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This video shows gang filing method of hammer reshaping. Is this acceptable even if hammers are angled like in bass and tenor areas where angles range from 6 to as much as 14 degrees?
Jim Busby’s a well-known technician, and he’s got some good ebooks and videos.
I’d just say this about filing hammers: Assess the particular piano and use some common sense. All the hammers should end up in the same place, so don’t gang file them to the wrong angle if you know that will necessitate correction later on.
Of course, it’s nice to save time and file a set of hammers in two minutes. The final, well-done outcome is what matters.
Dale Erwin recommends a Foredom flexible drive, rather than a Dremel, as the Dremel is not quite so heavy-duty. But some seem to use it without any problem.
Info on the Mini Belt Sander is here: (I don't have any financial interest - I'm just posting the link for information): Erwin Mini Belt Sander
I have filed hammers with a Dremel, and just once on a piano I owned. I'm not against the idea, but I'd just caution anyone considering machine filing/shaping to experiment first until you master the technique. In other words, not on a customer's piano.
Dale Erwin recommends a Foredom flexible drive, rather than a Dremel, as the Dremel is not quite so heavy-duty. But some seem to use it without any problem.
Info on the Mini Belt Sander is here: (I don't have any financial interest - I'm just posting the link for information): Erwin Mini Belt Sander
Ohh, a flexible drive shaft, that’s a good idea.
(Also small dc motor... anyways, dremels aren’t my preference, not sure I just don’t like them) :D)
I would think a low speed would be good, more controllable, I would want the belt/sandpaper to be pretty rigid so maybe there could be a bearing to guide the sandpaper across the gap.
I would think a low speed would be good, more controllable, I would want the belt/sandpaper to be pretty rigid so maybe there could be a bearing to guide the sandpaper across the gap.
There is no bearing in the gap. However, as can be seen in the videos, the belt is tough and the gap small, and the belt does not appear to deform significantly in use.
Caution: power tools are great...but just like computers and table saws, bad things can happen very fast and unexpectedly, esp in non-experienced hands. I prefer the hand paddle method (and I do this for a living...just sayin...
I would think a low speed would be good, more controllable, I would want the belt/sandpaper to be pretty rigid so maybe there could be a bearing to guide the sandpaper across the gap.
There is no bearing in the gap. However, as can be seen in the videos, the belt is tough and the gap small, and the belt does not appear to deform significantly in use.
Upon watching the video another time, the smalldeformation in the belt could be good.
Caution: power tools are great...but just like computers and table saws, bad things can happen very fast and unexpectedly, esp in non-experienced hands. I prefer the hand paddle method (and I do this for a living...just sayin...
Peter Grey Piano Doctor
The problem with this entire topic is that people who have never filed hammers at all are so concerned the time it takes to do it, with little thought of the risks. That is a recipe for disaster!
The problem with this entire topic is that people who have never filed hammers at all are so concerned the time it takes to do it, with little thought of the risks. That is a recipe for disaster!
Indeed it could be. Persons wanting to do in a hurry a very skilled task they have never done, are always quite likely to experience disaster, I think.
I don't have, and have never used, one of Dale Erwin's Mini Belt Sanders. I have always used paddles to re-face by hand.
However, I have been thinking about school pianos here. There was a buying spree by local authorities in the early 1970s. All those school pianos are fifty years old now, and the hammers very deeply grooved. Tuners do not have the time to do hammer filing in the course of tuning visits, nor do schools have the extra finance that would be needed to pay for the extra time to do the job properly.
It struck me that the Mini Belt Sander could make things a lot quicker and easier (there is also a video of Dale Erwin using one on an upright, where removing the hammer rest rail makes it eassier to use).
I think that for a person already experienced with hammer filing to at least some degree, and who HAS given much thought to the risks, the Mini Belt Sander could be used without disaster.
I guess it's the same with tuning - someone in a hurry and not wanting to pay a tech, buys a tuning lever from Ebay, gives little thought to rust bonds at bearing points, or how to manipulate the lever, and instead just barges in there and breaks strings.......
(I am not suggesting that fifty-year-old school pianos should get hammer filing for free as part of a tuning visit, but having the Mini Belt Sander might enable a tech to be more competitive, time and price-wise).
Resist it David! I attended a demonstration of a dremel hammer shaper and it was a shocking experience. Without the feel of the felt under our hands we all took off far too much felt. It really wasn't quicker either. Just removes the possibility of using the skill you've acquired over the years. Nick
Anyone who has used a belt sander (of any kind for anything) knows how fast things can go wrong. A moment of inattention and...
If you have 100 sets to do, it makes sense, and by the 6th or 7th one you'll have the knack and can really go at it. Your first set had better be something you don't care about DAMHIK! In my younger days I thought it would be a great time saver...hmmm.
Edit: BTW, I would not consider the exhibited job in the video to be ideal. I'm a little surprised they published that.
