Adrian Smith 1 Posted September 10, 2014 Share Posted September 10, 2014 As is my habit after every flying session I check over my plane meticulously, particularly my big scale petrol jobbies. Well after a flying session yesterday with my 50cc Dymond Sbach 342 I checked the pushrods that operate to throttle and choke on my OS gasser and got a fright of my life. The soldered coupler with attached clevis had parted company with the push rod! Fortunately the choke defaulted to open so no damage to the reed valve on the carby occurred. I decided to twiddle the coupler and clevis on the throttle push rod and low and behold there was play so that will go the same way shortly no doubt. I am not sure that soldered joints are up to the front end vibration although soldering has never been my strong point. I have bought a solder bath to help with pre-tinning particularly the iron tip before a job as thats how the heat is transferred. Mind you it takes a hell of a lot of solder to fill the bowl, but hey ho I will see how it goes. One thing I noted was the 3mm rod fitted very snugly into the coupler and it looked as though not enough solder had dribbled down into the coupler despite tinning the rod. Quote Link to comment Share on other sites More sharing options...
Stevo Posted September 10, 2014 Share Posted September 10, 2014 Any chance a photo of the bath, as intrigued .... Quote Link to comment Share on other sites More sharing options...
Philip Ogden Posted September 10, 2014 Share Posted September 10, 2014 Rather than soldering, I would get a 3mm die and roll a thread on the plain end of the rod therefore eliminating a soldered joint in preference for a good mechanical joint which will not come apart. Quote Link to comment Share on other sites More sharing options...
Keith Berriman Posted September 10, 2014 Share Posted September 10, 2014 Not sure of the system and if straight rods but how about using a fibre glass rods super glued into clevis Quote Link to comment Share on other sites More sharing options...
Martin Whybrow Posted September 10, 2014 Share Posted September 10, 2014 Some rods are stainless so you won't be able to solder them; I found I had a mixture of rods that looked identical, but some wouldn't solder; I checked with a magnet and found some were only weakly attracted to it, meaning that they were stainless steel. Solder is no substitute for a good mechanical joint, it should only be used to anchor everything in place; you only need microns of clearance for the solder to wick into a joint - plumbing fittings are often so tight that they jam together, but the solder finds its way in no problem at all. Quote Link to comment Share on other sites More sharing options...
Adrian Smith 1 Posted September 10, 2014 Author Share Posted September 10, 2014 **LINK** There you go Stevo, it comes supplied with UK 3-pin plug that you have to fit, but otherwise straightforward. RC plane flyer they were straight rods and I didn't have any GF rods at the time of the build and I needed adjustment via the clevis. I must admit Philip I have lusted after a tap & die set but thus far not splashed the cash on one. May be I need to think seriously about doing that. Quote Link to comment Share on other sites More sharing options...
Adrian Smith 1 Posted September 10, 2014 Author Share Posted September 10, 2014 Yes Martin your are right. Anything under pull pressure should not be soldered according to plumber I know as it just won't work, more a case of using soldering for anchoring them as you say. Lesson learned here. I take your point on stainless steel rods and I am sure that was a contributory factor. I have now used some heavy duty Du-Bro E/Z rod connectors for a proper mechanical job. Quote Link to comment Share on other sites More sharing options...
Martin Whybrow Posted September 10, 2014 Share Posted September 10, 2014 Don't buy a tap and die set, to get a good one you'll pay a fortune; instead, decide what sizes you'll likely need and just buy those from a decent model engineering supplier such as Chronos or Tracy Tools. Quote Link to comment Share on other sites More sharing options...
Adrian Smith 1 Posted September 10, 2014 Author Share Posted September 10, 2014 I notice that ModelFixings do them individually at a very reasonable price so I think that is the next move. Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted September 10, 2014 Share Posted September 10, 2014 If you are going to try and thread Piano Wire, the die's wont last very long at all, its a lot harder than Mild Steel Quote Link to comment Share on other sites More sharing options...
Malcolm Fisher Posted September 10, 2014 Share Posted September 10, 2014 As I have said on another thread, it is possible to solder stainless steel. However a phosphoric acid based flux is required. Years ago when copper tube prices rocketed, stainless tubing was used for central heating systems and these were soldered using capillary fittings in the same way as copper tube is done. I have soldered clevises to steel pushrods and Bowden cable types and never had one fail. As for soldered joints not being suitable for pulling situations, the nipples on brake and clutch cables for motor cycles used to be soldered and I never had one of those fail either. Cleanliness and sufficient heat are the prime requirements for successful soldering. Malcolm Quote Link to comment Share on other sites More sharing options...
Philip Ogden Posted September 10, 2014 Share Posted September 10, 2014 Go to **LINK** £11.15 for an M3 die and £5.40 for the die holder. You can buy M3 threaded rod in 10" lengths which will take a thread no problem, and if you need to thread piano wire, just anneal the last inch and you are away. No substitute for a good mechanical joint. Quote Link to comment Share on other sites More sharing options...
Adrian Smith 1 Posted September 11, 2014 Author Share Posted September 11, 2014 That's just what I ordered last night Philip, just the job I think Quote Link to comment Share on other sites More sharing options...
ceejay Posted September 11, 2014 Share Posted September 11, 2014 Hi all just a few thoughts re soldering/threading, if you are contemplating threading the other end of a 3mm push rod then you will not get a full thread, if you measure the rod you will see it is somewhere in the region of 2.6mm dia this is due to the threads being formed onto it not cut so the threaded portion is larger than its core, what you will get at best is a fine spiral that your clevis will thread onto, and indeed this is the very thing i do prior to then soldering the joint, as for annealing the end of piano wire, this just takes the very properties you have piano wire for in the first place away, ie if its now soft enough to cut its soft enough to bend! as has been sai soldering of extenders to push rods is all about clenliness i have allways soft soldered all my push rods and rigging wires for models upto 1/3 scale and never had one part, good quality 60/40 lead tin solder and good quality flux and a high power iron are a must. eg some years ago when investigating rigging for a 1/3 scale biplane we ran some tests, after soldering a 3mm solder extender to a length of bicycle gear cable inner, (its more flexible than brake cable) we attached (tied) the other end to the steel beam of a garage roof and a strip of metal to the extender via 3mm nuts and procceded to attack it with various size hammers, the result was a bent metal strip and a broken thread the solder held up fine and always has. cj Quote Link to comment Share on other sites More sharing options...
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