How to use a dial indicator and other stupid newbie questions

Your framing square will not be flat enough to be useful in the above situation. Let's talk about dial indicators. Some of the chinese ones are pretty good, some aren't. You need to use something of known thickness to find out. Use a set of leaf gauges, the kind for checking point gap etc. These have leaves that get larger by increments of .001" (in the USA). Using a magnetic base to hold the indicator with the shaft perpendicular to a hard, flat, surface, slide the leaves between the tip and the flat surface. The indicator should read .001 difference between adjacent leaves. It should also repeat to the same mark each time you slide the same leaf under the tip. To check the knives mount the indicator so that when you turn the jointer drum BACKWARDS the blades pass under the indicator tip. Backwards rotation so the blades don't catch on the indicator tip. All the blades should have the same reading in the same spot. This means they are running true at THAT SPOT. Check several spots. Checking whether the blades are parallel to the drum axis is harder. This is because you need a reference. And you don't know if the jointer table is flat. Do you have a micrometer large enough to measure over the blades? If so you just need to measure the blades and see if they measure the same. If they run true and measure the same then they are concentric to the drum axis. The drum axis should be parallel to the table. Maybe the best way for you to check this is to just cut some wood and see what happens. I'm sure that there are lots of folks here who will give you better advice than me and correct my mistakes in the above statements. ERS

A dial indicator is most useful when setting the knives. About

Most any decent straightedge 36" or more in length can be used to tell whether the tables are straight.

I can't vouch for all framing squares, but I do know the edge of mine checks out on a surface table. Try your framing square on a flat surface. If you can see light under the square try moving the square several different ways including swapping it end for end, and see if the light is alway in the same position of the square or if it is the same position of the " flat " surface.

Dan

I don't believe I've ever seen a dial indicator in an auto parts store, and I've been in a ton of 'em.

- - Rex B

stryped wrote:

Well, you know, the OP is stryped. And he saw a lot of instruments with dials and indicators in an auto parts store!

Nick

Use a D.T.I. about $30 has about 7 gram force , easier to read ....

D.I. is for measuring a distance . It has far more force to move its plunger .

stryped wrote: