HEEEEEYYYYY Mechanics........

[Bootlegger]

Broke a 5-40 screw off in the block of a RO Jett 40 rear exhaust due to viberation  and it is below the surface of the block.
What would be a good way to get the screw out, prefer not to tear down and ship off somewhere...
  Thanks a lot...

[Scott Jenkins]

Find you a left hand #43 drill carbide if possible, and carefully try to engage the broken bolt this with the addition of some lubricant will make the bolt back out of the hole. I have used this technique with bolts as small as 2-56. The hard part is getting centered up on the broken broken bolt to keep from gouging up the case. If you can get a #1 center drill into the bolt to start the hole all the better. Patience and cool head will get that bolt out.

Scott   

[Russell Shaffer]

Take a dental pick and work at it.  If it isn't actually bottomed in the hole you can probably work it out.  A gunsmith friend taught me this one.

[Randy Powell]

Depends on if it's jammed in there, bottomed out of otherwise stuck. If it's just sitting in the hole loose, then the dental pick is the way to go. If it's jammed or tight in the hole, then you will probably need to either use the left handed drill trick or an easy-out (if they make one that small).

[Randy Ryan]

If its flush with the surface or not too far below you can CAREFULLY grind a slot in the end with a Dremel and ues a straight screwdriver to turn it. Again, this will only work if tis not stuck or bottomed.

[GGeezer]

Broke a 5-40 screw off in the block of a RO Jett 40 rear exhaust due to viberation  and it is below the surface of the block.
What would be a good way to get the screw out, prefer not to tear down and ship off somewhere...
  Thanks a lot...

The R/C guys around here are always breaking bolts off in their mufflers and motors. What they do to remove a steel bolt from an aluminum part is they etch it out with concentrated nitric acid.
Build a funnel shaped dam around the screw hole using epoxy putty ( a hot glue gun may also work), carefully fill the funnel with the acid. Be very careful handling any concentrated acid. Leave it to etch for a while, when you see black crud forming on the screw, take a sharp pointed tool and break up this crud so that the acid can attack fresh steel. You may have to drain the cruddy acid a number of times and replace it with fresh.
Again, be very careful handling the acid but this will work and leave you with a nice clean threaded hole.
Here is a link to a site about nitric acid attack on metals.
http://www2.uni-siegen.de/~pci/versuche/english/v44-24-2.html

Orv.

[RC Storick]

Broke a 5-40 screw off in the block of a RO Jett 40 rear exhaust due to viberation  and it is below the surface of the block.
What would be a good way to get the screw out, prefer not to tear down and ship off somewhere...
  Thanks a lot...

Because of the cost of this motor I would leave it to the pro's.

[Bootlegger]

      Guy's I sure do thank all ya'll for your answers, I am thinking about sending the block to the engine mfg to have the screw extracted as it seem's to be bottomed out.
  Again thanks for the responses...

[James C. Johnson]

Here is what Joe Wagner used to do.. this is from Engine Collector's Journal Vol 1 #4

Click on the this link

http://www.modelenginecollecting.com/The-Model-Engine-Collector.htm

 and then click on Volume 1  #1

read down to bottom of page 5 ..."Tricks of the Trade"...  "an almost fool proof method of extracting screws."

It involves making an "easy out" out of 1/16th piano wire.. and using a drill press .. very interesting reading ... Joe remarks this is a "one time shot" with this set up and to take your time..

The Nitric Acid technique sounds interesting.. I remember dissolving pennies in Chemistry Class with this acid..

I don't recommend using a dremel on this engine. I don't care how careful you are.. it will cut into the case or at lest mark it up. I tried it on an OS 35 S case .. the screw is still in there.. the metal on the screw kept breaking. In my search for a way to get it out I came across this article ...


Also... Clarance Lee might be able to help.. I am unsure of this info. It came from the Engine Collectors web site. 

West Coast
HELICOIL REPAIR of STRIPPED SPARK PLUG HOLES (¼-32 only), REPAIR 0F 4-40 & 6-32 HEAD and BACK COVER HOLES, GENERAL MACHINE WORK: C.F. Lee Mfg. Co.   10112 Woodward Ave.   Sunland, CA 91040   Tel: (818) 526-9074

Here is another guy... East Coast
ENGINE RESTORATION, REPAIR and CLEANING SERVICES, NICKEL PLATING, TUMBLE POLISHING: Walter Craig    3664 Smoketown Rd.   Glenville, PA 17329   Tel: (717) 229-2840   E-mail: makenewagain@yahoo.com



Jim