a great way to set....

[toolguy1000]

the height of TS blades and router bits (in a rouoter table) is in the 05/13 issue of wood magazine. it's this month's top shop tip and involves using a digital angle cube referenced off the the tool's table. to set a blade or bit @ a height of 3/8", for example, a 3/8" drill bit is placed on the tool surface and a flat piece of material bridges the shank of the drill bit and the blade or router bit and the digital angle cube is placed on the flat piece of material. as the blade or bit is raised or lowered, the digital angle cube approachs zero. at zero degrees, the blade or bit is at the same height as the shank of the drill bit.

since i've always had a bit of an issue with seting accurate cutting depths, i found this to be an extremely useful tip and just wanted to pass it along.

[greenacres2]

Clever. I don't have set-up bars (or a digital angle cube)--been counting on my digital caliper which is okay. Set-up bars would seem an even better choice...no rolling off onto concrete floor. Good idea.

I need to remember that kind of stuff when it's Christmas.

earl

[pelligrini]

I thought that was a great tip too.

I have a few methods for height adjustment. The one I really like is my Wixey height gauge. It is a lot easier to read than a few other gauges I have. It always seems like the battery is dead at the most inopportune times.

[LCHIEN]

the height of TS blades and router bits (in a rouoter table) is in the 05/13 issue of wood magazine. it's this month's top shop tip and involves using a digital angle cube referenced off the the tool's table. to set a blade or bit @ a height of 3/8", for example, a 3/8" drill bit is placed on the tool surface and a flat piece of material bridges the shank of the drill bit and the blade or router bit and the digital angle cube is placed on the flat piece of material. as the blade or bit is raised or lowered, the digital angle cube approachs zero. at zero degrees, the blade or bit is at the same height as the shank of the drill bit.

since i've always had a bit of an issue with seting accurate cutting depths, i found this to be an extremely useful tip and just wanted to pass it along.

I saw that tip in the Wood Magazine. Theoretically this is a OK way to do it. However, I take issue with a couple of things.
1. He forgot to say to set the angle gauge zero on the table before using it to set the height. For every .1 degree the table and the gauge are off you'll get .005 to .010 or more error in height.
2. He forgot to say that the scrap used must be a perfectly flat, true, piece and the bottom and top must be perfectly parallel. I grabbed several pieces of scrap 1x pine in my pile about 4-12" in length and measured the thickness at one end and the other and I came up with around .002 to .010" difference - that'll be the error in your height setting in not perfectly flat and parallel.
3. He didn't mention how long the piece should be. The length affects the accuracy. Ideally the piece should be relatively short. The picture with the article looks to be about 4" long.
4. He claimed "dead-on" accuracy, but I have ways of measuring to much better accuracy.

Let's look at the accuracy. Simple high school trigonometry says the Delta H or difference between the height of your reference and the bit height, is R x Sin(Theta) where R is the length of the bridging piece and theta is the error angle.
Assuming the bridge piece has a length of 12" and the angle gauge has an accuracy of 0.1 degree (for practical purposes the best accuracy can't be better than the display resolution) then your error will be about .021" or more than 1/64th. It turns out you get better accuracy with short bridges so a 4" bridge gets you about .005"

For setting height I use a jig with a inverted U-frame and a digital caliper movement in the middle. That lets me span the bit or blade so there's no tillting errors and measures to .001" accuracy, or .0005 resolution of the caliper movement. That's 5 times better than the article's method. and quicker, too - you only need mess with one piece instead of multiple pieces. There's three pieces involved in the article's method, you have the angle error, the parallelness and straightness of the bridge and the error of the reference (DRILL BIT) which are sometimes off a few thou.

Now I'm not going to claim you need .001" height setting and that .005" is not good enough for woodworking. For most practical purposes this will work well. Or if your regular height gauge is broken or missing then this will do in a pinch.

I am going to say its not "dead-on" accurate as claimed and that ultimately making your measurements as accurate as possible will give you better results, because errors do compound.

Consider setting dado cut depth for a half lap, that an error of .005 on setting the depth of each lap cut will result in an overall error of .010" when the two are put together. Errors have a way of compounding themselves.

FWIW, I have made several DIY height gauges that all work really well.
http://www.bt3central.com/showthread...t=height+gauge