Thursday, June 9, 2011

Bench Planter III: Seating

I had intended to buy bluestone (sandstone), basalt, or some other nice masonry product for the top seating surface of the wall, but Jackie was intent on using some sort of composite decking material, like we used on our back steps.  Stone would have been much easier in some ways.  Mix up some mortar and plop it down...  But since the surface was going to be about 12" wide on top of a 6" wall, there would be some cantilever forces to deal with, and mortar isn't the greatest for that.

After several evenings of head scratching, here's what I came up with.  It's simple, strong, and removable if we change our mind or damage it.  First off, I mixed up a small batch of mortar and put a smooth coat on the top of the wall, pitching it very slightly so water wouldn't pool and (especially) have cracks to freeze in and damage the masonry.

We had to drive to Tualatin to pick up three 16' lengths of gray composite decking, because stupid Home Depot quit stocking the stuff I bought from them for the back steps.  I cut them down to 12'-3" and saved the offcuts to build the sides.  The front bench was made from three pieces, two 5" and one 2-1/2" in the center.  I ripped 1-3/8" off either side of the 5-3/8" stock for the center piece, and ripped a little 3/8" ribbon off one side of the other two to get the 5" pieces, because I wanted to get rid of the rounded edges in the middle of the seat.  Ripping them was a challenge I solved by building an oversized plywood sub-base for my circular saw and clamping a scrap fence to that.

Then I cut 11" sleepers from pressure treated 2x4, fastening them at the ends and every 16" along the front of the wall with 1/4" x 2-3/4" flat-head Tapcon screws.  Some sleepers got two fasteners to resist the cantilever forces.  I've never been a fan of Tapcons.  They seem like they're made more for the contractor who wants to get it done in a hurry than for people like me, but they do work and I'm installing a lot of fasteners so if one fails it's no big deal.  I've also got more experience working with concrete anchors and have learned the importance of drilling a little deeper and especially of cleaning out the anchor hole.  Concrete dust isn't like wood dust.  It doesn't compact past a certain point, and if you leave any in the bottom of a hole, it can cause the fastener to seize up, so brush & blow out big holes with an air gun, or at least run the drill bit in and out a few times to extract most of the excess.  The 3/16" holes go pretty fast with my big Bosch rotary hammer.  I also am now the proud owner of a small impact driver (I got a Milwaukie drill / impact driver set last year), which makes driving these puppies a piece of cake.  Install a #3 phillips bit into the driver and put on your hearing protection!  Bbbbbbbbbbbbbt.  Done.

Use a mason line to get them all lined up
The decking was fastened to the sleepers with #7 x 2-1/2" stainless steel finish screws, pre-drilled and countersunk, of course.  I left a minimal 3/32" gap between the decking, to keep the appearance neat and easy to clean.
Shorter sleepers on the sides
The sides were built in a similar way, but with a narrower surface made from 5" wide and 2-1/4" wide pieces.  Three 6" sleepers were installed on each side, and one of the 3'-9" offcuts was ripped in half to make the narrow strip.  I used the long 1-3/8" strips to trim around the lower edge of the seat, hiding the sleepers.  It doesn't look perfect from all directions, because the ends of the decking show the ribbed bottom, but it's very solid and should hold up well to the elements.
the finished seating surface
I think an idea that would have been more fun would have been to cast our own concrete pieces, like building a concrete kitchen countertop.  With the right reinforcing and some cast-in attachment hardware, it would have been strong and stable, and we could have stained it whatever color we liked, or put a cast or embedded design in it.  Maybe next time!

Wednesday, June 8, 2011

Bench Planter II: Carpentry

A few days after building the wall, when all the structural masonry had some time to cure, we started on the rest of the construction.  My plan was to use two pressure-treated 2 x 10 timbers to build the back wall, supported by three 4 x 4 posts that would extend up to support a trellis.  I dug three post holes, 20" deep, for the three 4 x 4 x 10' trellis posts; one behind each end of the wall, and one in the middle of the bed.

Four 3/8" x 6" galvanized lag screws were used on each side to attach through the posts into the masonry, sandwiching the 2 x 10's.  I countersunk the heads of the lag screws 1-1/2" into the posts with a 1-1/8" forstner bit so that they'd be hidden and also so that the 6" screws would penetrate far enough into the masonry wall.  We held everything in place while I used a long wood bit to drill through the posts and boards, and then a 1/2" bit in the hammer drill to reach through and start holes in the concrete before removing the wood temporarily.  I used a hammer drill to install eight lag shield anchors into 2-1/2" x 5/8" holes in the back before fastening everything with the lag bolts.  The post holes were backfilled with packed soil, instead of pouring a concrete footing.  Everything feels extremely solid, but shouldn't be a nightmare to take apart if we need to for some reason.

We immediately went and got a yard of compost mix and filled the planter up.  I'm not sure that was a good idea, but I guess, worst case, we shovel it all out some time and adjust the structure.  The main thing I'm worried about is the wood back.  I think there should have been a plastic sheet liner installed between it and the soil.  It would help the wood last longer (even p.t. eventually rots), it would keep nasty preservatives from leaching into the planter's soil, and it would keep the soil at the back of the planter from drying out.  The drying issue may be a problem against the concrete, too.

Bench Planter Construction I : Masonry

After deciding for sure on a location and size, and testing out the plan by stacking up some blocks, we started by digging a shallow (6") trench for a poured concrete foundation.  I built forms from 2x4 material that were exactly the outside dimensions of the finished wall, and we filled them with 12 bags of concrete, sticking pieces of rebar in at some locations where the web holes in the block would be.
Ready for concrete
This isn't a "real" foundation, like you'd build for a house or other serious structure.  It doesn't go deep enough, and doesn't have enough rebar, but I think it will be fine for this project.

The finished foundation
The next day, I mixed up a bag of type-S mortar and built the wall from 6 x 8 x 16 concrete blocks.  I'd carefully laid out the orientation and spacing before even digging the foundation, so it went pretty quick.  Basically I just buttered everything up with mortar, set a block in place, and tapped it into position with a chunk of 2x4 until it was level and plumb, being especially careful with the corners and ends.  I scraped off any squeeze out as I went, and used it for the next block.

All mortared together
We then filled some of the empty cavities with concrete (all the re-bar containing ones and a few others in structural spots) and filled any gaps with mortar.

Filling the cells
Jackie then applied a skim coat of mortar to the entire outside face, and textured it with a plastic broom so that it matches the texture of our house's foundation.
Mortaring in the dark

Using a template to cut shapes with a router

This is just a quick how-to on a technique I use to quickly cut shapes in wood.  I've used it for decorative shapes on outdoor projects and curved legs on furniture, among other things.  It's really a time saver when you need to make several of the same shape, and you can keep the templates and use the curves on other projects down the road.  I just re-used a template I made several years ago (for a garden arbor) to cut decorative ends on the cedar beam across the top of a trellis structure.

1.  Make the shape.  I usually draw the shape at full scale on a piece of graph paper, or sometimes with software, and print it out.  Sketchup (free and excellent) or Adobe Illustrator (expensive but powerful) can both be used to make all sorts of curves.  Pencils work pretty well, too.
A template design I made in Illustrator
2.  Cut the template.  Plywood or hardboard is best for this, and 1/4" to 1/2" thick is good, depending on the size of the  part.  You do need to plan ahead a bit here.  If you're going to clamp the template to the stock to be cut, you should make it big enough that the clamps don't get in the way of the router.  I tend to cut a piece of plywood the same dimensions as the stock lumber, and then about a foot longer than the cutting area will be.  Transfer the pattern you drew to the plywood, and cut out the curve with a band saw, jig saw, or coping saw.  A quick way to do this is to use spray adhesive to glue the paper down.  Cut a little outside of the line, and then finish the curve with a sanding drum.  There are cheap sets you can get to go in a hand drill or drill press, or you can invest in a dedicated oscillating sander.  One tip:  larger drums make smoother curves, so don't try to smooth out a 10" long shape with a 3/4" diameter sander.  Take your time and make sure the template is fair and smooth, because every bump will be faithfully transferred to your final work.

Trace the pattern first
3.  Prepare the workpiece.  You should rough-cut the curve with a bandsaw or jigsaw, within 1/4" of the line.  I usually just hold down the template, and trace it quickly with a pencil.  I also make hash marks on the waste side, which seems silly until you accidentally cut on the wrong side of the line because you got in a hurry.  You could skip right to step four, and do all the cutting with the router, but your results will be much better and your router and bit will be much happier if you're not hogging out huge amounts of wood.  If you're using a small router, this is a mandatory step.

Hash marks on the waste side prevent expensive mistakes
4.  Attach the template to your workpiece.  I usually just clamp the template in position.  If some small holes are something that can be dealt with, sometimes it's good to use a couple of small #4 or #6 flat-head screws countersunk into the template.  The router base can run right over them, and they can be used to fasten in the middle of a large or odd-shaped piece.  When deciding how to attach the template, consider the cutting direction of the router bit.  You want it to be working with the grain of the wood as much as possible, to avoid chattering and splitting.

Ready for the router

5.  Cut it!  My weapon of choice for this one is a 3/4" diameter x 2" template cutting bit with a bearing at the top (Whiteside #3023) in a fixed-base router.  Set the height so that the bearing runs along the template and watch the bearing as you cut, not the cutter.  Again, watch the grain direction and try to cut with it.  You might need to climb cut around some curves, which is no big deal if you pre-cut the shape fairly closely.
A big bit gets the job done easily
Ta-da!  I usually leave the edges crisp and smooth from the router, but a quick pass with a roundover bit or hand sanding will make a smooth edge if you want.  Otherwise, there's no more woodwork required.

No sanding required