Slightly Loco

[rake60]

Hey, never give an inch! LOL

I was convinced!!

Rick

 

[nkalbrr]

For the wheels try O guage one made by Lionel, MTH or Weaver. They have a large flange . O scale flanges are more prototypical and don't give you the fudge factor

 

[shred]

For the wheels try O guage one made by Lionel, MTH or Weaver. They have a large flange . O scale flanges are more prototypical and don't give you the fudge factor

Do I want a fudge-factor? Seriously. I made some wheels out of 1" steel bar I had handy, but I had to trim the suggested flanges even more.. I think they specified 26mm on the original plans and it's a bit tricky to get 26mm out of 1" stock I've never run trains on O-track (long ago I had an N-scale setup), so I'm pretty clueless in that regard.

Btw, for anybody curious, the loco is on hold at the moment.. I'm just not excited enough to work on it when it's 100'F in the shop as it has been lately.

 

[nkalbrr]

I just took some measurements(Cracker in parenthesis). The plans for the Cracker are metric . The dimensions are from a Weaver manufactured car made in the great state of Pa. Axel .093 (0.118 3 mm) outside diameter .960 (1.024 26mm) inner .709 (0.866 22mm)from hub to flange .154 (.197 5mm) from inner wheel -wheel 1.041 (1.102 28mm) Axel length 1.790 (1.185 47mm). the tread profile looks to be the same angle.The measurements may vary from manufacturer to manufacturer, but as you can see it's close like handgrenades and horseshoes

 

[shred]

Those of you that have been paying far too much attention to my whereabouts know I was out of the model engine work for a few months. I'm back now (34th in the world thankyouverymuch) and ready to hack away again.

The Slightly Loco build was wrested from the Forces Of Entropy and is under way again.

I got by the plumbing store on Friday and spent part of the last two days boilermaking. If Firebird is making a 'small boiler', this is a 'tiny' boiler, or maybe even a 'micro' boiler. The outer shell is 1.25" tubing and the whole thing is about 88mm long.. Metric plans and imperial stock and tooling is such fun. :

All that's left is to solder it up and pressure test it.

 

[J. Tranter]

Are there plans for that boiler you are making? I would really like to see them.
John T.

 

[shred]

The plans for 'Cracker', which this is a variant of are on http://home.iae.nl/users/summer/16mmngm/Articles_htms/Cracker.htm
I have taken those, plus Tony Bird's build notes (very nicely done) and mixed in a mash of my own ideas and tempered by the material I can get and tools I have.

The basics on mine are-- 1.25" (nominal) type L copper pipe x 85mm for the main barrel (type M is probably OK, but I went with overkill). The smokebox takes up the front 20mm or so of the barrel (I have half a pipe coupler over it for looks and to provide a recess for the smokebox door), so the boiler section is about 65mm long. There's one flue of 3/8 (nominal) pipe at the bottom of the boiler. Bushings for a steam dome and filler valve. Butane fired.

Instead of silver soldering the boiler I spent today making a pressure-test pump along the lines of Dick Summerfield's plans and silver soldered a lot of that to get practice with the new Cd-free solders. Yeek.. I'm not used to the bright-orange heat this stuff requires. Must remember to order some of the bad stuff before they ban it completely (it's already illegal to sell Cd-bearing solder in this town ???)

Pretty basic plunger-pump, but it should get the job done.. if I can manage to hang onto the frackin bearing balls long enough. I started with 4, need two and only have one left :-\ Two are somewhere in the shop debris, no doubt far under something inaccessible and one is locked in a mistake of a part (mental note; do not tap 1/4" balls into blind 1/4" holes and expect them to come out again, ever... De-metrification in my head and not writing it down got me on that one).

 

[Macca]

This is fantastic.
I must have missed this thread earlier, but am now ravenously devouring all the info I can find on both cracker and cricket.
Before I saw this, I didn't have any interest in model locomotives, but I now have another thing to add to my list.
All I need to do now is find a few extra hours in the day.

 

[Powder keg]

This is looking pretty neat Shread. Keep up the good work. I've alwayse wanted to build the Fizz Wizz car;o) Maybe this winter?

Wes

 

[shred]

This is fantastic.
I must have missed this thread earlier, but am now ravenously devouring all the info I can find on both cracker and cricket.
Before I saw this, I didn't have any interest in model locomotives, but I now have another thing to add to my list.
All I need to do now is find a few extra hours in the day.

Me too. Beyond a train set as a kid and a healthy interest in the full-size units, I've not the patience or time to build and run a serious live steamer, but this will run on O-gauge track, and I could probably stretch my interest enough to get a loop of that around the tree I'm considering some optional 'road wheels' too, but don't know if's going to have enough oomph for that.

One good resource for little live-steamer info is the 16mmngm modelloco16mm yahoo group-- that's where I found Tony's Cracker writeup.

I'm going a little light on the details, since boiler construction is covered so well over in the Small Boiler thread, but if anybody has more Q's or wants to see more pics, let me know.

 

[shred]

I think I'm getting the hang of the Cd-free silver solder now. When you can see what you're doing by the light of the workpiece, you're just about there

It turns out my silver soldering is far better than my plumbing.

I got the boiler soldered up last night and it's pressure-testing now. Spent a few hours looking at one piece of 1/4" copper tube and one piece of 1/4" plastic tube and trying to figure out how to join them together... $1.50 at the hardware store is the easy answer, but... they're closed today.. so I soldiered on with what parts I had. That turned out to be a problem. I figured out a mishmash of parts that got me there and made a few adapters, but all the screw joints created a leaky mess, so I had to go chase around with the teflon tape to seal them all up. I used a small valve to convert some odd pressure fitting to 1/4 NPT (the mating part if you look closely is an air tool fitting drilled out and soldered on-- I discovered too late my 1/4 NPT tap had run off and had no desire to learn to single-point NPT at the time), but turned out to be useful too; the pump check valve leaks enough that I had to use that valve to shut off the backflow once I reached pressure. The pump otherwise worked surprisingly well and can generate plenty of pressure.

There's still a tiny leak in the plumbing somewhere and I suspect the valve since nothing downstream is at all wet.. after 15 minutes the pressure has dropped 5 PSI, but there's no water evident anywhere around the boiler and it holds 80 PSI without objection.

 

[Macca]

That's great shred! Did you have a link for that pump? I tried searching for it but all I could find were sites promising to (quite painfully I would imagine) increase the size of my manhood.

 

[shred]

found it in the [modelloco16mm] Yahoo group (btw, that's where I found Tony Bird's writeup vs the other group I mentioned). As usual, it's a metric plan, but doesn't take a lot of work to adapt to imperial and is extremely tolerant of design modifications. I've attached the version I split to make it easier to print.

The only issue I ran into was using 1/4" balls. Were I to do it again, I might get 3/32" or so, so I could use a 1/4" endmill to do the flat-bottomed holes. The other mods I did were to use one piece of 3/8" drill rod for the piston and chrome steel balls since that's all that was available locally-- for occasional use they're ok, but you have to fish themout and WD-40 them right away or they'll rust. You'll also note that my piston cylinder is much shorter than the plans call for-- I had a piece already bored for a nice slip fit onto 3/8" drill rod in the junk box and it works fine.

 

[shred]

Not as much progress on the loco as I was hoping for-- the safety valve is on hold until I get proper bearing balls, and I got a new idea for the filler valve (Goodall style) that will require a trip to the hobby store tomorrow for some silicone tubing, but I did get a few things done-- started a steam-dome cover, banjo fitting for the filler/steam dome (which will need to be redone), temporary smokebox door and stopped some pesky squirrels from chewing the bottom off my birdfeeder ;D

 

[J. Tranter]

Since I saw this thread I have been wanting to build one. I have some questions if you don't mind.
How did you build the steam dome? How is the smoke box door attached? And can you show more pics. of the build process on the boiler that is what I'm having more trouble with.
thanks for all your help.
John Tranter

 

[shred]

Since I saw this thread I have been wanting to build one. I have some questions if you don't mind.
How did you build the steam dome? How is the smoke box door attached? And can you show more pics. of the build process on the boiler that is what I'm having more trouble with.
thanks for all your help.
John Tranter

No problem with the questions. I'll dig around and see what more pics I have on the boiler build.

As for the steam dome, I just remade that with a banjo-bolt fitting below a filler-valve. In the plans, the front bushing is used for the fill valve, but I wanted to put a safety there instead. The rounded dome cover is just a 1/2" copper pipe cap I annealed and hammered into dome-shape with a spherical doming punch and block (you can still see part of the 'nibco' stamp on it ). I cleverly took the photo so it looks like it's attached, but really it's just sitting over the safety bush. Once I get the plumbing run from the banjo bolt, I'll file it to shape on the bottom and drill the top to fit the filler.

The smokebox door is just a light push fit into the front of the smokebox. I plan to redo that as well-- I had some 1.5" Alu bar in the lathe and whacked it out just to have something to fill the hole while I did a steam test on the boiler. To remove it, I remove the smokestack and the smokebox (those aren't soldered yet) and poke it out.

 

[shred]

Here's more on building the boiler. Here's how I did the end plates:

I probably did these in an inefficient manner. Since there's no central hole, I formed them without holes, then drilled them for the flue after they were formed. In hindsight, it might be better to drill a hole in the flue area and use that to mount them to the forming mandrel with an off-center mount screw to avoid some of the faffing around with a c-clamp I had to deal with. Anyway, here's what I did, starting with a foot or so of 1-1/4" copper pipe:

First I bandsawed a short length (~2") off the end of the copper pipe (if the pipe wall thickness is enough for end plates, otherwise get some flat stock of the right gauge), then sawed that into two half-pipes. Annealed and flattened those into rough squares. Marked out a circle the diameter of the tube ID plus 1/2" to give 1/4" flanges, then rough sawed to that circle. In retrospect, I should have rough sawed a lot closer. I just kinda knocked the corners off the squares which meant I had to do more trimming later during forming.

Then I made up a forming mandrel out of 1.5" Alu bar I had in the short-ends box. Steel or something tougher would probably be better, but the Al worked. You can see the mandrel in the lathe chuck in the 2nd picture, but most of the time I used it in the bench vice, so I thought milling the reverse end into a thick rectangle for ease of gripping in the vice was a clever idea. The front end was turned to the ID of the tube minus two thicknesses of the end plates.

I then clamped the rough flat circles on the forming mandrel with a C-clamp and started tapping the copper edge down around it to form the end plates. I annealed a few times along the way and after the shape got close and the plate didn't move so much, skipped the clamp and just held the former in the vice. After I had two plates looking like the first picture, I set up to clean them up in the lathe.

For the lathe work, I used a variation on Bogstandard's 'friction turning' method for flywheels posted elsewhere here-- I put the mandrel in the 3-jaw, the plate on it, then a short length of scrap rod with both ends cleaned up and a center hole in one and masking tape on the other, slid the live center up tight to hold everything, and by taking light cuts, trimmed the end plates down to a light push fit in the tube and cleaned up the ends. That setup is in picture #2

(btw, I found some miniature boiler test-to-destruction results showing that in this size boiler flanged plates aren't strictly necessary for full strength, but I wanted to try it anyway)

 

[shred]

Here's drilling the boiler tube. Not much to say except the step drill works remarkably well. Mark on the drill with a marker the step(s) to stop at and drill away (well, pop and drill a pilot hole first). I did the drilling in the mill for better control of the hole location. I also used the step drill on the end plates for the flue. It's convenient that the pipe sizes available matched the step drill sizes so well. A little scraping with the deburring tool and it was good to go for silver soldering.

Sawn tube ends can be cleaned up and faced to exact length in the lathe, but be careful-- if a tool digs in and catches, it's instant scrap for that part.

 

[shred]

Btw, some good Cracker building info and pictures here: http://www.16mm.org.uk/mom2008-10.htm

 

[J. Tranter]

Thanks for your write up. I joined that group after you mentioned it when you started to show the boiler.

On the end plates did you just hammer them in to shape or did yo use a press with a form.
thank you again
John T