Types:
There were two different types of crossbars, which I've labeled as
type 1 and 2 for convenience. The type 1 and type 2 designation does
not refer back to any actual type study. The type 1 (from 1904
to ~1935) just had three holes drilled in it. Pointed thumbscrews
in the caps on top of the rods secured the crossbar. This was a pretty
weak design, and the screws and top caps were often worn or broken.
Pictures of the type 1 and type 2 top caps are shown below.
Around 1935 (just an estimate by me), Stanley changed the design to the type 2. They changed to captive-slotted screws in the top caps that actually threaded down into the crossbar. This design was a big improvement, as it was much stronger and not as subject to wear or breakage. Unfortunately, the threaded-hole crossbar is nearly impossible to make because of the non-standard threads that Stanley used.
Sizes:
The crossbar is different for the #246, #358 and #460, so be sure you
get the correct dimensions for your particular miterbox.
Possible Problems & Solutions:
Because of the weak design, the early top caps and thumbscrews
are commonly worn or missing. Usually both the top cap threads and
screw threads are worn, so replacing just one part doesn't provide much
improvement. Original replacement parts are impossible to find unless
you just steal them off of another miterbox.
Missing Type 1 Thumbscrews:Construction:
Option 1: If just your thumbscrews are missing or worn, it is possible to make new ones if you have a screw-cutting metal lathe. Ideally, you can make the new thumbscrew slightly over-sized to account for the wear in the topcap threads. I have a metal lathe and am willing to make new ones - email me for pricing or other information. A sample of a reproduction type 1 thumbscrew is shown below.
Option 2: You can also try to rethread the top cap for a standard screw size. If you want to try this solution, I would recommend rethreading using a 12-24 tap and 12-24 screws. While 12-24 is a standard size, it is still uncommon & may be tough to find. Another option is to re-thread with 10-32 threads. I don't recommend this, and have never tried it, since I don't believe it will provide good results over the long term. The new 10-32 threads wouldn't be perfectly formed & would be weak & easily damaged.
Broken Top Caps:
Your best option is to buy some steel of the right size from Home Depot. Then cut and file them to the right size & shape. Use a 10-32 screw, as this is the closest standard thread to the original size.Type 2 Crossbar:
If you are missing the crossbar, but the top caps and screws are good...one option is to replace the two original screws with smaller 6-32 screws. Just drill and tap your new crossbar for 6-32 threads. No modification to the top cap should be necessary. Save your original screws in a safe place! I'm investigating taps for the original Stanley special threads, so I may be able to make these at some point in the future.Missing Type 2 Screws:
If are missing the screws, but have good top caps and crossbar, then reproduction screws are your best option. I have a metal lathe and am willing to make new ones - email me for pricing or other information.
This is very important! Centerpunching keeps the drill bit from wandering when you first start making the hole. You can use an automatic spring-loaded centerpunch if you have one, or any other type of pointed punch with a hammer or even a large nail with a hammer. For best results, don't skip this step!Drill the holes (the sketches below show the TYPE 1 hole diameter!)
#358 Crossbar Coming Soon!
