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1/4 bits all undersized by .001

5482 Views 36 Replies 12 Participants Last post by  Herb Stoops
Is this normal? All my 1/4 bits are approx .249 rather than the full .250"
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"Getting back on track, Pat Warner once said what he thought was the maximum allowance in shaft size. Does anyone remember what it was? I'm sure it was less that 2 thou but it seems to me that it wasn't much under that."
-Charles

https://www.engineersedge.com/general_tolerances.htm
Does it say what the tolerance is for a collet fit? It doesn't want to let me in because of my ad blocker.
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I'll do a screen shot...it's a generalized reference, not specific to collets. I think you'd need to extrapolate from it.

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Collets by design should allow for a slight variation of sizes. They are probably designed exactly to the specified size, but can accommodate undersize bits.

I have a bunch of Porter Cable routers, and I think their collets are slightly undersize, as bits won't usually slide out even when they are loose.
And then there are the tolerances when two parts have to fit together or only look the same. I see posts where someone thinks that two parts have to be alike and spend a lot of time and effort doing that when they really only have to look alike and it takes very little time or effort to do that.

Getting back on track, Pat Warner once said what he thought was the maximum allowance in shaft size. Does anyone remember what it was? I'm sure it was less that 2 thou but it seems to me that it wasn't much under that.
Another thing that I've said several times on this forum is "if it looks right it is right" who is going to take a magnifying glass to the project.
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Collets by design should allow for a slight variation of sizes. They are probably designed exactly to the specified size, but can accommodate undersize bits.

I have a bunch of Porter Cable routers, and I think their collets are slightly undersize, as bits won't usually slide out even when they are loose.
The MUSCLECHUCK is so accurate that a bit will slowly lower itself into the collet. At least one other member has confirmed that.
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The MUSCLECHUCK is so accurate that a bit will slowly lower itself into the collet. At least one other member has confirmed that.
This true,Harry, I have found bits though that are undersized by.005",that will not tighten up in the musclechuck, but will tighten up in a regular router collet chuck.
Herb
Paul, remember the old military saying- Don't force it, use a bigger hammer! The bolt can measure under the 0.250 at the body but when the threads are cut, they are slightly bigger than the stated diameter. Ran into this many times.
John, the bolts had a shoulder where I was expecting rotation... but I never measured them! :)
This true,Harry, I have found bits though that are undersized by.005",that will not tighten up in the musclechuck, but will tighten up in a regular router collet chuck.
Herb
I haven't found that with the chuck itself but I have a couple of 1/4" bits that won't lock in the reducer sleeve supplied by Derosa engineering, makers of the MUSCLECHUCK.
Realistically, a precision tool like the Musclechuck does deserve precision bits.
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I have found that when I buy dowels the nominal size is close to what it is supposed to be,but can vary enough that it is too loose or way too tight.
Many times I have used the metal reamers which are very accurate to enlarge the hole for the dowel. I have found that wood working bradpoint and forstner bits vary in dia. from actual size too.
Herb
Years ago when dowels were smooth with a slot down the length I often found them over or under size but with the advent of the splined ones they are usually a gentle hammer fit without danger of splitting the wood and still have room for the adhesive.
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Well made dowels are supposed to be like biscuits. They get compressed and are designed to swell up when you glue them.
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Well made dowels are supposed to be like biscuits. They get compressed and are designed to swell up when you glue them.
Those dowels are different, I am talking about the 3' long dowels sticks. I use the long ones for a lot of projects. I also find the wood working drill bits are a nominal size,not as accurate as metal working bits.
Herb
All I want is a machine that can do this, is that too much to ask?

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I heard decades ago that (NASA?) had developed polishing techniques that could polish fine enough that two metal surfaces would weld themselves together when they came into contact with each other. They were looking at using the technology in outer space where regular welding would be impossible.

Herb I used to use a lot of the Ramin dowels too. They aren't all that accurate so maybe the bits were good and the dowels weren't. I've cut grooves along the sides before when I was worried about too much hydraulic pressure.
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Now THAT is precision. Fortunately not required on wood.
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I would say that the Muscle Chuck is in the Class IV on the Chart listed above.
Herb
Herb I used to use a lot of the Ramin dowels too. They aren't all that accurate so maybe the bits were good and the dowels weren't. I've cut grooves along the sides before when I was worried about too much hydraulic pressure.
There is something to that too, getting the dowel and the drill bit to match. I have never had problems with short dowels for joinery, just the hydraulic presser you mention and the grooved dowels work great to solve that problem.

HErb
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