|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.
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.
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
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
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|
14 June 2012