03-09-2020, 09:02 PM
The stud remnant is out, and I'm pretty sure the thread is still perfect!
for future searchers I thought I'd write out what happened.... as I was very scared by this process, but needn't have been I think.
This was the stud remnant we were working on - quite lucky in some ways, as it's neatly sheared off flat, and is slightly recessed in the block:
Following a neat suggestion for head studs from another post, we bolted the manifold on to use as a guide. We then checked the alignment with a boroscope (very useful thing, and very cheap on ebay).
this showed us that the natural alignment was way off. We tweaked it and got it pretty good:
2nd boro.png (Size: 401.8 KB / Downloads: 381)
As suggested in the other post, we then drilled with a bit that was a snug fit in the manifold hole. The result was an impression in the centre of the stud remnant - good. however, that impression has a flat in the middle of the hole, as my drill bit creates a small flat area (all of my HSS bits seem to have this): this meant that after all that, I still had to eye it up & centre punch it.
The next step was to try and drill straight down the stud. We went to great lengths to arrange the block on the dillar drill, but TBH we weren't sure we were truly lined up and the depth of drilling isn't that much, so I'm not sure I'd bother next time:
On the advice of another friend I then proceeded to drill out with successively larger reverse threaded drill bits, in a hand drill on reverse.
(The idea being that they might whisk out the remains of the stud). I'm not convinced that they really did this, though if I'd progressed to a big enough bit they may have. instead, we stopped having just nudged the biggest bit I dared to use in to the opening. This then exposed enough thread for a bottoming tap to grip, and we then very gently cut the rest of the stud out working the tap back & forward, leaving a lovely clean thread.
On to the next challenge!
for future searchers I thought I'd write out what happened.... as I was very scared by this process, but needn't have been I think.
This was the stud remnant we were working on - quite lucky in some ways, as it's neatly sheared off flat, and is slightly recessed in the block:
Following a neat suggestion for head studs from another post, we bolted the manifold on to use as a guide. We then checked the alignment with a boroscope (very useful thing, and very cheap on ebay).
this showed us that the natural alignment was way off. We tweaked it and got it pretty good:
2nd boro.png (Size: 401.8 KB / Downloads: 381)
As suggested in the other post, we then drilled with a bit that was a snug fit in the manifold hole. The result was an impression in the centre of the stud remnant - good. however, that impression has a flat in the middle of the hole, as my drill bit creates a small flat area (all of my HSS bits seem to have this): this meant that after all that, I still had to eye it up & centre punch it.
The next step was to try and drill straight down the stud. We went to great lengths to arrange the block on the dillar drill, but TBH we weren't sure we were truly lined up and the depth of drilling isn't that much, so I'm not sure I'd bother next time:
On the advice of another friend I then proceeded to drill out with successively larger reverse threaded drill bits, in a hand drill on reverse.
(The idea being that they might whisk out the remains of the stud). I'm not convinced that they really did this, though if I'd progressed to a big enough bit they may have. instead, we stopped having just nudged the biggest bit I dared to use in to the opening. This then exposed enough thread for a bottoming tap to grip, and we then very gently cut the rest of the stud out working the tap back & forward, leaving a lovely clean thread.
On to the next challenge!