Have any of you ever experimented with a slight chamfer style relief cut around your dowel hole end drilling to get a tighter joint? When the units are in the case clamp, everything looks tight but when they come out, I'm occasionally getting some very slight gaping that probably most wouldn't notice - but I do and it's bothering me. Or, is this indicative of another issue I'm not seeing here? Thanks for the help!

Hi Stewart,

It could be a number of things causing your gap. I would look at your hole depths, you neet a little bit of room, about 1mm, of clearence at the bottom of your hole. This leaves room of a bit of extra glue to go. You also need to ensure that there isnt to much glue that your extra depth cant handle. You could also be seeing your scoring if parts a being flipped over. Another thing our guys do is run the air gun across the joints after they are put in the clamp, but before they are squeezed, just to blow any dust or junk out of the joint. Also be sure to blow your holes out before applying glue at the assembly bench.

We don't use dowels and case clamps for assembly so I cannot speak from firsthand experience, but I can appreciate what you're talking about.

I know that the Grass Ecopress machine uses 10mm forstner style bits with a relief chamfer, but I'm not sure if that bit has the right geometry for your situation.... especially the depth, you have to stop the hole at something like 12mm deep to get the chamfer right.

But it does basically what you're fighting-- helps prevent wood from pooching out when the dowel gets inserted, and also helps center the dowel at assembly which makes life easier.

And the Ecopress I'm talking about is for drilling the backside of drawer fronts for drawer systems like Zargen, just for clarity. So definitely not the same machine you're doweling with, but perhaps they off the bits you'd need to get that chamfer.

Thanks for the responses! I do allow a 2mm gap on each end of the dowel for excess glue/water and we use our blow nozzles religiously to clear debris from the holes and joints. I might try slightly turning down the glue dose to see if that does anything but I'm really thinking it has more to do with the edge itself. The machine shoots water into the end holes before firing the dowels and I have noticed that, when using plywood, I get several drips to come out each hole after the dowel is inserted. This doesn't seem to be as much of an issue with the particle board core products. I'm wondering if that extra water is causing some slight swelling and making my plywood joints not quite as tight.

I find plywood to not perform aswell as, say particle or mdf core materials, I find that the water runs out of holes in plywood as well. In my experience plywood cases never keep joints tight as well as other materials. Ive never figured out why, justdoent seem to hold the dowel as well. We only use ply construction if absolutly need, or if a customer is dead set on it, the quality and consistency just isnt there, and its a pain to work with warped panels and panel thickness variations, thats a different topic all together. Anyways back on topic, if using plywood i would double check the hole depth in the gable, if your programs are set to 19mm and you panels come in thin, I've seen import plywood sold as 3/4" come in at 17mm, your holes may be shollow. Having said that, more often than not, regardless of how tight the joint is in the clamp, plywood cases do open up a bit for us as well. We have yet to find a solution.

I am guessing you are using an 8mm dowel. You can get a countersink for your bit, I uses a set screw so can be adjusted to provide a small or large sink. Most euro bit suppliers will have a sink. I am using one when I drill HPL doors as it helps with the ram in hinge.

Anybody have a source for the grass ecopress 10mm bit with the countersink on it? I can’t find anything online for it but I have been looking for that. We put thousands of rafix fittings in and have a 20mm with a slight countersink and it goes in so much smoother. Would like a 10 set up same way

Nathan, I'm glad to hear I'm not the only one with this issue - not that I would wish an "issue" on anyone else but it does mess with you when you have chewed on it for a while and can't seem to figure out where it's coming from. The dowel protrusion to depth of hole is just fine. I'm thinking for my plywood projects, I will dial the water dosage back and see if I can find an 8mm bit with a slight countersink to relieve any inconsistency right at the joint. Other than that, the only thing I can conclude is there must be a little amount of natural "springback" once the plywood case comes out of the clamp. Again, joints look great in the clamp and then occasionally gap once the pressure is off. Cases are left in the clamp for about 5 minutes.

I don't think 5 minutes is long enough for the glue to set.

5 minutes actually works really well in most cases, but just for grins, I've tried up to half an hour to see if I could achieve a tighter joint. It doesn't make a difference at all. The "springback" is still there.

if you are having a problem with plywood, then check the thickness and depth you are boring into an end, meaning that you accommodating for its actual thickness. IT could be 18.5 and melamine is 19.3

Thanks, cabinetmaker! I have checked and double checked to make sure I wasn't missing anything. I actually have my boring set up for an 18 mm panel since that is the thinnest we would work with. So, anything thicker obviously isn't a problem and if, by chance, the panel was a scant 18, then I have a 2 mm gap programmed on each end of the dowel to accommodate any further variations.

Derrek, you asked where to get the Ecopress bit, we buy them from True32.com

10mm Dowel bit with countersink