How to measure runout?

[maspeir]

This video shows runout being measured on a Porter Cable router. However, it really doesn't show the set up they used clearly and the dial indicator they used is not described:



I cannot find precision collets for my Milwaukee router, so I'd like to measure the runout with the standard collets. How do I do this?

[jalessi]

Maspeir,

Mount your dial indicator to a fixed surface and with the tip touching the inside of the router shaft rotate the shaft to measure the router shaft run out.
If run out is acceptable install a end mill with collet and measure run out of end mill.

If your collet has run out give Think & Tinker / Precise Bits a call and ask if they can make them for you.

PH: 719 488-9640

PreciseBits Search Engine Output Page

Jeff...

[CarveOne]

The dial test indicator that they use in the video is made by Mitutoyo and is the type that (in the video) moves up and down. There are other types that move in and out relative to the way it is shown mounted in the video. These have a very short stroke and are graduated in 0.001" (cheap ones) or 0.0001" (better ones) increments. Best ones might be 0.00001".

Think and Tinker's website shows the router models that each version collet set they sell will fit. If your router model is not shown, they may be able to tell you if one of them will fit your router, or if they will have a custom one made for you. If the router shaft or bearings are worn then new router bearings or a new router is called for.

CarveOne

[brtech]

Go out to your local Harbor Freight and get a dial indicator and magnetic base. Your router isn't made of steel, so the mag base doesn't have anything to grab on to. My solution is a heavy cast iron griddle pan we have. All you need is something heavy and big enough to not slide around on your table. Lock your gantry so it doesn't move.

Use the adjustments on the mag base to get the tip of the DTI to touch the shaft of the router. Best if you are touching a smooth part, not a threaded part. Zero the DTI, and rotate the shaft by hand, observing what the DTI does. The biggest change is the runout.

[Aryantes]

I bought the Harbor Freight Dial Indicator. It is accurate to 0.001". I use a Hitachi MV12C router.

Just yesterday I was wondering why my 0.25" bit was plunging holes that were 0.27" in diameter.

I checked alignment on everything to see if it was square.

I then cut a few squares, 2", 3" for the sides. Each one came out about .03 inches short. so 1.97" instead of 2".

Didn't realize that it might be runout.

I took the collet off the router, mounted the dial indicator magnet on a piece of cold rolled steel i had, and put the tip of the indicator against a small smooth surface on my Hitachi router spindle. I tried to keep the indicator as perpendicular as possible.

I then rotated it by hand and the dial indicator stayed true, 0 runout from the actual spindle.

I then chucked my 1/4 inch bit back in with the stock collets and measured the runout at the top of the shank on the bit.

To my surprised, the reading on the TDI was oscillating from 0.000 to 0.012.

Thats a huge amount of runout, and this is right at the collet!

I took the bit off, put the bit back in, re-tightened the collet and got 0.07 instead. Tried a few more times and every time was a bit different.

I measured as far down on the shank as I could before the flutes and was able to measure 0.020 of runout.

I didn't have a drill rod to go further than that, but a guess would be that at the tip of the 2.5" bit, my runout was between 0.030 and 0.040, which would explain my messed up squares and enlarged holes.

Just placed an order for a set of PreciseBits collets and will report back later.