Shopsmith Forums

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:
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.
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.
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.
I like to make it easier to find by making it with a * as shown here:
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

In this picture you can see the situation I have in this build. I have a curved line meeting a straight line and while guessing is still an option I find I do better when I find a better way. So lets look at what I'm talking about.
Now there are several ways that I could go but since I want this to be educational I'll show you a simple way to get the radius I want. In my case I have a lot of scrap Sam's Club cutting board pieces so I picked out one of these and drilled the same 1" diameter hole that I want to use for the 1/2" radius. Any scrap will work.
Now I can visually look in the hole and see the tangent points of the lines and hole. I then can use the same bit to again mark the center point.
And I again mark it with the *:
And as mentioned in the last post this can also all be done at the drill press.

Now with the holes drilled I'm ready for some other cutting, and that will happen later today.
I'm not sure I will post anymore of the project because it is pretty much miter saw dependent and would not be all that useful to most people.

Ed

But on the other side of the coin I think it only fair to let you see the finished product.
Ed

As usual, Ed, outstanding lesson.

However, it is as useful as a lesson in layout as it is a drilling tip.

I assume the cutout was done with a router.

The outside curves were done on the bandsaw and the inside with a jig saw. Had this been something of more value yes I would have used a router.

This is an experiment as previous versions either covered the angle gauge or broke apart at some point from lack of strength. After the initial cuts are made there is little material to hold things together. I don't know how well this one will work but I have a project coming up where I will be cutting a bunch of smaller parts and wanted a nicer way of doing them..... and not have the little parts thrown about.

In the past I have just cone with clamps to attach them. This time I have cleats on both ends so it slides on and the alignment seems to work well enough so the kerf will not get to big to fast.

Ed