bambuko loco works 0-6-2 (Fowler)

[bambuko]

Combined reply to all of you guys (and thank you for your contributions )

...I've been using the soldering iron to distribute the solder...

Yes, I've tried that as well, and apart from the difficulty of heating 1.5mm steel sheet
(particularly with high temp soft solder like Comsol, which melts at around 300degC),
soldering iron will not apply pre-tin in a thin even coat as well as one is able to do it with silicone brush.
At least this is my experience YMMV
Of course for brass, relatively thin and using standard tin/lead solder, there is nothing wrong with soldering iron.

...I stopped using Bakers Fluid years ago because it is so corrosive, especially when you knock the can over!
I prefer Fluxite which is much more controllable and less likely to cause a disaster...

I use dishwasher to clean and neutralise things after solderng - never had any problems with rust.
Used Fluxite and similar before and they are perfectly adequate for normal tin/lead and lead free, not sure about high temperatures
(I tended to end up with black mess ).
Bakers Fluid is officially recomended (by Comsol people) flux for use with their solder.

... aluminium rail is so incredibly inexpensive that it might well make up for the shipping cost.
...Aluminium rail is weird though. Steam oil and oxidation make it very black on top and it is quite soft...

Nothing is "inexpensive" if you are in UK
Sterling exchange rate has gone down so much of the last couple of years...
So I will probably stick to the choices available locally

I'm using Accucraft code 250 rail which is available in the US and Aust., but I don't know if Accucraft UK stock it.
The rail profile is the same as Sunset Valley rail and they are interchangeable.
I've just been through all this while planning my new track.............

Thank you for the links to Sunset Valley and Llagas Creek Railways- most useful info.
Don't think they do Accucraft code 250 rail here, but I could be wrong?

Just to make choosing even harder check out Cliff Barker's code 180 rail...

Yes, but this one is only bullhead and if you want to use his track, it is canted 1:10 instead of the correct 1:20



That's quite an error and it is noticable (unless he has replaced the tooling? but I doubt...)

[dewintondave]

...I've been using the soldering iron to distribute the solder...

Yes, I've tried that as well, and apart from the difficulty of heating 1.5mm steel sheet
(particularly with high temp soft solder like Comsol, which melts at around 300degC),
soldering iron will not apply pre-tin in a thin even coat as well as one is able to do it with silicone brush.
At least this is my experience YMMV
Of course for brass, relatively thin and using standard tin/lead solder, there is nothing wrong with soldering iron.

I've preheated large items with the torch then used the large soldering iron (with chisel tip), working away to get good smooth coverage of solder

[GTB]

I've preheated large items with the torch then used the large soldering iron (with chisel tip), working away to get good smooth coverage of solder

I use the same technique for tinning large chunks of brass such as the cylinder blocks on the Baldwins, using a small pencil torch to keep the metal hot and the soldering iron to tin the metal.

My 100w soldering station fitted with a 3mm chisel tip works fine for tinning sheet brass and steel sheet up to 1mm. Never had the need to tin thicker steel sheet, as I prefer to fabricate frames with mechanical fasteners.

I refuse to use chloride based fluxes like Bakers and all my soft soldering is done with phosphoric acid as a flux. It works well for tin/lead solder, low melt solder and even lead free solder (which I avoid if possible) and I get good results on steel, brass, copper and whitemetal. Cleanup is a simple water rinse. I don't use much and usually apply it to a joint with a toothpick. The last 50ml bottle lasted me about 10 years, even including knocking it over twice......

Regards,
Graeme

[bambuko]

It's been quite some time since the last update
but now that summer is gone and I am back in the workshop (at least occasionally), here is the latest:



I have decided not to spring the axleboxes, but left original hornblocks and hornstays.
So it is bit more complicated than necessary, but it's good practice for the next loco which will definitely be sprung
Also, the beauty of this arrangement is that if things do not work out (for example, I am not sure about these bearings), it is an easy thing to produce another design of axlebox, without any mods to the frame.

I have chosen FR168-ZZ bearings, two for each axlebox:



Next step I am pondering, are cranks.
I want them to be removable if necessary, rather than permanently Loctited as per Brian Wilson's book.
I am thinking square ends to axles and cranks with square holes.
The only question (in my head) is securing of cranks to axles - either csk screw into axle end as per Roundhouse practice? or a grub screw to the side of axle square.
Prefer the latter, but not sure if it will be secure enough?

[DonW]

For a grub screw to work you could file a flat on the axle or better make a small dimple. If you are going to the trouble of milling square ends to the axles a small screw into the axles to secure the crank does seem to be a natural option.

For tinning the ideal thing is a plumbers moleskin. I wish I had kept mine using a torch you heat the item add some solder then use the moleskin to spread it thnly over the surface. The moleskin becomes soaked in tallow in use. I have used an ordinary cloth to remove excess solder when tinning but it is not as good at spreading.

Don

[FWLR]

Don's answer is what I would do if you need to take them off easily. The more permeant way would be Roundhouse. Go with what you feel is better for you

[GTB]

I have decided not to spring the axleboxes, but left original hornblocks and hornstays.

I think we've had this conversation before. I'm not a fan of springing in garden scale, but I like to make my loco wheelsets removable for later maintenance.

Not sure about ball bearings in model steam locos. They won't wear as fast as bronze bushes and don't need regular lubrication, but miniature ones may not be able to handle the reciprocating loads on a steam chassis in the long run.

Next step I am pondering, are cranks.
I want them to be removable if necessary, rather than permanently Loctited as per Brian Wilson's book.
I am thinking square ends to axles and cranks with square holes.
The only question (in my head) is securing of cranks to axles - either csk screw into axle end as per Roundhouse practice? or a grub screw.

My Fowler has the outside cranks fixed with Loctite. The wheelsets are easily removable from the chassis and I recently removed them to fit slightly larger driving wheels to the loco. I had no problem removing one crank from each axle with a punch, changing the drivers and refitting the crank with Loctite. The quartering jig was the one I used when I built the loco, so no adjustments to the con rods were needed when the chassis was reassembled with the new wheelsets.

It isn't difficult to dismantle a joint made with Loctite, as it's designed to make a strong joint, not an unbreakable one. The shear strength of the cured polymer is only about 10% that of the metals being joined.

Milling axle ends square is the easy bit with using the Roundhouse quartering arrangement, accurately broaching a square hole in the crank that is in line with the crankpin is the real trick. I have a couple of locos built with R/H parts and ince I dislike the slotted screws used for fixing cranks, I replace them with hex socket CSK screws. From normal viewing distances the small hex socket resembles the centre holes on real loco axles.

There were some recent posts on the group about making outside cranks and fixing them to the axles with grubscrews in a discussion on building battery powered chassis. You'll find it towards the end of this topic -

https://gardenrails.org/viewtopic.php?f=1&t=12467

Regards,
Graeme

[bambuko]

...If you are going to the trouble of milling square ends to the axles a small screw into the axles to secure the crank does seem to be a natural option...

yes Don, that is my thinking as well

...For tinning the ideal thing is a plumbers moleskin...

It's amazing what you can learn by just asking on the forum
I googled and found an old book which describes how to prepare plumber's moleskin - fascinating

...The moleskin becomes soaked in tallow in use...

That is the only thing that leaves me puzzled, with tallow being oily contaminant?
Normally I degrease everything before soldering.
I guess being used after soldering just to spread the solder it is OK.

Will have to try it, instead of my silicone brush.

Chris

[bambuko]

...but I like to make my loco wheelsets removable for later maintenance...

Totally agree with you on this one.

...Not sure about ball bearings in model steam locos....but miniature ones may not be able to handle the reciprocating loads on a steam chassis in the long run...

I am also concerned about this, but... I understand that similar bearings are used sucessfuly in G1?
Plus if it all goes to pot, it wouldn't be too complicated to replace them with "conventional" bronze axleboxes.
BTW this is another reason for having everything removable.

...My Fowler has the outside cranks fixed with Loctite... I had no problem removing one crank from each axle with a punch, changing the drivers and refitting the crank with Loctite...

I guess it depends on the grade of Loctite?
Which one did you use, please?
Loctite 648, which I use to fix wheels to axles has got a shear strength of 3900 PSI.

...It isn't difficult to dismantle a joint made with Loctite, as it's designed to make a strong joint, not an unbreakable one...

I know it's not impossible, but not something you would want to be doing too often?
Will have to make some tests.

... accurately broaching a square hole in the crank that is in line with the crankpin is the real trick...

Yes, hence I am approaching it the way dog approaches hedgehog
Equipment is not a problem (have vertical slotting attachment for my Bridgeport - it's the skills that might be lacking

... There were some recent posts on the group about making outside cranks and fixing them to the axles with grubscrews ...

thanks for that - useful and interesting.

Chris

[GTB]

That is the only thing that leaves me puzzled, with tallow being oily contaminant?

In the past, tallow was used as a soft soldering flux and also as the flux for lead wiping. It's not an oily contaminant in the sense that mineral oil would be.

It works much the same as as rosin flux, being mildly acidic and also wetting the surface to exclude air from the area being tinned/leaded. It would be easier to initially spread on the surface than rosin I imagine, but cleaning up could be more interesting.

It is still used by the more traditional stained glass workers when soldering lead and comes as a waxy stick that looks like a candle without the wick. I assume it is a purer grade of tallow than what is scraped out of a frying pan after cooking...........

Graeme

[GTB]

I guess it depends on the grade of Loctite?
Which one did you use, please?
Loctite 648, which I use to fix wheels to axles has got a shear strength of 3900 PSI.

I'm still using up my bottle of Loctite 603, which was the predecessor of Loctite 648. Looking at the data sheets, 601 has a slightly lower strength, 22.5MPa compared to 25MPa, but it cures faster, so I'm not planning on changing until I have to.

I've only had to remove cranks/wheels from the axles of a loco in one case. Predictably it was the only loco with outside cranks fixed with Loctite.......

I didn't need to use any heat to dismantle the cranks, but I carefully cleaned the crank seat on the axles with solvent before remaking the joint.

As you say, make up a test joint and see how much effort it takes to dismantle it.

Graeme

[bambuko]

I have finished axleboxes, fitted the bearings and made some dummy axles from mild steel (proper ones will be made from silver steel) just to try the fit etc.



Quite pleased with the result.
Everything is smooth and just as it should be , although it was quite a challenge - difference between sloppy fit and just right fit of the bearings on the axles is measured in 0.01mm (or less than 1/2 thou for you imperial types) so rather tighter than my usual tolerances

[tom_tom_go]

Excellent work, I can appreciate the effort you have put into that finish.

[Keith S]

That frame looks excellent. There's something about how square it is and the level of detail that makes it look "right". May I ask why you decided to omit the springs?

[bambuko]

...May I ask why you decided to omit the springs?

Number of reasons (in no particular order)
- my personal preference is for equalisation rather than simple springing, but my original design (which looked OK on CAD screen ) turned out to be a bit too complicated... in real life
- trying to limit experimental/unproven aspects of the design (keen to get this loco running, rather than learning what works or doesn't work)
- couldn't do it neatly enough

I will probably try it on another (simpler?) loco, just to get an experience
for now, I just want to get some progress - this project is taking far longer than I was hoping it would

[Hydrostatic Dazza]

How about skipping screws and broaching etc and using a mild Loctite for the crank to axle bond via the quartering jig, then cross drilling the crank and axle (use PCB type carbide drill, not a twist drill) and fitting a pin. For pins the smooth shanks of 1.50mm HSS drills worked well for me. Insert the pin with a retainer compound. One can use a small drift made from a 1.40mm drill shank inserted into a small piece of round, to knock the pin out if the need arises to pull the wheel, axle crank assembly down with a warming to break the Loctite crank to axle bond.
Might save a lot of fluffing about and still look sweet. 1.5mm HSS pins will be more then strong enough to handle the torque loads. Heck 0.50mm would be enough.

[bambuko]

How about skipping screws and broaching etc ...

yes, this is another option under consideration
I usually start with most complicated one and then reality takes over and a simpler one becomes more appealling

[DonW]

How about skipping screws and broaching etc and using a mild Loctite for the crank to axle bond via the quartering jig, then cross drilling the crank and axle (use PCB type carbide drill, not a twist drill) and fitting a pin. For pins the smooth shanks of 1.50mm HSS drills worked well for me. Insert the pin with a retainer compound. One can use a small drift made from a 1.40mm drill shank inserted into a small piece of round, to knock the pin out if the need arises to pull the wheel, axle crank assembly down with a warming to break the Loctite crank to axle bond.
Might save a lot of fluffing about and still look sweet. 1.5mm HSS pins will be more then strong enough to handle the torque loads. Heck 0.50mm would be enough.

That thought occurred to me but it does preclude giving a slight tweak to the quartering so the drilling for the pin needs to be very precise.

Don

[FWLR]

Brilliant work Chris. It sure is coming along nicely.

Things can get to be longer than expected to do mate, my Garage for our line took nearly 2 months or more....

[Hydrostatic Dazza]

How about skipping screws and broaching etc and using a mild Loctite for the crank to axle bond via the quartering jig, then cross drilling the crank and axle (use PCB type carbide drill, not a twist drill) and fitting a pin. For pins the smooth shanks of 1.50mm HSS drills worked well for me. Insert the pin with a retainer compound. One can use a small drift made from a 1.40mm drill shank inserted into a small piece of round, to knock the pin out if the need arises to pull the wheel, axle crank assembly down with a warming to break the Loctite crank to axle bond.
Might save a lot of fluffing about and still look sweet. 1.5mm HSS pins will be more then strong enough to handle the torque loads. Heck 0.50mm would be enough.

That thought occurred to me but it does preclude giving a slight tweak to the quartering so the drilling for the pin needs to be very precise.

Don

For what it may be worth, I did one crank to axle, Loctite, let set, drilled and pinned it.







then I fitted the other side and Loctite in the quartering jig, let set.





The tapered wood wedge is to ensure firm positive location of the crank pins in the jig while the Loctite cures.



I then fitted the wheel sets in the frames along with the rods and bushes etc to check all is rolling sweet. When satisfied the quartering was sweet, I dropped the wheel sets out and drilled and pinned the remaining other side of crank/axles.
I am thinking if I need to pull down the wheel sets, tap-tap the pins out, a slight warming of the wheels with the LPG torch to break the Loctite.
I reckon the important thing is a good accurate and stable quartering jig. Take the time to make a nice one.