Hints & tips
by
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JAMMIN'
“Whilst removing a propeller from my model I encountered a jammed collet-type prop adaptor”, writes Henry Leong from Brisbane, Australia. “This wasn't the first time this had happened, and the subsequent firm, twisting and tapping required to separate the tapered outer collar from its shaft is always a worry, risking damage to the airframe. What I needed was a set of claw-like fingers, precise enough to pull the outer collar whilst a central finger pushes the collet shaft in the opposite direction. Memories of my dad's crank pulley removal tool flashed past and I came up with an improvised tool that would act as a very effective collet puller, based on a (cheap) skeleton-type caulking gun from my local hardware store.
This type of caulking gun usually has a plunger rod operated by a trigger, a simple construction consisting of a forward fairing connected to the trigger mechanism by two strips of metal that act in tension. My conversion involved removing the end stop from the frame to leave behind two metal strips with short 90° elbows at the ends, and then removing the flat end plate at the tip of the plunger rod. This leaves three fingers: the two metal strips with bent tips being the outer (pulling) fingers, the plunger rod acting as the central (pushing) finger.
The two outer fingers act as pulling claws that fit at the back of the tapered outer collar of the prop adaptor (you can grind the tips of the metal strips to a rounded shape for a better fit to the prop adaptor's circular outer collar), whilst the central plunger rod pushes onto the collet shaft. With a few firm squeezes of the plunger trigger, the pushing action of the central plunger finger combined with the pulling action of the outer claws causes the collet shaft to separate from the outer tapered collar with a 'pop'. Job done!”
LOST LEADS?
If you've ever suffered the frustration of having to retrieve aileron servo lead plugs from the depths of a built-up wing, this simple idea from Gareth Gates of the Slough RCMC might come in useful.
Loop a small cable tie around the servo wire, small enough that the plug can’t get through but the wire can move freely. Cut the cable tie's tail short and then glue the tie to the inside of the wing skin, near the wing root rib. This allows the servo cable to move freely while keeping the lead within easy reach at all times. A lightweight, cheap and simple fix to a problem that can potentially cause a lot of frustration!
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MIGHTY MOUNT
Unimpressed by the somewhat flimsy ply engine 'box' mount of his latest electric-powered ARTF, Paul Hinson from Balgowlah, Australia had a rummage through his hardware collection and came up with a far more substantial alternative.
All you need is a length of threaded rod and some nuts & washers, arranged on the firewall as shown in the drawing, to provide a mount that's fully adjustable for both downthrust and sidethrust. The example shown uses M4 fasteners for a rear-mounted X-plate type mount, but the idea can be easily modified for front mounting and motors of different size.
DE-CREASED
Having cartwheeled his Pitts during landing and creased the wing l.e. sheet in the process, Steve Hargreaves set about making good:
“The sheet wasn't broken, but it was cracked & slightly pushed in under the film. I cut through the covering behind the spar for access, and I wanted to overlay the break
internally with some 1/32” sheet to strengthen it…but how to hold it in place whilst the glue dried? The section is too thin to get clamps in, and I wanted to press the 1/32” strengthening sheet down all over to ensure a good bond…so what to do?
The solution was to cut some foam rubber that was slightly taller than the l.e. D-box which, when compressed and pushed into place, not only held the sheet in place but also pushed the original l.e. sheet back into shape. Once the glue was dry I pulled the foam out and the crease had gone….a quick iron to get rid of the wrinkle in the film & you can't tell there was ever anything wrong!”Advert
“The sheet wasn't broken, but it was cracked & slightly pushed in under the film. I cut through the covering behind the spar for access, and I wanted to overlay the break
internally with some 1/32” sheet to strengthen it…but how to hold it in place whilst the glue dried? The section is too thin to get clamps in, and I wanted to press the 1/32” strengthening sheet down all over to ensure a good bond…so what to do?
The solution was to cut some foam rubber that was slightly taller than the l.e. D-box which, when compressed and pushed into place, not only held the sheet in place but also pushed the original l.e. sheet back into shape. Once the glue was dry I pulled the foam out and the crease had gone….a quick iron to get rid of the wrinkle in the film & you can't tell there was ever anything wrong!”
ANGLED AERIAL
Mark Allinson writes, “As it's necessary to keep 2.4GHz aerials at 90° to each other I decided to make this right-angle triangle out of old snake tube to thread the aerials into – this way they always retain their relationship to each other, even if the receiver comes loose in the airframe.”
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BRASSED OFF
Take two easy steps to stop countersunk bolts from pulling through plywood, courtesy of David Osborne and some brass cup washers from B&Q:
* Place a cup washer over the bolt, pass the later through a hole in a piece of metal and add a nut; tightening the nut pulls the bolt head tight onto the cup washer, forming it neatly into the profile of the bolt's countersink section.
* For the washer to sit flat (so that the ply and screw can mount close to another component if needed), simply beat the raised part of the cup washer down gently with a hammer.
Shown here fitted to the bulkhead of David's YT International P-47 electric conversion, the washers provide a sturdy foundation that prevent the screws from pulling through.
For a tidy, permanent reminder of where your C of G is, take a leaf out of Harry Pickles' book and fix a pair of self-adhesive ring reinforcements to your wing, centred at the appropriate positions. This provides an instant reference that can be easily found by feel, and saves you holding the model over your head whilst trying to guess the locations.
Another plus point here is that the centres punched from the centres of the reinforcements can be used to cover the ends of pegs used for the 'belt & braces' securing of Mylar hinges. The cost? Around 85p spent at your nearest stationery supplier will reward you with more than 100 reinforcements – should keep you going for a while!
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