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Hello

In my farther adventures in restoring old henri herz
piano I will be facing pin replacement,I was searching around the forum and seen some related info but still haven´t come to conclusion and I would be very thankful to find some help to this specific problem.
As I mesured the old pins there are various sizes going from 6,28 to 6,76 ,they were usually thinner in the treble section of the pin block so the holes are also a bit smaller there too.
I wonder which new pin size 6,75 or 6,90 or bigger ,I must say the holes are uneven inside and covered with corrosion from old pins so I reckon reaming or drilling will be called for.
So I was wondering what would be the good reamer size for those new pins?
and if I could also ream directly (bypassin drilling) the small holes from 6,28 pins to fit the new pins or will I have to drill first ? In that case which drill size would be recomended.
Thank you .

You need first hand technical advise, hire a professional. Your concern should be when installing over-size tuning pins is whether the pins will touch the plate at the rear of the pin (speaking length side), or if the old pins are already touching; in which case, a new pin block is in order.

The quality of the pin block (density) determines the proper reaming diameter.

We mostly measure tuning pins in thousandths of an inch in North America. I am wondering what is being used to measure those pins, a caliper perhaps? A micrometer is much more accurate for this kind of work.

Tuning pins measuring 6.28-6.76 are quite small in diameter. That is from.247 to .266 in diameter. In order to get rid of all the dirt and metal deposits inside the hole it would be best to ream out to .270 (6.85mm) and then install .281 (7.13 mm).

Use a hand reamer with a T handle like this one in the photo

Hand reamer with T handle

I would do one tuning pin at the treble end first to see if the #3 tuning pins will fit as Jon has mentioned in his posting.

Thank you Jon ,is this issue of plate valid in wood frame pianos also?
All the way to 7.10 I can get 52 mm size lenght pins,the same as old pins

Hi Dan thank you very much for help ,I am using micrometer to mesure , so as you sugest 7.13mm(here available 7.10)is way to go ,thus bypassing 6.90 and 7.00 pin size ,that´s what I was hesitating about ,this way the holes would be evened better (as some also appear a bit ovalish in the entrance)
I was a bit reluctant go thicker since the pins in this piano are very near each other,but I hope 7.10 won't be a problem.
I suspect the pinblock is solid wood

You are dealing with a very old piano, possibly made before parts standardization, so advice given on the basis of modern pianos may not be applicable to your piano.

We might be able to give better advice with pictures, but it still may be beyond the experience of people here.

You will need to have the holes 9-11 thousandth of an inch smaller than the tuning pin you choose. If this is wooden frame instrument then there is no problem with fit against the plate as there isn’t one.

Reaming out to .270 will leave enough to drive in a number 3 pin. I would load test the block first by doing one hole at the treble end see how it goes. You might find that you can ream out a little less but it is best to ream back down to clean wood.

That will also give you uniformity in the holes as you mention.

For the tuning pin holes that have gone oval; this is most likely the 3 ply finishing veneer in front of the pin block.

That product is about 3/8 of an inch thick. The oval holes are probably in the bass section as that section pulls a lot of weight. You might consider drilling out the front of the hole and inserting what are called hardwood plate bushings. These come in different sizes and lengths. I have done this in the past with open faced pin blocks. A little stain will match the colouring of the rest of the veneer.

Just came back with something I forgot;

Use blue tuning pins in that one. if you use nickle plated it will not look good.

I think Herz was the guy who invented the butterfly spring for the whippen lever.... now in use by Steinway and others.

>Thank you Jon ,is this issue of plate valid in wood frame pianos also?
>All the way to 7.10 I can get 52 mm size lenght pins,the same as old pins

Are you saying that is piano has an exposed pin block?

BTW, a .281 tuning is is 2/0.

If you have a variety of pins sprinkled throughout the pianos, go with the largest diameter and upgrade from that, install all new pins that are the same size.

Ado, you really didn't mention the exact reason for the piano needing "pin replacement". Is it cosmetic reason (rusty), or are there some loose ones amongst better ones, has a technician recommended it?

The reason I ask is that there are several pitfalls you should be aware of. If there are some pins which fall in line with each other and are significantly more loose than their neighbors, you could have some major deterioration/splitting on the pinblock in that area and driving in larger pins will just make it worse. Sometimes plugging and redrilling is needed in these cases. If there a dozen or less pins that are marginally loose you can aquire oversized pins in partial sets also from certain suppliers.

Not meaning to scare you off the piano if your a DIYer with your heart set on doing what your doing, just pointing out some things that techs look at when faced with the same situation.

Yes, my mistake Jon, thanks for the correction. When I wrote “ream out to .271” for some reason I started to think that .271 was a number 1 pin, that is actually a 0/0 pin I believe. Here in N. America anyways.
I will leave the error in place without edit or the thread will not make much sense to readers.

So for the OP the reaming tolerances would be the same and the pin size would not change just the label of pin size.

Good additional comments from Emmery.

Going back to my previous comment which too many people have ignored, I have a question:

Are the tuning pins threaded or not? If not, are they tapered?

BDB, I haven't run into "unthreaded" pins myself but since you mention this, are unthreaded pins hammer forged/ground or what? I had figured the fine threading was the final machining method to get the pins nicely round and to final size and wonder what the logic would be behind spending extra money to remove the threads or using a more expensive process to get them smooth. I've looked at many different pins with a loupe and most are machined with die that has about 1/4-3/8" length of multi toothed tool engagement...more like a fine toothed scraper. (The "threads" are not 60 deg standard depth threads like used for machined fasteners.)

Hey Emmery,

Some English instruments, in particular Broadwood, maybe Collard too, had oblong tuning pins with traditional threads like a wood fastener. I just sent you a photo direct.

I don’t know if any European makers in Germany used threaded tuning pins.

I have only come across one piano with unthreaded tuning pins, which seemed to have come from Austria sometime around WWI. I have dealt with conical tuning pins in a harpsichord. I do not know how they are made, but whatever process that makes threaded pins could be used to make unthreaded ones round or conical.

I am just trying to establish what we are dealing with here. As I said, pictures might give us a better idea.

There certainly are numerous things to consider when replacing some or all the pins. I've had a fair amount of marginally loose pins get additional life in them from just tapping a bit deeper if it hasn't been done already. In fact, there are some older pianos I've seen where it almost appears like the coils were left a bit higher than normal just for this purpose. Open pin block, no bushings, older piano, almost seems to scream CA treatment for me too... Lol

It looks the oval parts are only on the front venner.As for reaming back to clean wood ,that sounds like the thing to do ,so you sugest no less then 7.10 for the new pins? Might 7.00 be ok also ,Thank you

I will be using blue pins



Yes I think this is what you call exposed pin block


Thank you Emmery, I decided to repin because some of the pins were stuck hard and some loose.Although majority pins seemed ok and there was no rust from outside when I started to take them I could pull them out with gently jerks once they were half way unscrewed,so I believed that was kind of loose pin situation.Some of the tough ones to turn
were swollen and expanded by corrosion also.


They are threaded and tapered

I will try to get some up soon ,thank you very much all for your kind advice and help

With old instruments like this it depends upon how the wood reacts when the new tuning pin is driven. This is what Jon meant when he posted about the density of the wood pin block.

That is why I suggested doing a test pin at the treble end.
Sometimes with old instruments I ream one hole and install a test pin, install the new string and pull to pitch, then measure the torque resistance to see where I am and how the wooden plank is reacting.

With the tuning pins that have distorted the bottom edge of the front of the hole we do not know if the back of the hole is damaged too. This is why I suggested reaming out to .270(6.85mm) to make the holes uniform in size but also to get rid of any distortions that may be hidden inside the back of the hole at the top. This will also clean out the holes completely and give you straight, clean holes, all the same size to work with.

This part here quoted;



The corrosion damage in the back of the hole cannot be seen. This is why you need to ream out to .270 to get rid of all the contamination.

The smallest tuning pin you have is 2.47mm. In order to ream out to .270(7.13mm) you might have to set the reamer to take out half of that distance and then reset the reamer again to ream out the rest of the way. This is why I use the adjustable hand reamers, instead of a spoon bit or twist drill.

If you want to use 7.00mm tuning pins these are .275 thousandths of an inch. The reamed out hole is.270 thousandths of an inch and that makes the hole too big for a .275 tuning pin. The pins will be loose right away especially in the bass…..

You need a minimum of 9-11 thousandths for good torque ratings. So if the reaming is.270 (7.13mm) the tuning pin should be a minimum diameter of .279(7.08mm) to .281(7.13mm) That should get you there.

But again do a test pin in one reamed out hole, string it up and then put the torque wrench on to see what rating you have.

The tuning pins you mention that are 7.10mm are the ones I would use for this job.

From what you have written it seems that the tuning pins being removed are conventional pins.

They cannot be threaded and tapered.

Dan Thank you very much for your valuable advice, I see it all much clearer now ,I will order the 7.10 pins to be on the safe side

BDB ,they are threaded and very soft easy to break so I thought they might be tapered,I might be mistaken maybe the iron thosedays was like that or it is the age.