# Dowels: Do you drill a hole that's 0.5mm smaller?



## alex8542 (19 Mar 2021)

I'm just wondering why do I do that, and if that's the common way to do it. I have no idea why for a 8mm dowel, I'll drill a 7.5mm hole, then ram the dowel into it along with the glue. Because it's smaller, the glue always squirt out, and I do wonder how strong they actually are because all the glue, I've squeezed them out.

is that common practice? should I stop doing that?


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## Spectric (19 Mar 2021)

With the Dowelmax the Dowels are 10mm and the drill produces a 10mm hole but they are still tight, and with say six dowels the joint can take some pulling together. Also once drilled sand across the holes to remove any potential wood fibres and the dowels need to be fluted other wise you will not close the joint, the glue is not compressable. You will always get glue coming out, only a thin film is needed round the dowels but at least you know there is good coverage and I just wipe off the excess with a damp cloth. I think a dowel joint is strong provided it is used in the right situation, and can be as strong as the Domino, just a much slower process in most circumstances. If you are making a heavy door then dowels may not be ideal, they are not going to compete with an M&T but 12 & 14 mm Dominos are used if you watch some online videos.


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## alex8542 (19 Mar 2021)

Spectric said:


> With the Dowelmax the Dowels are 10mm and the drill produces a 10mm hole but they are still tight, and with say six dowels the joint can take some pulling together. Also once drilled sand across the holes to remove any potential wood fibres and the dowels need to be fluted other wise you will not close the joint, the glue is not compressable. You will always get glue coming out, only a thin film is needed round the dowels but at least you know there is good coverage and I just wipe off the excess with a damp cloth. I think a dowel joint is strong provided it is used in the right situation, and can be as strong as the Domino, just a much slower process in most circumstances. If you are making a heavy door then dowels may not be ideal, they are not going to compete with an M&T but 12 & 14 mm Dominos are used if you watch some online videos.







yeah, i usually use fluted dowels, and it's been working fine for me, but this time, i wanna try making a miter joint with dowel reinforcement, which is something new, and is what prompted me to ask the question.

because if i use fluted dowel, it's not going to look as nice... If i'm not going to use fluted dowels, but rather dowel rods, and they're 7.89mm instead of 8mm thick (or maybe you have a better supplier that you can share..?) so in this case, would you still recommen the 8mm hole and glue? or 7.5mm hole and just jam it in?

Cheers


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## Spectric (19 Mar 2021)

That joint is not going to move!

If your dowels are undersize then make the holes proportionaly undersize, unless you can make your own dowels. I buy fluted dowels from Falcon Woodworking Supplies



Amazon.co.uk : Dowel Pins



What doweling jig are you using? I know the dowelmax has a 45° attachment plate for doing mitres.


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## JohnPW (19 Mar 2021)

I think drill bits are available in 0.1mm increments.


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## Dee J (19 Mar 2021)

alex8542 said:


> View attachment 106282
> 
> yeah, i usually use fluted dowels, and it's been working fine for me, but this time, i wanna try making a miter joint with dowel reinforcement, which is something new, and is what prompted me to ask the question.
> 
> ...


Or spin up a length of dowel in a drill, a quick application of sandpaper will soon ease the diameter a fraction...


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## Just4Fun (19 Mar 2021)

alex8542 said:


> I have no idea why for a 8mm dowel, I'll drill a 7.5mm hole, then ram the dowel into it along with the glue.


What wood are you using? I can imagine that this would work OK in something like pine but in some hard woods I think you would risk cracking your work piece.
Personally if I dowel anything I drill the hole the same size as the dowel. I have never had a problem doing things that way but please note that I don't have too much experience with dowels.


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## hunter27 (19 Mar 2021)

Only recently started using dowels but soon learnt not to let too much glue get into the holes especially in MDF, using 10mm dowels in 10mm holes, because of the hydraulic pressure created. Only noticed later that the dowels had expanded the MDF slightly.


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## pe2dave (19 Mar 2021)

AFAIK applying glue to the dowels (fluted) causes them to swell, hence and 8mm dowel in an 8mm hole 
is tight, and gets tighter as moisture enters the dowel. My view, match the drill to the dowel size.


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## EddyCurrent (19 Mar 2021)

The dowels sold here look to be quite good, Wooden Dowels | Hardwood Dowels & Timber Dowel Rods


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## Nic_the_Urchin (19 Mar 2021)

I don’t really have much to add but I’ve been making a workbench (from laminated ply) and I wanted to add hardwood dowels to reinforce the holdfast holes. (I actually purchased my dowels from g&s (the link above). My plan was to drill a 30mm hole and add a 30mm dowel and then drill a 19mm holdfast hole through that... it didn’t go well. The 30mm dowell was oversized for the 30mm forstner bit. I also wanted to make custom bench dogs from 19mm dowel. Again the dowel was 19.05 so again it was an absolute pain. Does anyone have any advice please? (sorry if this is thread hijacking) is this common? How do people inlay dowel neatly?
cheers
Nic


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## Orraloon (20 Mar 2021)

alex8542 said:


> View attachment 106282
> 
> yeah, i usually use fluted dowels, and it's been working fine for me, but this time, i wanna try making a miter joint with dowel reinforcement, which is something new, and is what prompted me to ask the question.
> 
> ...


 I would go the 8mm hole and glue. You risk splitting the wood if too tight.
I have been thinking that a doweled miter joint would look quite good for some projects and you could use contrasting coloured dowels from scrap wood.
Regards
John


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## dzj (20 Mar 2021)

Try making a dowel plate, you have more options when matching best fitting diameters.


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## JoshD (20 Mar 2021)

I buy dowel in long lengths or cut my own and it's not fluted. Probably fluted would generally be better, not just at holding glue but also releasing air trapped in the hole. I have at times used 9.5mm bit with 10mm nominal dowel, but checking with calipers shows that the dowel was a bit small; when the dowel is actually 10mm then you can easily break stuff that way. Nowadays I check with calipers before choosing drill bit, and may sand the dowel a bit while spinning it on a drill to get to the ideal size. With epoxy ideal size is dowel ~0.1m smaller than hole, but probably want it smaller still with Titebond 2. Epoxy is a lubricant and doesn't cause swelling, Titebond 2 is often grabby and does cause swelling, and I've had a few cases where dowels I thought were seated had just got stuck half way.


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## RobinBHM (20 Mar 2021)

having worked in the furniture industry I can say the vast majority of dowels used are 8mm.

The machinery uses dowel drills that are 8mm

The key is to uses quality dowels that have been stored right. They will fit perfectly in an 8mm hole

Dowels for glued assembly work are always fluted, smooth dowels aren't much use as the glue gets pushed to the hole bottom.

Drilling depth is important and is done with regard to glue quantity. 
When dowels are hammered in, the glue at the bottom gets pushed up the flutes.

You have to be careful with glue qty as hydraulic pressure can easily split the wood.

I'm not sure if they are available for the hobbyist market but manufacturers often use glue pellets which pop in the dowel hole.


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## Spectric (20 Mar 2021)

RobinBHM said:


> I'm not sure if they are available for the hobbyist market but manufacturers often use glue pellets which pop in the dowel hole.


They sound interesting, probably a much cleaner method of getting glue where you want it, are they like little paintball pellets?


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## RobinBHM (20 Mar 2021)

Spectric said:


> They sound interesting, probably a much cleaner method of getting glue where you want it, are they like little paintball pellets?



This is an eBay seller that has them (at a silly price)









PVA WOOD GLUE CAPSULES / PELLETS FOR USE WITH 8mm WOODEN HARDWOOD DOWELS * | eBay


Find many great new & used options and get the best deals for PVA WOOD GLUE CAPSULES / PELLETS FOR USE WITH 8mm WOODEN HARDWOOD DOWELS * at the best online prices at eBay! Free delivery for many products.



www.ebay.co.uk


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## Spectric (20 Mar 2021)

I suppose the furniture industry buys them in at a really low price so making this guy seem dearer. I will have to work out cost, I suppose the glue is as good as anything else, I use Titebond 3.


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## TominDales (20 Mar 2021)

You are having to balance strength with appearance, as with all joints. 
Dowel joints are not as strong as say M&T or dovetail etc - sorry to state the obvious dowels are useful, so its important to bear in mind the things that compromise strength of a dowel joint.
If you need strength in the joint then maximising surface area of glue is good, ie fluted dowels and not too tight a joint as lots of glue coverage so 8mm dowel with 8mm drill. For appearance you can either compromise and have a tight fit not fluted and looks nice or actually go for a slightly undersized dowel (especially in the inner part of the joint by lightly sanding the dowel to leave 0.1mm or so for the glue to sit and leave the surface tight for a nice finish. And as others have said, go easy on the glue and let the air/glue get out. MDF is quite tolerant of a tight fit, within reason, but be careful with hard woods as they will split if too much glue.


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