Proper Insertion Depth of Router Bit into Collett. Help please.

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Forum topic by RonInOhio posted 06-06-2013 10:02 PM 1870 views 0 times favorited 2 replies Add to Favorites Watch
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720 posts in 2282 days

06-06-2013 10:02 PM

Topic tags/keywords: question

Usually I can figure these things out either from an online search or manufactors directions.

This time I’m not satisfying myself that I’m positive, and I want to be positive before spinning
this bit at 30K revs a minute.

First of all I want to use a 1/4” straight bit to cut mortises. I have a Rotozip and know that Rotozip (Bosch) sells a three pack of router bits for this tool to fit the 1/4” collet. From the pics of that product the bits appear to be only about 1 1/2 long from tip to tip.

I have a 1/4” Diablo bit that is 1 3/4” long from tip to tip.

My understanding is at least 3/4” of the bit should be encased inside the collet. But that the bit should not be buried in the collet. Am I correct in assuming that this means not to slide the bit down so far that the bit cutting surfaces are inside the collet ? Duh, that seems reasonable. Or does it mean the bit should not extend all the through the collet. ?

Words are confusing so I inserted the some pics to show various depths the bit is inserted.

Could someone point out the correct depth for this router newbie ? Thanks alot.

^ Image A. Notice the collet is not slid down to the minimum mark on the bit. So this is not inserted far enough down the bit . Correct ?

^ Image A1 Here the collet is slid down to just past the minimum mark. But the bit shaft is protruding out the both ends of the collet. Is this what is known as burying the bit in the collet ? Or is this a correct insertion depth ?

^ Image B Here I didn’t slide the collet all the way down to the minimum line on the bit. Is there suppose to be
a space like this from the end of the collet to the bit ?

^ Image C And here the bit is slid through the end of the collet so as the other end is at or near the minimum mark.

Is it possible I need a bit that is a little shorter ? Feel a little foolish . But would rather feel foolish than to work unsafe. So maybe this is a specialty bit I have to order the Bosch 3 bit set for the Rotozip ?

2 replies so far

View NiteWalker's profile


2735 posts in 1995 days

#1 posted 06-06-2013 10:31 PM

You’re over thinking it; put the collet on the rotozip and screw it on a bit so it doesn’t fall off. Now insert the bit all the way until it stops. Now pull it up about 1/8” and tighten the collet. The amount you pull it out isn’t critical; you just want to make sure it’s not bottomed out.

-- He who dies with the most tools... dies with the emptiest wallet.

View RonInOhio's profile


720 posts in 2282 days

#2 posted 06-06-2013 10:55 PM

Great. Thank you.

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