Loose Dowel Fit After Drilling

[Jay Knobbe]

This is my first time working with dowels. I have a new Jessem 8350 kit with the adapters to do 1/4" dowels. Here is my concern:
I built a wall to wall bookcase/TV unit, sprayed in Inslx Cabinet Coat. Cabinets below, shelves on top. We decided after it was built the 3/4" shelves (edge banded birch ply) look too skinny so I am reducing the depth of the shelves by 3/4" and using 1x2 maple, ripped to 1"x3/4" to add some thickness to the front edge of the shelves. I thought the splined dowels would press into place holding everything in accurate alignment for glue up. What I have are dowel/holes that are a bit loose in the holes. We're talking a small amount of movement. If I soak the dowels in water they swell enough for a nice hand press in fit but I'm not certain I should be doing it that way. Of course I'm looking for a flush top surface with the additional 1/4 width extending below the 3/4" shelf for a little beefier appearance.
The Jessem is a nice piece and I am taking great pains to accurately mark and drill each hole, keeping the chips cleared out of the hole as I go. My goal here was alignment more than strength so my biscuit jointer would be no help.
Your experience and advice is appreciated.

[John TenEyck]

I would have made a rabbett in the back face of the maple edging so that it was just proud of the shelf and glued it on w/o any other joinery. But if your parts will fit well if you soak the dowels in water then that's what I would do. They aren't needed for strength; the glue on the mating edges will be plenty strong enough.

John

[Richard Coers]

Must fluted dowels are made to expand from the glue, not soaking ahead of time. I'd grab some scrap and do a few experiments on how to make them work.

[Rick Potter]

I have found there are 'good' and 'bad' dowels, usually differentiated by price. The cheapies are usually smaller than the more expensive. I have a lifetime supply of good ones my dad left me, so no real recommendations.

I suspect most are a metric equivalent to standard sizes, close but not correct. I have found long dowel stock from the home centers is usually small.

Further, I find that not all drills are the same. Try drilling a half inch hole using spade bit, then a metal drill bit, then a forstner, then a brad point. Then try some half inch dowels in each. I was certainly surprised that some were loose, some tight.

[Jay Knobbe]

Inever considered that. I may go in that direction. Thanks!

[Jay Knobbe]

Yes, that is how I learned the fitment is loose. Experimenting on scrap. I tend to do that whenever I can due to my inexperience. After reading and watching vids on youtube I assumed the dowels would fit snug for "instant alignment" not waiting for the glue to expand while I fiddle with the alignment and cauls. Just kind of disappointing I guess. Thanks for the tip.

[Tim Andrews]

I use dowels for a lot of my joinery, with a Dowelmax jig. Since I live relatively close to the ocean in the foggy SF Bay Area, humidity often causes the dowels to swell too large. I cook them in the microwave for 1 to 3 minutes to get them to roughly the correct size. Not every dowel will be exactly the same, so during the dry fit I pick the ones that go in by hand but still produce a snug fit for good alignment. I once cooked them a bit too long and they were too loose, so I sealed them in a plastic bag with a wet paper towel overnight, and they regained their original size. I store them in a tightly sealed plastic bag to keep out the moisture.

[Curt Harms]

I suspect most are a metric equivalent to standard sizes, close but not correct. I have found long dowel stock from the home centers is usually small.

Further, I find that not all drills are the same. Try drilling a half inch hole using spade bit, then a metal drill bit, then a forstner, then a brad point. Then try some half inch dowels in each. I was certainly surprised that some were loose, some tight.

I think dowels are sort of like plywood - really metric dimensions, or perhaps just sloppy manufacturing tolerances.

[Jim Becker]

I think dowels are sort of like plywood - really metric dimensions, or perhaps just sloppy manufacturing tolerances.

Anything like that made from wood is going to become misshapen over time from moisture content changes...they get "unround" most commonly but can also change overall dimension because of that. When they are hidden, such as with joinery, doing what's necessary to make them fit is kewel. If they are going to be exposed, it's worth considering getting or constructing a dowel making plate to "make them fresh" from the same stock as the project, IMHO.

But yes, some could be manufactured to metric sizes while being marketed as Imperial.

[Kevin Jenness]

High quality fluted or spiral dowel pins matched with high quality drill bits and accurate boring methods fit well and give predictable results, that's why they are so widely used in industry. I can get quite accurate registration with 20 y/o fluted pins boring with Lee Valley brad point bits on my horizontal mortiser. Using a Dowel-it jig and a hand-held drill, not so much, and with hardware store dowel rod all bets are off.

Another reliable way to get a flush glue surface is with well-fitted splines in a groove routed with a slotting bit in a router. Do you really want a flush joint here, though? With pre-finished material any minor unavoidable discrepancies will show unless masked by a micro-groove or a small height difference. To get a really clean flush joint you will probably need to sand and respray the shelves and edgebands. My typical cabinet shelf uses pre-finished plywood and solid edges with a 1/32" offset established with routed grooves and biscuits.

[Edwin Santos]

Have you tried a different brand or different batch of dowels?
The Jessem jig is excellent, and capable of insanely accurate work. Your plan seems pretty good to me.

Was the dowel fit loose in both mating pieces? I ask because it can be harder to securely clamp the Jessem to narrow stock, so I am wondering whether the hole is accurate in the shelf and loose in the new trim piece. If so, it points to a clamping issue.
HTH

[Mel Fulks]

I’ve got a piece of junk steel plate ,1and 1/4 inch thick . Drilled under sized holes ,then used big counter sink to champher top and bottom
Driving the dowels through the right size hole . They don’t lose any wood ,just get compressed. I thin the yellow glue with a little
water. The dowels never split the work ,and never loosen. Standard procedure in many old shops.

[Kent A Bathurst]

I don't use dowels for primary joinery. But I do sometimes use dowels to pin M&T joints. In which case I use a hunk of actual dowel - good quality stuff, various hardwood species and sizes on hand. It is basically a perfect fit for for a forstner hole, or brad point hole from quality [LV] bits.

I take the dowel hunk and a pair of pliers and crunch around the dowel to create a low-tech version of fluting, out of the plier teeth indentations, for glue channels, and use any handy sandpaper or rasp to put an alignment bevel on one end

I am pretty doggone certain I have a few store-bought fluted dowels here somewhere, but I don't know where. Musta come from Highland some years back.

I do realize that this is of no help to the mainline theme here. But maybe someone needs only a few and can use this.

[andy bessette]

You could try dipping the dowels in catalyzed epoxy, and letting that partially cure before inserting them, using epoxy for glue.

[Jay Knobbe]

Have you tried a different brand or different batch of dowels?
The Jessem jig is excellent, and capable of insanely accurate work. Your plan seems pretty good to me.

Was the dowel fit loose in both mating pieces? I ask because it can be harder to securely clamp the Jessem to narrow stock, so I am wondering whether the hole is accurate in the shelf and loose in the new trim piece. If so, it points to a clamping issue.
HTH

Yes, the fit was loose in both pieces. What I ended up doing was drilling my holes on opposite sides of 1x3 maple so I had good stable clamping faces, then ripped to final dimension. For this project I ended up soaking the dowels for about 15 mins which made them too tight. I waited about 30mins as they dried out a bit and I could push them in with some slight resistance. I pulled them out, glued everything up and clamped in place. The outcome was acceptable to my finicky eye.