How to find opposite sides of a cylinder

Drill all the way through and then plug it with a short piece of dowel so that you end up with a short hole either side ?
 
the way to go is to make the cylinder a part of something that hat two opposing parallel flat surfaces so you can turn it around without distrubing the orientation
clamping in a v block will do so
but there are other ways
it depends on the size of the cylinder
what size is the cylinder?
 
Center punch 1 hole. Cut a strip of paper longer than the circumference of the cylinder. Overlap it and mark it at the punch mark. Take the paper off and make a mark half way between the two spots that came together at the punchmark. Put the paper back on the cylinder and make a second punch mark at the half way mark you just made. The punchmarks will be opposite each other. If the end of the piece has been trued you can measure off one end to get them square. If not, you can stick it in a lathe and lightly scribe a line all the way around with a pointy cutter. Drill any way you want. This is how I made the fixture in attached photo.
Ed P

DSC_1077.JPG
 
Last edited:
I've enjoyed reading the different ways of doing this.

Also enjoyed reading a previous post about getting 2 holes at exactly 90 degrees.

Any good books websites or previous threads that would help a newbie get attuned to this geometrical thinking ?

Bill
 
Hi, you need to tell us how big in diameter this part is? Because the method can differ depending on how big the thing is…Good Luck, Dave.
 
The most accurate way with only a drill press is to mount it to a square block fixture as previously mentioned. Carefully measure the needed distance from the top/bottom edge. Mark the first hole/high spot with a center finding gauge, or scratch the high point with a height gauge, or use a dial indicator to find the highest spot. If you have none of these, just use anything with a pointed tip to "very lightly" scratch the highest spot. Center punch it and use a center drill to start the hole and finish drill it. Flip the mounting block 180* and do the same thing.

Rick
 
You must log in or register to reply here.
Back
Top