Quote:
Originally Posted by Ed in Maine
The problem you will have with drilling out the hole for the Helicoil is that the drill will try to dive into the hole, cocking the drill to one side and opening up the top of the hole. It is very hard to hold the drill 90 degrees to the block also. You might make up a 1 1/2 in. hardwood block and drill two holes in it on a drill press so they are vertical. Use one hole to fasten the wood to the block and the other to insert the drill correctly.
Buy two new drills in sizes that lead up to the Helicoil drill size. I don't remember the size of these bolts but one drill would be about 0.003 smaller and the second drill 0.006 smaller than the Helicoil drill. This way you are increasing the size of the hole in the block in increments and just skimming the hole larger until you finish up with the Helicoil drill. It is easier to hold the hand drill when you are removing less material. Good luck with your repair. Ed
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Good advise on making a drill guide to ensure 90 degree alignment. This technique is often used to drill and tap rocker studs. Recommend an aluminum block for more precision. A second guide should be used for the tap.