drill the hole out and fill the new larger hole with a good epoxy (cat epoxy, marine tex). after hardening you can drill and tap the hole. I have seen a tooth pic set into the epoxy to make the drilling easier to keep centered.

here is another option.

http://www.ezlok.com/inserts-f...hreaded-inserts/kits

Andre.

Loctite Form-A-Thread might work.

Is it possible to post a photo of what is stripped.  Most repairs I use JB Weld, and depending on whether it needs screw threads, I drill and tap new threads into what I need.  I did a repair on a broken hub on a 1681E wheel, for the side rods to attach to the motor, and I used JB Weld to build up what I needed, did judicious trimming, drilled a pilot hole for a 3-48 tap, and all fixed.

I tried the Loctite Lehigh74, but it's too far gone to grab.  TeleDoc; I can try to take pictures, but to give you a better idea, it is a screw post from a PS1 Big Boy tender.  It was upgraded to ERR, then repaired a couple of times, hence it is now stripped.  I have access to a tap set, the smallest tap being 32 SAE.  I am going to borrow it to see if it is within reason.  I'd hate to destroy the post.  Seems every time I DIY it ends up costing a whole lot of money.

Thanks for the advice everyone!

Rich

I do what mytrains does and recently had luck with JB Weld.

JB weld is also a good choice. after the repair use a thread lubricant such as never-seize for screws that are used often. keeps those soft threads in the cast material from wearing. a very tiny dab will do.

My vote is JB Weld also ... I discovered it a few years ago .. used it to attach the throttle piece that turns the disk in the carburetor And has been working for 5 years .. I guess you can tell I am not a car mechanic.  I have used it for all sorts of things ... including what you are trying to fix ... mix a little put it on your broken, it is gooey at first, if you can make it a little bigger than the broken piece.. as it dries you can form it with a craft stick or your fingers to neaten it up. I really like the Tooth pick idea from the other guy, drill, tap or screw.

JD Weld comes in two small tubes in a blister pack .... Walmart carries it in the hardware /glue area. Good luck ... you will find other uses for it/it has a long shelf life even after opened. 

I don't know exactly how much room etc you have but you can get a brass hexagon standoff used on computer motherboards, drill it out to the correct threads. Then insert the threaded end into your problem area and secure it on the other side with a washer and nut on the original hexagon threads.  I would simulate it and grind the hex part of the body to the length I need.  They are fairly cheap so you could make multiple attempts at it.

And here is the computer video card it was removed out of

I dont have a picture of a brass one but they are yellow and probably much softer than the steel one shown here.  They come in different lengths and thickness.

I would prefer to drill out the thread pattern I wanted in the standoff and then secure it using the threaded end with nut, washer or a plate and liberal JB Weld.

Check with local computer store or Goodwill for dead pci card, motherboard or computer.

I like the KISS approach with JD Weld along with the toothpick suggestion (genius!).  I'm hoping I can just drill out what's left of the damaged treads and drill/tap to the original machine screw.

Question is; does anyone know what the specs are on the presumably common screw MTH would use on their equipment.  I know there are probably a number of them, but anything to get me in the ball park, or if I can find a parts list for the engine 20-3021-1.  The 2 screws to the engine side of the tender are tapered, and the 2 screws to the rear of the engine are round head (for some reason) but are the same size/thread.  I am repairing the post for one of the round head screws.

Probably the biggest challenge would be finding a tap for the aforementioned screw, so I may have to go with SAE.

Thanks,

Rich

quote:

Probably the biggest challenge would be finding a tap for the aforementioned screw, so I may have to go with SAE.

I don't know about your particular engine.

It seems to me that a lot of self-threading screws are used by the toy train companies these days. Maybe you can find something suitable.

(Self tapping screws are different than sheet metal screws) Folks might find the attached PDF handy

I've rebuild many posts, both diecast and plastic.  I typically use JB-Weld and fill the hole, redrill it, and then use a new screw.  For diecast that had a machine screw, I pick a coarse thread over a fine one for the replacement, better grip.  You can also use a self-tapping screw in the repair to replace a machine screw.

For posts that have been really busted, I use a piece of brass rod to provide structure and fill that with the JB-Weld.

Rich ... you may try :

1.Take a hunk of the JD weld and experiment with it ... take your existing screws...drill hole smaller than the screw, no tap, when it dries and see if it will work for you before repairing the engine.

2. or do the same thing but use a small screw, hobby shop will have them ( the existing screws are may be small bolts) if so the small screw will have deeper threads than the existing ones.

Hope this helps ...good luck.  Rick

Parts list for 20-3021-1 is here on the MTH site.

http://mthtrains.com/sites/def...loded/20st15115e.pdf

Just saw Johns post when I replied, I think he explained it better than me .... I also like the brass tube approach .... life is good on the Forum / you will always learn ....Rick

Wow, you guys n' gals are the best!  Great suggestions and information.  I will go with the JD Weld and self tapping screw. Thanks C.W. for the handy reference chart! Lehigh74, that is just what I was looking for. I didn't even bother trying the new MTH site because I thought they had eliminated all their older reference materials (for some reason).

Thanks!

Rich 

I drill the hole deeper and tap it for a longer screw.  Simple?

If the MTH screw is a machine screw, it's almost certainly metric. My guess would be M3, but that's a guess. The only way to be sure is to test it. You can either use a known nut or get yourself a Screw Chek'r, which is an aluminum plate drilled and tapped with all kinds of different holes to check your screws. There are two different ones, one for inch and one for metric. They are pricey, but it's a lifetime tool and really handy.  You can get a tap set including an M3 tap and the correct size drill at an auto parts or hobby shop for a few dollars. It's a good idea to get a miniature tap wrench as well. Mine has a reversible ratchet and cost less than $20. 

The screw may also be self-threading. Look for a slightly tapered end on the screw with three or four small cuts in the threads. If your tender screw is self-threading, it will cut its own threads in something as soft as JB Weld. It also could be a sheet metal screw, but that's unlikely. 

Not really true, I believe many of the tender screws are actually SAE screws, strange as that seems.

I have both, and I discovered the SAE screws when upgrading MTH stuff to TMCC, to float the tender shell for an antenna, I use nylon screws and Kapton tape around the edges.

Anybody that's doing this on a semi-regular basis can't go wrong with a thread gauge of some kind. Read off the threads per inch and get a diameter, and almost any screw can be identified.

Google " Thexton THE432 Universal Thread Gauge " for example.

I have a pair of these, one SAE and one Metric

I agree - but consider just dropping a few strands of copper wire down that hole and threading the original screw in?

I gotta get that metric screw checker - I know nothing about Metric, except that MTH uses them.

   First thing I'd try is drive a tooth pick in there and break it off flush and see if the screw then holds. If not then look for a slightly larger screw :> ......DaveB

I would try a nylon screw of the same thread size, but fine vs. coarse or vice-versa. or if it's SAE try a screw size that is close in metric.

You need to identify the screw first. messing with pot metal is no fun.

I's also be tempted to try the self-tapping screw in a similar size, but change the thread type from coarse to fine or vice-versa. Use the hex head to make the thread, then replace with the size in pan head. That will let you get a nut driver on it.

You may find these screws locally at your hardware store or Home Depot. The links are for reference.

Plenty of ways to skin a cat.  MTH also sells the plastic post repair kits.  The new post is slipped over the old broken one.   G

This is a great option! We use helicoils all over the aircraft I work on.

   On most MTH tenders that I have upgraded to Tmcc the screws that I use are 6-32 nylon.

Bill

That's been my experience as well Bill, I have a pack of the 6-32 screws that I use for MTH tenders.  I have several sizes of metric screws, larger for Lionel and tiny ones for the brass tenders.

John gunnerman.

Where can I order these thread gauges?

Alan

GGG do you know that MTH part numbers for the kits.

Plenty of ways to skin a cat.  MTH also sells the plastic post repair kits.  The new post is slipped over the old broken one.   G

On most MTH tenders that I have upgraded to Tmcc the screws that I use are 6-32 nylon.

Bill!

Alan

]thanks for any help all!

Both of the styles are on this page, metric and SAE: http://www.threadtoolsupply.com/_bymfg_3-0-1.html

The tender is supposed to be floated, but the repair person only used one nylon washer next to the screw head.  Now I'm thinking I should replace all four screws with the nylon 6-32 screws.  Is that something Ace or big box stores would have, or do I need to order from somewhere?

Thanks,

Rich

http://www.amazon.com/s/?ie=UT...f=pd_sl_6icmugzqwb_e

I have used these on plastic bodies with stripped out holes:

https://www.grainger.com/conte...toffer?offerId=2T7AB

Marty