On Fri, 13 Apr 2012 10:03:30 -0400, Ecnerwal
wrote:

Pics anywhere?

Not so far. I'll see about that, not that it's much to look at.

Even a basic image of something provides ideas. I'm always fiddling
in the workshop, and taking pictures of interesting things when I'm
out and about just because they provide some spark of an idea.

What are you using for a press? An offset lever, a screw jack, ?

Nothing so beefy. The commercial block makers (as best I can tell
without owning one) are just a form the size of the final block, which
is jammed into the soil mix to pack them

There seemed to be a finger-pull assembly that either gives a little
final side compression, or opens up the form to release (I think the
former - then when you release the grip, the block is smaller than the
relaxed form). A local (well, 40 mile round trip from me) farm supply
has some, but I didn't pay close attention to their design after
looking at the price...

soil mix being stacked 3 times deeper than the form. This obviously requires excess soil mix - no problem for the folks making thousands, annoying if making 25 or 100.

Set up a smaller diameter container to hold the soil. Or, start out
with a medium sized bin, and when you're half done, and the level has
dropped, dump it into a smaller bin (more height, less girth). A
moveable partition within a bin would serve a similar purpose, keeping
the soil from spreading out: when half done, tilt the bin, drop in the
partition, then set it back down and continue making soil blocks.

A milk carton with the top cut off would probably work sufficiently
well to hold a small volume of soil mix.

My current version is a square plastic package for a drill bit and a
piece of wood that fits in it. I put about 2X the final block height of
mix in it (3x would not compress that far), and lean on the wood plunger
with body weight to compress it down. Then I pull the plastic up to
"eject" the block. Not being fully committed to the idea, I wasted
little time making it nice, fancy, or efficient. I'll save those for
version 2, if I end up feeling the blocks are worth bothering with.

A short section of square tube stock (think trailer frame or receiver
hitch stock - but it wouldn't need to be the thicker gauge), would
probably work well. In fact, a section of metal (or even PVC, easy to
cut, cheap, available in multiple sizes) pipe should as well, with a
suitably sized dowel at one end. Drill a hole through the form
tubing, with the plunger material inside at one end of its travel, and
then push the plunger through to the other end of desired travel
(without rotating it), drill through the same hole, then remove the
plunger and cut out along between the two holes (probably by drilling
a series of holes, then cleaning it up), and then you could put the
plunger into the form, pass a machine screw through the middle of the
form, and a locknut on the other side, and your plunger will have 'x'
range of motion to accept incoming soil, and to eject the block.
There's several other ways to accomplish that slide range limiting.


Not really, for a lot of things. Even in pots one is usually better off
"firming" the soil rather than leaving it completely loose

Well, firm is one thing - compressed from 2-3x the volume though seems
pretty compacted.

plant falls over from no support. Plant roots are remarkably robust at
pushing through soil.

As anyone with an asphalt roadway can tell you once the weeds get into
a crevice.

Also, you are not making concrete-like bricks - a high peat content
is most of what's holding the blocks together, rather than a massive
amount of compression.

Ah, I don't use a lot of peat - I have a few bales of it for mixing,
but it's not a prime component of my potting soil.

added soil over the pushed-up root part, and they have since grown into
the block just fine. That aspect may have been aggravated by following
the advice to more-or less lay the seed on the surface of the block,
rather than covering it over and firming it in.

Sounds as if your blocks don't have a divot at top centre.

One of the nifty looking things about the commercial forms is that
they can batch (like 3 or 6 at a push), and that the size progression
uses a divot the size of the prior block. So small blocks have
something appropriate for dropping a seed in and covering with a small
amount of soil, larger ones have a hole about the size of the smaller
blocks so you can "plant up".

They are a bit more fragile and fiddly to water than flats/six-packs,
but so far have held up better than I thought they would. Someone else I
know moves things around more than I do, and has had more problems with
blocks eroding or crumbling than I have (so far.) She is "not a fan" of
them, at least for herself, though she did like the air-pruning aspect.

Hrm. I have several starting trays I constructed, which have fine
screening on the bottom - window screen material, which itself is on
top of a coarser, but more sturdy hardware cloth, to actually support
the soil. You can set these on a few spacers, and then the starts
don't sit in a puddle, and the screening is supposed to provide an air

one could make a stand with something more of a squared cross section
of a wavy screen:


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where the soil blocks could be set into the channels. Then you could
move around a tray of them without manhandling the blocks.