Replacing bolster pins with screws...

[mmagliaro]

A few times, when I have gotten fed up with pins that keep loosening, I have used screws.   I slice off a short length of 1/8" styrene tubing which very neatly fills the MT bolster hole, with a 1/4" 2-56 screw right through it, up into the body.   I just did this today on an IM stock car with pins that kept annoyingly working loose.  I use machine screws, not tapping or any other type.  They can self-tap into plastic very easily.

But I don't think I'd replace every pin with a screw.  No need to.

[davefoxx]

But I don't think I'd replace every pin with a screw.  No need to.

I agree, Max.

Coincidentally, I just bought an old HO scale IHC passenger car, which, surprising to me, had bolster pins.  Unfortunately, the car also had severe side-to-side rocking.  The plan to correct this was to tap and install 2-56 screws, but the holes in the car were too large.  So, I found some coarse thread screws that came from other projects and just self-tapped that right into the plastic bolster.  The car rides much better now.

DFF

[Sokramiketes]

For those using screws, I finally ran across an easy way to add the shank to the screws to fill up the bolster hole in the trucks. This tubing cuts much cleaner and faster than styrene tube.

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[narrowminded]

I've not seen any issues crop up as yet re moving screws in more than a year.  If that were to become a problem, you could probably just use a threadlocker...or some tacky glue.

A word of caution on using Loctite on screws going into ABS, which is a common plastic in model trains.  When in contact with ABS (and others, check Loctite for specifics) the plastic is embrittled and will mysteriously shatter where contact is made.  The plastic becomes harder than glass.  I learned this the hard way on a work project. 

The warning that appeared on the Loctite bottle was, "May attack some plastics".  Well "attack" to me meant soften like acetone or MEK does so I tested a piece, no evidence of "attacking", or softening of the ABS insulator block so went ahead and applied Loctite to the mounting screws on hundreds of computer docks we manufactured.  The following day there were little black shards of plastic laying all over the bench where the completed units were lined up for packaging.  A little inspection and found the shards had come from the vicinity of the bolt holes where the loctite had been applied.  Just the off gassing did it.  There were small chipped craters in the vicinity of those holes and they continued chipping while sitting on the bench untouched.  I was VERY pissed.  I called Loctite to see if ABS was one of those plastics that got "attacked" and they said, "Yes, it is one of the worst.  It is embrittled when in contact or in the immediate vicinity of uncured Loctite."  The effect takes about eight hours to surface and once it starts it continues for another eight or so.  Now I was REALLY pissed.  Why in the wide, wide, world of sports didn't the warning say "May embrittle some plastics?!"  As you might detect in the post, all these years later that still pisses me off every time I think about it.   

OK, I'm better now.

[peteski]

Loctite threadlocker is designed for metal-to-metal contact.  I would have never even through of using it on any sort of plastic.  I have seen the warnings on the bottle and now seeing Mark's experience looks liek I made the right decision.

I have not looked at the MSDS for it but I have in the past, but IIRC chemically Loctite is somewhat similar to CA glues.  I have used slow set CA as a threadlocker with metal screws installed in plastic.

[narrowminded]

Loctite threadlocker is designed for metal-to-metal contact.  I would have never even through of using it on any sort of plastic.  I have seen the warnings on the bottle and now seeing Mark's experience looks liek I made the right decision.

I have not looked at the MSDS for it but I have in the past, but IIRC chemically Loctite is somewhat similar to CA glues.  I have used slow set CA as a threadlocker with metal screws installed in plastic.

As long as one side is metal it will cure.  The curing time will be slower but it will cure.  And one plastic material that IS compatible is Delrin/ Acetal.  And the stuff comes in plastic bottles so obviously there are others that are safe.  If in doubt for a specific application do some research on Loctite's website.  It's there somewhere.  I know ABS is bad news but I think Styrene is, too.  Worth a check if ever tempted.

One thing that can work for applications in doubt is to just put a little bit of silicone on the threads.  That's enough to foul the thread and keep a screw from walking out but can always be disassembled with the proper tool.

[SkipGear]

Never use Loctite on plastics. It ends up attacking the plastic as Narrowminded mentioned and usually ends up with the opposite effect, acting as a lube and causing the screw to back out easier. This comes from years of experience in the RC car hobby....the correct solution in plastic is a smaller hole or a bigger screw.

One solution that works is Micro Krystal Clear from Microscale. It works well on sloppy king pins but can still be removed easily.

[mmagliaro]

I must say, I've never seen any thread locker destroy plastics like this.  I've seen them not work very well, but not cause damage.  But then, the only places I think I've ever used it on plastic are on metal-to-Delrin, and Delrin seems to be one of the plastics it doesn't attack.

[Chris333]

Thread lock works from a reaction to metal.

[carmelmodelrr]

I've tried to order the above-mentioned screws from Amazon and they say they are out of them and don't know when--or if--they will re-stock them.  Has anyone found an alternate source?  I can't locate one on the internet.

carmelmodelrr

[mmagliaro]

They are just 1/4" long 2-56 thread machine screws.  You can even get them at your local Ace or other hardware store.

Here's an Amazon link for some others (there happen to be black oxide, which might be nice if you want a black screw):
https://www.amazon.com/Machine-Finish-B18-6-3-Phillips-Threaded/dp/B00F34TWZC/ref=sr_1_3?keywords=2-56&qid=1649640988&s=industrial&sr=1-3

[John]

I just took apart some old cassette tapes to recycle .. they have some small screws in them that might work .. .

[SAH]

I've been using the kingpin itself.

MT and Atlas kingpins have a built-in centering dimple.  Use it as a guide and drill a 00-90 #61 tap hole all the way through the kingpin.
Tap the hole for a 00-90 screw.
Slice the part that goes into the bolster from the part that goes through the hole in the truck.
Force fit the part that goes into the bolster.  A tiny bit of CA will hold it in place if the fit is loose.
Drill a 00-90 #55 clear hole in the other part.
Use a 00-90 screw to hold the trucks to the bolster.

I've also used 4-40 or 5-40 machine screws (depending on the diameter of the truck hole opening) doing away with the kingpin altogether.

[nickelplate759]

I've been using the kingpin itself.

MT and Atlas kingpins have a built-in centering dimple.  Use it as a guide and drill a 00-90 #61 tap hole all the way through the kingpin.
Tap the hole for a 00-90 screw.
Slice the part that goes into the bolster from the part that goes through the hole in the truck.
Force fit the part that goes into the bolster.  A tiny bit of CA will hold it in place if the fit is loose.
Drill a 00-90 #55 clear hole in the other part.
Use a 00-90 screw to hold the trucks to the bolster.

I've also used 4-40 or 5-40 machine screws (depending on the diameter of the truck hole opening) doing away with the kingpin altogether.

Clever!

[Sokramiketes]

I've been using the kingpin itself.

MT and Atlas kingpins have a built-in centering dimple.  Use it as a guide and drill a 00-90 #61 tap hole all the way through the kingpin.
Tap the hole for a 00-90 screw.
Slice the part that goes into the bolster from the part that goes through the hole in the truck.
Force fit the part that goes into the bolster.  A tiny bit of CA will hold it in place if the fit is loose.
Drill a 00-90 #55 clear hole in the other part.
Use a 00-90 screw to hold the trucks to the bolster.

I've also used 4-40 or 5-40 machine screws (depending on the diameter of the truck hole opening) doing away with the kingpin altogether.

Sounds like we just need to 3D print the right size parts. But this makes sense.

I’ll try something similar on this car, in your honor Steve. It still needs trucks mounted.

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