Railroad Warehouse 2.8.2 Mikado Logger Build

[Odyknuck]

Awesome! I love CNC machine work. It produces functional art.
Those crossheads will meet your needs!
RussN

Thanks Russ, they sure do look nice, more importantly they will give me the very much needed accurate base to work so all the parts function correctly. While we were making them, we used the old just for a reference and discovered the piston shaft centers to the slider bearing surfaces were .044" shorter than spec. This explains why I could not get the piston shafts parallel.

[Odyknuck]

So, it occurs to me that I have a coal burning stove to supplement heat in my house. Can this be used as a heat-treating oven for this steel? Also, would I still need the Heat treat compound and how long would I leave the links embedded in the red-hot coals?

Hmmm. Not sure about that. It's desirable to use the correct temperature, which you most likely could not do.
The harsh reality is if you have red hot coals, they alone may provide the needed carbon. Think of a blacksmith's forge. As long as the piece is surrounded by carbon and is heated to the critical temperature, you're bound to achieve some degree of carbon absorption. What would be important, then, is that you don't expose the heated piece to free oxygen. When one pack hardens that doesn't happen, so the part isn't altered by oxidation (scaling).

You should also understand that heating a piece in the open (or in an oxygen rich atmosphere) can be the cause of carbon loss. That's why they talk about decarb when you purchase tool steels. The outer surface (which has had the needed carbon burned out) has been removed so the material will heat treat to specs.

H

Thanks for all the information Harold, as I have a little better understanding of how heat treat works. At this point I think I will run with what I have and make the Bearing blocks from 954 Bronze. If it wears quickly, we will remake the parts from better material with an EDM. Fortunately, my Buddy has one in his shop.

[Odyknuck]

Not much work done this week however I did get the Pilot truck completely assembled and ready for install. Need to get it mounted so I have a better ideal on where the drivers sit when I start Valve Gear work soon.

[Odyknuck]

I also finished up the Cross Heads. Drilled the mounting holes in the other Slide bearing. Drilled and tapped the required holes in the Cross Heads. This is where the DRO comes in handy. Set the first one up and move over .500" per hole. In lieu of running a taper in the Cross Heads as per print I decided to just thread them 3/8" - 24 and use a lock nut on the back side. This was a suggestion from RussN to allow adjustment for the piston in the bore. I still need to remove the taper from the piston rods and continue the thread. Worst case scenario, I make new shafts.
First Pic is a comparison of the old and new Cross Heads.

[NP317]

Excellent progress on the crossheads.

When you mount the pony truck be sure to modify required clearances for lots of vertical motion.
With the loco sitting on its drivers, let the front end hang over the end of the track stand to test vertical motions.
I had to modify mine that way after experiencing derailments on rough track.
I tested the loco on the nastiest track I could find, and learned a lot. The radius bar required modifications.
RussN

[Odyknuck]

Thanks Russ. Did you elongate the pivot hole to alleviate the issue? If so, did you also need to remove material above and or below the mounting bar(s)?

[Bill Shields]

So, it occurs to me that I have a coal burning stove to supplement heat in my house. Can this be used as a heat-treating oven for this steel? Also, would I still need the Heat treat compound and how long would I leave the links embedded in the red-hot coals?

as for using a coal stove for heat treating -> got any ZERO Sulphur coal?

parts have to stay heated until they meet the time / spec on the compound.

I generally heat them up on a piece of steel heated underneath by my oxy torch. I then measure part temp with one of these hand held IR temp sensing things. This measurement would be difficult if the part is inside a coal stove...unless it was sitting on a sheet of steel as described above.

when part is up to temp, I drop it into the can of Kasenit, or roll it around in a shallow pan full of the stuff to get the part fully covered and let it sit until cool.

Not rocket science....try it on a few random pieces of whatnot before you go after a finished part.

[NP317]

Thanks Russ. Did you elongate the pivot hole to alleviate the issue? If so, did you also need to remove material above and or below the mounting bar(s)?

Yes and yes. I may even have hinged (!!) the radius bar...
Need to look at it... 'Will snap a pic to share if true.

I honestly don't remember the details.
Something to do with my wife's second paralyzing stroke... (She's OK again now!)
Russ

[NP317]

Yes, I did hinge the radius bar, as crazy as that sounds! And slotted the radius bar pivot hole to prevent fore-aft binding.
Pic attached.
Fortunately the operating forces are not on the hinge which successfully allows increased vertical motion of the pony truck.
So far so good.

This scale Mikado design seems to follow prototype drawings accurately. This is not a good idea when it comes to the required increased flexibility of the model locomotive. Experience speaks loudly.
RussN

D2A39DB6-0BB9-4885-B4E4-438CB0D4B7CB_1_201_a.jpeg (211.1 KiB) Viewed 90 times

[Bill Shields]

FWIW a solution I used involved a cheap spherical rod end bearing.

[NP317]

Bill:
That is a good idea.
However...This locomotive would require serious frame cross-bar mods from the beginning to accommodate the ball fitting.
And I had no idea the increased flexibility would be needed when the frame was built per the scale drawings.
Which is why I offer my modification here for others potentially building this Mikado.
RussN

[Bill Shields]

Ah...I recognized the need during design and included it. Was not aware of tight quarters in your situation.