Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Sometimes, it takes me a while to come around on some things

In the past week, I've hung my first two sets of Renner hammers (Premium Blue Points, to be specific). It's funny; I never had a call to before, so I always used Abels from Schaff.

Never. Again.

These were the easiest hammer jobs I've ever done. I feel like an idiot for taking so long to come to the light on this one.

Oh, and the customers ADORE the sound.

I have never done hammers - just learning this piano tech stuff. But just curious, what makes one hammer easier to install than another? I assume that it is the dressing and voicing because it would seem to me that the wood cores would be pretty similar, as long as the holes were properly drilled. A short answer would be fine. TIA

Regarding installation, it's all in the boring and tailing (on grands). These were bored so well I didn't have to do any additional reaming prior to installation, and the fit was perfect; not too loose, either. The bore angel was perfect all the way across. All I had to do was pop the old ones off and glue the new ones on. The alignment was even acceptable, all the way across. It went so well I told the customer I'm charging him less for the labor.

To top it off, this was without sending them samples; the boring and tailing were done from their on-file specs. I didn't even send them a serial number.

My past experiences were nothing like that: Lots of reaming, and the bore angles were all over the map by comparison. Lots of alignment issues.

Very hard hammers take more time to voice. The same can also be said for very soft hammers.

Here is the finished set:



This is an original old hammer on the right, with its corresponding replacement on the left, which is also a Renner (from 1980):



Another thing about the hammer on the right: That's my resurfacing work.

Unless you are working from scratch, I think it is important to have someone you really trust do the work. Sounds like you've found what works for you. While I think the Blue Points can be made to sound nice (i.e. Ravenscroft pianos), I'm more of a Ronsen guy. I use Dale Erwin to prep my hammers and the end result is always world class.

I'm not set up to bore and tail my own (don't have the shop space or equipment), so I have to have it done for me.

Yup, me too! Isn't it nice that there are great people to do these things for us?

Indeed it is!

hello, great you are happy, I like those jobs.

your new hammers are longer or is the left one a bass hammer and right one from mediums ?

the back-checks could need to be lowered then.

their angle may need to be reset, also.

I stopped ordering bored hammers but in any case what matters is knowing how to decide of the bore, see what was installed originally, was it right, and use a good dimension.

longer bore can put you in trouble easily. longer tails often can be an advantage but the backcheck height is a parameter of touch. (too tall they make it a little less firm)

I wonder if the piano is a Foerster ?

Isaac, those are the same number hammer in the scale. What I think it is, is that the old hammer had been resurfaced so much over the past 35 years that that is all that's left of it. This is the Baldwin SF-10 I've posted about previously with the voicing issues.

I did a spot check of the back checks yesterday after the rehanging, and they were generally checking where they should be. I still need to go through and check each individual note, and regulate the hammer height

Jim,

I read a post sometime by some experts in rebuilding, and what they do before gluing on the hammers, is counter sink the bore hole of the hammer moulding a little bit, and for the entire set, for a better gluing/bonding job.

My mentor taught me what I understand to be the factory method; spin the head onto the shank for even glue distribution. I've never had a head come off.

Interesting that this is an SF-10. I replaced a set of hammers on a 1986 SF-10 this summer... original hammers with red underfelt.

Just out of curiosity, did you measure action ratio and mass of sample hammers?

The action ratio was way off; too much travel, of course.

I didn't weigh samples because I didn't have to provide them; Renner has the specs on file. Call me lazy...

I estimate that the old hammers had had ~â…“ of their original mass removed through resurfacing over the years.

Did the SF-10 you did have a Renner action, or Baldwin? This one had Renner.

I am pretty sure all SF 10s had Renner actions.

I am also pretty sure if you took all the felt off the top hammers on any piano, you still would not remove a third of the mass.

I seriously doubt it.

Filing hammers (properly) does not remove as much hammer mass as one might think.

Everyone should try this test: take a hammer, weigh it and then start removing felt, trying to take off one or two grams. I have done it. I finally put away the hammer file and took a knife to it. By the time 1.5 grams had been removed the hammer was very, very much smaller and severely compromised, essentially unusable

On the one I did, the action ratio is 6.17, as measured by the Fandrich-Rhodes ITF calculator. Crazy high! Yes, the action is Renner. Baldwin never used its own action for the SF-10 and SD-10, to my knowledge.

Hammer mass is not consistent, so that's not a spec anyone would have on file. On my project, the Cs were as follows (in grams):

C1: 9.1
C2: 8.3
C3: 7.6
C4: 6.7
C5: 6.2
C6: 5.2
C7: 4.8
C8: 4.4

These hammers were heavily filed, so I assume they were probably 1g heavier to begin with, except in the treble, of course. As a result, this piano was probably quite difficult to play, when new. Because the action ratio was so high, I wanted to keep the hammer mass in the same ballpark, so I had Dale weigh the new hammers to Stanwood curve #6, which is on the light side. After installing the hammers, dialing in friction, and releading the keys, it is now a really nice piano!

Yeah, I overshot my estimate.

It was still lot of material that came off over the years. The old hammers seemed tiny compared to the Blue Points.