Question from a newbie

One way would be:

In the drill press, drill a 1/2 inch hole through the block. Then "step drill" in 1/16", or smaller, increments until reaching the final size. That is 9/16, 5/8, 11/16, 3/4 etc. The well known "Silver and Deeming" set of reduced shank (1/2" ) drill bits could be used here. As the final size is approached it will be necessary to use increments smaller than 1/16 to stay "just shy of 1 inch".

Step drilling is recommended to reduce the holding and cutting forces required to hog out a large hole all at once.

Bob Swinney

How many pieces in what time?

Several ways to do this, depending upon how you want to do it and how fast you want to go. Setup a lathe with a 4 jaw chuck and drill a 3/4" hole or so and then bore with a boring bar for the final distance. This is a two operation without having to change tools. Drill with a drill press or mill to the finished diameter. This may make for rough surfaces on the inside of the hole as there is no finishing cut. You can also do a hand ream if you want to have a decent finish on the hole but that ends up again being a second operation on the part. Drill with a drill press or the mill to near the final dimension and then bore with either the lathe or a mill. With the mill/drillpress operation, a V stop will probably be good enough to hold the block in place unless you need to have a very accurate location of the hole with the location in the final operation to be the most accurately located. I'll also note that it may be worth while to have an angle cutter on a drill press to deburr the corners of the hole. I suspect that the machinist was doing a two operation on that hole to get it centered nicely in the block.

-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works every time it is tried!

Bingo!!!

"PrecisionMachinisT" wrote in news: snipped-for-privacy@uni-berlin.de:

One more question: What finish do you need on the hole?