type of glue for bridle staps

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atocp
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type of glue for bridle staps

Post by atocp » 24 May 2012, 23:06

Hi all,

I have taken apart my upright piano, and cleaned it out. Instead of replacing the felts as I have been advised not to do myself, I am replacing the bridle straps and putting it back together. I bought Copydex glue when I got felts, but as Im not using them I am wondering if Copydex is ok to secure the clip on bridle straps, or should I pop on a small amount of hot glue? Its brass securing to wood, which Copydex will do, but others have suggested hot glue as its easier to chip off in the future.

Any advice would be greatly appreciated, as Im halfway through putting new straps on and want to make sure they wont move. A lot of people say the clips should be strong enough, but there's no harm in popping on a dod of sticky stuff.

Many thanks,
atcop

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Re: type of glue for bridle staps

Post by Barrie Heaton » 25 May 2012, 08:00

First off don't use clip-on tapes they are rubbish. In the workshop we tend to use animal glue for tapes and felt. However, contact adhesive or PVA is very good for tapes.

If you use PVA you need to clamp them or embed them into the balancer hammer

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Re: type of glue for bridle staps

Post by Colin Nicholson » 25 May 2012, 20:16

The clip-on tapes are really just for emergency use, so if I tune a piano and it has a broken tape, I just clip one of those on. The brass clip can also be squeezed slightly, but they don't need to be glued - just clip it onto the balance shank (the very small piece of wood dowel sticking out towards you).

The proper way (as Barrie says) is to use either hot glue, or PVA - and its best to make a small slit into the back of the butt (bit with leather on) with a junior hacksaw.
Then when gluing, just push the end of the tape into the slit with a BLUNT knife.

However, the trick is also to make sure you cut every tape to the same length - and measured from the hole on the red tip to the end - not measured from the end of the red tip.... as the holes sometimes vary in their location.

Hope that helps....

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Re: type of glue for bridle staps

Post by vernon » 25 May 2012, 23:10

clip-on tapes are always too long. It's essential al tapes are the same lenght ergo the previous excellent advices pertin.
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Re: type of glue for bridle staps

Post by atocp » 30 May 2012, 12:21

thank you for the advice and help on this.
i have clipped on a few clip on ones, just to see the overall length, as was discussed, and they are all about 1.5cm too long. didn't notice that when the action was outside the piano.

couple of follow up questions though, in order to put in new straps that are not clip on, should i disassemble the action further in order to get to the back of the catcher, or do people work around the cramped spaces to minimise the amount of disassembly?
im obviously not working in a workshop, and not working with jigs or anything, is completely taking it apart an immensely huge task, or just complicated and laborious?

many thanks again for the help and advice with this,

atocp

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Re: type of glue for bridle staps

Post by Colin Nicholson » 30 May 2012, 13:16

The info here is only for general reading really, we can't enter into detailed technical descriptions & measurements to protect the trade.

You can shorten the clip-on tapes by wrapping the hessian once around the clip - depending on the orientation of the tape front (red bit) - the tapes may have to be clipped on underneath the balance dowel.... then simply slide it to get the right length.
To glue on proper tapes, yes, you'll need to take off all the hammers. I have special action trays 4ft in length to stack them 5 high (17 times). You can then successfully cut off the old tapes, and clean the area. However, it depends on the design - some are glued to the balance, others are glued to the butt (passing through a hole in the butt).... and the flanges may vary in location - either behind the jacks, or at the rear of the action (same place as the levers)....

Before removing the old tapes, set up a small jig and sit a hammer down facing up, then measure the distance to the tape end hole. Then when you glue the new ones on, they should be the right length.

Problem is of course, I reckon its not the tapes that caused the 'non working' notes? - they are only there to support the levers when removing the action (to stop the jacks collapsing) .... and assist in returning the hammer/ left soft pedal..... if they break, the action will still work - unless you have removed the action, then the jacks will jam underneath the cushion felt lip?

If you have any problems, just pop all the hammers in a box (numbered in order).... leave the old tapes on, and send them to me - and I'll do a proper job - not that expensive - and will take me about 2 hours to do. Get a price for p&p first, and let me know. I can also reface the hammers for you at the same time.

(Johnkie's just taken the words out of my mouth!) .... I tried to post this, and we were both posting at the same time!! .... hope you are well Johnkie!

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Last edited by Colin Nicholson on 30 May 2012, 13:23, edited 1 time in total.
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Re: type of glue for bridle staps

Post by Johnkie » 30 May 2012, 13:19

Clip-on tapes are not very good, but ok as has already been said "in an emergency". They are nearly always too long, but you can get around this by wrapping the tape one complete turn around the brass clip before cipping it on to the balance hammer. It's very fiddly to get it butted up to the back of the balance hammer, however the length is then acceptable, and can be finely adjusted by bending the bridle wire slightly.
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Re: type of glue for bridle staps

Post by atocp » 31 May 2012, 16:13

thank you Colin and Johnkie for the advice on the next step, and thank you colin for the detailed help.
I understand that the forum is for general reading, and would never want anyone to divulge info that could harm their profession.

I decided to take the plunge, and thinking that the hammers were screwed into place on a wooden rail using pressure from the screw (which would allow big differences in movement when reattaching), I was pleasantly surprised to find a screw hole behind each hammer, so they can only go back in the right place.

I have 'normal' straps coming in the post, hopefully by monday, so will be able to get back to it and finally get it properly fixed. I will remove each hammer, use a sharp scalpel knife to make an incision instead of a hacksaw, and push the strap in as mentioned, using hot glue to hold. Back out now to buy glue sticks.

I believe that it was most likely the cushion felt lip, as you mentioned Colin, where the jacks jammed, holding up the hammer. However, as all the keys affected also had broken bridle straps in common, I believe this was the root cause where the distance between the hammer and butt was too great because there wasn't a strap and allowed the slip under the felt.


Thank you all once again for the help. Someday I might actually get this thing back up and running. Although, im definitely gonna get it looked over and tuned once I'm done, because as careful as I am, I really don't trust my own work sometimes.


Many thanks,
atocp

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Re: type of glue for bridle staps

Post by Colin Nicholson » 31 May 2012, 18:09

atocp wrote: I will remove each hammer, use a sharp scalpel knife to make an incision instead of a hacksaw, and push the strap in as mentioned, using hot glue to hold.
????? !
You will probably find that using a scalpel on hornbeam hard wood will just scratch the surface, and the thin blade will not make a wide enough slit in the wood for the tape to push into.... the thickness and course blade of a junior hacksaw is perfect for the job (and much quicker).... but it's your call..... and I reckon the surgeon's blade will just break! .... I use scalpel blades for things like cutting the tapes to the right length, and for cutting certain thin cloths & felt for pianos - and a retractable blade for things like leather.

Best though you learn the tricks your own way first, then if needed - upgrade your tools and cutting equipment.
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Re: type of glue for bridle staps

Post by Jonathan the 2nd » 18 Jun 2016, 23:18

A follow up question for Johnkie. "The length can be finely adjusted by bending the bridle wire slightly". Can I delve into the exact aim of finely adjusting ? Is it just to get it in line with all the others or is there a fine exact point where all the weight of the "gubbins" hanging on the ttape begins to suddenly reverse the direction of the hammer after it has struck the string?
The hammer will rebound naturally and there is also a spring involved somewhere but will the springy wire attached to the tape be tensioned at all before the hammer strikes or is it not involved at all until after the note is played ? One site mentions the redundant aspect of the tapes apart from keepng it all together when the action is extracted . Are the tapes really that redundant? They are a clue to the big difference between Grands and Uprights when trilling. Grands don`t have them at all .
The two aspects of tapes seem to involve all the bits dropping down when taking out the action and dropping down to speed up the hammer when trilling . Why have not cost conscious makers scrapped all that fiddling about with tapes and springy adjusters and just simplified the whole lot of it ?

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Re: type of glue for bridle staps

Post by Colin Nicholson » 20 Jun 2016, 16:32

The bridle tapes do various jobs, one in particular is when the left (half blow) pedal is used.
When the left 'soft' pedal is pressed, the crank lever moves the front hinged section of the hammer rest rail forward (or if a Otto Higel action, the whole rail moves on pivoted levers).. this in turn "tows" the hammers by the tapes dragging the hammers away from the jacks to create (what we normally don't want) lost motion. Have a look and see what happens. If no tapes, then effectively no soft touch by use of the left pedal.

Early actions didn't have hammer butt springs & loops, and purely relied on inertia and a small tug of the tape to bring the hammer back. The springs are more effective for repeating the same note quickly, but to be honest, playing rapid scales don't need the springs. I also suspect that if a hammer flange needs re-pinning at some stage, the return journey sometimes helps by the bridle tape.

The bridle wire is not a spring.... this is adjusted by bending it forward or backwards to get a little slack in the tape.... then the key capstan makes the final adjustment.

I tuned an old Hopkinson once with no tapes / not spring & loop either, but had an unusual catcher on the jack toe to prevent the undercarriages from collapsing.... a bit weird, and sometimes the catchers didn't work.
All exciting stuff!
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Re: type of glue for bridle staps

Post by Jonathan the 2nd » 20 Jun 2016, 23:24

I was wondering whether a piano could work without either spring or tapes as a mechanical oddity. I had a peek behind the butts last night and saw for the first time where the butt springs lived. A spring in that position needs to be under pressure before it can do anything so that would be felt as part of the key pressure (?). It shows what an ingenious idea the tapes are .They don`t create any extra work before the hammer reaches the string. The Grands , just using ever present gravity ,must win the race against the Uprights because the tape needs to straighten out for a split second before it tugs the hammer back . But how close to the string can the hammer be before the tape operates. is it a balance point just following let off ? I became more interested in this last week when I applied some fresh grapite to the jacks. The slow down pressure of the key was giving a sort of resistant chewy bite feeling. After the graphite powder the bite almost disappeared . It`s all a fascinating combination . The other part of this was the way the jacks behave when trilling. The key does not (This is me realising something and not explaining to anyone else ) need to be pressed more than half way down in a trill . So that comes under "Touch". Is that right? If I press the key all the way down the jacks get upset and don`t want to play any more . At present the little brass capstans need some adjustment as the hammers settle in different positions if I hold down the keys in a row . Those were the notes I have been playing the most . It`s good to learn how it all combines without doing any damage. That`s the famous phrase ,"You can observe a lot by just looking ".

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Re: type of glue for bridle staps

Post by Jonathan the 2nd » 08 Jul 2016, 22:03

Sometimes ideas percolate through the old subconscious and drop an answer on the table without any warning. The bridle tape subject must have been in the system this week . So here is what popped out.
There are 3 states for bridle tapes to be in .One extreme state is ; Fully fitted but too loose to have much effect apart from holding the works together if the action is removed.
The other extreme state would be too tight so that there was little or no slack as the hammer hits the strings.That might even interfere with hammer action. If the tapes were almost exactly straight at let off then the action of gravity would start to influence repetition speed ,but it would still not be ideal . The best state is where the tapes are just slack enough so that as the whippen drops it makes the tape Jerk back. The Jerk is where the tapes are valuable. Think about walking through a doorway and the door handle gets caught in a pocket or sleeve. It`s not a steady pull. It`s a bit violent and sudden and more effective than a steady pull .
So that`s my idea about the value of bridle tapes . An elegant and underestimated invention .

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Re: type of glue for bridle staps

Post by vernon » 09 Jul 2016, 23:04

The adjustment of tapes is one of the many actions done by the skilled regulator as a mater of course and is no cause of discussion
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