Tuesday, April 2, 2013

A Slip of the Bit

This past weekend I experienced one of those days when I was really excited to be out in the shop.  I was anxious to try a new technique of making fitted lids for some boxes that are in the works.  I had watched a video online several times, making sure that I had accounted for all of the steps.
Then it was time…

Bit selected…check!
Router set up…check!

Test piece selected and marked…check!

I even traveled to the Fourth Dimension to set the max bit height on my test piece.

The first step of this process is to route a groove in all of the inside surfaces of the box, before assembly and glue-up.  In this case I’m routing a 3/8 inch wide groove to a depth of half the thickness of the box walls…5/16 of an inch for these boxes.

My plan was to route these grooves in three passes to reach the final depth.  My test piece and the first box part were successful on the first pass.  Upon routing the second part (one of the longer sides of the box) I noticed a little different sound and feeling as I came to the end of the cut.

I shut down the router and examined the piece…oh man!  As I pushed this part over the router bit it had gradually slipped up and cut my groove deeper and deeper along the length of the piece.  It would not have been too drastic had it not gone beyond the final depth I was shooting for, however…

Start of the cut…
End of the cut…
At this point all excitement became frustration.  I was sure that this piece was ruined and that all my planning was for naught.  I decided it was time to step away before I tried to fix it and make it worse. J

The time away has been very fruitful though.  By stepping away and giving the problem some good thought I believe I have a very workable solution that will allow me to salvage this piece and complete the box.  Stay tuned for a post on that process!

The time away (surfing the internet) also revealed that a common cause of a slipping router bit is the presence of any debris or rust on the bit shank or collet.  Sure enough I did find a little bit of dust and rust on the collets of my M12V router.  A little WD-40 bath and a good wiping have them cleaned up nicely.  I also learned that the M12V has a reputation for slippage when using 1/4 inch shank bits because you’re using a 1/4 inch collet insert inside of the 1/2 inch collet.  My DeWalt DW621 has dedicated collets for both 1/4 and 1/2 inch shanks, so I believe I'll swap routers when I’m ready to finish routing these grooves.

It’s always frustrating to see a plan fall apart or experience an error where you weren’t expecting it.  The key is to take a step back, stay calm and give it some thought.  Solutions will come to those who look for them and ask the right questions.  I’ll confess to getting a little angry and sulking for a few minutes, but if you’re passionate about something you’ll come back to it quickly, renewing your focus and digging in to repair or even reinvent.  Don’t give up!



M. Wood said...

I feel for you. During my last project the fence on my router table worked its way loose and I cut a wider dado than planed.

Pete said...

Oh man! I bet the fix is similar to something I'm considering...filling the dado with a strip of the same wood and then re-routing?