OK, I bought a 1/4 UNC tap (3rd) and have cleaned out the holes, spent about an hour on this, i literally dug through what was probably years of crap, and have found the bottom of the holes...
I have 3 different sized set screws, 1", 1 1/4" and 1 3/4".
The holes with the dowels in had 1x1 3/4" in one, and 1x 11/4" in the other. (are you with me so far?)
The other 9 should, have 1" in, but will comfortably (I have tried these one by one as i don't want the bolts 'bottoming out'!) take 1 1/4" bolts, except for the one furthest to the left (left of the dynamo drive) which will take a 1" bolt comfortably.
Now from experience i think that using ALL the available thread is definitely more beneficial than some of it (so long as we are NOT bottoming out)??
So, now on to the one (circled in the first picture) that is 'partially' stripped. Now I have cleaned it out thoroughly, and run a tap down it, i can get it to tighten to the accepted level using a 1 1/4" bolt, without helecoiling it, so this is what i am going to do. Main reason for this is that the guy i normally buy my helicoils from was not at the auto jumble i went to yesterday, so I couldn't buy any, plus I thought of the worst case scenario, I tighten this up and the last 1/4"+ of thread pulls, i am still in the same position, but no longer have to worry about the last remaining bit of thread left in the hole!
Last question's are I guess going to be a matter of choice but i would like your opinions, especially on the last question please...
Stainless or Mild Steel?
Plain slotted screw head or Allen screw head? (How did they come from factory??)
What were the original threads? It was my understanding that UNC/BSW were different in pitch thread angle by 5º? I am guessing BSW...
Best regards,
Steve.
