Router Collet Problem

[KC7CN]

Hello everyone. I know it's been a long time since I posted anything, but I need your help to solve a mystery. My objective was to cut a 1/2" deep slot,10" in length; to hog out material prior to using a 'T' slot cutter. The depth of cut was set at 1/8" for the first pass! The problem is, the router bit 'depth' changed - the bit actually raised up! As if the collet was trying to spit it out! I removed the bit, inspected the collet, and tried again. Same problem! I am using a Porter Cable 7518 router, mounted in a table.

When I inspected the router bit, I noticed an extremely small ring depression on the shank. I also had this problem on another project - same type of cut. In that case, the bit actually came through the stock! In both cases, I had the depth set low, with the intention of making several passes to reach the desired depth.

I ordered a new collet, and selected a different bit, a 1/4'' diameter, and had no problems!. Comparing the new and old collets, the only difference that was significant, is the new collet has a tighter grip on the bit when you insert it.

Han anyone had problems with worn or otherwise defective collets?

Any comments an thoughts will be appreciated!

-Don


5/16'' Bit:
http://

 

[McRabbet]

The shaft of the bit looks rough to me as well as having the ring you described. I would use some 0000 steel wool and perhaps a little WD-40 to clean the shaft to remove and soil or roughness. One cannot tell if the collet has clean threads or is also a bit dirty, but I'd clean it and the tapered receiver in the router shaft, again with some steel wool and WD-40. You may also need a brass wire brush to clean the spacing in the collet to insure it can grip solidly. Always lock the collet nut down securely and never allow the bit shaft to bottom in the router before tightening (I use a small grommet or faucet washer in the bottom of the hole to keep the shaft from bottoming -- usually more of a problem with larger bits dropping to the fillet where the shaft meets the bit head).

 

[ehpoole]

The bit certainly has seen a good deal of corrosion, so I would first clean it up with some synthetic steel wool (you can use a dishwashing scouring pad if more readily available) to clean the corrosion off. If there are burrs in the shaft, and there will be if it really slipped, then you will need to file down the high spots to remove those burrs. The ring seen in the photo is most likely either a region of galvanic corrosion where the bit has been in extended contact with bare metal of a different type in the presence of moisture or the demarcation line separating a portion of the shaft partially protected from air and moisture by a storage system and the portion that is more exposed. Once you have cleaned off the corrosion, buff some oil (I just use 3-in-1) onto the newly cleaned bit and work the oil in, then use a clean cloth or paper towel to remove as much of the oil as possible using only a clean dry towel. The very fine film of oil that remains will not interfere with the collet's ability to tightly grip the bit and will help to greatly slow down further corrosion of the shaft.

However, I really do not think your router bit has slipped at all as I do not see the telltale wear pattern and bright shiny sections that would suggest you ever had a bit spinning freely within the collet (and PC has a very good collet design that tends to hold bits quite tightly). What you most likely experienced, and is much more common with many routers, is a drift in the depth setting of your router base. This occurs if one forgets to fully latch the locking lever or if the locking lever has become too lose over time and is in need of adjustment to tighten things up (usually a very simple adjustment of the linkage). Without adequate clamping pressure from the locking lever the motor is free to rotate within the base and the depth setting will change as you feed the router.

Once this is addressed you may wish to look into finding a better place to store your router bits as that is a good deal of corrosion for a router bit and they are much too valuable to sacrifice to corrosion. If there are no good places in your shop where they can be adequately protected from moisture then they can always be brought indoors to help protect your investment. I have 40 year old router bits with considerably less corrosion. Corrosion also increases the runout of your bits since the shafts become roughened over time which leads to added vibration and reduced dimensional accuracy of the bits, so reducing corrosion really does help to protect your investment and allows you to get the most out of your collection of bits.

Good luck and please keep us informed of your progress. Your issue is not uncommon among router owners, so you are in good company.

 

[marinosr]

I would guess that Ethan is right on... the bit shank would likely be polished if it had spun loose in the collet. Are you sure the bit crept up? Did it drop back down into the collet when you loosened it?

 

[KC7CN]

Thank you for the quick response Rob! I'm certain the bit was not inserted too far into the collet! That's something I've learned to pay attention to over the years.Read my reply to Ethan for more info.

-Don

 

[KC7CN]

Yes, that bit looks sad - I need to retire it! Actually need to get the 1/2" shaft version for the table router! Some history should clarify the corrosion! We have been on the move! Up until last summer, we lived in Deltona, Florida - we were there for 3 years! As you know, the humidity is high in that region of the country - it's a constant battle against rust. I kept a constant eye on my router bit collection - but this bit certainly appears to have been neglected! On a side note, we did move back to the west coast!

The router is a PC 7518 mounted in a WoodPecker router lift; there is no lock on the depth setting! However, I did pull the router out and check to mounting bolts to be certain it was not slipping or loose in the lift! All my router bits are stored in dedicated drawers in the router table cabinet. This is an old 2007 photo! Your comment about corrosion and the obvious ring around the bit shank is a concern!

As I think about the problem, I suspect that cutting a shallow slot, where the cutter is plunged into the stock, may be more prone to the lifting of the bit during the cut. Going back to the collet, the only difference I see comparing old to new - is when you hold the Collet in you hand and insert the bit! Loose fit on the old one, tight on the new one. The indications are that something may have changed with the collet!

I plan to do this setup and process again within the next couple of days - I' report back and let you know how it goes.

Link to my album pictures of the NYW router table from 2007: http://www.ncwoodworker.net/pp/showgallery.php?cat=852


Thanks again to everyone that's replied.

-Don

 

[Joe Scharle]

I've had 2 collet failures over the years. The most memorable was during a jigs class, a 1/4" bit that had been set to 1/4" depth on a router table, poked it's head through the work material! That was on a Milwaukee 5625. The other was on a almost new PC890 using a keyhole bit. In both cases, I could reproduce the failures on scrap and in both cases the bits wouldn't crawl up on other collets. New collets didn't fail with the same bits and routers. That said, I've never had any failures with 8mm or 1/2" collets.

 

[Pop Golden]

I bought a used DeWalt plunge router. The collet would not tighten down at all. The problem was someone had messed up the threads on the router so that the collet could not tighten down as it should. Had my son the mechanic run through the threads. Problem solved.

Pop:widea:

 

[CDPeters]

One other thing to check is the axial slots in the collet, be sure they are not packed in with sawdust or other detritus that would keep it from clamping down tight.

 

[Skymaster]

KC7NC de OLD HZ1AB Howdy

 

[KC7CN]

73's

 

[junquecol]

Depending upon the age of the router, I wouldn't just replace collet nut, but whole collet. The part that is attached to motor is easily removed with a socket and impact gun. Did you clean the bore on the part on the shaft?

 

[KC7CN]

I've had 2 collet failures over the years. The most memorable was during a jigs class, a 1/4" bit that had been set to 1/4" depth on a router table, poked it's head through the work material! That was on a Milwaukee 5625. The other was on a almost new PC890 using a keyhole bit. In both cases, I could reproduce the failures on scrap and in both cases the bits wouldn't crawl up on other collets. New collets didn't fail with the same bits and routers. That said, I've never had any failures with 8mm or 1/2" collets.

Joe, this is good to know! Today's project was remaking the piece I ruined with the old collett! I used the new collet and a different router bit (1/4") - no problems were encountered! At this point, I'm convinced the problem was caused by the collet! Down the road I will make a test cut with the 5/16" bit pictured above, but for the time being - it has been retired along with the old collet.

Thanks to everyone who replied!

-Don

 

[Skymaster]

73's

CQ CQ CQ DX :gar-Bi

 

[KC7CN]

Depending upon the age of the router, I wouldn't just replace collet nut, but whole collet. The part that is attached to motor is easily removed with a socket and impact gun. Did you clean the bore on the part on the shaft?

I replaced the entire collet! Cleaned out the top of the router! Thanks for the note about replacing the part on the router. The new colleet has solved the problem! Thanks again!