When we started to refurbish our ex-display windmill it became apparent that the curved strips were in need of ‘smoothing’ as well as cleaning. After blowing the dust off of some old magazines and a bit of Google-time I came up with a design that was a combination of published ideas and the availability of parts. I can not lay claim to the basic design as it follows established principles. Most of the constructional details of my version can be seen in the photographs but here are a few notes and observations.
The strip bender was built so that it can be used to bend strips and flat girders and double angle brackets. Although it will bend the thicker strips, it is better suited to lighter gauge strips. Its initial purpose was to bend the strips for the windmill but it soon became clear that this machine would open up a whole new area of modelling. A new thought process could be adopted.
If like us, you have not got around to building one of these then you should. The other bonus is that it will ‘refurbish’ all those old bent strips and with a bit of practise it is possible to roll them perfectly flat! It will even roll painted strips without marking them if you are careful!
Bending machines need to be rigid. There is quite a bit of force being applied to the strip, a good firm base makes this easier to control. I started off building some compound girders and subsequently bolted the whole thing down onto a piece of 18mm thick MDF. Holes were drilled and tapped to a Meccano thread. The bolts holding the base down are ¾ inch long round-heads. The washers are there to ensure they do not protrude through the bottom of the MDF.
Strips, angle girders and cranks make up the legs and bearings. Couplings and collars are used for the bending rollers. Use the short grub screws on the rollers where the bending is going to take place. I have used some six hole collars on my machine but that was only because they arrived in a lot we purchased in ‘the bay’.
The spoked wheel was used because it looks good, the idea being borrowed from Bert Halliday’s “Comprehensive Rolling Mechanism” featured in issue No 12 of the MMGG, September 1987. The wheel is attached to the boss of a 19t pinion via a socket coupling. This eliminates the risk of wheel/pinion slipping on the rod under load.
On the opposite side of the machine the rods are extended so that further couplings can be added in order to make some mini rollers with open ends that are used to bend double angle brackets and full circles of strip. Two loose couplings are used to prevent the rods from spreading during the bending process. They are easily slipped of to enable the fabricated part to be removed.
The legs of the machine are adjusted by a simple mechanism employing a threaded rod and some couplings. The rod passes through a clearance hole in the coupling at the winding end and is held in position by a threaded boss, locked onto the threaded rod with a nut, on one side while the other side is retained by the screwed rod adaptor that has the bush wheel winder attached. The other end of the threaded rod is passed through the threaded holes in a coupling that is, inturn, attached to the legs of the machine via a second coupling and an axel rod.
The sliding mechanism may look good but it has to be adjusted perfectly to work smoothly. The rods were carefully selected to be free from any grub screw marks and polished with wire wool.
With the bender open (legs closer together) insert the strip to be bent. Wind the legs apart until the strip is held by the rollers. Roll the strip through the machine until the end of the strip is sitting top dead-centre on the nearest roller. Turn the wheel two full revolutions counter-clockwise and roll the strip through until the other end is sitting top dead-centre on the furthest roller. Repeat the operation until the required bend is obtained.
With the success of the strip bender the next thing on the list had to be a plate bender. The main components here are the rollers. I have seen lots of articles suggesting methods of making rollers from tube and couplings and I did consider them for a while. Dave Taylor lists some rollers that secure themselves to rods to make rollers. I was keen on this idea for a bit. Then I discovered Stuart Borrill’s purpose-made rollers. A set of three silver steel rollers with ends turned down to Meccano rod diameter - perfect! A set was duly ordered.
Having used a lot of my less plentiful brassware on building the strip bender I needed to be a bit more economical with this build. I also realised that my stock of silver angle girders was not in good health either. Needs must and it was the week before the TIMS exhibition in Ironbridge. We had agreed to attend with the shop display windmill and were going to make a couple of the ‘60’s set 3 windmills. These had some plates that needed bending to go with some ‘tightened’ formed strips. No time for any more parts we had to make do with what we had.
Plates do not need as much force to bend as the strips, so the construction could afford to be lighter. Strips and cranks were laminated up to make the legs. A similar screw thread arrangement, as used on the strip bender, was employed to adjust the rollers.
The sliding guides are made from slide pieces running along perforated strips. This arrangement was a necessity as I was low on brassware. As it turned out the sloppiness made the machine work much smoother! It must me the same inverse engineering that allows Meccano clocks to work - nice and loose… Again, the machine is bolted to a piece of MDF to improve the rigidity.
In fact I think I have used it for straightening plates as much as I have used it for bending them. This little machine is really useful. It makes a superb job of putting nice smooth curves into any length of plate. Use in the same manner as the strip bender. To flatten and smooth bent plates. Roll them up tight and then open them out by hand until they will fit into the machine to bend them the other way. Repeat this a couple of times and them reduce the amount of curve until the plate emerges flat. It will not get rid or really tight creases but it will sort out a lot of what I would have considered scrap a few months ago.
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