How many 8mm dowels do I use?

[Packard]

I recently got a CMT dowel jig which is designed for sheet goods only.  It allows for an 8mm dowel hole on 32mm spacing over a span of about 26 inches.

I am building Euro style (no face frame) kitchen cabinets.

Clearly putting in 8mm dowels every 32mm is going to be overkill. Especially since that attaching the cabinets to the wall makes the wall a structural element and pretty much eliminates any racking issues.

For uppers I am thinking 2 dowels towards the front of the panels and two dowels towards the rear.  I think I am on safe ground there.

For lower cabinets  I am thinking either 2 dowels towards the front and two towards the rear plus either 2 or 4 more in the middle.

Any thoughts about the lower cabinet dowel placement?

Note:  This jig allows for the holes to be deeper into the edges to prevent board rupture.  Roughly speaking, 1/2" goes into the flat side of the boards, and 1" goes into the edges.  They use 35mm long dowels.

 

[AlexThePalex]

There is no set rule for this as it depends on the material you use and the weight you want your cabinets to take.

I mostly use dowels with particle board or plywood and tend to keep a distance of around 20-25 cm between dowels.

 

[Packard]

For the lowers I am thinking two at the front, two at the rear, and to prevent bowing of the panels, one approximately every 8 inches (about 20mm). 

I might mention that the Ready to Assemble trade association and the Kitchen Cabinet Manufacturers trade association ran tests on various fasteners in the building of boxes.

They agreed on many points, but the one that struck me most was that "no fastener should be less than 2 inches from the end of a panel". 

This because the sheet goods need some supporting surface to prevent the fastener from splitting the the boards.

I am making a sample upper now and I will see how it feels to me.

 

[Packard]

I found this DowelMax article online.  They are saying one dowel every 6 inches.  But the photo has the last hole about 3/4" from the edge of the panel.  That would not be excellent according to what I've read.
https://www.dowelmax.com/dowel-jig-system-projects/how-to-build-a-diy-kitchen-cabinets/

 

[AlexThePalex]

You know, you can do what you want, it is not that critical, unless you put in too few.

If you want to do them 1 inch from the side, that's fine. I f you want to space them 2 inch apart, that's fine, but not needed.

A 2 foot panel would get 3 or 4 dowels from me, evenly spaced.

 

[Svar]

For uppers I am thinking 2 dowels towards the front of the panels and two dowels towards the rear.  I think I am on safe ground there.
For lower cabinets  I am thinking either 2 dowels towards the front and two towards the rear plus either 2 or 4 more in the middle.

Sounds reasonable. I'd put 1 dowel every 10 - 15 cm.

 

[Packard]

I was comparing it with the Mafell video.  They show registering off the pin and putting in 2 dowels at each end of the 12" upper. 

I have not seen one of their videos for the lowers.  But I know I want at least a couple in the middle just to prevent bowing of the side panels. 

 

[mino]

Anywhere from 4 to every hole is a valid.

You need to think about the load the joint needs to hold. This is the beauty of these 32 mm dowel jigs - you can tune your joint approach to the use case.

When I make (mobile) workshop cabinets expected to take a beating, and want them to last a couple decades I used every hole + glue + screws as I do not want the joint to break. Not before the board breaks.

I would do the same if wanted to have a bottom board of a hanged cabinet go over the verticals - then every dowel is good given the axial force scenario.

The second thing you should consider is the "bend-ness" of your material in cases  where the face glue cannot be relied on.
E.g for plastic-ky non-glueable material like thinner laminated boards you want more dowels to hold the material to the joint plane, say every 3rd hole + doubled edges
- for a low-load MDF, or low-load chipboard scenario or where some face-gluing strength can be counted on, double-edges + one each 15cm or so are fine, this is how IKEAs of the world do it

In practice I would say double-edges + every third/fourth hole and you are good. More when you want a stronger joint or if joining very weak materials.

Every hole makes sense for super-strong joints or where the value of the piece is high enough that the saving would be pointless.

 

[Michael Kellough]

For euro style cabinets it depends on whether they are base cabinets or wall cabinets. Not so many dowels needed for wall cabinets and if base cabs it depends on what the cabinets sits on. A ladder  plinth, as recently discussed, or legs?

If a plinth, not so many dowels. If legs, it depends on whether the leg supports the side panel as well as the bottom panel or just the bottom panel. If bottom alone then more dowels are needed since they will be supporting the weight of the cabinet, counter top, and whatever the content load adds. Obviously legs that support the side panel are better.

 

[Packard]

Thanks, everyone for your input.

I am assembling a shelf unit this weekend to try out the dowel jig. 

I will report.

 

[blues]

I built a base cabinet for a kitchen island. Mitered the edges as i did not want the cut edge exposed. Used mafell ddf40. It uses 2 dowels 32mm apart. From the 2nd hole i used the attached jig and placed my 2nd set of holes 150mm. So on the base cabinet with a height of 36" you will get 6 dowels - 3 sets. I just love the ddf40. It makes building 32mm cabinets a breeze. Adjust the fence to 37mm height and start drilling shelf on holes. No complicated set up time. Use any drawer slide measure the middle hole and make one mark. Use a straight edge or a rail and ride the ddf40 against the edge. It's a fantastic machine. For larger builds that does not use sheet goods,  it's my trusty domino xl. Nothing beats that.

 

[Packard]

I built a 15" deep x 16" wide x 32" tall upper cabinet for the shop using 6 dowels per joint.  Two at the front; two at the rear and two midway. 

It seems quite strong (but I did not make a destruction test).

It was the first time I've used the CMT dowel jigs.  These are not available in the Americas, so most Americans, Canadians, Latin Americans and South Americans are not familiar with this jig. 

Fast and easy for sheet goods, this was the first time I've used a new dowel jig where I did not make at least one error: usually a mirror image error, or a register from the wrong end error, or just something upside down.  [big grin]

Very happy with this jig.  Expensive (plus the freight from Germany), but I'm still very happy with it.