[Rhodes22-list] Fw: Preparing To Set New Dock Pilings With AHydraulic Drill

Roger Pihlaja cen09402 at centurytel.net
Mon Jun 28 08:18:23 EDT 2004


Michael,

Thank you.  The article & pictures look great!

Roger Pihlaja
S/V Dynamic Equilibrium

----- Original Message -----
From: "Michael Meltzer" <mjm at michaelmeltzer.com>
To: <rhodes22-list at rhodes22.org>
Sent: Monday, June 28, 2004 1:49 AM
Subject: [Rhodes22-list] Fw: Preparing To Set New Dock Pilings With
AHydraulic Drill


I am pretty sure Rodger wanted this posted to the list with the picture
attached, Doing that for him now.

MJM

----- Original Message -----
From: Roger Pihlaja
To: Michael Meltzer
Sent: Sunday, June 27, 2004 5:10 PM
Subject: Fw: Preparing To Set New Dock Pilings With A Hydraulic Drill


Michael,

Enclosed is an article for the Rhodes List along with 3 annotated pictures.

Roger

_____________________________________________________________

Hi Everybody,

As many of you recall, my dock on Sanford Lake was destroyed by ice this
spring.  We've spent the previous month demolishing & removing the wreckage
of my dock as well my neighbor's boat hoist from in front of my property.
We are now just about ready to start building the new dock.  To that end,
I've built myself a new toy, a hydraulic drill for sinking the new dock
pilings.  The three attached pictures illustrate how it works.

In picture 1, you can see the entire set-up.  The hydraulic drill is run by
a 6.75 hp pressure washer.  Our house well water is stepped up to 2-1/2
gal/min @ 2800 psi in the pressure washer & this high pressure water is fed
to the hydraulic drill thru 25 ft of high pressure hose.  The hydraulic
drill itself is fabricated from 2 inch nominal diameter, schedule 40,
galvanized steel pipe & fittings.  High pressure water enters the drill thru
the T-Handle on the upper end.  The drill runs hydraulically full in order
to give it sufficient weight to reduce the tendency to lift up in reaction
to the water jet.  There is a small hole bored in the cutting head.  The
high pressure water is forced out thru this orifice at sonic velocity, about
1200 ft/sec.  Yes, this is a highly dangerous tool!  It can cut right thru
your foot if you get in the way of the water jet.  That's the reason for the
large T-Handle, in order to provide sufficient leverage to keep the drill
under control when it is cutting.

Picture 2 is a close-up of the cutting head.  The lake bottom where I live
is composed of hard gravelly mud.  Note the four 7/16 14UNC grade 8 bolts
protruding out of the cutting head.  The ends of these hardened steel bolts
have been ground down to chisel points and 7/16 14UNC wing nuts have been
epoxied in place on each of the bolts.  These wing nuts act as "mud
impellors" or stirrers.  The chisel points on the hardened steel bolts acts
to pop the gravel particles loose as the hydraulic jet blasts its way down
thru the hard mud.  In use, the T-Handle is used to rotate the cutting head
90 degrees back and forth.  The gravel and mud cuttings are forced up and
out the annular space in between the 2 inch pipe and the bore hole.  Yes,
this tool makes an incredible "mud slick".

Picture 3 shows my son, Daniel and his friend Keith using the hydraulic
drill to set new stairway pilings for my next door neighbor, whose dock was
also destroyed by ice this spring.  Hey, when you're trying something new,
it's good to experiment with someone else's dock 1st!  Note that the hill
Daniel & Keith are working on is so steep that they are both wearing
climbing harnesses & belayed off to trees at the top of the hill.

The new hydraulic drill worked great its 1st time out.  The cutting rate is
about 12 inch/min.  The installation of our new dock should go smoothly with
this tool.

Roger Pihlaja
S/V Dynamic Equilibrium






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