The first thing to admit about this photo etch bender is that it is NOT my idea or design! I came across this one on Youtube a few months ago and it was put together by a very clever modeller from (I think) Czechoslovakia, called David who goes under the name of PLASMO. You can find his ten minute video of how he put it together on youtube.com/watch?v=JbMH5Audl-k (or just put ‘diy photo etch bender’ into the search box and it should come up.
The basis of the bender is a steel ruler as shown in Photo 1, in this case, as in the video, a twelve inch ruler cut in half. Although this is a money saving exercise, I did actually spend quite a bit in seeing it through! When trying to drill the holes through the stainless steel for the bolts and springs coming later, the first two of my HSS drill bits were worn down completely flat before they got anywhere near going through. So I took the opportunity of getting something I’d been thinking about for a long time since first coming across them on the Ideal World TV shopping channel. That ‘something’ is shown in Photo 2 – a set of “Drill All” Cobalt drill bits. They start at 3mm and go up to 10mm in 0.5mm stages. At the top left is a very useful countersink bit for good measure. In the TV demo, a drill bit is put through a layered block of wood, ceramic, steel, brick and concrete all in one go! They are not cheap – this set cost all but £50 but the bits are guaranteed not to blunt, bend or break for ten years with free replacements if they do! I’ve only tried them on wood and stainless steel at the moment but that ruler which flattened two HSS bits was drilled right through in about five seconds flat (and not the drill bit this time!)
The first task however was to grind out the right half of the top ruler with a series of notches under which the PE brass would be clamped for bending. I must admit, in David’s video, his dremel thingy cuts through the stainless steel a heck of a lot easier than mine did! I did however notice a slight flexing in his ruler as he was holding it – mine won’t flex anywhere so either mine is a thicker ruler to begin with or I have a different grade of stainless steel! I bought my ruler down the local DIY store – made by amtech and £1.99 for a pair of rulers, one twelve inch and one six. I also sent off before that for one on ebay which arrived just after I got the local ones and was definitely much thinner and more flexible!
As you can see in Photo 3, the two rulers are ground and drilled, the last indent is rounded as once I got those drill bits, adding a large cut out with the drill and cutting wheel was a lot easier! The indented ruler at the bottom has 5mm holes to take an M5 bolt whereas the straight ruler at the top has 7mm holes to allow for an M5 compression spring to sit into the wooden base (the spring is 5mm diameter on the INSIDE)!
Photo 4 illustrates the wooden base for the bender, in my case, not a beech door step but a pine plank off cut. The reason there are four holes and not just two is that the first pair were, ‘ahem, not as aligned as I thought they were! The underside of the base is shown in Photo 5 with the end of the M5 bolt countersunk down into the base. Back to the topside in Photo 6 with the M5 bolt coming up through the base and the compression spring sitting in the 7mm countersunk hole (about 5mm deep). In David’s video he used spring washers to secure the bolts in the wood, in mine the hole drilled through the pine for the bolts was tight enough that the bolts cut their own thread as they were screwed in so no extra securing was needed. In Photo 7, the bottom ruler is placed over the bolts and springs and then glued down onto the base. To hold the steel in place whilst the glue dries, simply add the wing nuts to the bolts and tighten them up locking the ruler down tight.
The indented half of the ruler is then placed over the bolts as shown in Photo 8, as the drilled holes are only wide enough for the bolts to pass through, the top ruler sits on top of the springs as seen here. The bolts, wingnuts and springs are shown in Photo 9, not shown are the M5 washers which fit beneath the wingnuts (I got them down the same DIY store I bought the rulers from after this photo was taken – I thought I had a pack already but they turned out to be M3’s!)
The last three photos were also taken before I got those washers – Photo 10 is the bender essentially completed with the top ruler screwed down tight to the bottom. Photo 11 has the addition of a 1mm strip of black plasticard which lifted the working surface up to the level of the bottom ruler (so I couldn’t accidently add an unwanted kink to any parts being bent if they overshot the ruler width). Unfortunately a couple of days after gluing that card down with a contact adhesive it developed a ‘hump’ in the middle which was strange as I didn’t think the contact glue would affect the plastic. Anyway, I removed the plasticard (fairly easily which wasn't a good sign) and replaced it with a strip of 1mm thick black self adhesive neoprene as seen in Photo 12, (left over from lining the inside of the DIY dew shield I’d just made for my new telescope). Note that I stretched this photo to fit the space – the actual dimensions are as in the two pics above!
So that’s the perfectly workable etched brass bender. So far as I mentioned, I’ve found the pliers and tweezers perfectly adequate for the small parts on the lander, this gizmo will I hope come into it’s own on the longer spindly bits like the crane jib arms and landing gear coming later on. Many thanks to PLASMO or David for that design and video and in the next instalment we get down to the start of the build itself (coming together well at the moment with just one unfortunate ‘error’ so far!

Until then, Happy Modelling to you All!

Robin.