Greater Noida's Parched Summer Fields |
It has been a terrible summer here in North India with temperatures topping 45 degrees Celsius and hot winds searing the landscape. My tiny workshop has become a furnace and I do not dare step in. A spattering of rain and cool winds last week lowered temperatures allowing me to survey my workshop which is full of half-finished projects and pieces of wood cut for unimplemented jigs. After a brief respite temperatures have begun to climb once again. I have a short window of opportunity and I intend to get at least one simple project finished, a basic drill press table I have planned for a long time.
I have an old but trusty Hitachi drill press which isn’t the
most accurate of machines – wobbles about quite a bit – and I have been
planning to make a drill press table to make it easier working with larger
pieces more accurately. For, most drill presses including mine come with only a
small metal table that is meant more for metal work than woodworking. Balancing
larger pieces and clamping small pieces at times presents a problem.
Basic Platform
The basic platform is a 29 by 17 inch piece of ¾ inch MDF on
top of which I have glued on a ¼ inch thick piece of hardboard. These pieces
were cut accurately and easily with my circular saw and trimmed with a flush
trim bit in my router. Next, at one side of the table I drilled a ¼ inch hole
for the bolt that will hold the fence and at another side I cut out a recess to
take my old drill press clamp which is very adjustable and easy to use. This
basic set up is fine for most purposes as it allows me to move the fence around
for various widths of work pieces and the top is flat and large enough to hold
most pieces.
Fixing T-Tracks
To make the table more versatile I decided to add a couple
of 12 inch pieces of aluminium T-tracks to allow for the attachment of
hold-downs. Sometimes, for very accurate results it is important to secure the
work piece in place so that it does not wander. Some sort of clamps are
required for this and the cheapest and best are the simple aluminium hold-downs
made of a curved piece of aluminium, one hex bolt and a Bakelite knob.
The problem is attaching the T-Tracks accurately. First, two
accurate channels – ¾ inch wide and 3/8 inch deep – have to be routed parallel
to each other. The job is best done with a ¾ inch straight cutter. The T-tracks
are inserted in these channels. To secure the channels so that they do not pop
out under pressure, it is necessary to secure them with screws to the
Hardboard-MDF base. The task seems simple enough but is not necessarily so as I
found out.
I first drilled three 3.5 mm holes along the centre of the
T-Tracks for the 3.5 mm diameter half inch screws. This was easy enough but of
course the screws would not sit, the top protruded above the T-Track bottom. I
needed to bevel or countersink the hole so that the screw would sit flush with
the surface. The T-Track recess normally is too narrow not allow a counter-sink
bit. I decided to use a 5 mm bit to cut a chamfer or bevel along the sides of
the 3.5 mm holes already drilled at the bottom of the T-Tracks. I drilled
carefully and slowly and sure enough the required bevel was created. The screw
head would now fit perfectly.
The other issue was to drill a pilot hole into the
Hardboard-MDF base right at the centre of the existing hole in the T-Track.
Experienced woodworkers can probably eyeball the dead centre, punch a centre
and then drill away. However, I often find it impossible to find the dead
centre of a hole, especially slightly wide ones and invariably the screw does
not sit properly in the chamfered hole. This leads to poor fit, inaccuracies
and so. This problem is similar to that encountered while fixing hinges. The
holes in the hinges are usually quite large and unless the screws are inserted
in the dead centre of these holes, they do not sit properly and can even cause
the hinges to shift slightly and misalign.
After a lot of frustrated attempts at acquiring skills to
dead centre screw holes, I finally decided to invest in a set of self-centring
drill bits. They come in different sizes (usually according to screw numbers 6
to 10) and work incredibly well. The drill bit is hidden inside the sleeve which
is bevelled at the end to fit into a bevelled screw slot. Once in position, the
drill bit is pushed down and makes a hole in the dead centre of the screw slot.
This is the only way I can perfectly fit metal hardware to wood.
Self-Centring Drill Bit
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Once the T-Tracks are in place, the hold-downs can be
slipped in and their clamping pressure is more than adequate for most jobs. The
fence is attached to the table top at one end with a ¼ inch diameter six inch
long hex bolt. I used a long shank Forstner drill bit in my drill press to
drill through four inches of the fence. It would have been very difficult to
achieve the same with a hand held drill.
Hold-downs in the T-Tracks |
MDF tends to absorb moisture, especially through the sides
that have been milled. To ensure longevity of any MDF product it is best to
seal it with enamel paint or a finish like Polyurethane. For this project, I
decided to use paint. Jigs look nice and stand out from other stuff if painted
nice and bright. I decided to paint this a dazzling white.
The Table with two coats of primer
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The basic table is ready and the simple fence is attached by
a quarter inch bolt that runs through it. The other side of the fence could either
be secured by a C-clamp or by the drill press clamp. The hold-downs would secure
the work piece. Over time the centre of the table where the drill bit will
descend will get pitted and will have to be cut out and replaced. I intend to
do this later with a pattern cutting template. I will rout out a recess and
then rout an exact pattern to fit. I could thus indefinitely extend the life of
the table. When I have the time I will make an improved fence with a T-Track slot to fit feather boards and stops. But this will do just fine till then.
My Basic Drill Press Table |
Indranil Banerjie
14 June 2012
good job!! btw where you bought these T -track in india?
ReplyDeleteThanks! You know as well as me that you don't get these T-Tracks in India! I searched for more than one year, even contacted aluminium extrusion manufacturers, nobody was interested. Finally, had to get them from the US.
ReplyDeleteThat is really nice. I had always wondered how to clamp things on the table. Now to search for T tracks...
ReplyDeleteThanks !
ReplyDeleteVery nice article
ReplyDeleteThanks!
DeleteThank you for the post.
ReplyDelete