[Dog Pants]

I've had an Artley Open Hole Flute come in which needs a full re-pad etc. It has a slight banana bend (no crease) that seems to have its apex at approx the G keys. The bend is towards the long stack and trill rods. Placing a straight edge opposite the bend, the deviation from straight and true is about 1/16th of an inch. Enough to be noticeable to me at first glance, but the player either didn't notice it or neglected to mention it.
I'm embarrassed to say that of the many school flutes I've done, I've never had to deal with this yet.

Dents in head joints, dents in tenons, dents in the body, etc.I've handled those but not yet this banana bend.

I had a good hunt around and came across very little excepting a discussion on a usegroup that stated something to the effect of inseting a mandrel and whacking the end on a bench block. Similar to straightening a sax body I suppose.

Thorpe suggests inserting a mandrel and applying pressure by hand with the keys in situ.

I'm wondering which methods you guys use?

Is there much danger of the posts becoming unstuck if I bend it back with the keys in place? etc.

 

[hornfixer]

I'm wondering which methods you guys use?

I use the Thorpe Method, or maybe he uses my method.

 

[Dog Pants]

I use the Thorpe Method.

Haha. I did a quick youtube search of your videos hoping to find one on this. Make more videos!!!

Is there any danger of the end of the body mandrel putting a crease or dent in the flute body when straightening this way? I have the Allied mandrel which although it isn't sharp on the end, it isn't rounded much.

 

[Stephen Howard]

I always tend to remove the keys before straightening the body, using the mandrel method.
Couple of reasons - I don't want to run the risk of crushing/bending any keys, thus adding to the job, and I don't want the additional stiffness that the body will have with its keys in situ.

I would say that there's a slight risk of pillars detatching if the keys are left in place, as they will act like levers. The most common outcome is that the strap under the right hand stack lower pillar will come away.

There's always going to be a risk of putting a dent or a crease in the tube, but you can lessen this considerably by using a sliding motion as you apply the pressure (your mandrel must be spotless though).
A crease tends to occur when you bend the body past its elastic limit (which is another good reason to remove the keys, as it gives you a better feel for when the body gives).

Regards,

 

[tictactux]

Does the customer *want* the flute unbent?

(Cousin-in-law has a flute with a similar bend and says it doesn't bother her at all, or not enough to justify even 10$ to unbend it. Truth be told, the bend is not strong enough to compromise the keywork in any way)

 

[Dog Pants]

Thanks guys. I don't know why I'm nervous about this. I've had success with crushed trumpets and saxophones but I guess I'm having trouble visualising the process in a way that will get the tube perfectly straight without distorting tone holes or marking the inside of the body. I think it seems harder because it's a bend with no obvious focal point to zone in on. If that makes any sense at all.

 

[Dog Pants]

Does the customer *want* the flute unbent?

(Cousin-in-law has a flute with a similar bend and says it doesn't bother her at all, or not enough to justify even 10$ to unbend it. Truth be told, the bend is not strong enough to compromise the keywork in any way)

I have no idea. The flute is an "add on" to the school fleet. Meaning all the school fleet comes in and you also get a few privately owned instruments with them. I want to fix it simply because

a) It seems like a job half done if I don't.

and

b) It's a job I need to learn.

 

[clarnibass]

I've never had a lot of success using the "whack" method. But any method without the entire length of the flute supported by a mandrel is risky. So IMO just be very careful with any force you use. I've used the Thorpe method with some success. One other thing you can do is to insert two mandrels into the flute and have them (almost) meet at the "middle" of the bend. Gently and very carefully use them as lever in the opposite direction of the bend. Gradually move the mandrels farther away from the "middle" of the bend and again use them as levers, etc. How much force to use, where to put the mandrels when using that force (you might not want to start with them close to each other), changing the amount of force depending on where the mandrels are, etc. are all things you just need to feel when doing this, which I imagine you will if you try. Sometimes I prefer to hold one of the mandrels in a vise, sometimes I don't.

 

[griff136]

I use the method descirbed in Reg Thorpe's book - just go easy and take care not to bend it too far in the opposite direction.

 

[simso]

I dont drop by very much any more, but Im more than happy to help out drew, Im only going to make a singular response and leave it at that, so the repercussions of those that are better than I will go un-answered.

When you straighten a flute first leave all the keys on, it just makes it a bit easier IMO.

Extra Tooling needed

Two steel mandrels, I have 9 and Ill explain later why I have 9
Rawhide hammer
Straight Burnisher
Roller

Repair Process.

Clamp mandrel one in a vise
Insert flute onto mandrel and push it all the way home,
Hammer out and major creases with rawhide hammer
Remove flute from mandrel and re-insert it until it binds slightly
Look down inside the instrument to see which part of the flute is touching the mandrel.
Rotate touching section to the bottom, this way your always working the dents/bend down (the bannana shape should go upwards)
Insert second mandrel down inside the flute and use the second mandrel as a leverage bar.
Lever and work binding areas and move the mandrels meeting points as required until the flute slides easily on the main clamped mandrel
Remove all the keywork
Work on the dents and creases that remain
Rawhide hammer and just flatten any more bent areas (with the mandrel still inside)
Follow up with straight burnisher and rollers and burnish the areas smooth, vary your pressure to change the finish
Tweak any binding areas of the flute with the two mandrels
Leave the instrument body to sit overnight, check next day to see if the mandrel slides all the way back in,
- if it does then re-assemble and finish the normal repair
- If it doesnt redo the process and let it sit another day to accomodate for metal memory.

Back to my original statement, I have 9 mandrels. The two main ones I use as above, all other mandrels are 5 thou wider and increase in size, I use these to take bent flutes to a finer tolerance, after doing the first round I use the next size mandrel and do the same and then the next and so forth

Dents are best taken out with a smooth rawhide hammer, then follow up with a straight burnisher, then a curved roller

Dont forget to re-level tone holes if they have become somewhat damaged and or warped

If you need more info mate, you have my personnel email, so just email me, Im not here on the board very often, so you could be waiting a month or two for a reply. Ill do a photo tutorial up for you if needed, Im sure there are bent flutes amongst my christmas repairs.

 

[Gordon (NZ)]

I do it much the same as Simso.
Main difference is instead of a rawhide hammer, I use a small steel hammer, over a strip of 3 or 4 mm acrylic. I find it gives more dent-removal effect, with still no risk of bruising the metal.

 

[griff136]

I also use a heavy nylon hammer for dents - in conjunction with a mandrel

 

[gwysham]

The biggest risk I see is the focal placement being around the G keys; that implies that you're around the G# tonehole also, which means there is very little metal holding the flute together at that point. I would generally use the single mandrel/hand bending method with no keys on (since that seems to be when I notice the bend anyway!) being especially careful around the G/G# area.

 

[hornfixer]

I dont drop by very much any more

Welcome back simso, it's not been the same without your input. Hope you are doing well.
Merry Christmas and Happy New year.

 

[KEN K]

I use two mandrels one in each end ,almost meeting . I look down the body an see which way the bend is them I drop the flute down and let one rod hit on a table to force it back the other direction. I always leave the keys on.

 

[wilsaxo]

I've got a wonderful tool from David Straubinger which is delrin mandrel that fits tightly into the bore of a flute. You can gently bend the instrument back into the proper shape quite easily with it.

Cheers,
David

 

[Gordon (NZ)]

For straightening a banana-shaped flute, there are bending methods and impact methods.

IMO, any gentle bending procedure (i.e. using two mandrels), is far more controlled, hence better, than any impact based procedure
Impact involves a very large force over a very short time. Whether it takes 0.1 seconds or 15 seconds is rathter immaterial, so why impose the very large force on the body, when a small, controlled force can do the job?