What to do with a broken screw?

depending on the diameter, you can get a screw extractor aka ez-out.  Basically, these work by drilling a smaller hole down the center of the screw, and then turning a left-hand thread plug into it.  The extractor wedges itself into the hole, and you can back out the screw.  Or, if there is enough metal, you can drill out the screw and tap it for a larger one.

I found a very small ez-out at Lowe's that might fit in that hole. Since it shouldn't be in there very tight, it may back it out.

Not sure the exact diameter, but it is EXTREMELY small. I don't think ez-out would work because it would be very difficult to get it in the center.

The best and safest way to remove the broken bolt is by Electric Discharge Machining by a local machine shop. Second choice would be for a machine shop to set up the casting in a milling machine and carefully mill out the bolt. I do not believe there are bolt extractors for very small bolt sizes, and drilling a straight, centered hole in the broken bolt would require a machine shops' service also.

Larry

If you are going to try drilling it out, drill it out with a left hand drill and the broken screw will probably come out as you are drilling.

You could also cut a narrow sharp groove across the broken end with a Dremel tool or a jewelers file. Then you could use a small screwdriver and unscrew it.

Between machining a trode (either copper or graphite) and the set up and run time of the EDM, you're looking at $250 minimum. If the trode is not exact, it'll end up eating the threads.

Have mercy on him, he's only a kid

Cesar

MicroMark carries a set of 8 miniscrew extractors in sizes .039-.079. They apparantly work by a specially formed tip that engages the broken end of the screw, no drilling needed. Not cheap at almost $40 for a set of 8. USA made by Moody Tools. Might be an idea if they weren't so expensive.

Scotie

Assuming the the screw was threading in loosely you have a couple less expensive options.

1. Use either a small flat bladed screw driver ( grind it thinner if need be) or and awl to try to catch the broken surface and start turning it out.

2.  this one's a little risky - use your own judgement if it will make the problem better or worse.   find another screw, piece or rod, wooden dowel etc that will fit down the opening and touch the top of the screw, and only the top of the screw.  once you are confident that you have found the right item dap a very small amount of epoxy on the end of your reaching device and touch it to the top of the screw.  NOTE - IF YOU USE TOO MUCH AND GET EPOXY NEAR THE THREADS YOU WILL MAKE THE SITUATION MUCH WORSE!!  Anyway if you have enough room to give it a try, the epoxy can join the broken screw to your reach tool long enough to get it started backing out.  This is basically the low budget version of welding a new bolt to end of a broken one.  If you have enough room to pull it off with getting excess adhesive stuck to another surface in the hole, then this should do the trick.  However I would still try #1 first.

that's my $0.02. Good luck!

How about gluing the screw back together and then try to back it out.  Before gluing, do a dry fit with the other piece to find the orientation for the best fit.  Note the orientation so you can repeat the best fit when gluing the 2 pieces back together.  Place a small drop of super glue in the center of the screw that is not in the tapped hole.  The glue will spread when the 2 pieces are press together, so you want to be stingy with the glue.

Does the screw extend beyond the thread on the side/inside not pictured ??

Surprisingly there are left handed or Counterclockwise drill bits. There is a good possibility that the screw is soft enough to be drilled/removed with one of these bits. Click on the underlined phrase to link.

Do you know if the hole goes all the through or is it blind? If its a through hole you can use a standard drill carefully centered to drive it out. Use a drill about half the diameter of the screw. If its a blind hole use the same small diamater drill or better yet one just slightly larger than a piece of .040" music wire. Take the music wire and bend it in to a right angle like an allen wrench and put a drop of super glue on it and insert into the hole. Don't try and super glue the screw together. The glue will get sucked into the threads making removal even more difficult.

Pete

Good ideas so far. This is a long shot, but if the screw didn't break flat across you may be able to get the tips of jewelry-sized needle nose pliers in, get hold of any small projection and back it out.

I've never had any luck with Hanson EZ-Out screw extractors with small screws. I don't think they are small enough. Maybe the Micro mark ones work better. Here is the Irwin (Hanson) brochure.

Read this article, while about removing broken drills and taps, some of the information will apply to screws. (Of course he is also trying to sell his service)

If the screw isn't bottomed out in the hole, there shouldn't be any tension on it. You should be able to spin it out with a dentist pick. If not, an ez-out is the best option.

I'd suggest taking a dremel and grinding a tiny hole in the top of the remaining threaded bolt and tapping that hole counter clockwise with a pick to back it out....hopefully it's not jammed or bottomed.

Work it slow and it should come out....

Looks like the screw is well below the surface, so making a slot in it seems problematic.

I vote with JHZ and Mike.  If it is in there loosely it should back out easily.  If you try to drill it it will bottom out and then become a very real problem.

However, if it all goes to worms, go ahead and drill it out. If you are careful, your drill will go through the screw and not get off to one side.  Then keep drilling until you have a hole that can be tapped about twice the diameter of the screw you will ultimately use.  Then insert a tapped screw.  Not a big deal if you have a good drill press and some good taps.  Use cutting fluid for all operations.

IMHO, there certainly wouldn't be any harm in Lionmaster trying to coax out the bit of broken screw by one of the techniques that do not involve drilling, cutting, or gluing.

Certainly there are techniques for removing broken screws. I don't think the chassis of a current Lionel Mohawk is the place to learn. If the screw won't coax out, I'd suggest bringing the engine to an experienced repair person.

I second this recommendation... give it a good soaking with a penetrating oil too.

If drilling is involved, I'd go with Mike's link for the left-handed drill bits, that seemed like the best recommendation to me.  However, coaxing it out with no drilling would be my first attempt as well.

When we talk about using a left-handed twist drill, please remember that one thing may not be obvious, and needs to be stated:

When you drill into the remains of the screw with a LH drill bit, the drill motor must be turning in reverse, that is, counter-clockwise.

I would be surprised if left hand drill bits can be had this small. The thread is likely << 1/8". Use a pin vise, not a drill motor. It will give better control and less likely to damage the existing threads plus if the hole is blind you are less likely to jam the screw which would make it harder to remove.

Pete

The ones Mike posted go to 1/16", so they're reasonably small.  I'll bet even smaller ones exist.

I like the idea of the pin vise to attempt the removal with the left-handed bit, it would minimize things getting away from you.

The EZ-Out (possibly not that particular brand name) that I found at Lowe's was small enough to fit inside the hole in the end of a driver axle of a Lionel Hudson. It also fit well enough that it did not damage the threads.

I used the NYC Mohawk to get a look at what's going and it seems that it is a stud with circlips that attaches the trailing truck. Am I wrong?

http://www.lionel.com/Customer...cb-baa0-cbf783d1c3a4

I believe this is a part from a Pullmor motored L3 Mohawk.

It appears you will have to fabricate a replacement as this item is listed as out of stock. The thread is listed as 6-32. Easiest way would be to take a common 6-32 screw and cut a piece of brass tubing to fit over it similar to the broken item.

Pete

If you search for the bolt as part #700E-036 you will find it is available at online parts dealers such as Train Tender and Brasseur.

Larry

Ok, so the broken screw piece is in the drawbar and is the pivot point. The drawbar should come out now, yes?

Replace the drawbar and screw?

Drawbar part # 6108064287

If he can't find an original drawbar and screw, would a newer version be the same?

The screw goes through the front of the trailing truck as well as the front of the drawbar. The broken thread is in the loco frame. There is a stud similar to part you pictured that goes through the center of the truck and drawbar but doesn't attach to the frame. 

Pete

Thanks, Norton. So, the problem remains...a small piece of screw in the chassis.

Brassuer has the screw in stock, lionmaster.

Get a piece of masking tape, fold it and put it on the screw and try to turn it to loosen it. Then keep turning it. This just may work.

Be sure to cue this classic before you attempt the repair

Here's a variation on the cut a slot theme that was mentioned earlier.

Get a pin vise, and drill 2 small holes in the broken screw. Drill them close enough together so they connect at their edges. Then just use a jewelers screwdriver to remove the piece. Slightly tedious, but nothing fancy.

When you buy the new screw, order 2 or 3. Murphy's law will prevent you from breaking another.

Look Ma! No hands!

Introducing vibration to the frame may cause the screw to back out enough to grab, if threads are loose enough. Ive done this on auto restorations on rare occasions using a pneumatic chisel/hammer. Takes time and patience. For trains? Maybe a back massager? Electric toothbrush? Cell phone? 

Oh yes, screw will naturally want to fall as it moves. Take advantage, face the subject accordingly if you can.

Also with loose threads, a sharpened tip of eraser(pencil) pressed on top the screw shaft might get it moving.

The first thing to do is buy or make a bushing to go into the hole.  The bushing will keep the drill centered.  It is very hard to drill out a steel screw when the screw is in a softer material.  The clearance hole diameter for a #6 screw is 0.146.  You can make a drill bushing in the following way:  

Take a piece of rod that is about the same diameter as the screw hole, or slightly larger.  Cut a small piece, about an inch long.  You can use a #8 machine screw for this which you can buy at Ace Hardware or Home Depot.  Cut head off of this screw and chuck it in a drill press.  Turn the drill press on and use a flat file to reduce the OD of the screw to fit into the #6 hole.  

Put a 1/8" drill in a vise with the drill pointing up.  With the drill press running, and the #8 screw in the drill press, you should be able to drill a hole into the #8 screw sith the 1/8" drill and the hole will be close to center.  I have done this when no lathe was available.  

When yo have a hole about 1/4" into the #8 screw, take the screw out of the drill press and cut off the end where the hole is.  Put this small bushing into the hole where the broken screw is and drill a hole in the broken screw.  You can then use an easy out or left handed drill to remove the broken screw.  

If you cannot make the bushing, or cannot find someone to help you, you could have a machine shop make the bushing for you.  I am sure it wouldn't cost much as the shop can make the part in about 10 minutes with a lathe.

I have a set of screw extractors I bought at Sears about a hundred years ago.  The smallest of the extractors has a tip 0.080" in diameter which would work just fine for this problem.  

If this were my problem, I would make a bushing and use the extractor that I already have.  

An alternative to making the bushing would be to use a #27 drill which is 0.144" diameter and spot the end of the broken screw.  (Make a dimple in the end of the screw.)  Then use a smaller drill to drill a hole in the broken screw.  The dimple made by the #27 drill will keep the smaller drill on center.  

You can buy wire gauge drills at Harbor freight.