Northern 4-8-4 Build 3/4”

[Odyknuck]

Bill you are correct as in any process of machining there needs to be a sequence of events so as to not box yourself into a corner.

[bushav]

Hallelujah! The Union links are finished. These guys took quite a bit of time for me. Made them twice as I over drilled the first ones. I didn’t take into account the threaded area. Ughhh. The second set turned out quite good if I’m allowed to appraise my own work.

Used a rotary table to go from this to that.

IMG_5396.jpeg (912.03 KiB) Viewed 1256 times

Nice!

IMG_5397.jpeg (949.89 KiB) Viewed 1256 times

[Bill Shields]

[NP317]

RussN

[Odyknuck]

Having to make parts twice is not uncommon, been there done that! Nice job.

[Bill Shields]

having to make them ONLY TWICE is cool....

[Bill Shields]

You may find that your fork opening is not long enough to keep from binding on the combination lever when the crosshead is full forward.

Most of my links have "squared out" fork openings to provide just a little extra clearance when un FULL GEAR position.

[Greg_Lewis]

You may find that your fork opening is not long enough to keep from binding on the combination lever when the crosshead is full forward.

Most of my links have "squared out" fork openings to orovidw just a littke extra clearance when un FULL GEAR position.

"Orovidw." A technical term. It's the impingement of the inverse catch finger on the oscillating scratch gate.

[Bill Shields]

that's geek talk for 'provide'

[bushav]

Big day today! I finished one of the combination rods and took a chance on trying to run the locomotive on the left cylinder only. The first step was to put some thought into how to make sure the valve and piston were positioned correctly within their respectived bores and the eccentric rod was positioned correctly. In my video you can see some timing marks I made so I could see the throw of the valve and piston. I basically just made sure the piston and valve were centered when they should be centered. I had to adjust the valve several times and did this by adding air and letting the air vent out the cylinder drain cock holes. Using this method and watching the timing marks I could keep adjusting the valve until the cylinder starting venting air from the front cylinder drain and the back cylinder drain at the proper time and in a balanced manner (Choo Choo not Chooooooo Cho). I then plugged the drain cock holes with a couple of ugly 8-32 screws (scale for full size airplanes not 3/4" locomotives). Air was added and low and behold the wheels took off running. I could throttle it down to a low rpm and then rev back up. Keeping the air on I could adjust speed with reversing rod and run in reverse. I've got to resist running again until I get the other combination rod built and get everything tightened down. I still need piston rings, drain cocks, and head gaskets to really see everything run like it should. I believe I am going to build a model vertical boiler and run the locomotive on an external boiler before I start building the real boiler. I need to practice building a boiler before I start cutting on my $1,000 copper tube I got from the UK. This will also allow me to see if the locomotive will run properly on heated steam. I assume I am not the first guy to try this test method? I will definately have a bourbon and sleep well tonight

To see my posted video click on the link below.

https://www.youtube.com/watch?v=4N5avfVqUIk

Lane

[Charles T. McCullough]

Glorious! Yummy! I am sure you feel good, given how good I feel seeing it run!

[Odyknuck]

That,
That's awesome, keep up the good work.