Plywood cabinet assembly: screws vs. dominoes

[Stan Tillinghast]

I am planning on building replacement bathroom cabinets from pre-finished maple plywood.
This will be my first build of conventional cabinets. They will be Euro style, using the LR32 system for hinge holes and shelf pin holes.
I've just watched (again) Greg Paolini's video of cabinet building, and Brett Shiveley's Festool video series on cabinets.

I have all the tools needed to do Domino or pocket-hole joints, and step bits for Confirmat screws; also I have an as-yet unused Milwaukee 23 gauge pin nailer I can use to tack the parts together.

It seems to me that for these cabinets, where all ends will be hidden, that dominoes are overkill and screws, such as Greg Paolini uses, would be more than adequate. I know confirmat screws are recommended for MDF, but are not bugle-head GRK screws fine for assembly of plywood cabinets (#8 x 2 inch?)

I haven't yet tried using the GRK screws without pre-drilling; I can try and see if that seems to produce a neat result.

 

[ChuckM]

My take:

Just get the job done (probably cheaper too): Screws or pins.

To get more practice and experience with the domino joinery and techniques: Dominoes.

 

[tsmi243]

If you already own the Domino, it takes about 3 minutes and two dollars to add them in. 

Having them in also means you can go a little large on your pilot holes, to minimize any risk of splitting when you drive the screws in.  Since the dominos are doing all the work in the vertical plane, the screws don't need to be all that tight- they're just making sure the parts stay ON the dominos in the horizontal plane. 

I know some of the nicer screws from GRK or Spax say "no predrilling needed"- but I don't think I'll ever be that brave. 

 

[Lincoln]

If the sides aren't seen, or covered by end panels, screw and glue.
I'd definitely pre-drill the screws.

 

[semenza]

I like pocket hole screws and dominos together. Sometimes glue , sometimes no glue ..... just depends.

The dominos are more for ease of assembly and alignment (for my purpose) than strength. They will also hold panels vertically without any other clamps or supports while you drive the "no guesswork" PH screws.

The pocket hole screws are, of course, predrilled taking care of that issue. PH screw are also a better choice for pulling parts together and basically no chance of splitting or blowing through a surface.

If using glue the pocket hole screws act as clamps too.

          A little more prep time but the combo makes the assembly soooo , fast and easy.

Seth

 

[guybo]

Hi, if using glue remember to remove the finish on the pre finished ply. You will do fine. guy

 

[waho6o9]

Dominoes make the job so efficient.  This will be a great job to expand your skill set.
Have fun and please post pictures when it's completed. 

 

[afish]

do a test panel with the confirmats before doing the main cabinet. confirmat screws can bulge or separate the plys even with pre drilling. just seems to depend on the quality of the plywood.  also if its pre finished I wouldnt put much faith in the glue. narrow crown 18ga. staples work well with plywood and helps pull the pieces tight followed up with a few coarse spax or drywall screws.

 

[mrFinpgh]

Dominos do make it a lot easier to get everything lined up for assembly. In my opinion, that's the hardest part of building a cabinet - putting it together.

I tried Greg Paolini's stapler approach, but it led to a couple blow-throughs with the stapler.  Maybe just a technique issue.

I think that 2" screws are more than enough. I think I bought type 17 coarse threaded 2" square drives from quickscrews.com for my kitchen a few years ago.  It seemed like the key was to have a good jig for laying out your holes and a sharp countersink bit.  The dominos add a helping hand and are very useful when you're doing something like a 5' tall cabinet box.

 

[semenza]

Hi, if using glue remember to remove the finish on the pre finished ply. You will do fine. guy

Yup, that too. I just put together some prefinply drawer boxes. I use the LS130 with 60gr Cristal to sand off the edge for glue.

Seth

 

[woodferret]

I haven't yet tried using the GRK screws without pre-drilling; I can try and see if that seems to produce a neat result.

I've tried.  When you're 3/8" away from the edge of the plywood, the countersink drill on the GRK can compress and lever the layer up.  Varies by plywood quality, but eh... I've taken to predrill and even pre-countersink.

 

[Stan Tillinghast]

Thanks very much for the advice.
I do have a domino (500) , and feel comfortable using it. I understand the importance of referencing from the same face.
I appreciate the advice on the need to pre-drill for the screws.
I even bought the Woodpeckers drilling guide which would make that job neater.

Currently I'm mocking up a couple of types of panel door: one with cherry frame and maple inset, one all maple.

I just ordered Blum Tandem undermount slides and Blum full overlay hinges, thinking there is likely to be a supply problem with items like that.

I need to get busy choosing faucets, sinks and medicine cabinets too. Don't want to get half-way through and find something not available.

 

[Rick Herrick]

Check out the series on YT by Eric (former/current member here ?).  I think his 7 part series is under 'The Poplar Shop'.  Excellent series for exactly what you are doing.  I used it as reference several times when I did my Euro cabs.

 

[semenza]

  [member=1170]Stan Tillinghast[/member]  Which pocket hole jig do you have?

Seth

 

[slavi.yordanov]

Dominos for alignment, glue and Spax MDF screws. I have used these screws for all my kitchen cabinets- no pre-drilling, no countersinking. Just mark a straight line half the thickness of the panel and that’s it.

Don’t forget to sand the finish where the glue will be, as others have mentioned.
https://www.homedepot.com/p/SPAX-8-...MDF-Screw-200-per-Box-4351010400456/100582153

 

[Stan Tillinghast]

Seth - I have the simpler Kreg jig.

I presume the advantage of the pocket hole method is that the screw isn't going into the edge of the plywood?
Nevertheless, it is more time-consuming than just screwing directly into the plywood, is it not?

I could easily do a combination of dominoes and screws; whether the glue is needed is another question. These cabinets aren't going anywhere, after all.

 

[Birdhunter]

I’ve had bad misalignment results using only pocket holes. I’ve had better luck using a combination of Dominos with thoughtfully placed pocket holes. I’ve had the best results using only Dominos. However, I have a vast array of clamps.

I have not failed to predrill a screw hole since my long ago beginning days. It is heart breaking to see a nice piece of wood ruined by a blown out screw.

 

[bruegf]

I used dominos and glue and clamped with the cabinet press

 

[Packard]

You can probably find the reports online, but I will summarize what I learned from the testing done by the RTA (Ready To Assemble) industry association (think "Ikea") and the Kitchen Cabinet Manufacturers association. 

They each industry group tasked a different laboratory to test the strength of various fasteners. I am working from memory having read these articles about 10 years ago.  Details may be lost.

Included were:

1/4 turn fasteners
Drywall screws
dowels
dadoes
Confirmat screws.

Both ran similar tests and they were mostly testing for racking strength.  Note that the requirements strength differ for the two groups.  The RTA was mostly interested in racking strength.

The kitchen cabinet people were less concerned about that as the wall the cabinets are mounted against becomes a structural member.  But, it is a factor for free standing islands.

The test was run by having a vertical panel with horizontal "shelves" attached on one end only using the various fasteners.  No glue was used as they were rating the fasteners independent of glue.

They would load the end of the shelves to see when the joint would fail.

Both groups ran very similar tests with very similar results.

The worst performer was the dado.  That joint failed before any reading could be made on the scale.
Next was the 1/4 turn fasteners.
Then there was the drywall screws.
(The above performed in what was viewed as having unsatisfactory results.)
Confirmats and dowels performed similarly.  Confirmats have the advantage of drawing the surfaces together.

Confirmats have the advantage of not requiring clamps.
Dowels are cheaper to buy and cheaper to install (using automated equipment to gang drill and install.)
Dominoes were not tested but probably did as well as dowels in terms of strength.

They both noted that no fastener should be within 2" of the end of any panel as there would not be enough panel to support the fasteners.

I settled on confirmats and dowels.

For face frame cabinets, where I cover the end panels where visible, I use two confrimats per joint and I through dowel making sure that the dowels are below the surface when tapped in.  It is fast and alignment is guaranteed.  The confirmats replace clamps.  I have been known to back out the confirmats after the glue dries and install dowels in the re-drilled holes.

I don't recall them using pocket hole fasteners, but judging from the fasteners used for those I would imagine they would fare about as well as drywall screws.

I had long used dadoes for cabinets.  I think they are excellent for carrying a load when the shelf is fastened at both ends, but apparently not very good for racking strength.

Note:  I have been throwing out the term "racking strength" and to be clear this illustration shows racking as applied to the framing.  The same would apply to a cabinet.

Note:  If you are going to use through dowels after assembly, then the box must be square prior to drilling the dowel holes.  You will not be able to square things up afterward.

 

[Michael Kellough]

That test is interesting but when you do have a secure back panel glued dados are very strong.

Over forty years ago I assembled my kitchen with readymade cabinets from Quakermaid. They were very well engineered so even though they only used 1/2” and 3/8” ply they are very strong and rigid because they used glued dados for every joint, including the face frames. They probably used one of those giant cabinet clamps. The wall cabinets were wonderfully lightweight.

Pocket holes screws are much stronger than screws driven into plywood edges. You could use PH screws alone except they tend to misalign the work pieces as the screws are tightened, especially if wet glue is in the joint. The combination of PH screws and Dominos is best for one person assembly IMO.