I'm working on a project which is a fixture for my mitersaw. It requires me to make some cut outs and match radius on the saw. As I was getting the layout done it occurred to me that I have not done any tips in a while. To the relieve of some I'm sure but for other these might be helpful.
The more common one when you have a right angle and want make a radius to match both the sides is often done by measuring using the radius from each line to locate the center. But measuring takes time and is not always needed. Besides some people are fractional phobic and don't want to have to figure the radius of a 1-7/8 drill bit..... right??
As always I've taken some pictures to help explain. First lets look at two lines that are forming a 90 degree angle. They would look like this:
- IMG_4416ac.jpg (241.65 KiB) Viewed 10511 times
For our purposes lets say you want to use a 1" dia bit and this is not a critical hole but one that you might make on a fixture for the shop. Mmmm sounds like my project. So option one that I mention before is the addition of line 1/2" away and parallel to the existing lines. Where those line intersect would be the location of the center point for you to drill at. But what if we didn't want to do that? Well guessing works, sort of and depending on your skill level.....
So you can see this better I added some tape along the lines. You do not want to do this in real life but I think it helps for the purpose of this discussion.
- IMG_4417sc.jpg (250.93 KiB) Viewed 10511 times
In this next photo I'm showing a small Rockler corner square but any square will work so long as it is tall enough to touch the edge of the bit at maximum diameter. You can even make your own out of a piece of scrap. The edges of the square align with the edges of the square.
- IMG_4418sc.jpg (244.77 KiB) Viewed 10511 times
Now you can take the bit and have it touch both sides of the square and mark the center with the center of the bit. A very light tap will leave a center point for to to use later.
- IMG_4419sc.jpg (247.24 KiB) Viewed 10511 times
I like to make it easier to find by making it with a * as shown here:
- IMG_4420smc.jpg (263.35 KiB) Viewed 10511 times
Now I'm doing it here in the layout stage but you can do the same sort of thing at the drill press. In that case you can chuck the bit and use the quill feed to locate and drill the hole.
Now this works great for thing that meet at right angles and things that are very close to a right angle. So what do you do when that is not the case? Check in on the next post and find out how I handle that situation.
Ed
