1/4" dowel too big for a 1/4" hole-what do I do?

[dennis thompson]

I am making a toy fire truck for my grandson. It calls for many 1/4" dowels to be inserted in 1/4"holes. i've drilled all the holes with a 1/4" drill & find that the dowels I purchased are too big to fit in the hole. I tried forcing them & broke the parts they were supposed to fit into. I tried microwaving the dowels, thinking maybe I could shrink them, didn't work. I redrilled the holes with a different 1/4" bit, still didn't fit. Other than sanding down all the dowels , can you suggest any solutions?
Thanks
Dennis

[Jim Riseborough]

can you get a 9/32 bit or close to that?

[Charles Wiggins]

My first thought is to make a dowel plate (http://brownellfurniture.com/2012/04/07/split-top-roubo-diy-dowel-plate-for-drawbore-pins/). Or you could buy one (http://www.lie-nielsen.com/catalog.php?sku=DP) if you don't mind waiting. I usually have the opposite problem, that my dowel is undersized.

Addendum: I just found this method that might work for you: http://www.videozu.info/72703ccd8.html

[mreza Salav]

if the drill bit is exactly 1/4" and the dowels were also 1/4" then probably it's moisture; put them in the oven for a while.

[Prashun Patel]

I would make a dowel plate. Drill a hole the same diameter in piece of steel. I like the Stanley braces that you can get in the cabinet hardware section of HD - because they are predrilled. It's easier to widen that hole than start from scratch and step up IMHO.

Then hammer your dowels through. You might have to resharpen the hole (read, drill a new one) every umpteen dowels.

[Dave Richards]

If you've already got the dowels, why not sand them a little until they fit in the holes? You could chuck them into a drill and spin them against a bit of sandpaper. Are they supposed to be a loose fit or are you gluing them in?

[Peter Quinn]

I chuck them up in the drill press and sand them with a little flexible sandpaper. Takes them down quick and easy. The dowel plate should work too, a piece of mild steel angle iron works well, you only need to take a few thousands off.

[George Gyulatyan]

I recently ran into the opposite issue. I drilled 3/8" holes using my brad point bit and the holes were too big. Luckily I had only drilled 2 at the time and had tested the holes with the dowels. I switched to my DeWalt pilot point bits and the holes matched perfectly.

Either your drill bit is too small or your dowels are too big. Either way, can't hurt to try a different bit.

[dennis thompson]

Thanks for the quick replies. I made a dowel plate and it worked very well.
Dennis

[Matt Day]

How about bringing a part with the 1/4" hole drilled in it to the hardware store to see if any of their 1/4" dowel stock fits?

[Myk Rian]

How about bringing a part with the 1/4" hole drilled in it to the hardware store to see if any of their 1/4" dowel stock fits?
That's what I do, unless I make the dowels on the router table.

[Larry Frank]

There are many good ideas in this thread. I think the bottom line is that you can not expect a 1/4" dowel to be 1/4" round. They can be too large, too small or not round. It always pays to drill a trial hole in the wood that you are using and see if the dowel fits. You could also put a caliper on the dowel and measure it.

I have also found that the diameter of a drilled hole depends on many things such as the type of wood, the direction of drilling, how fast you drilled it and the type of drill bit. It sounds so simple to drill a hole for a dowel and ends up not being always that simple.

[Roger Feeley]

Just to add one more consideration: Twist drills, when used on very thin material don't drill round holes. The holes are a bit triangular. Drill a hole in sheet metal and you can see it easily.

[Jacob Reverb]

if the drill bit is exactly 1/4" and the dowels were also 1/4" then probably it's moisture; put them in the oven for a while.

Size-to-size won't work, regardless of moisture.

If you had a steel dowel of .25000000" diameter and tried to insert it into a steel hole with a .25000000" diameter, it wouldn't fit.

The hole has to be bigger than the dowel.

[Jim Neeley]

Another consideration is that a particular .25" drill bit isn't exactly .25". Some are too large, some too small. Same with dowels and yes, humidity (moisture) plays a role too.

I suggest using a micrometer to first check for consistent dowel diameters because if they are inconsistent, you are chasing your tail trying to find the correct bit.

If they are consistent, purchase a bit slightly larger than the dowels. If there's nowhere local I'd consider ordering a HSS lipped brad point bit from Lee Valley. They offer them in 1/64" steps so you can choose your "gap" and they cut mighty fine holes. At least for the set I bought, for the ones I checked, they were pretty much dead-on for accuracy.

Jim in Alaska

[Ronald Blue]

Actually it would fit. It's called an interference fit or a press fit and it is done all the time in metalworking. An interference fit means it has light resistance and a press means just that. It may also be driven with a hammer. You can't get good results in most woodworking applications with either fit.

[Richard Wolf]

I always re-size drill bits to custom fit balusters into railings. I always use spade bits which can easily be sanded down on a belt sander to a custom size. Start with the next larger side and sand down a little on each side until you have a fit. Spade bits come in 1/16 increments, so you never have to remove much.

[Paul Symchych]

Try what the old time shipbuilders did back before the steel era. Ribs and other parts of wooden ships were dowel pegged. They heated the dowels to dry and shrink them, put 'em in and let them swell to fill the hole.
An oven with very low heat for a few hours could shrink your dowels.

[Eric DeSilva]

+1 exactly what I'd suggest.

[Brian Kent]

Size-to-size won't work, regardless of moisture.

If you had a steel dowel of .25000000" diameter and tried to insert it into a steel hole with a .25000000" diameter, it wouldn't fit.

The hole has to be bigger than the dowel.

I have been fascinated with this statement since you posted it. Under the best practical conditions, how much larger would the steel hole have to be than the steel dowel for the snuggest fit?

[Howard Acheson]

I always recommend taking a pre-drilled sample with you when buying dowels if the fit is critical. Many dowels are really made to metric sizes. Even "inch" sized dowels are frequently made with poor quality control.

That said, both the diameter of the dowel and/or the diameter of the hole is affected by wood movement due to changes in relative humidity. Folks I know who need a free running axle will drill the hole slightly oversized. I have a couple of bits that are 1/64" oversize just this type of situation. 9/64" would be the bit to use for a "nominal" 1/4" axle.

[Rich Engelhardt]

Under the best practical conditions, how much larger would the steel hole have to be than the steel dowel for the snuggest fit?While I have no idea how much larger it gets - I've had some success in the past putting the rod or roundpart in a freezer for a day or two and heating the hole with a torch.
You have to work really really really fast and you only get one real shot at it.

A friend of mine, Jim, was an expert at doing it with ball joints..

[Jim Koepke]

If you had a steel dowel of .25000000" diameter and tried to insert it into a steel hole with a .25000000" diameter, it wouldn't fit.



I have been fascinated with this statement since you posted it.


Rich has the right idea on this.

While working in a large (ship & power plant) diesel engine shop the flywheel bolts were an interference fit. The bolts were machined to match the holes. Before installation the bolts were "soaked" in liquid nitrogen. The bores were lubricated and a hydraulic jack was used to press in the bolts.

jtk

[Jim Neeley]

I always recommend taking a pre-drilled sample with you when buying dowels if the fit is critical. Many dowels are really made to metric sizes. Even "inch" sized dowels are frequently made with poor quality control.

That said, both the diameter of the dowel and/or the diameter of the hole is affected by wood movement due to changes in relative humidity. Folks I know who need a free running axle will drill the hole slightly oversized. I have a couple of bits that are 1/64" oversize just this type of situation. 9/64" would be the bit to use for a "nominal" 1/4" axle.

+1 I think having a couple of sizes around the nominal size is the most efficient approach for small runs. :-)

[Kevin Guarnotta]

I'm not sure why, but dowels never seem to be the size the are supposed to be. I've learned this recently when trying to build toys for my son. I have tried some heavy duty sanding, or wallowing the hole a tiny bit by rocking the drill. Ideally, I just keep trying slightly different size drill bits, until I get one that has a decent fit.