@Redneck_Sophistication
Question - is that area circled in yellow (see below) rusty in a few spots? If so, why? It almost looks like there is some porosity in the casting there. One of the pores looks like rust has been creeping from the outside down the pore toward the inside. See the bottom-most blue circle below.
If there is porosity and rust there, it might more easily explain the total failure of the compound when it crashed.
Regarding the fix - I prefer @Darren's proposed fix. However, there may be reasons why you cannot do that or even just prefer not to. So the following is just for your consideration.
My BXA compound is 3" wide x 1.5 high x 7" long. I don't know what size yours is. It looks similar.
The dovetail eats about 1/2 x 1-3/4 without the Gibbs and 1/2 x 2-1/4 with. There is about 1/2" of solid meat between the top of the dovetail and the bottom of the T-slot. This is the primary section that is broken in your compound. I marked it with a big orange-red rectangle below.
The purple marks are where I would install some threaded holes for countersunk #10 or 12 socket head machine screws. Whatever fits best after taking into account your compound leade screw system. These don't have to be grade 8 as the threads in the cast iron will be the weakest link. They should be torqued to about 10% of a grade 8 rating so a thread locker is required to prevent them from coming loose.
The green is where I would drill all the way through the entire casting of the compound for two full length 3/8 fine thread Grade 8 bolts with nuts on one end and the bolt socket head on the other. The other bolt is on the other side of the compound. Both ends can be countersunk to avoid interfering with the dial or the busy end of the compound. These need to be grade 8 and torqued to specification as they will basically hold the entire cantilevered load of the toolpost T-Bolt. Two grade 8 bolts should be about the same strength as the original casting at around 30,000 pounds for two. I advocate a very thin film of epoxy in the joint - not for strength but rather to seal it for corrosion protection and to prevent it from sliding or slippage while it is being tightened. It could be applied and cured before drilling.
To visualize the strength of this fix, think tie-rods on medium duty (2500psi) hydraulic cylinders.
Although I doubt it, it is possible that these tension bolts might bend the casting very slightly when they are torqued down. I would certainly never say never. Any porosity in the casting will not be your friend here. There will be a relatively huge clamping force there, however the compression strength of cast iron is 4x its tensile strength so that shouldn't be a problem.
Question - is that area circled in yellow (see below) rusty in a few spots? If so, why? It almost looks like there is some porosity in the casting there. One of the pores looks like rust has been creeping from the outside down the pore toward the inside. See the bottom-most blue circle below.
If there is porosity and rust there, it might more easily explain the total failure of the compound when it crashed.
Regarding the fix - I prefer @Darren's proposed fix. However, there may be reasons why you cannot do that or even just prefer not to. So the following is just for your consideration.
My BXA compound is 3" wide x 1.5 high x 7" long. I don't know what size yours is. It looks similar.
The dovetail eats about 1/2 x 1-3/4 without the Gibbs and 1/2 x 2-1/4 with. There is about 1/2" of solid meat between the top of the dovetail and the bottom of the T-slot. This is the primary section that is broken in your compound. I marked it with a big orange-red rectangle below.
The purple marks are where I would install some threaded holes for countersunk #10 or 12 socket head machine screws. Whatever fits best after taking into account your compound leade screw system. These don't have to be grade 8 as the threads in the cast iron will be the weakest link. They should be torqued to about 10% of a grade 8 rating so a thread locker is required to prevent them from coming loose.
The green is where I would drill all the way through the entire casting of the compound for two full length 3/8 fine thread Grade 8 bolts with nuts on one end and the bolt socket head on the other. The other bolt is on the other side of the compound. Both ends can be countersunk to avoid interfering with the dial or the busy end of the compound. These need to be grade 8 and torqued to specification as they will basically hold the entire cantilevered load of the toolpost T-Bolt. Two grade 8 bolts should be about the same strength as the original casting at around 30,000 pounds for two. I advocate a very thin film of epoxy in the joint - not for strength but rather to seal it for corrosion protection and to prevent it from sliding or slippage while it is being tightened. It could be applied and cured before drilling.
To visualize the strength of this fix, think tie-rods on medium duty (2500psi) hydraulic cylinders.
Although I doubt it, it is possible that these tension bolts might bend the casting very slightly when they are torqued down. I would certainly never say never. Any porosity in the casting will not be your friend here. There will be a relatively huge clamping force there, however the compression strength of cast iron is 4x its tensile strength so that shouldn't be a problem.
