1970s Rivarossi 4-8-8-4 Big Boy Front Bell Screw

Hi all,

Maybe a dumb question. Trying to remove the boiler on an old AHM/Rivarossi Big Boy. The screw on the rear underside, and the screw under the center dome both take a flat head. There is a screw up front that runs through the bell bracket all the way down through the front plate into the chassis. This is a tiny hex head. It does not appear that there would be room for any type of socket to fit inside this bell bracket. Any tips on getting this screw out? I have already knocked the bell loose once as well as put some scratches in the boiler trying to get it out with a pair of tweezers.

Help!!!

 

Is there enough of the screw protruding above the bell bracket to get a tool on there? If so, you need to get a set of small hex head drivers similar to the jeweler's screw driver sets. Probably metric.

Doug

 

Harbor Freight has many choices. Mill's Fleet Farm does as well. Or try any lumber yard.

 

I have some Italian steam from RR (see avatar ), I confirm, you will probably need a metric one (should be 3mm). Do not try with tools that can smooth it like pliers, otherwise you will not get it out even with the correct tool.
If you do not find the metric, you may try the closest match 3mm+, if the hex is still sharp you may be able to work it out anyway.
Since the space around the hex is very limited, try not to get a bulky tool (on the outside)

 

No, the sides of the bracket come up higher than the screw head, and there is less than 1mm clearance between the points of the hex head and the inside of the bracket.

Put calipers on it and it's 4mm. going to need to look for a 4mm nut driver with a ridiculously thin side wall. Maybe I can have my buddy with a 3d printer try to print me up a specialty tool here

Thanks to all that have replied!

 

Besides the usual socket set, I have a set of screwdriver types that the tips a a part of the shaft and the outside of the tip is small diameter. Not like the sockets were the tips are removable square drive. They do get into tight places like you described. They aren't as strong as sockets but more than enough for small screws and bolts. They are called Nut Drivers.

 

Grangers, Harbor Freight and Home Depot have them.

 

If you can't fit a 4mm crescent wrench, then try epoxying a lever to the bolt head. Acetone (nail polish remover) should dissolve the epoxy when you are done. If not, MEK (methylethylketone) will do the job. Be super careful with that stuff (gloves etc.).