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.
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
josephbwI 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.
-Matt
Returning to model railroading after 40 years and taking unconscionable liberties with the SP&S, Northern Pacific and Great Northern roads in the '40s and '50s.
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.
I had the same problem with my loco (broken tabs). Changing the cab solved it.
Simon
OvermodThe '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.
snjroyYes, on the 2-6-2, two plastic tabs slide onto the frame and hold the cab and boiler at the rear of the engine.
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.
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.
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.
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).
'
MattYou 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=threadlockThe 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.
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.
RR_MelIt’s hard to determine where the screw would terminate in that drawing. You obviously have the locomotive opened up, can you tell where the threads would be.
crossthedogI do know that there are four screws aft of the one we've been talking about
A = This hole is where Ye Vexsome Fastener goeth.
B = Short screw holding the pilot truck, temporarily removed.
C = This screw holds the plate over the axles.
D = D for 'ditto'
E = This screw reaches through the chassis to hold the motor plate.
F = This screw holds the back end of the plate over the axles, and also holds the trailing truck.
G = Short screw holding the tender bar.
As far as I can tell, only A and E go all the way through the chassis. If you remove A, you leave the boiler on the cradle. If you remove A and E, you leave the motor lying in the boiler.
@Kevin, I am nonplussed by your statement.
snjroyMatt, if you can reach the thread and engage the screw directly on the boiler, without the armature, then you shoud be able to assemble the piece together. With the loco on its back (get a good craddle if you don't have one), insert the screw through the armature. Lift the armature with one hand and look underneath to align the screw in the hole of the boiler. Once aligned, gently push the armature down against the boiler and turn the screw. There should be no gap between the boiler and the armature once the screw is tight. If there is a gap, something is preventing that - could be a loose wire or flash. By the way, there are two other screws at the other end of the engine, as you know. Put these in last. But I've had Mantuas where I had to insert all the 3 screws and engage them in their holes, without tightening them completely before all of them were engaged in their respective holes. Otherwhise, the angle would prevent the insertion of the other screws.
With the loco on its back (get a good craddle if you don't have one), insert the screw through the armature. Lift the armature with one hand and look underneath to align the screw in the hole of the boiler. Once aligned, gently push the armature down against the boiler and turn the screw. There should be no gap between the boiler and the armature once the screw is tight. If there is a gap, something is preventing that - could be a loose wire or flash.
By the way, there are two other screws at the other end of the engine, as you know. Put these in last. But I've had Mantuas where I had to insert all the 3 screws and engage them in their holes, without tightening them completely before all of them were engaged in their respective holes. Otherwhise, the angle would prevent the insertion of the other screws.
I do know that there are four screws aft of the one we've been talking about, all in a short line. Two of these hold the pilot truck and the trailing truck to the chassis, one holds the plate over the axles, and the fourth reaches through to hold the motor in place.
But I will look for these other screws you mentioned, and thanks for the suggestion.
Matt, if you can reach the thread and engage the screw directly on the boiler, without the armature, then you should be able to assemble the piece together.
I hope this helps.
Matt... I wish you lived close by.
I could invite you over and show you how to fix it, but I have no desire to write a complicated 10,000 word instruction or make a 20 minute video.
Sorry.
-Kevin
Living the dream.
Thanks for everyone's input here. Just to provide some temporary closure on this, I think I may have figured out all the bizarre twists (threads) in this mystery. For one thing, I tried putting the screw in while holding the loco right-side-up, thinking maybe the weight would sit tighter against the bottom of the boiler, but this didn't work and really, I didn't expect it to once I had the front of the boiler off. The weight is cylindrical and fills up the boiler's interior space, so it doesn't move.
However, there was that piece of info I supplied in my last post -- that the screw still bites when it doesn't have to go through the chassis. This suggests that there are still threads in the hole in the boiler (or the weight, whichever).
Looking at the screw through a magnifier I believe I could see that the very first two or three threads (where the self-tapping part is) are worn away. I think this explains why the screw will not bite through the chassis but will bite through just the boiler. Those missing threads mean that the screw's "grabbing length" is shortened and it cannot reach the threads in the hole.
I ordered a replacement screw. Nine cents, and eight dollars shipping. The new one will not have the taper because it is not self-tapping, so I am hoping that it will be wide enough to grab the sides of the hole at the bottom. I figured this is the easiest and least disruptive thing so I'm trying that first.
I'll follow up here in a week or three to let everyone know how the quest is going.
Somewhat akin to Dr Wayne's suggestion -- I have used this on big things like screws on a garage door that came loose and could not be tightened, so obviously the inner threads were stripped -- a small tip of a toothpick into the hole, with just a bit of glue or cement on the wood. The screw crushes the wood enough that it finds the "good" threads for lack of a better term. This might be easier than finding a larger screw that will otherwise work given what else the typical Mantua/Tyco design expects that screw to do
Dave Nelson
Matt,
From Your description of how the screw does not seem to bite threads in the hole leads Me to believe that the weight did almost exactly what You describe. You're missing the hole when You attempt to tighten the screw.
Good Luck!
Frank
I put in the above before reading whole thread. I'll blame it on My age..lol.
Anyway, after reading the whole thread, I believe You have a part of the Locomotive not seating properly in the assembly stopping the screw from grabbing any threads in the hole. Could be a wire or part. I had a similar experince with a old AHM Dockside I was repairing for a friend. Somehow the screw got shorter???
Nothing like a good mystery novel, that You may have created without knowing.
I agree with the larger screw solution. I doubt epoxy would hold very long.
doctorwayneThe easiest fix (not necessarily permanent, but easily redo-able) is to slip a small strip of styrene, perhaps .010"x.030" and roughly as long as the screw, into the hole, then re-install the screw.
But first, here's the new weird news: I was curious about what people were saying about a weight inside the boiler so I removed the boiler and its front cover to have a look. The weight doesn't move and there's not room "above" it for a nut, and no way even to see where the screw ends. But get this -- when I put the screw in JUST the boiler hole -- that is, without going through the chassis first -- and turned it gently it grabbed immediately and firmly.
I'm not sure what to make of this. It's the same screw, and this screw used to bite, and it's the same screw that now doesn't bite when inserted through the chassis, even though I checked to make sure the chassis was seated firmly against the boiler. But it suggests that if I had a slightly longer screw it might hold the chassis and boiler together.
So I have a number of simple fixes to try and then a stairway of increasingly drastic measures I can try.
Thanks all,
The easiest fix (not necessarily permanent, but easily redo-able) is to slip a small strip of styrene, perhaps .010"x.030" and roughly as long as the screw, into the hole, then re-install the screw.
This generally creates enough interference to keep everything held together. If you later need to remove the boiler for maintenance, I'd suggest removing the styrene strip, and replace it with an identical one when re-assembling the loco.Filling the original hole with epoxy and trying to re-tap it to the original size will likely result in the same sloppy fit.
If you want a permanent fix, I'd opt for a larger diameter screw..either a 3-56 or a 4-40.
Wayne
Repair it
https://www.mcmaster.com/helicoils/thread-size~2-56/
Some of my brass engines with boiler weights use these threaded inserts in order to prevent thread "tear out" just as you have experienced:
https://www.amazon.com/Tapping-Inserts-Combination-Slotted-Furniture/dp/B07GB78C4W
* these are metric. I'll try to dig up a fractional set.
I used to make some repairs in cast iron or other stripped holes using what we called Helicoils. They are available in many sizes and materials.
https://www.mscdirect.com/product/details/00060038
Self tapping screws are good for the first assembly. After that if the threads don't catch in exactly the same orientation they wind up cutting out even more precious material.
As others pointed out you might want to find a machine screw with full threads to the very end which would give you more engagement with the metal. Perhaps there's a chance to find or make a screw that's an eighth of an inch longer.
Good Luck, Ed
Guys, wow, thanks! So much good insight here. I didn't know, for example, that I could get into the boiler. I haven't tried it, but when I get a chance to get to the garage I will do so.
And who knew there was a weight in there? That give me a new thought... what if the reason the screw is not biting is because it is only intended to bite in the weight, and since the locomotive is upside down in the work cradle, the weight fell down, or moved just enough that the screw cannot reach it? Possible? If that's the case, I may be able to get the screw back in just be trying it while holding the loco upside right.
Anyway, lots of good ideas here. I'm very grateful.
Thanks,
If all else fails, you could drill the hole all the way through the weight in the boiler weight. Get a length of 2-56 threaded rod and make a length that would reach through it, to a nut on top of the weight and another under the plate you need to hold up. (Unless you can find a 2-56 screw long enough.)
Or you could run the rod up into the smoke stack and epoxy or superglue it and just put the nut under the bottom of the plate.
Dan
I would look for a slighly larger/coarser screw and see if you can work the tip into the topmost orifice into which it's tip normally inserts. Retap if you must.
Or, bore oversized that topmost orifice, fill it with a plug (brass tubing....too soft??) that is tapped to the screw's exisiting specs, and you're back in business.
That screw goes through the smoke box, and into the weight.
The threads in the weight may be to blame. Depending on what metal the weight is made out of, you could just melt some solder and pour it into the hole. Then use the screw to re-tap the threads.
Or: get a slightly larger diameter screw.
Rust...... It's a good thing !