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Notes from after building the shelving unit (already!)

Posted by joeabbott on January 2, 2012

imageOK, admission time. And I don’t mean letting someone in … I mean letting something out: such as letting the cat out of the bag. I had posted my last note including a description of an “easy to build” shelving unit, but I hadn’t actually built it when I wrote the notes. I’d only sketched it up on SketchUp. I sit here now, aching back, ripped up fingers, and my frustration abating and feel I need to come clean on building that unit. I learned enough and made more than a couple mistakes so, I feel it only fair that I lay it all out there … not wave my hands glibly and proclaim that you could follow those instructions and get a “nice, sturdy set of shelves”.

Sturdy my tukas!

imageWhen I drew up the plans for those shelves, I had 3/4” plywood in mind for the job. And, basing it off some 8’ tall units I’d made previously, I was thinking about cabinet-grade plywood … not some void-pocked D-grade sheeting. But, when I was at the store and costed out the project at $60-$90 for 3/4” material or under $25 for the stuff I used, I got the cheap stuff and reworked my project plans.

However, I’d never worked with chipboard (OSB) before and just assumed it would work about the same.

I’ll say it simply and clearly and then move on: I’m an idiot.

OSB and cabinet-grade plywood do not work the same, do not handle the same, and do not give you the same quality and integrity of a finished product. I’m sure some of that is because I went to 1/2” instead of 3/4”, but while using a jigsaw to cut the slots (more on this later), it was like running a hot knife through butter, driving pins through it was a joke, and nailing was hit-and-miss (no pun intended). OSB is a porous material so it just ate the glue, it was hard to clamp up (bent like a wet noodle), and if I hadn’t nestled it against two walls it would be an unstable structure to say the least. I’m even regretting that I didn’t fasten it to the walls!

But, it was super easy to work with, very easy to cut, and it was a fraction of the price I’d have paid for the plywood. And yet, beware: following the plans from the prior post will not give you a “sturdy” shelving unit; it will give you a passable, light-duty set of shelves.


The Mistakes I Made Things I Learned

I make mistakes all the time and don’t get too caught up with that fact. I don’t make the same mistake twice (well, not often) but I do continually find ways to screw things up. Out of the gate, I made a couple rookie errors that I’m chalking up to not being in the shop since before the remodel (they started the first week in October). So, in the order that I boned things up or learned something new, here we go!

Cut to the line … just be sure you know which side

While routing the dados in the end panels, I measured off 15 3/4” from one end, setup my straight-edge and appropriate offset (for the size of the router base), and routed the groove. Easy, I then went to the other side and repeated the process, however, instead of cutting on the “far side” of the line, I started cutting on the near side for about 6” before I realized I made an error. With a bit of glue and a thin piece of wood this was remedied but I wondered how I could have avoided this mistake.

So, for the subsequent dados, I not only struck a line, but I struck two lines … and then colored in-between them so I could easily see the wood that was actually supposed to be removed.

Measure Twice … or Build a Jig

I now wear reading glasses for close up viewing and I found myself squinting hard as I knelt on the garage floor, looking at 1/16” increments, and wishing I had more light, was doing it during the day, or I wasn’t on the floor. But somehow, after measuring and checking my measurements no less than three times, I managed to set my straight edge at 6 11/16” on one side (a sixteenth less than 6 3/4”) and 6 7/16” (a sixteenth less than 6 1/2”) on the other. And then cut my slot. Straight across the entire panel.

Holy cow.

That was the night-ender for me right there. I completely boogered that up. Yes, fixable, but when you make an error in measuring after checking that many times, you’re really ready to call it a day. That, my friends … that was frustrating.

To avoid this on subsequent cuts I built little jigs for every cut. What’s a “jig” in this situation? I usually got away with cutting a scrap of wood to the exact size I wanted, and then used that as the offset or the measurement wherever needed. This way I only relied on my tape measure once, not twice.

Omission in the Instructions

In the last post I noted the following for cutting slots in the shelf:

The picture below shows the slots to be cut at 31 5/8” from the ends. This is very specific. Above I noted you didn’t really have to cut the dados in the top/bottom panels at exactly “31 7/8” “ … you could use “32” “ or something, Well, to be clear, whatever spacing you used for the top panels, back off a quarter inch for the spacing of the slots in the shelves.

This is true but only if you cut your shelf boards down to 95 1/2”!! I don’t say anything about cutting down the boards by a half inch in the write up so, if you followed those instructions, you’d have left the shelf at the nominal 96” length.

I’ll update those notes to include this comment.

Use a Jigsaw, Luke!

This wasn’t an error in construction but in the notes on building the shelves I entered this on how to cut the slots:

The tricky part here is “how do you cut these?

If you have a table saw you can cut a stopped slot; you can use your router to cut through, too (but that’s a lot of wood to remove). There’s no right answer but by using a jig to find the right place to cut the slots, you should be able to do this without too much concern for being exact.

“Cut a stopped slot”? Not sure what I was thinking … or why I wasn’t thinking … but you use a jigsaw for situations like this. And a jigsaw works fantastically well at cutting in OSB! I doubled up the vertical dividers on one pass, and then doubled up the shelves on the second, and very easily cut nice, clean freehand slots. I needed a rasp to widen a couple of the slots that pinched a bit much, but otherwise this worked very well.

Getting it Right

After all the parts were cut, routed, and jigsawed, I dry assembled the unit on the garage floor before pulling it apart and moving the pieces to the loft for assembly up there. But before the move to the loft, I noticed all the parts weren’t perfectly 24” wide: on one end they were about 23 3/4” and on the other they were just over 24”. I’d spotted that earlier but , for a set of shelves in the garage that I’d be using once a year, I figured it was fine.

Well, it wasn’t. As I was dry assembling, it just looked sloppy and I had to fix it.

So, I pulled out the table saw, setup a 23 3/4” cut, prepared the necessary outfeed supports, and pushed the boards through. And boy was it nice when all parts were perfectly the same width. I pat myself on the back for not living with the error.

Slots in 1/2” OSB

imageCutting slots in the interior parts (the vertical dividers and shelves) allow you to nest them together to form a strong matrix. However, by doing this, you do allow one edge of the shelves to be unsupported and “floppy”. This will be most obvious in the center bay (as the right and left sides will be supported by the exterior side panel).

Slots in cabinet-grade 3/4” plywood don’t need to be supported for the type of weights I’m storing; in 1/2” OSB, depending on what you’re storing, you may need to prop up your shelves.

In the picture to the right, you can see the normal state (image on the left) and when I push down how it defects relative to the other shelf (image on the right). I was pushing reasonably hard but I was still just using one hand.

If you plan on storing heavy loads, you should add some sort of block to help support the free end (the end in which the slots were cut) of the shelf. Most of my boxes are only holding garland or light ornaments and won’t be stressing the shelves; the few heavy boxes we have can be put on the bottom where they will essentially be resting on the ground.

I’ve Nailed It!

After spreading the glue and seeing it seep right into the wood (even after a second application), I tried clamping the unit. The combination of a large, unwieldy structure and the fact that my support blocks were too low to allow clamps to sneak under drove me to try nailing the joints together.

Now, the joints in mind are the plywood edges that are sitting in the dado grooves.

I first tried to use my pneumatic nail guns and drive pins into the joints. My first try with 2” nails saw spectacular failures as the nail would bend and exit the panel out the side. I then went to 1” nails but, even after driving a half dozen into a 24” seam, they had no holding power. The headless pins just didn’t have enough to grab into in the OSB.

I then used roofing nails and that worked reasonably well. Roofing nails are short (nice), somewhat fat (the OSB layers would expand to a tighter fit in the dado/groove), and have a big head (the better to avoid pulling through). So, it took a few tries but this worked out OK.

Move It!

Once I had the unit assembled, I wanted to move it into position. Any attempt at putting a tensile load on one of the panels would result in that panel leaving the assembly; ouch. In the end, I pushed it off the riser blocks (and re-aligned/re-nailed those joints that came apart), and then set a 2×6 against the front, bottom lip and, from a seated position, used my legs to push the whole thing into place.

Once I got it against the wall, I set heavy items on the top and pushed it against the side wall well enough so it was supported on one side while the glue dried.


Next time

P1040438While I don’t get hung up on making mistakes, I want to be clear that doing it right the first time is preferable to having a handy fix-it solution. I don’t have any woodworking mentors, though, so I’m sorta winging it. A friend of mine who does a bit of woodworking (and picked it up from his father) said that his dad had a saying, “good woodworkers don’t do it right all the time, they just know how to hide their mistakes”. A reasonable bit of insight, but I’m still working on having fewer mistakes to hide.

I’m under no illusion this shelving unit is “sturdy” but it should hold our holiday decorations. Or yours. Best of all, it’s the idea that matters here: if you have heavier duty storing needs, use 3/4” material! The nested/slotted/egg crate interior shelving can be made very strong, the routed daods will have superior holding to butted joints, and you can add a shear panel back or diagonal supports if you are worried about lateral loads.

Drop me a line if you have a question; I’ll get back to you as quick as I can… right after I get out of the shop!


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