Today in the shop "Making 3/4" holes in to 20mm"
Posted: Tue Mar 22, 2022 2:18 pm
I do not recall the who or the when but I got this idea from somewhere. Wish I could give credit.
Let start with what is happening. You have a nice 3/4" hole. Thing is you wished it were say 20mm. As you may know 3/4" is smaller then 20mm so it clearly can be done, right?
Say this is your hole:
The bit you want to use looks like this compared to the hole.
You could take various routes to do the drilling but today we will look at using a step drill. In this case I happen to have a 20mm spiral groove version.
By design the bit is self centering and has a chamber to help get it started. As a result you can get a hole that looks like this:
Now the bit has a nice place to start as shown here:
This is of course not the only way to do this but it sure works slick.
Ed
Let start with what is happening. You have a nice 3/4" hole. Thing is you wished it were say 20mm. As you may know 3/4" is smaller then 20mm so it clearly can be done, right?
Say this is your hole:
The bit you want to use looks like this compared to the hole.
You could take various routes to do the drilling but today we will look at using a step drill. In this case I happen to have a 20mm spiral groove version.
By design the bit is self centering and has a chamber to help get it started. As a result you can get a hole that looks like this:
Now the bit has a nice place to start as shown here:
This is of course not the only way to do this but it sure works slick.
Ed