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  1. #31
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    Nov 2020
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    Default dent-removal-brass

    Quote Originally Posted by BaronJ View Post
    Hi Wooly,

    Can you solder a pair of small brass washers to the inside of the lever ?
    Hi Baron. Yes I could solder these washers but why would I? The gap between the lever and the posts was meant to accomodate the spring. Unless I use a spring which mounts somewhere else. Actually I prefer that solution in which case you are right about using washers. Presumably to prevent the key from wobbling? Actually soldering is a bit of a risk because the cap on the end of the lever is soft soldered and I'd have to use a wet cloth to prevent it falling off. But the washers could be done using solder although I'm finding epoxy resin is much easier.
    Looking at the download of my previous post I see the photos of the trombone before and after the dents were removed didn't get sent. I'll try again, Right this is my problem in sending trombone photos. They arrived by e mail and I can't find a way to link them to this post on the forum. They have a reference number img1688.jpg in the e mail section but how do I refer to it in the forum attachments?
    Last edited by woolyhead; 26th Nov 2020 at 01:01 AM. Reason: omission

  2. #32
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
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    Default

    Hi Wooly,

    I don't think that a pair of washers would impact the spring at all, indeed if you didn't want to solder them a dab of super glue would do the same and could be removed if needed with a little heat.

    I've just been looking at the drawing you posted. Is the key solid or folded ? Is the 2 mm you called out a gap or is it a solid piece. Good pictures would make understanding what you can see a lot easier.

    I was looking at a cornet and the spring on the little lever was quite small looking like a pair of chopsticks with a loop of wire at the end. Your drawing seems to show a much more complicated spring, probably to reduce the side twisting of a hairpin spring.

    As far as pictures in an Email simply copy them to the desktop or somewhere you can find them, then go to "Manage Attachments" below the post, click on "Add Files" then click on "Browse" which will open a window on your machine, navigate to the pictures you want to post and click on it. Then click on "Upload", Insert, then "Done".

    HTH.
    Best Regards:
    Baron J.

  3. #33
    Join Date
    Nov 2020
    Location
    Cambridge, uk
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    27

    Default dent removal in brass

    Quote Originally Posted by BaronJ View Post
    Hi Wooly,

    I don't think that a pair of washers would impact the spring at all, indeed if you didn't want to solder them a dab of super glue would do the same and could be removed if needed with a little heat.

    I've just been looking at the drawing you posted. Is the key solid or folded ? Is the 2 mm you called out a gap or is it a solid piece. Good pictures would make understanding what you can see a lot easier.

    I was looking at a cornet and the spring on the little lever was quite small looking like a pair of chopsticks with a loop of wire at the end. Your drawing seems to show a much more complicated spring, probably to reduce the side twisting of a hairpin spring.

    As far as pictures in an Email simply copy them to the desktop or somewhere you can find them, then go to "Manage Attachments" below the post, click on "Add Files" then click on "Browse" which will open a window on your machine, navigate to the pictures you want to post and click on it. Then click on "Upload", Insert, then "Done".

    HTH.
    Much obliged BaronJ. I'll give it a go soon. Meanwhile the key is solid and the 2mmis also solid. If the washers don't impact on the spring they would have to be smaller in diameter than the coils of the spring. But what would be the purpose of using these washers? With the original maker's springs there was barely enough room to get them in. I'll send the trombone pictures soon. Sorry about the quality of my hand drawn sketches but this object is difficult to draw right. I have moved the photo to documents where it is called scan0008 but I can't seem to pick it up for adding to my forum post. Still working on it.
    Last edited by woolyhead; 27th Nov 2020 at 07:30 AM. Reason: omissions

  4. #34
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    Sep 2012
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    York, North Yorkshire UK
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    Default

    Hi Wooly,

    Thanks for the extra bit of info, I originally got the impression that the key was a folded part, that was why I suggested small washers.

    I look forward to the pictures.
    Best Regards:
    Baron J.

  5. #35
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    Nov 2020
    Location
    Cambridge, uk
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    27

    Default

    Quote Originally Posted by woolyhead View Post
    Much obliged BaronJ. I'll give it a go soon. Meanwhile the key is solid and the 2mmis also solid. If the washers don't impact on the spring they would have to be smaller in diameter than the coils of the spring. But what would be the purpose of using these washers? With the original maker's springs there was barely enough room to get them in. I'll send the trombone pictures soon. Sorry about the quality of my hand drawn sketches but this object is difficult to draw right. I have moved the photo to documents where it is called scan0008 but I can't seem to pick it up for adding to my forum post. Still working on it.
    <br>
    <br>
    Attached Images Attached Images

  6. #36
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    Nov 2020
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    Default dent removal in brass

    Quote Originally Posted by woolyhead View Post
    <br>
    <br>
    The attached is my trombone after I removed some of the dents. I used 11mm steel balls for removing those dents lying in curves and an 18 inch by 3/4 inch steel rod for straightening out the big dent which was 7 inches from the bell. I put one end of the rod in the bench vice, very tight and made a wooden jig going down to the floor to hold it even more steady with the rod inserted into the bell end. I then had two hands free for gripping the trombone and pushing the dented part down onto the rod. The jig prevented the rod from moving down towards the floor. Where the brass tubing is creased it takes a lot of force to push it out. I was surprised how clean and even the outside of the trombone looked after doing this work on it. Very pleased. The quality of the photograph isn't very good but at the extreme left hand side you can just make out the two little posts each with a ball on top which are part of the water key assembly. This trombone is very old, probably about 140 years and some of its construction is quaint.
    Attached Images Attached Images
    Last edited by woolyhead; 28th Nov 2020 at 12:11 AM. Reason: omissions

  7. #37
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    Nov 2020
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    Default Removing dents from a brass trombone

    Quote Originally Posted by BaronJ View Post
    Hi Wooly,

    Can you solder a pair of small brass washers to the inside of the lever ?
    That's a good idea Baron. It would save having to fill the big hole worn in the water key while providing a support for the sleeve that goes through the key and touches the support posts. I know that everyone wanted a picture of the water key assembly but my sketches are a bit difficult to decypher at the moment. I had another idea about how to remove dents from the trombone tube 7 inches away from the bell. Point 1: the force required is outward, at right angles to the sac but's axis. Point 2: to generate this force requires the input force to be virtually along the axis of the tubing ie down the trombone's throat. What device does this? A car jack of course. But the internal width (dia) of the tube at this 7 inch point is only 30mm so it would have to be a very small car jack. I considered using a hydraulic or pneumatic ram for this but I couldn't buy anything small enough. So what about using a nut and bolt? The expansion is outward as required and the input is down the throat of the trombone using spanners on the hexagon head of the bolt and the nut. There isn't much room for turning the hexagons when inside the 30mm space but I reckon it could be possible, After all, the expansion of the nut and bolt assembly only needs to be 2 to 3 mm, the depth of the dent. Another idea that came to mind is the use of a worm thread whose axis lies parallel to the main trombone tube's axis. The worm could be made to push its mating screw outward. But the nut and bolt is simpler. I have already removed the big dent in my slush pump as I described elsewhere on this forum so I'm keeping the nut and bolt idea in my pocket for another time. In case anyone didn't know, a sac but and a slush pump are alternative names for a trombone.

  8. #38
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    Nov 2020
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    Default Dent removal from brass

    Quote Originally Posted by woolyhead View Post
    And the ones I've seen advertised are expensive. But on the net I found this idea (diagram attached). The idea is to thump the hammer head into the stop so that vibrations travel down to the magnet and make it vibrate strongly. The claim is that the ball then vibrates and thereby hammers the dent out. But the magnet has to be very powerful to make it work. But at least the ball doesn't have to be the exact size. Anyway I can't try this idea out because I haven't got access to a powerful magnet.
    For dents closer to the trombone's bell the idea is not to hammer on the dent but to press the brass back into place. I did this with what amounts to being an anvil and a press but the anvil took a bit of making and I've hit on a simpler method. Lay a nut and bolt from side to side with the bolt head resting on the dent and the nut resting on a load spreader right opposite. Then unscrew the nut (or the bolt) and as the nut and bolt assembly expands it presses the dents out. What do we think of that idea?

  9. #39
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    Sep 2012
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    York, North Yorkshire UK
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    Default

    Hi Woolyhead,

    You would have more control with a scissor type device that expanded as you squeezed the handles !
    Best Regards:
    Baron J.

  10. #40
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    Oct 2015
    Location
    melbourne
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    474

    Default

    This popped up following a link from my wife..

    (the whole series is interesting)

  11. #41
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    Location
    Cambridge, uk
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    Default

    Quote Originally Posted by BaronJ View Post
    Hi Woolyhead,

    You would have more control with a scissor type device that expanded as you squeezed the handles !
    Yes I understand what you say Baron J. It takes quite a lot of pressure on a dent to push it back where the brass belongs. One of my ideas was to place a nut and bolt at right angles across the trombone tube and unscrew it. But unscrewing needs a spanner, or so I thought, and a spanner could foul on the side of the tube, as I discovered. So I thought of using a nut with a disc attached, the disc to have a string of holes right round near its edge and two thin rods which remain central, along the axis of the tube and which hook into the holes in the disc. Then one rod is pushed while the other, which is diametrically opposite, is pulled, thus rotating the disc and unscrewing the nut. When the maximum rotation is achieved the rods are unhooked and moved round to the next suitable pair of holes and further rotation becomes possible. In my trombone the tube diameter was30 mm so the disc could be 28mm to allow clearance. With a 13mm nut the dia of the ring of holes could be on a 19mm pc dia allowing 2.5mm thickness for the rods and adequate space between push-rod hole and edge of the disc. In that case the mechanical advantage of the push-rod over the end of the bolt is 3.14x19 / 1.25 = 60 /1.25 = 48. 1.25 is the thread pitch on an M8 thread. I may have made small errors in this calculation but it's approx correct. I could increase the mechanical advantage by a factor of at least 10 if necessary. I could draw this and sent it as an attachment if I could remember how.

  12. #42
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    Hello Woolyhead,

    Actually if you watch the video, the old guy has the perfect tool to remove dents even in very small diameter tubes. A hundreds of years old idea and so obvious its brilliant ! One that I will certainly be noting for future use.
    Best Regards:
    Baron J.

  13. #43
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    Default Dent removal from brass

    Quote Originally Posted by BaronJ View Post
    Hello Woolyhead,

    Actually if you watch the video, the old guy has the perfect tool to remove dents even in very small diameter tubes. A hundreds of years old idea and so obvious its brilliant ! One that I will certainly be noting for future use.
    He seems to support the dent inside the sax tube using a rod whose other end is held in a vice. My question is that if he hammers down on to the outside of the tube ie in the same direction as the dent goes, how does that push the dent out, ie in the opposite direction?

  14. #44
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    Quote Originally Posted by woolyhead View Post
    He seems to support the dent inside the sax tube using a rod whose other end is held in a vice. My question is that if he hammers down on to the outside of the tube ie in the same direction as the dent goes, how does that push the dent out, ie in the opposite direction?
    Hi Woolyhead,

    If you watch closely he doesn't hammer the dent from the outside at all !

    He taps the steel rod that has the curved end placed inside the tube, so that the rod vibrates and gently pushes out the dent. Basically a miniature hammer inside a very narrow tube.

    Absolutely brilliant !

    The skill would be knowing how hard to vibrate the rod and exactly where where to place the curved end.
    Best Regards:
    Baron J.

  15. #45
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    Default

    Quote Originally Posted by BaronJ View Post
    Hello Woolyhead,

    Actually if you watch the video, the old guy has the perfect tool to remove dents even in very small diameter tubes. A hundreds of years old idea and so obvious its brilliant ! One that I will certainly be noting for future use.
    Oh yes. I agree, this is brilliant. Thanks for pointing it out BaronJ. It's certainly worth remembering for the future.

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