Hello and a part-built blowfly

[Lisa]

Just made a couple of pins for jig drilling the second crankpin hole in the coupling rods. Will also make the retaining collars, as they'll come from the same material. Still need to silver solder the three piece rods together, but am going to make up some rough test pieces to experiment on first, as it's been a while since I did any silver soldering (especially with steel).

Here's the rod sitting on the loco, along with the extraordinarily rough adjustable coupling rod made from scrap. The two of these were adjusted till the wheels rotated freely, and will be used drill the actual rods to the correct hole spacing. The two pins are used to fit the adjustable rod to the coupling rod when drilling.


This is the assembled drilling jig, one pin through the front crankpin hole in the coupling rod and the adjustable rod, second pin through the adjustable rod with a 5mm hole for spot drilling the coupling rod.

[Jim]

That's a very handy jig Lisa. I adapted mine to set the length of the eccentric rods on my Britannia after having first used it as you have, to set the centres for the coupling rods.
You're making good progress. Hmm that reminds me to get back to my loco. I'm currently tied up on a job for my son.

Jim

[Lisa]

After making those pins to drill the coupling rods, I went ahead and made the rod retaining collars, seeing as they're from the same material. The front retaining "collars" are finished, the rear/driving collars still need to be drilled and tapped for a grub screw to hold them in place. Unfinished coupling rod, and the boss for the connecting rod all sitting in place as well.


Next I'll make up some dummy rod bosses, and try out my silver soldering by joining that to some offcut of the centre section of the rod; rather than relearning on the actual rods. It's been a while, so any tips for silver soldering biggish bits (12x7 to 25x10) of steel together?

[Deleted]

Hi Lisa

re silver soldering steel, you will require a fair amount of heat so use a largish burner and keep the heat contained with suitable bricks/blocks etc.. Mix up a good paste, not too runny as you need it to last while all that steel heats up. If you paste the parts before assembly which is what I would probably do be careful as they will tend to push apart as the metal heats up, I would make a jig with pins at the correct centre's to ensure things stay as required. When the flux goes clear while heating you are close to the temp needed depending on the silver solder being used, the metal will begin to go red, remember to avoid direct flame on the silver solder itself during heating up, heat the metal from behind with the solder the other side if possible, it will flow easy enough around the whole joint once the correct temp has been reached. Add more solder if you think it's necessary (this type of joint won't need much) and don't overheat.

good luck

Pete

[jma1009]

i agree with Pete. you dont want to hang about with steel silver soldering and i use the same flux i use for boiler work either J-M Tenacity 4A or Thessco F. whack the heat up and when the flux says all is ok apply the silver solder wandering the torch off the job momentarily. sheild the end not being silver soldered first, then whack the heat up on that end for the second stage knocking off the sheild. shouldnt take more than 5 mins to do both. dont be stingy with the flux or silver solder.

Stepney's conn rod big ends were done in this fashion.

cheers,
julian

[Lisa]

Pete, Julian, thanks.

I've got half a dozen fire bricks (intended for pizza ovens, 1200°C) getting delivered next week, so as to have somewhere to do silver soldering. Plus some CIGweld Comweld General Purpose Silver Brazing Flux, and 42% silver solder rods on hand too; these are both the norm for boiler work, so I'm hoping they'll be fine for this task. Also have several burners ranging from needle to huge, so will see which feels best when experimenting on the dummies.

Pete, the rods are threaded into the bosses, so I don't imagine they'll move too much (and I won't be drilling the second crankpin hole till after they're joined properly anyway). Hopefully, anyway.

[Lisa]

I just did the experimental silver soldering with some offcuts of the coupling rod material. Which turned out ok, but I'm glad I did a practice run.

About 5 minutes after taking the heat off, here's how it looked. This is still hot, and resting on the (vermiculite) fire bricks:


After cooling and cleanup, this is about how I'd hoped the join would come out:


The other side though shows my over eagerness with the silver solder. This was the bottom, which I couldn't see, and I fed a little too much solder in afraid that this side wasn't done; now I know better:


Lessons learned:
1. Don't be shy with the heat.
2. Really don't be shy with the heat.
3. Don't use so much silver solder, though a bit too much is probably better than not enough, maybe.

I ended up using my biggest burner, which isn't really surprising given the size of the boss (32x25x10mm), heating till the steel was just a dull red, and would stay that colour with the heat off it for a few seconds. By this time the flux just looked like a translucent stain on the metal. Then heat off, apply solder, and heat back on the boss till it all flowed into the join and looked nice.

P.S. Julian, I just noticed I misspelt your name, oops, sorry.

[Roger]

Filing off too much is preferable to not hiving enough in my opinion. I'm new to this too, and I'd say be cautious with the heat. Dull red is all it takes, and getting that too bright causes all kinds of problems. You need a different flux for Steel too, although I've managed with Easyflo.
Another thing I've learned from Julian is not to rely on things staying in the right place. If at all possible arrange things to press together so that they don't fall apart when you apply the rod! Very annoying!
It's best to heat the back rather than directly on the joint, and take the heat away briefly as you apply the rod.

When I started I mixed far too much water with the flux, you want very little indeed. Just enough to be spreadable and cover the joint. The first application of the heat needs to avoid that boiling, as soon as it starts to bubble, move the heat away. It takes a while to get it dry, but doing it that way avoids ejecting the flux from the joint.

Ed's tip of dimming the lights is a good one too, another hint that you don't want it bright red.

Anyway, a good result and that's all that matters.

[ejparrott]

I would actually do that job standing up rather than lying down - the job that is, not the operator!

[Lisa]

Roger, the rod is threaded into the boss, so the parts can't shift apart anyway. I used the flux straight from the container (after a bit of mixing), which was a good thick paste that seemed quite ideal. Nice idea with the lights, I working in the middle of the night I had wondered if I had enough light at the time; was probably ideal by accident!

Ed: I did actually consider holding it upright, I just wasn't sure how to hold it in that position.

[ejparrott]

I generally prop things up with firebricks, but I have got a prop that I built to hold boiler bits vertical when I was doing boiler work, usually to hold the firebox tubeplate up in the air while I was soldering in tubes and the wrapper (sometimes)

[Lisa]

Probably wouldn't have been such an issue with the test piece, but with the actual rod(s) it would then mean having to turn it around, while hot, to solder the other end.
Anyway I've got 8 joints to do (2 coupling rods + 2 connecting rods - later - with 2 joints each), so I might end up experimenting with standing it upright.

[ejparrott]

Do it in two sessions, don't rush it and try and do the lot at once. More speed less haste.

[Lisa]

Not directly loco related, but I finally managed to steal borrow the neighbour's welder, and with some pleasant workshop-friendly weather got this tacked together this afternoon:



An assortment of offcuts and scrap (that lower frame is actually part of a printing press), and I've got the beginnings of a work stand for the loco. Chassis put there for the pic', but I'm not going to keep it there till there's some bracing in place, and the welds strengthened to more than just a tack. A bit of plywood on the lower frame will give somewhere to put parts and tools etc.

[Jim]

I dips me lid to ya Lisa. My attempts at arc welding resemble nothing on earth and nowhere near where it's meant to be.
I should add great to see you back on the site with some progress albeit on a work stand but progress none the less.

Jim

[Lisa]

Jul 17, 2016 10:36:13 GMT Jim said:

I dips me lid to ya Lisa. My attempts at arc welding resemble nothing on earth and nowhere near where it's meant to be.
I should add great to see you back on the site with some progress albeit on a work stand but progress none the less.

Jim

Thanks Jim, I've been rather lacking in motivation lately as it seems I won't have the kit needed to machine the cylinders for a few years... barring a lotto win or something similar. But at least I can tinker with other things, and may end up turning that old tender chassis that's in the background of the photo into a battery electric loco, just to get something running in the meantime. I've got a couple of electric wheelchair (I think) motors on hand that'd do the job nicely.

My arc welding mostly involves bad language, and half-blinding myself. But the joints come out all right, I'm mostly just out of practice again.

[Lisa]

A spot of silver soldering this afternoon, sees the coupling rods a little closer to completion. I've done both of the front bosses, and when they're cooler I'll clean them up a bit; probably do the others tomorrow.

Here's the first one, photo taken not long after taking the heat off:


As can be seen I took Ed's advice and did it standing up (me and the rod!), and it went really nicely... the second (not pictured) one even better than the first. Unlike the test piece, I bent the solder into a rectangle, and had it in place while heating; last time I did it soft solder style by heating the job then feeding the solder in. Though I did add a little more on each of the longer sides where needed; a good sign as it means the solder penetrated (and disappeared) into the thread joining the two pieces.

[Lisa]

So the other end is now done on both rods:


Here's one of the bosses after a light clean up:


After a proper clean up all 'round, I'll jig drill the blank ends. Then I'm on to the bushes, and oil holes.

[Jim]

Very nice progress Lisa and yet another step along the road to completing the loco. As a matter of interest what do you use heating?

Cheers,

Jim

[Lisa]

Thanks Jim, it's just regular LPG (propane/butane mix), and the burner head for this job is the the biggest (I believe) Primus Full Flame Burner (about 20mm/¾" diameter), which pumps out quite a bit of heat. That and the fire bricks make quick work of it. Also the bricks are fairly soft, so I could easily put some screws in them to hold the rods upright while heating.