Wire bending tips/howto

[Robin Kearney]

Hiya,

I wonder if anybody has any tips they could pass on about bendingnup a wire undercarriage. I have a sturdy vice and the mini KS wire bender, the model I'm just starting is the Ben Buckle Diamond Demon which has a undercarriage that bends outwards again after the two legs meet at the fuselage. If that makes any sense. Anyway, it's the bending up an accurate uc that s putting me off, previous attempts at anything beyond a z bend have not gone well!

R.

[fly boy3]

Hi Robin, you will need a hammer as well. What is the Dia. or SWG of the u/c wire ? I normally make a trial one from copper wire from the plan, then transfer it to the piano wire. Cheers ps it not as difficult as you think.

[Biggles' Elder Brother - Moderator]

I use one of these. Excellent bit of kit makes getting a precision undercart possible everytime with minimum effort.

BEB

[Alan Cantwell]

same as BEB for me, but i havnt done one for a looooong while, failing that, some wooden blocks, to but behind the wire when you bend it, stops it flying all over the place, and some wooden templates to bend to, DONT heat the wire up

[Andrew767]

I too have one like BEB. Mines an MFA from Model Shop Leeds. Very easy to use, even with 8swg wire and doesn't score the inside of a bend like a vice does.

Andrew

[Ernie]

Hi Robin, You do need a good wire bending tool. The one shiown looks great, think i'll invest in one......If you heat the wire, it will bend more easily, but you will loose the temper and it will bend more easily in use. Bet someone knows how to put the temper back in.

ernie

[Peter Miller]

Try putting the temper back in and you make it brittle. I would say almost impossible to get it back to its original condition.

But with that wire bender (I have one) you can do almost anything. It just takes practice.

[Robin Kearney]

Thanks for the tips guys, heating it was one thing I considered, I'm glad I didnt now!

The wire is 12swg, which is about the limit for the mini K&S bender (very similar to that shown above). I've only ever tried to bend wire 'in the air' so to speak with two pairs of pliers before. Now I've tried this wire bender in a sensible sized vice I'll not be going back to that insanity again!

Its taken me an hour or so and a couple of minor corrections along the way, but I think I've got a good enough UC for the DD, the top horizontal bit isnt exactly level, but the two legs match and the axles are level when held upright so I'm happy with that!

The UC was the only bit of the build I was worried about, so now I can crack on

Thanks again for the advice!

Bit late to get the dremel out to cut it off, that can wait until tomorrow

r.

[Myron Beaumont]

You can heat the wire up to a bright red heat ,bend it with precision tools like a hammer and vice ,then plunge into cold water .Afterwards,clean up the surface with wet and dry ,reheat gently 'til it goes from a strawcolour to blue .Keep there as long as possible ,then plunge into oil (blacksmith type job).Job done .Of course with"proper" drawn piano wire it will not be as good as original but I doubt you have that anyway these days .If you do have proper piano wire ,then just grip and bash it about as recommended but be careful not to bend more than the angle required.It does NOT like being bent back and will eventually shear .

[Erfolg]

Believe Alan, and Peter. Do not heat treat, it will never be the same, whatever you do.

I could bore you with why.

Just one other pessimistic note, after bending it will never be the same again, it will have further work hardened. Just the same I would leave it in this condition.

I made a wire bender from an Oak plank, steel pin and a steel bar with steel follower. Although my own worked, it was rubbish. Best to buy a heavy duty tool, with a good roller follower. I have seen commercially made springs, similar to nose legs, using essentially a lathe with a bar in the chuck. Wonderful job, but I do not have a lathe and I guess you do not either.

[Joseph Smith]

Hi all,

I'd like some wire forming done professionally (don't trust my skills ) and wondered if anybody could recommend a company, I think I may use Gordon Products as they are fairly local, I don't suppose anyone has used them before?

Regards.

[Biggles' Elder Brother - Moderator]

Welcome to the forum Joseph. Sorry I have no experience of that company. However I really would urge you to buy half a dozen lengths of mild steel rod to practice on and one of the devices I link to above. You'd be amazed that with a bit of practice you really will be able do this! Once you have the knack you can do it for real on a bit of piano wire. Its not difficult - it just takes a bit of thought and practice - that's all.

Come on - you know you want to do it yourself really and learning a new skill is all part of the fun. Not to mention that, even in the medium term, this will save you a lot of time, effort and money!

BEB

[kc]

It's fairly easy to do with the proper tool. However the bender seems quite expensive, so I would suggest asking around at your club for someone who has tthe tool and will bend an U/C for you.

It's amazing that some aeromodeller doesn't bend U/C as a part time business!

[Nigel Day]

I'll third/fourth/fifth BEB's tool recommendation. I bought one recently for some 8swg wire and it was a doddle.

Mind you, I think you'd still need a good vice and a good hammer to get sharp 90 degree bends.

[Erfolg]

Joseph

I can see that Gordon Products have all the appearance of a professional out fit.

I am sure that they are more than capable of bending anything that an aeromodeller could pass in their direction, that is at a price. If you wanted a thousand springs, then the cost would be possibly reasonable, a million, and now you are talking.

I have mixed feelings about bending spring steel, with the appropriate equipment, dead easy. Without it, it can be done, although coil springs of any sizable gauge becomes a challenge.

So in my case, i bend simple shapes using a vice and the occasional use of a hammer for getting that well formed bend, to stop the wire taking on a slight bend/radius when used as a lever, I would slip on a small bore heavy walled piece of pipe and lever on that. To stand a chance of bending accurately (as needed), I would draw out the shape, against which i could compare the work,. In my case i would probably do more thinking than bending, estimating, or should that be gauging, where to start the bend, taking into account the material lost in the radius.

I personally do not like really sharp bends, as the stress at these points, can have a detrimental effect on the integrity.

For an undercarriage with a coil spring, I would look to buy what i want, it is easier and often cheaper than struggling to produce an acceptable item.

[Don Fry]

Get a piece of inch thick plywood or mdf board, and some quarter inch steel rod, the rod must be the same diameter so your wire bender slides onto it to form its fulcrum. Draw/stick a copy of the undercarriage onto the wood, and drill tight quarter inch holes in board at the bend points. Hammer a 2 inch piece of the quarter rod into board, and line up undercarriage wire to the bend point, holding it in place with a couple of screws with washers. Put your wire bender on the quarter rod and bend away. Then hammer a second piece of rod at the second bend point, and repeat process. If the undercarriage is not a flat unit, modify the board so it is hinged, bend the wire as above, then hinge the board in a vice so form the second bend direction. It also helps to attach the board to the workbench, so you can use two hands when you bend the wire, and all your weight.

[Koen Smits]

Hi All, in he past i already posted a drawing from a wire bender to make your own.

http://www.modelflying.co.uk/forums/postings.asp?th=82878

In this post are also some links with short video's how to use the tool.

The tool can be used up to 4 mm ( 5/32" ) piano wire.

 

Edited By Koen Smits on 06/01/2015 09:33:35

[Pete B]

Hi Koen,

Just had a look at the PDF and videos - a nice simple tool anyone with a workshop or an engineering mate could make up! Pity I've got one already.....

Well worth repeating the videos here for everyone's benefit, I think:

Pete

[kc]

Does the video actually show bending piano wire?   Just using a machine vice clamped with one clamp to light bit of board does not look as though it would be secure enough to me!  Maybe it's just  for the video.  Anyone planning to bend 10 SWG or 8 SWG piano wire should plan on using a more secure vice, preferably an engineers vice or mount the bender on a block of wood and fix into a woodworkers vice built into a sturdy bench.

That looks a fairly simple design to make Using bolts as designed would require reducing the thread part to 8mm and also need an M10 tap - no problem for model engineers but not so easy for most aeromodellers. I wonder if instead of using bolts just using 8mm rod into a tight fitting hole with some Loctite would be easier yet still work OK. What do others think? It might still be better to use bolts as a source of material as the steel is usually better than mild steel rod, so just using the plain shank of a long bolt of 8mm dia would be my choice.

 

Edited By kc on 07/01/2015 12:33:07

[Koen Smits]

Hi KC,

The vise is actual clamped on the table with 2 clamps. The smallest radius you can bend piano wire without the possibility to get cracks in the wire is equal on the diameter. The thickest wire you can bend with this tool is 4 mm. In video #4 i bend pianowire from 4 mm.

The reason i used M10 bolts is, if you look at the video you see at the other end from the in the vice clamped part also 2 treaded holes. these hole are positioned on the centerline. At the end where i bend the wire in the video the treaded hole are positioned on approx. 45 degr. this is done so you are able to bend right hand- and if you turn the in vice clamped part upside down you are able left-hand springs.

(p.s. I don't own an engineers vice.)

Koen

[WolstonFlyer]

Kc, of course the video shows bending wire, it doesn't take much force to bend thin wire with a tool like that. It looks like a nice design for a home made tool if you have the tools to make one.

In my experience that design of vice is normally called a 'drill press vice' used to hold work while performing drilling operations.

[Erfolg]

As a modeller I see 10 swg to be about the maximum practical diameter to bend, perhaps 8 swg if you are into the bigger models than I would ever envisage.

Wolsten does raise an important aspect of bending wire, heavy gauges = difficult to hard to bend, smaller dia guages are quite easy.

Koen also raise another important aspect, the minimum radius to bend, to 90 degrees is considered to be *1 diameter, i take this to be *1.5 as heavily drawn/processed wire, may still have surface cracking at less a radius.

In my youth I did see wire bending on an industrial scale, which I did watch with some interest (the spring shop, was next to the Gear Cutting shop where I was actually supposed to be working). Later pipe bending machines were seen on a daily basis whilst working in on Chemical Plant construction.

Where these machines differ from the methods used by most modellers, is in some of the detail and additional features. The most obvious is that the wire or pipe is clamped, very firmly, to stop any movement of one end during bending, this improves dramatically the accuracy of the bending process. The second detail is that the follower, on the arm doing the bending has a roller. The purpose of the roller is to impart a force which has no sliding component, where a fixed pin is subject to often heavy sliding forces.

Bigger commercial bending machines have shoes to form a precise inner radiuses to the bend,

In the case of the industrial spring shop, there the springs were mainly bent on machines based on lathes, where the lead screw feed would determine the spring pitch. On smaller sizes, they were just hand wound on a cranked rotating bar, held in two supports, to permit rotation, whilst also taking the forces involved.

I do like the idea for UC type bending to use a heavy ply base with drilled holes holding heavy pins. It does require a little work, although I would guess providing consistent accurate items. For a number of, must be the way to go, for the hobbyist.

The other comment on using Thread Locking Fluids, I would have baulked at this in my youth, the emphasis being on accurate reamed holes, to fit drill rod or Fitted Bolts, or using liquid nitrogen to shrink dowels to insert quickly into a reamed hole. However, I have seen these fluids used increasingly in commercial as well as more casual users, very effectively. Today i would say why not, particularly as much of the techniques once used depended on items that are not easily obtained in the UK as it has become an industrial minnow from what it was.

[kc]

Koen has confirmed it handles 4mm piano wire. 4mm is virtually the same as 8 SWG - actually 4.064mm - (Standard Wire Gauge = English ) So it should suit most u/c designs. Beware if building from American plans as in the USA 8 gage means AWG which is 3.2636 mm, so they would often specify 6 gage AWG which is 4.1154mm.

Erfolg's points are interesting and actually the MFA design of wire bender uses a roller. Its just about the same except the roller replaces a pin.

Machine Vice is the correct English name for that vice although Drill Press Vice is now often used as our language becomes more & more 'americanised' - no doubt they will also be calling them Vises here soon! Whatever you like to call them the very heavy cast iron type are very handy in aeromodelling as they can be used anywhere in the middle of a table for odd clamping jobs or supporting things. But I wouldn't really use them for holding a wire bender although it seems to work with 2 clamps! Better to drill a couple of holes in the bench and use nuts & bolts to secure which should give much more control over the bending.

Allowing for 'Bend Allowance' is the key to accurate bending for thing like cabanes etc. For U/Cs the main thing is to get two legs just the same, so just positioning the marked place in the same spot of the bender is the thing.

Edited By kc on 08/01/2015 16:59:47

[Erfolg]

KC

As with any device Keon's bender has a range of viability. In this case one aspect is size, both the upper and lower limit. The smallest diameter wire is not going to bother many of us aeromodellers. At the upper end of dia, the limit, does have some relevance, in that both more force is required. Although the moment arm of the lever can be increased to reduce the effort of the user, one aspect of the limitations will be the strength of the pins etc.

A second limitation is probably is the radius of the bend and the effect on the outer grains of the steel.

I have left to last, what tends to be a major impediment to accurate bending at the upper limit. This is the very high frictional forces between the moving pin on the arm and the wire. This tends to move the wire in the direction of the rotation of the bar. Any movement, however slight reduces accuracy. It is surprising how even slight errors are noticable to the human eye, particularly on bent wire UC.

The sliding problem on pipe bending machines and commercial wire benders, is that the pipe or wire is very firmly clamped. Again the force required to stop movement is higher than you would expect. Requiring that the clamping mechanism itself is firmly attached to the devices.

For one offs, and making the assumption that I do not make many UC, I am increasingly attracted to the heavy ply base and pins. I have been pondering the practicality of a variation on the pins, by using blocks in place of pins/bolts. The problem that I foresee with this method, is spring back. From real experience in designing some tools for pressed steel tooling and just watching sheet-metal workers with folding machines etc. You always have to over-bend, allowing for spring-back, to achieve the angle you really want.

Being a very ordinary builder of models, I tend not to worry about the finer points accuracy and often good practise (particularly as this is often a prejudice, where people are prepared to die in a ditch, for their version of what is right). On the other hand, there are modellers who would be and are aghast at what I think is acceptable.

[kc]

Donald's method of using a heavy base with pins ( each becomes the fulcrum in sequence) would seem to overcome the spring back problem. I assume he draws the u/c outline on the board and bends until it reaches the line. A piece of melamine coated board would allow easy removal of a pencil line so it can be used for different models. It seems to me that an offcut of kitchen melamine worktop might suffice. as they seem to be a very dense and thick chipboard. Obviously sink cutout offcuts might be utilised and they would be about the right size. I will give that a try I think - using the arm with roller from my MFA bender ( almost the same as shown in the link above)

For anybody new to bending piano wire note that it's much better to leave the wire oversize whilst bending so there is plenty to hold or clamp. Cutting to length is done at the finish. Cutting can be done by nicking the wire both sides with a sharp triangular file, placing in a vice and giving a sharp blow with a big hammer. Use eye protection!