Cabinet with Pocket Screws

[rinconmike]

Hi.  My son and I am building some cabinets to hold some band instruments for the local school (an Eagle Scout project).  We are using 3/4" baltic birch plywood (60" x 60" pieces) and Kreg pocket screws.  Here is a link to a drawing for the first of 6 cabinets. 

https://www.dropbox.com/s/0ehuo58efq7siym/cabinet%205.pdf?dl=0

This one just has three cubbies.  Some others will have more.  We already cut the pieces to size and next step is doing the pocket screws and biscuits. The attached shows the spacing of the pocket screws and biscuits for alignment.  The drawing also notes which joints we are thinking about gluing.  We have not decided on if we should use glue or not glue.  I am hesitant on using glue in that I feel that we will be rushed in assembly if I was to glue all joints and also concerned with allowing wood to move, although I read that with Baltic Birch plywood seasonal movement might not be an issue. 

One thought is glue the sides and back to the top and bottoms but not glue the sides to the back.  We would assemble the lower cabinet by laying the back down flat and then assemble all dry with clamps, screw the sides to the back, then we can unclamp and glue and screw the top and bottom on.  The middle shelf will just be screwed and I will do that with the sides.

We would then assemble the upper cabinet in a similar way and then once that is assembled, screws the upper cabinet to the lower cabinet.

Note  I have an upper and lower cabinet since the baltic birch we can get is 60" square.  There will be no face frame and we will slightly round over the inner edges.  I have done that on another project and end of the baltic birch looked good.  We may add a little platform in the room to raise the cabinets off the ground.

thanks,

Mike

 

[Chestnut]

I thin a little glue would go a long way in stiffening p the cabinet and ensuring many years of hard use. When attaching cabinetry together with pocket screws you can just apply glue to the edge of the ply as you go along. If you use a glue like titebond extend you'll have at least 15 min of open time to work. 15 min may seem short but that is a lot of time. I use titebond 2 which lists open time of 3-5 min and I've pushed that to 10 before. So with extend saying 15 it might be possible to push that to 20.

Do a dry run or 2 and get the method down then disassemble and do the real deal with glue. On the dry runs don't tighten the pocket screws down very tight. The dry runs will allow you to figure out what order pieces need to go in and are a good practice to do.

Good luck with the eagle scout project, i remember helping with quite a few of those myself when i was in scouts. I made it to Life and then had to make a choice between sports and scouts and sports won out. I wish I'd have been able to finish eagle.

[Mark J]

Baltic Birch (as well as other plywood) is dimensionally stable.  It won't move with the seasons.

[treeslayer]

+1 to the above, sounds like a great project, be sure to post some pictures when done

[Ronn W]

With that many pockets screws I am not sure that glue would add much to the project.

[elrodk]

I use pocket screws on plywood projects and rarely use glue. No problems. Bookshelves, coat rack with cubbies, shop shelving units, miter saw station, and outfeed assembly table with screws and no glue. I mix in some confiramt screws. This is a step screw with special threads for ply and mdf. They are great for attaching shelves through the sides and case construction when it won't show. You get more strength with the confirmant screw for a side to end joint. I got a kit and a big box of screws from Rockler and have been using them for 3-4 years.

 

[Chestnut]

4 hours ago, elrodk said:

I use pocket screws on plywood projects and rarely use glue. No problems. Bookshelves, coat rack with cubbies, shop shelving units, miter saw station, and outfeed assembly table with screws and no glue. I mix in some confiramt screws. This is a step screw with special threads for ply and mdf. They are great for attaching shelves through the sides and case construction when it won't show. You get more strength with the confirmant screw for a side to end joint. I got a kit and a big box of screws from Rockler and have been using them for 3-4 years.

 

While i agree in a low stress setting you never know what kind of life it will receive in a school setting. it is worth the minimal effort to add glue for the extra strength. I'd be surprised if the shelves didn't get used as a jungle gym.

[rinconmike]

Thanks all for the input.  We are near ready to assemble the first cabinet.  Before we do, I have a question.  we are making this cabinet in two pieces, a lower and upper  We will be gluing along with pocket screws the top and bottom pieces (in red) so the biscuits will be clued in too.  

Since the top of the lower cabinet and bottom of the upper cabinet share the top/bottom, we need to offset the pocket screws and any biscuits.  

Question 1: is the first pocket screw at 1.5" from the front too close to the edge?  This is connecting the upper cabinet to the lower.  This provides a 1/2" offset of the lower and upper pocket screws.

Question 2: Any issues with pocket screws going into a glued biscuit?  I assume not but figured I would ask.

Question 3: In that shared piece (top/bottom), on the sides and back, we will have two biscuits connecting the lower side and one on the opposite side but offset connecting the upper side.  I am assuming since since we are gluing the biscuits in, that is not an issue and not too many biscuits.

Here is the sketch where I noted in yellow the locations I am referencing.

https://www.dropbox.com/s/u4cojaa3k92ag30/cabinet 5 - Pub.pdf?dl=0

thanks,

Mike

[rinconmike]

We assembled the cabinet.  We started with the upper cabinet and glued the top to the sides and back.

We then did the lower cabinet.  We did not glue this at all.  It is solid.

We did not screw the upper cabinet to the lower cabinet yet.  It is prepped though with all the pocket screws and ready to go.  My only concern is when moving it after we attached the upper cabinet to the lower cabinet, do we need to be careful with that joint?  if we hold it horizontally to move and one person holds the bottom and the other the top, will the joint move or will it remain solid?  That joint we will glue with the 15 pocket screws (5 on each side and 5 on back).  If a concern, we will move with a hand truck to not stress that joint.

We also notice the baltic birch did warp a little.  We purchased it back in March and it just took a while to do this cabinet.  Pieces 30" x 60" were stored on two horses.  Then cut to size, and then stored again on the two horse until we started pocket screws and then stored on a make shift work bench that is a sheet of plywood on 3 horses.  That board has a mild warp to it as well.   I am wondering if we purchased, cut, prepped, and assembled in 2 weeks oppose to 3 months if we would see less movement in the baltic birch.  And/or if I am better storing in on the concrete floor on 4 pieces of scrap baltic birch spaced out along the 60" length.

Overall the warping is not an issue.  The bottom piece, front left I had to shim slightly so it does not wobble.  I do not think it is the floor; rather, the board.  

The biscuits for alignment did not work as well as we thought it would.  I have a porter cable biscuit joiner.  After watching some YouTube I used the bottom of the joiner for the reference point and used my table saw for the flat surface for the biscuits that go in the end of the piece and the table saw fence for the biscuits that go in the face of the piece.  Some lined up fine and others did not.  I am not sure where I went wrong on that.  Maybe the slight warp in the board?  Where they were an issue, we just did not put it in.

Another thing we may change for the next one is right now we have the top and bottom pieces overhanging both the back and sides.  I think if we change that so the top does not overhang the back, we can place four pieces (sides and top and bottom) on the back, square it up, screw these pieces first and then attached to the back last.

Here are some photos.

thanks,

Mike

 

[gee-dub]

2 hours ago, rinconmike said:

Overall the warping is not an issue.  The bottom piece, front left I had to shim slightly so it does not wobble.  I do not think it is the floor; rather, the board. 

Looking good.  You may want to take a look at a Kitchen and Bath cabinetry book and see how they build a little leveling platform for their cabinets.  This may help with your install.

[rinconmike]

Thanks.  Others have also recommended a toe kick.  We planned on building a platform with a plywood top 2 to 3 inches off the ground (not sure yet).  However, I think we may still need to do some shimming so this does not rock.  I will look into the kitchen and bath cabinetry.

[rinconmike]

Well, almost done with the second cabinet.  Got the lower part done and need to finish assembling the top.  I still am still struggling on the assembly.  This one I attached the back last by laying the back down and then placed the piece with the bottom, top, and middle shelf all screwed on together onto the back.  It was tough keeping it square (checking diagonals).  After it was assembled, I noticed I pushed the middle shelf to the side 1/16" and wound up undoing most the side to the back pocket screws and screws from middle shelf to the back and was able to move it back and it lined up better. Luckily all the pocket screws went back in tight. I was prepared to cut a new back if any would not tighten up due to holes being close.  Photo below.  

I still have not glued anything. With the two pieces next to each other, there is around a 1/8" gap between the pieces (zero gap that opens to 1/8" at 52").  May not be visible in photo.  The cabinets are a little out of square (left one - first one a little more than the right).  I do plan on attaching these together when we install.  If I clamp these together it closes that gap between them, when I put the 18" triangle on the middle shelf on the right, it gets a little better on being square.  Almost perfect.  I did add another pocket screw on several of the joints on this one.  So the side attaches to the back with 10 instead of 9 and to the top and bottom with 6 each instead of 5.

See second clip.  Using an 18" TSO triangle on the middle shelf looks to be maybe a 1/16" to 1/32" out from touching the side wall on the bottom of the angle.  If I clamp the two pieces together to remove the gap between the cabinets, the space between the angle closes up and is near perfect.  I cannot see any movement in the screwed joints when I do this, but I think something is moving.

I spoke to Kreg Tech Support and they stated glue is not needed, but if I do glue, it will be more rigid (others noted) and you cannot take it apart.  I do not want to take it apart, but do want is strong.  in the case of these two cabinets, I think if I glued it, I would have an issue closing the gap clamping together if the glue makes it more rigid.

I did a test piece of gluing biscuits and although I am using Tight Bond III, those biscuits swell quickly and I do not think I have much work time to work.  Things got tight fast.  So for now, I still do not want to glue.  However I also want to make sure these will not go anywhere in the future.  For installation, we will be securing to each other, to the wall, and possibly the platform.  The two cabinets clamped together is pretty solid.

The next cabinet we have more interior shelves.  I think for this one, we will put the bottom between the sides like the middle shelf on the last one.  Only piece that will go over the sides is the top of the lower cabinet.

For assembly, I might lay the side flat and then install the shelves straight up perpendicular to that one side sticking up.  What I did on the last one is had the side sitting on the 3/4" back edge and then brought the middle shelf in (see last clip).  After I did the middle shelf, did the top.

Any tips on assembly?   

thanks,

Mike

 

 

 

[wtnhighlander]

First tip, get a shave. That beard is so out of control, we can't even see your face!  

For assembly, I still like glue. Titebond should work fine with the screws. If you use biscuits and want to avoid swelling, polyurathane (Gorilla) glue or epoxy will do the trick without swelling the wood. Both are messy, so tape around the joints.

[rinconmike]

Ha.  That is my son so I did not want to post a photo of him.  He is the older but shorter of my two boys at 6'3".  Younger one is 6' 6" and needs a haircut.  I am the short one at 5'10".

I am still debating on glue on the next one thinking if I put the side flat (rotating it 90 degrees from what I show in the last assembly photo) and start with the bottom, then interior shelves.  One by one, gluing, squaring with the 18" triangle, securing with Bessey parallel clamps (one on each end), and then screw it up and then move to the next one.  When I assembled the last ones, the shelf and each peice did seem solid, but maybe there is minor movement that I cannot see.  The shelf is 25" wide b 28" deep so it is not small span but should not be too big with 3/4" baltic birch..

I am also wondering if the minor movement I am seeing is the side 3/4" plywood deflecting a little around the middle shelf at the front.  In the back of the cabinet I do not see movement on the triangle (side is secured to back).  It is in the front I do.  Here is a photo that shows how the side was pushed out a 1/16" before I adjusted it I noted in the last post.  The 4ft level clamped at the bottom shows the gap at the top due to the side being pushed at the mid point.  After I fixed it, he level is flat.