points.

The most likely cause is the wood swelling over the years as damp/humidity gets into the exposed end grain. So once you have them turning smoothly I would rub some candle wax into the wood of the holes. That will act as a lube and also seal the grain.

Andy

[zenguitar]

And before getting the tools out, try removing the fat white plastic barrels and fitting them on their own. You can try turning them manually and confirm that they really are bonding in the holes.

Andy

[ef37a]

And before getting the tools out, try removing the fat white plastic barrels and fitting them on their own. You can try turning them manually and confirm that they really are bonding in the holes.

Andy

Ah! So there is no need for the bigger radius for nylon strings?

Dave.

[Sam Spoons]

The big posts are much better for nylon strings 'cos the stretch about 10 x as much as steel so would need loads of turns on a 'normal' machine head post. I think Andy means dismantle the machines and make sure the posts are turning freely in their respective holes, if they are it may be the mechanism that is stiff or, possibly, they are out of alignment with the holes (due to poor qc or a mis matched replacement).

[zenguitar]

Yep, Sam's spot on. Exactly what I meant.

Andy

[ef37a]

The big posts are much better for nylon strings 'cos the stretch about 10 x as much as steel so would need loads of turns on a 'normal' machine head post. I think Andy means dismantle the machines and make sure the posts are turning freely in their respective holes, if they are it may be the mechanism that is stiff or, possibly, they are out of alignment with the holes (due to poor qc or a mis matched replacement).

Thank you Sam and Andy both for the advice AND for not saying "why do you come here bothering us about this cheap ****! Fact is I USED to play guitar, learned a lot of Beatles chords (and the 3 or 4 for Quo!) but have not really done anything for 30 years. I found a cheap narrow necked acoustic but as I said, fingers wont fit. I gave that to the charity shop then paid them the £13 for this one.

I really just need something I can re-learn on and do recordings.

I have about 200 drill bits in various tool boxes. I dare say I can find one to ream the holes out.

Dave.

[Sam Spoons]

[Wonks]

You can of course simply measure between the centres of the posts and see if you can find some replacement strips that will fit if you want to perform an 'upgrade' if you still feel the tuners should be working better. Stress on the gears due to the stiffness of the shaft may have bent some of the brass teeth a bit over time.

[ef37a]

You can of course simply measure between the centres of the posts and see if you can find some replacement strips that will fit if you want to perform an 'upgrade' if you still feel the tuners should be working better. Stress on the gears due to the stiffness of the shaft may have bent some of the brass teeth a bit over time.

Indeed! Thought I had cracked it. One of the cogs had very mutilated teeth. Had it off and cleaned it up with a file and off guitar it ran beautifully. Back on with a string load? GRRAAAAGH!

I might take one side off and hawk it round the local music shops (I think we have two left of nearly a dozen ten ago. Oo! Three, forgot PMT but parking for them is a PITA) If I find a set to fit, fine, if not I shall "adapt" the holes!

Dave.

[Sam Spoons]

Measure the centres and post here I have a spare set somewhere (if I can find them) but, odds are they won't be right but somebody might have some that are?

[Wonks]

I recently replaced some on an old classical that had sentimental value for its owner, (though the banana-shaped neck meant it was impossible to play past the third fret). It took a while looking through the sets available on eBay and Amazon, especially as not all of them had dimensions listed, but eventually I found a set that were correct and they slotted right in.

There will be some suitable ones out there if you look.

[ef37a]

Found a 7/16" HSS bit and in mole grips that has shave some wood off the holes.
That process showed up a design error! The holes in the headstock are bored straight through NOT referenced to the angle that the machines are mounted on! This obviouly means the string barrels enter the holes at an angle and are BOUND to bind up!

A very silly and careless bit of engineering. All it needed was to mount the head on a block with an angle complimentary to the side and drill each side separately. "Quicker" is obviously "cheaper".

Couldn't find a candle so I have used a B pencil and lubed the gears and the white barrels where they impact the wood. Better but I did not watch the D string as I wound it up and it has jammed against the inner side of the headstock. (MUCH prefer electrics!)

Got it near pitch and in tune. Shall wait now until expert son pronounces on it. If he says it is worth a set of machines and new strings ok. If not I shall donate it to another shop!

Dave.

[Wonks]

What's the action like? It can be pretty bad on old cheap classical acoustics. You can often take the saddle height down a bit, but if the neck is bowed there's no truss rod to correct things.

[ef37a]

What's the action like? It can be pretty bad on old cheap classical acoustics. You can often take the saddle height down a bit, but if the neck is bowed there's no truss rod to correct things.

Pretty dire Wonks, about 5mm at the 12th but with nylon strings and the fact that I shall not get out of the first position much at all it matters little. If I am going to keep it and fix the tuners there is plenty of meat on the bridge so I could take a mm or so off that. There is the very slightest bow in the neck and as you say, no truss rod.

Dave.