glue

[Ron Nossaman]

>Actually I don't see any reason why you could not successfully do the job 
>exactly as you describe, with thin hide glue and proper sizing. 

*Possibly so, but at the cost in time and R&D to develop a less forgiving
process to accomplish a similar end, I see no need to make the change. There
are more interesting trails to blaze.


>In general I do think that the advent of multiple laminations (i.e.
>plywood) was the stimulus that pushed the invention of modern glues that
>are better able to meet the needs of such a manufacturing process (You can
>see the turn-of-the-century factories were struggling). However
>laminations and hide glue are not incompatible, even large size plywood
>sheets which I have seen used on 19th Century pianos, as early as 1807.

*So why shouldn't I avail myself of the products of this evolutionary
process? If hide glue is the end-all now, it was then too and there was no
reason to have discontinued it's use in the first place. The industry
didn't, overnight, forget how to properly use hide glue to best effect when
the newer glues came along. They abandoned it wholesale (literally) as being
less desirable (by whatever criteria they chose to make the assessment) than
the newer glues.


>Why so many laminations though? Maybe there is room to reduce the
>number...ten is great for making bridges in a factory setting using urea
>formaldehyde glue cured with ultrasound and careful handling of toxic
>fumes. But transferred to a small shop making a single bridge alone, would
>it not be feasible to use fewer laminations i.e. adapt the process to meet
>the needs. 

*Adapting the process to fit my needs, and abilities, is something I do
continually. I assume that we all do. The materials I work with are not so
accommodating. If it weren't for maple's unreasonable insistence on being
hard and stiff, I could bend it much easier. It also would be useless for
bridges. The minimum bending radius of any stack of maple strips, and the
spring-back upon removal from the cauls, is determined, to a large degree,
by the thickness of the laminations. The tightest curves in a bridge usually
occur at the scale breaks, where the bridge dog-legs under the plate strut
to maintain the speaking length progression across the break. If the
required curve radius at that point was twenty meters, I'd use three
laminations and take the afternoon off. If, however, that radius needs to be
more like 60mm, I'm either going to need more laminations, or a different
construction method. The choice of the 60mm bend radius here is purely
arbitrary, and was purely to illustrate a point. There is no intended, or
implied, assertion that this parameter is manifested, either intentionally,
or accidentally, in any bridge, existing, or planned, in any piano, or
piano-like object, anywhere on the planet. My choice of the number 10 in the
previous post was also purely arbitrary and therefor not acceptable as a
hook from which to hang an argument. (how 'bout that %-) ) However, just to
cover myself, I went out in the shop just now and counted 10, that's 'ten',
laminations in the tenor bridge of the Mason & Hamlin 'A' In fitful
progress. I neither know, nor care, what kind of glue was used to accomplish
this.     


>Also as I described in my original response re:  Graf's
>bridges, why not do it the same way i.e.  take a single piece and slice
>longitudinally but not all the way to the end of the piece. The uncut
>portion keeps everything lined up. You can easily get hide glue into the
>laminations if you use proper thin glue and size everything first. In fact
>I could imagine even doing this with ten slices. But if you don't mind
>titebond glues.... 
>
>Stephen

*Interesting idea, but I don't have enough trouble keeping the strips
aligned to need to do it. In fact, it sounds  to me like a way to spend more
time than is necessary for the result. No, I don't *mind* Titebond glue, nor
do I worship it as the ONE TRUE GLUE. I use hot hide glue regularly, where I
feel it is appropriate. Laminating bridges with it, at least in my shop,
isn't practical for me. This isn't a Holy mission, it's a shop process, and
I don't consider the use of Titebond over hide glue in any given application
to be 'slumming'.

So how about those Historical temperaments?

 Ron