J-B Weld works fine, but it cures to a light gray. For tenders, bakelite transformer cases (post-war) and many locomotive repairs, I also like Marine-Tex.
It's "gray" version cures to a smooth black color which, if you don't disturb the finish by sanding or filing, is a pretty good match for Lionel-black. (If you knock the sheen off, it is almost the same gray as J-B Weld.) It's rather expensive, though, and comes in a two-part kit containing a small jar of "putty" and a little bottle of liquid hardener. It's a tad delicate to mix. Two cautions: don't breathe the vapors, and do seal the putty jar and set it aside before opening the hardener. (Exposure to its vapor is enough to cause the putty to lose shelf-life and harden in the jar.) Properly mixed, the stuff turns to a honey-like liquid that can be worked for about a half an hour with a full cure in about 24 hours at room temp. It oozes and fills gaps very well. I have cast slightly curved surfaces using Johnson's paste was as the parting compound, and wood or plastic to fashion a mold of sorts.
Find it at boat supply stores or the internet. I always keep a little bottle on hand, I have repaired transformers, including my personal 1033 and a friend's post-war ZW, each of which not only had cracks, but also a hole punched completely through the case and the pieces lost and gone forever...
To repair cracked loco or other shells generally, I generally use one of those ultra-thin products that actually dissolve the edge of the plastic, such as Tenax or Testor's. When the joint has re-hardened fully, I scratch up the back side of the cracked-piece to provide some "tooth," and slather a bead of one of the two-part expoxies across the break as reinforcement. The repairs are strong and virtually invisible -- especially if you repaint the piece.
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Thank you all for the information.
Think I will try the epoxy method to try & get this done.
Be glad when it is done so I cane work on my own stuff.
Thank you & take care.
bf,
Thanks for the reply. I'll give it a try when time permits.
trainrat The best way I have seen and used so far is the epoxy fill method. And if the post is broken off you can use a soda straw over the broken off post and fill it with epoxy to remake the post. Before the epoxy sets up you thread in a screw coated with wax or something similar and leave it until the epoxy dries. Then remove the screw and you have a perfectly threaded hole that will last. I like J-B Weld for this job. Roger
The best way I have seen and used so far is the epoxy fill method. And if the post is broken off you can use a soda straw over the broken off post and fill it with epoxy to remake the post. Before the epoxy sets up you thread in a screw coated with wax or something similar and leave it until the epoxy dries. Then remove the screw and you have a perfectly threaded hole that will last. I like J-B Weld for this job.
Roger
Roger....This is an outstanding way to fix a broken post. Thank you!
Celebrating 18 years on the CTT Forum.
Buckeye Riveter......... OTTS Charter Member, a Roseyville Raider and a member of the CTT Forum since 2004..
Jelloway Creek, OH - ELV 1,100 - Home of the Baltimore, Ohio & Wabash RR
TCA 09-64284
I have had some where half of one side of the standoff was missing. Like someone mentioned earlier, I too tried using the green Squadron Putty to build them up. I found this did not work well. I then decided to drill deeper and too used 4-40 machine screws. The difference here, after I seated the 4-40 screw into the tender body, I cut off the head with my Dremel, cleaned up the threads, hot glued around the remaining screw and post. I then used a nut after seating remaining screw thread thru the tender bottom. Haven't lost any nuts, it looks good, and I don't worry about future wear on the remain plastic posts.
I've never tried this; but it just occurred to me that one might use those little brass gadgets that come screwed onto the terminals of spark plugs. The ones for my cars are threaded for 4x.7 millimeters and are 10 millimeters long, just about right for this job, and have an undulating cross-section that would prevent their pulling out. You could drill out the hole in the shell and glue the thing in, or perhaps embed it with heat directly into the plastic, with a long screw in it temporarily to align it and keep the inside clean as it sinks into the plastic.
Bob Nelson
Hi Jim, nice to see some interest.
What matters is to get the screw coated with epoxy, so that the cast-in threads that form the plug become "as one" with the screw. Gaps and bubbles are the enemy, so I work the liquid epoxy down into the hole but do not fill it completely. I use something like the wooden stick cut from a Q-tip and slosh it up and down to coat the inside of the hole and work out any air bubbles. It's easy.
After covering the screw threads and underside of the head with a thin coat of Johnson's Floor wax (to serve as a parting compound) I then use the stick and coat the screw threads with epoxy, to ensure that all surfaces are covered (except the underside and cap of the screw head) and then just gently push it straight down into the epoxy, trying to keep it centered and vertical. If it tends to lean over, support it with tape or something until the epoxy firms up just a bit, or simply check it every half-hour or so to see whether it remains centered and vertical. If not, adjust it.
You can reduce the curing time by adding a little heat from a hair dryer. Not too much though. The working time of regular JB Weld is such that you have more than enough time to ensure that the screw stays where you want it throughout the full cure.
The "parting compound" is essential. You don't want the wax (or whatever you use -- some folks have reported using a little grease instead of wax) to be mechanically wiped clean, which is why I do not spin the screw until the cure is complete and I am ready to unscrew it and clean any remaining wax off of it.
I have never known this method to fail. I do recommend trying it first in a piece of scrap wood until you are completly comfortable with it. If you do apply heat early on, don't allow the screw itself to get hot. You don't want the wax (or grease) to turn into a liquid and ooze off the threads. The worst thing that could happen would be to epoxy the screw permanently into the post. Support the shaft the first time you go remove the screw in case there is the slightest bit of adhesion of epoxy to screw.
I keep a wooden plank in my shop into which I drilled a 3/8 inch or so hole, and filled it with epoxy and cast threads as above. As a test, I backed the screw out just far enough to get the claw of a 30 inch crowbar under the head. I have not been to budge the either the screw or the epoxy plug despite many tries although the screw can be fastened and unfastened with virtually no effort at all.
I'd appreciate hearing about experiences with this method.
I read through your method, but I am confused on one thing. Do you push the screw straight down into the epoxy, or do you turn it down into the epoxy?
The principal advantages of my casting method are:
1. You actually strengthen the post;
2, You are not nearly as likely to break it again as you are if you decide to re-drill and retap. The fact that epoxy makes for a hard and precisely-tapped hole is exactly what makes it difficult to drill and tap after it has hardened;
3. You can remove and replace the shell a great many times without damage;
4. Machine screws are wonderful, should you decide to use them. They are readily available, don't tend to crack the post from the inside as you screw them down, and there is no need to overtighten them;
5. If the machine screws tend to vibrate loose and vibrate out (unlikely) just use a little non-permanent Lock-Tite.
If the post is bad I grind it out. Close the corner with a duct tape mold and use two part epoxy.You could tap but I just drill and fit the screw. I use modern philips machine screws in a size 6 or 8.
Check out this thread. My"casting" method works quite well, is very versatile, can use relatively fine-thread machine screws, and the finished product enables you to assemble and dis-assemble the tender or whatever repeatedly with virtually no stress or strain. I have used it many times, especially on tenders and passenger cars.
http://cs.trains.com/trccs/forums/p/131576/1479130.aspx#1479130
If the hole is okay,just the threads wiped insert a small piece of plastic in the hole and glue it.Don't fill the hole just get a sliver of plastic or two into it. Now when you put the screw in it will bite.
Ed
I have fixed broken screw holes by drilling them deeper and tapping them with a 4-40 tap. The 4-40 machine screw will not cause the plastic to split. I have fixed 022 switch motor covers and scout locos this way. Cheapest place to buy the drills and taps if you don't have them is Harbor Freight.
What is the best way to repair broken screw holes in plastic tender/loco shells ?
I have some that I need to fix up for people. I have tried to use the green plastic putty to rebuild them but it dose not last. I would just replace the top with ones that are better but they are getting harder to find. I bought some new tender tops but when I got them they looked to be just like the ones I needed but they have the oval hole in the top of the coal pile. 2 of the ones I need have no hole. They are for the older scout type engine's.
This is the only thing that is holding me back from completing the repair.
Any suggestions?
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