# 1/4 bits all undersized by .001



## martik777 (Jan 17, 2010)

Is this normal? All my 1/4 bits are approx .249 rather than the full .250"


----------



## Stick486 (Jan 4, 2013)

shank or cutter??


----------



## martik777 (Jan 17, 2010)

Shank


----------



## difalkner (Jan 3, 2012)

My 1/4" compression bit measures 0.245" (cutter), the shank measures 0.249".

David


----------



## Stick486 (Jan 4, 2013)

normal...


----------



## DesertRatTom (Jul 3, 2012)

So? That is a pretty close tolerance. Is it loose in the collet? I can't imagine that it's significant.


----------



## martik777 (Jan 17, 2010)

No, I made a collet for someone and they mentioned they could not easily get a .250 shank to fit. I machined it to slip fit a .249" shanked bit.

Checked all my bits and not one is .250. They are all between .249 and .2493


----------



## DaninVan (Jan 1, 2012)

Well if the hole (collett) is .250 than the shank _has_ to be smaller (.249) otherwise it ain't gonna fit.


----------



## harrysin (Jan 15, 2007)

DaninVan said:


> Well if the hole (collett) is .250 than the shank _has_ to be smaller (.249) otherwise it ain't gonna fit.


I just checked these three bits picked at random and the accurate one happens to be one of two that I bought off E Bay some years ago and they cut just fine. 1/4" = 6.35mm


----------



## TenGees (Sep 12, 2012)

Making a 'roller' for a roller stand the other day. I noticed the same issue, drilling a 1/4" hole and expecting it to turn on a 1/4" bolt. I could barely get the bolt in (without using a hammer). So I measured some bits to see if I could find an oversized one... all of them were undersize! I finally found a knurled punch that opened the hole a bit. I guess the knurling added a little width to 1/4" material it was made from???


----------



## DaninVan (Jan 1, 2012)

Things they never told us in 'shop'...
https://www.engineersedge.com/manufacturing/drill-mechanical-tolerances.htm
I did not know that.
That would bring up the obvious question, what if you actually _want_ a hole .250"
Everything manufactured has upper and lower acceptable tolerances (ie .2493 to .2489 for example...no idea what the actual parameters are).

I'm guessing you need to place a custom order. I know that my machinist neighbour worked to incredibly exacting specs in the aero-space sector.


----------



## DaninVan (Jan 1, 2012)

From that last link...
https://www.engineersedge.com/general_tolerances.htm

Not woodworking then?


----------



## Knothead47 (Feb 10, 2010)

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.


----------



## ger21 (Feb 10, 2019)

> That would bring up the obvious question, what if you actually want a hole .250"


That's what reamers are for.


----------



## harrysin (Jan 15, 2007)

DaninVan said:


> Things they never told us in 'shop'...
> https://www.engineersedge.com/manufacturing/drill-mechanical-tolerances.htm
> I did not know that.
> That would bring up the obvious question, what if you actually _want_ a hole .250"
> ...


Very interesting Dan, it reinforces what I have said on this forum many times when members talk about attempting to get to 0.001" in wood!! Such members seem to forget that, unlike metal, it moves with the weather, even if 0.0005" is achieved on the day, tomorrow the sun may not be shining and it's raining, how accurate is it then?


----------



## harrysin (Jan 15, 2007)

ger21 said:


> That's what reamers are for.


Metal!


----------



## Herb Stoops (Aug 28, 2012)

harrysin said:


> Metal!


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


----------



## Cherryville Chuck (Sep 28, 2010)

harrysin said:


> Very interesting Dan, it reinforces what I have said on this forum many times when members talk about attempting to get to 0.001" in wood!! Such members seem to forget that, unlike metal, it moves with the weather, even if 0.0005" is achieved on the day, tomorrow the sun may not be shining and it's raining, how accurate is it then?


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.


----------



## DaninVan (Jan 1, 2012)

harrysin said:


> Very interesting Dan, it reinforces what I have said on this forum many times when members talk about attempting to get to 0.001" in wood!! Such members seem to forget that, unlike metal, it moves with the weather, even if 0.0005" is achieved on the day, tomorrow the sun may not be shining and it's raining, how accurate is it then?


That reminded me of the conversation I had with the owner of an Italian coffee shop/restaurant. He was explaining to me that they grind their beans for the day based on the weather! Apparently it makes a big difference in the quality of the finished product, the cup of coffee.
(He also said that the roasters of Starbuck's beans should be in jail...  )


----------



## Stick486 (Jan 4, 2013)

DaninVan said:


> (He also said that the roasters of Starbuck's beans should be in jail...  )


why stop there...


----------



## DaninVan (Jan 1, 2012)

"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


----------



## Cherryville Chuck (Sep 28, 2010)

Does it say what the tolerance is for a collet fit? It doesn't want to let me in because of my ad blocker.


----------



## DaninVan (Jan 1, 2012)

I'll do a screen shot...it's a generalized reference, not specific to collets. I think you'd need to extrapolate from it.


----------



## ger21 (Feb 10, 2019)

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.


----------



## harrysin (Jan 15, 2007)

Cherryville Chuck said:


> 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.


----------



## harrysin (Jan 15, 2007)

ger21 said:


> 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.


----------



## Herb Stoops (Aug 28, 2012)

harrysin said:


> 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


----------



## TenGees (Sep 12, 2012)

Knothead47 said:


> 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!


----------



## harrysin (Jan 15, 2007)

Herb Stoops said:


> 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.


----------



## harrysin (Jan 15, 2007)

Herb Stoops said:


> 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.


----------



## Cherryville Chuck (Sep 28, 2010)

Well made dowels are supposed to be like biscuits. They get compressed and are designed to swell up when you glue them.


----------



## Herb Stoops (Aug 28, 2012)

Cherryville Chuck said:


> 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


----------



## BalloonEngineer (Mar 27, 2009)

All I want is a machine that can do this, is that too much to ask?


----------



## Cherryville Chuck (Sep 28, 2010)

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.


----------



## harrysin (Jan 15, 2007)

Now THAT is precision. Fortunately not required on wood.


----------



## Herb Stoops (Aug 28, 2012)

I would say that the Muscle Chuck is in the Class IV on the Chart listed above.
Herb


----------



## Herb Stoops (Aug 28, 2012)

Cherryville Chuck said:


> 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


----------

