Mel, sorry I didn’t address your question sooner. I can’t see where the screw terminates because that giant weight cylinder (item #4919 in your figure) fills up the entire boiler space and doesn’t seem to move. I tried gently pushing on it but it seems pretty content to be where it is.
Oh, I did not notice that this is the little Prairie model. I have one of those. You are correct, the cab has two slabs that slide in the frame. Make sure that they are not broken (mine had a broken one when I bought it used, I had to change the cab). No need to play with the other ones. Especially the one that holds the motor…
Hopefully, with a longer screw, you will be able to reach some thread.
Simon
Matt
You mentioned that you were able to get the screw to engage the threads. So a longer screw would work. I would simply use a 2-56 all thread with a 2-56 nut then flush cut the all thread.
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2060353.m570.l1313&_nkw=2-56+all+thread&_sacat=0
I keep all sizes of all thread in my stock for fixes like this one.
To prevent the nut from coming loose I would use a drop of Threadlock BLUE, simi-permanent.
https://www.harborfreight.com/search?q=threadlock
The Harbor Freight Threadlock Blue works great for crank screws too.
Mel
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
Turned 84 last July, aging is definitely not for wimps.
I suggest this:
With the lead truck removed, you can easily see the ‘bottom’ of Hole A, and can easily insert something as a ‘feeler gauge’ if not.
Put the boiler ‘correctly’ on the cradle, with the screw inserted down into the correct Hole A as far as it can be inserted – this is the condition you report as not engaging. While holding down the head of the long screw so it stays ‘bottomed’, turn the chassis so you can observe how far down into Hole A the screw actually goes. If necessary, gently ‘feel’ the depth with some sort of thin probe, and record the distance to the physical bottom of the screw.
Then, remove the boiler and see how many turns into Hole A the screw needs to be turned before it clearly engages. NOTE that I wouldn’t be surprised if it feels like it is ‘threading in’ but you could pull or wiggle it out of the first few threads…
The measurement you pulled in Step 1 will give you a more-or-less direct measure of ‘how much longer a screw’ will engage the threads in Hole A right down to the bottom but not foul the engine-truck pivoting. If this is not a ‘whole number’ length it will tell you how far to stone the screw end down, put a pilot end or conical end on it to simplify engagement, etc.
We can address ways to improve the threads in Hole A if necessary, and figure out what the arrangement at the rear of the chassis to retain the boiler casting at that end is now (perhaps “modified” over the years).
’
Just to tidy up here:
A new 7/8" machine screw from FMW Fasteners did the job. It would have been better if it had been 1/16" shorter in length, because the last few turns were pretty stiff, but it went down almost to the head. There’s not room for a washer.
Someone mentioned that I should look for a corresponding screw at the back of the locomotive. Instead, there are two knobs on the plastic boiler/cab component that fit down into slots on either side of the chassis. I suspect these knobs were L shaped at one time so that they sort of “locked” the cab end down when the front screw was tightened, but it appears that the bases of the Ls were broken off. Hard to tell, they’re tiny. Anyway, the front screw holds the whole engine together well enough so that you can pick it up off a track without it falling apart.
I also found the wire for the headlight folded up in there. I tested it with a battery and the bulb lights up a little. Someday I’ll figure out what that wire should be connected to, but I’d rather wait until I “learn up” about LEDs because I’d like my locos to someday have bright headlights.
Thanks everyone for the ideas. I’ll flag this post because the fat lady may not have sung on this one yet. I’m not sure the screw will work if I take it out again.
-Matt
The ‘washer’ on an arrangement like this is made of brass or plastic tubing that just fits over the threaded shaft of the screw, cut to as short a length as allows the screw to bite up to the point it starts to ‘hard thread’ as the screw head seats solidly on the tubing.
If the tubing tries to slip through the hole in the boiler or ‘cock’ in the hole, use something like the tapered part of a punch or nailset to mushroom-cone one end of it out a little – the coned end goes down.
Yes, on the 2-6-2, two plastic tabs slide onto the frame and hold the cab and boiler at the rear of the engine.
Simon
Overmod, I assume you’re meaning that the tubing would have a diameter only as wide as the screw head, because that’s the issue here. There’s an adjacent portion of the chassis very close to the hole, which impedes putting a normal washer there. Thanks for the suggestion.
Not anymore. But thanks for confirming my assessment. I’ve been trying to think of a way to reëngage those knobs, but it would amount to some serious microengineering.
-Matt
I had the same problem with my loco (broken tabs). Changing the cab solved it.
Simon
I’ve had similar problems throughout the years and I came up with a fix that has always worked just fine for me.
I took a flat toothpick, broke off the pointy end, and inserted it into the hole followed by the screw. I’ve never had that process fail me in all the years I’ve done it.
Joe
Joe, does this solution stay viable after you’ve removed the screw a time or two? Say, to do maintenance like lubing the bearings?
-Matt
I don’t think I’ve ever had to remove one after performing that operation. If it was me, just to be safe, I would just break off another piece and start over. You are still only into it for less than a penny.
Joe
I was thinking from the prior description that the screw went down the stack. You could drill to the bottom of the stack to get a good tapered seat… in which case you would just let the bottom of the tubing piece ‘center’ as it bottoms.
If you have a ‘rib’ or other irregularity, file a notch or cut out the side of the tubing. The ‘rest’ of the periphery should hold it.
Note that the ‘toothpick repair’ will be more permanent if you use a little white glue or Ambroid on it before inserting in the hole. Put a drop of corn oil on the screw end before inserting it, or use some other release agent, if you don’t want to wait for the glue to harden but don’t want the threaded end to stick hard to the repair.