Problem With Spiral Upcut Bit

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Forum topic by gfadvm posted 829 days ago 1262 views 0 times favorited 32 replies Add to Favorites Watch
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10557 posts in 1288 days

829 days ago

Topic tags/keywords: upcut router bit problem

My Woodcraft 1/4” solid carbide upcut router bit will not stay chucked in my collet. If I start to route a 1/4” deep slot, it will creep to over 3/8” within 3” of routing. This is a 1/4” shank but I have no problems with ANY of my other 1/4” shanks. I have tightened it tighter than the other bits to no avail (but I haven’t tried torqueing it down REALLY hard as I’m afraid I’ll ruin my collet). Any suggestions? Edit: This is a new bit and I have cleaned collet and shank.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

32 replies so far

View a1Jim's profile


111999 posts in 2175 days

#1 posted 829 days ago

Have you used a Micrometer on it to see if it’s undersize.

-- Custom furniture

View gfadvm's profile


10557 posts in 1288 days

#2 posted 829 days ago

a1Jim, I don’t have a micrometer but that’s a good thought. I assumed that buying a quailty bit would give me an accurate shank diameter. Maybe not.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View Monte Pittman's profile

Monte Pittman

13258 posts in 936 days

#3 posted 829 days ago

I have one that does that also. Not sure why though. Ruined a couple pieces because of it. Causes some definite noise pollution to occur :-)

-- Mother Nature created it, I just assemble it. - It's not ability that we often lack, but the patience to use our ability

View a1Jim's profile


111999 posts in 2175 days

#4 posted 829 days ago

If Woodcraft is not far away you might have them mic it for you ,if nothing else they should have calipers to check it.

-- Custom furniture

View Sawkerf's profile


1730 posts in 1667 days

#5 posted 829 days ago

If you’re using a reducer to accomodate a 1/4” shank, make sure that it’s lined up right before you tighten the collet nut.

My reducer has a narrow slot that runs the full length of it. That slot needs to line up with a similar slot in the 1/2” collet or the bit will move. When the slots are lined up right, it’s rock solid.

-- Adversity doesn't build reveals it.

View Loren's profile (online now)


7231 posts in 2246 days

#6 posted 829 days ago

I would take it back or measure it to make sure the
size is accurate. Carbide shanks tend to smoother
than the steel ones. It may be worthwhile to rough
up the shank.

Collet reducers do vary in size. So do bit shanks.


View DS's profile


2131 posts in 1018 days

#7 posted 828 days ago

There is a high likelyhood that your collet is worn.

Router bits, especially solid carbide bits, are manufactured to a very tight tolerance.

Though it may be possible to get a size mismatch, (never, ever have I seen this), the worn collet is the most probable cause, IMHO.

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

View KenBee's profile


108 posts in 1233 days

#8 posted 828 days ago

I agree with Loren about collet size. I just bought a new DeWalt 611PK and the collet must be undersized, because even off the router it is a struggle to insert a 1/4 inch bit into it. I tried 3 or 4 different bits and all were the same.

I also have a Spiral Upcut bit that will work its way out of the collet in 3 of my routers that I have tried it in. That one bit is the only one of my 1/4 inch shank bits I have used that will work its way out though.

-- If it won't fit get a BIGGER hammer.

View Dallas's profile


2855 posts in 1085 days

#9 posted 828 days ago

Sounds like a metric shank on a SAE/Imperial collet. Metric: 6.000mm, Imperial 1/4”: 6.35mm

.35 mm is 0.01377952755905511”

-- Improvise.... Adapt...... Overcome!

View Greg The Cajun Box Sculptor's profile

Greg The Cajun Box Sculptor

4934 posts in 1906 days

#10 posted 828 days ago

andy…it seems as if this a common issue with several people and I have had the same problem with my 1/4” shank bits. I use a 1/4” spiral upcut to cut the channels for my box bottoms and noticed creeping with the 1/4 shanks. I switched to 1/2” shanks and have not had a problem since. I guess it grabs tighter on 1/2 shanks due to greater surface area. I use the whiteside router bits and have been extremely happy with them.

-- Every step of each project is considered my masterpiece because I want the finished product to reflect the quality of my work.

View gfadvm's profile


10557 posts in 1288 days

#11 posted 828 days ago

Thanks for all the input guys. My collet is a 1/4” (not an adapter) and note that this is the only bit I have ever had problems with. I tend to think that the upcut configuration tends to pull upward on the bit. The next time I go to Woodcraft, I’ll see if they can measure it but it is a 60 mile round trip so I’m waiting until I have to go for something else. Greg, I bought this one to cut the channels for my box bottoms. I may see if they’ll exchange it for a downcut.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View mcase's profile


438 posts in 1727 days

#12 posted 828 days ago

Sixty miles? Well that makes for an afternoon trip. Why drive sixty miles to pay Woodcraft prices? You may be better off ordering online from a reputable router bit manufacturer. Try Whiteside, Better prices, better quality and American made.

View NiteWalker's profile


2704 posts in 1175 days

#13 posted 828 days ago

A great place to get whitesides.

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

View jumbojack's profile


1149 posts in 1222 days

#14 posted 828 days ago

Andy when you chuck your bit do you back it off a bit? That is do you send the bit to the bottom and then tighten. If so that could be your problem. when you chuck your bit, back it up an 1/8” or so. Some bits have a bit of a shoulder on them where the base meets the cutter. Give it a try.

-- Made in America, with American made tools....Shopsmith

View gfadvm's profile


10557 posts in 1288 days

#15 posted 828 days ago

Did that Jumbojack even though this type bit has no shoulder. Still creeps up.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

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