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My drill press column-mounted fence
Copyright (c) 2012, all rights reserved.

My normal drill press table and fence have served me well, but there was one type of operation where it fell short:  Drilling holes in the EDGES of workpieces.  Especially when the workpieces were larger rectangles and I needed to drill holes in all four edges.  This would require moving the table, which meant the fence lost registration.

This need arose again when I was working on a dust shoe for a CNC router (more on that some day in the future).  I had very nicely machined a piece of polycarbonate (on the CNC router itself) and was now needing to drill 1/8" diameter holes around the perimeter of this 4" x 7" (or so) piece of plastic.

Using the shorter fence on my drill press table was futile.  The fence itself is only about 2" high, so it simply didn't provide enough support near the top of the workpiece.  The result was holes that weren't perfectly centered in the edges of my little piece of plastic.

Now, if you know anything about me, you know that just wouldn't do.  Because I'm certifiably insane, I see a line of holes that aren't in perfectly alignment as abject failure.  So it was time for me to revisit my need for a tall fence, and something that didn't register off the table.

I knew I wanted something that registered off the column, that would solve both problems I was having.  With a fence registered off the column, the table could be moved up/down/sideways and neither the fence nor the stop block ON the fence would move.  Also the fence could be placed immediately below the bit, so my workpiece would be perfectly supported and my holes would all be in a perfect line.

So I started googling things like "drill press column fence" and was getting nowhere.  I knew I had seen one design, an old Skil "HD" (stood for "Heavy Duty" and the stuff was actually pretty good) had a fence that was an adjustable bar on a collar that attached to the column.  Primitive but...

Nothing else much turned up.  So I decided that once again, I'd need to come up with something on my own.  The pics here are what I've philgineered.

Basically, a nearly 1-1/2" thick piece of Baltic birch plywood (technically two pieces that are glued-up) is made into an 11" wide split collar.  There are two 5/16-18 carriage screws and knobs that squeeze the collar around the column.  Finally, there are two dadoes, each 3/4" wide by 3/8" deep in which some Rockler t-track slides.  T-bolts (4) in those dadoes with accompanying knobs on the bottom snug the t-track up.

The other ends of the t-track are connected to a small block of wood that is really the subfence.  This block of wood also has some 3/4" wide by 3/8" deep dadoes to capture the ends of the t-track.  And the block has some perpendicular holes (two of them) through which t-bolts extend.  With knobs, these t-bolts snug the actual fence against which my workpiece rests.

That is a lot of words to describe what a few pictures will probably do better, so there are plenty of pictures and an incomplete (I'm working on it, my SketchUp skills are very slowly improving).

 

How to make your own...
I always look at pictures and plans and wonder where exactly to start.  Well, I'm going to give you the exact steps I used to make this one, as best as I can recall.

Glue up two pieces of 3/4" Baltic birch plywood large enough to net a single piece 11" x 5-1/2" x about 1-1/2" thick.  I used the BB plywood sold as 3/4" thick.  It isn't, quite, but whatever you net from two layers 3/4"-ish thick will be fine.

Cut the glued-up piece to final dimensions (11" long, 5-1/2" wide).

You're going to need the subfence to match the 11" width, so now would be a good time to also cut a piece of BB plywood that is 11" long by 1-1/2" wide.  Try to use a single stop-block setting while cutting both the larger block and this sub-fence to the 11" long dimension, it will save some time in the next steps if they are exactly the same length.

Mark the center of the larger block that will become the collar.  You could use a longer steel rule and draw diagonals, but I typically use a combination square and make four marks.  First, I set the combination square to half the 11" dimension (so 5-1/2") and then use it to make a mark from both ends.  Now I change the combination square to half the 5-1/2" dimension and again make two marks now from both of the long edges.  In the middle of your workpiece you will now have a sort of "#" and you should be able to visually split the differences very accurately.

Measure the diameter of your drill press column.  I used a digital calipers (just a cheapie I purchased at Harbor Freight, the one that eats batteries like they grow on trees).  I took several readings in a few different spots along the length of the column, and came up with 2.885".  My drill press is a Ridgid floor-standing model, I imagine column diameters will vary from manufacturer and model to model, so make sure to measure YOUR drill press column.

I now divided my column diameter in half (1.4425) and adjust my digital calipers to 1.442".  I then took a drafting compass and adjusted it using the calipers.  Now draw a circle on your plywood.

Now I moved to my router table to create the dadoes for the t-track.  I used a 3/4" router bit and made a few passes to get to the 3/8" depth I needed.  I used a scrap piece of wood behind my workpiece to prevent the bit from blowing-out when it exited.

Now is the time you also want to route those dadoes in the sub-fence.  If you do it now, the dadoes between the collar and the subfence will align nicely when it comes time to assemble the thing with the t-track.

Now mark your workpiece for the carriage screws that will soon squeeze the collar to the column.  In my case these carriage screws are 5" apart, or 2-1/2" in each direction from the centerline.  Mark your lines on the top of your workpiece.

Now we get to cut the collar in half.  Align the fence of your table saw so the blade will as nearly as possible tip the collar into two equal halves.

Use a bandsaw or scroll saw or jigsaw to cut the column hole from the two halves of your collar.  I used my little Skil bench bandsaw with a 1/4" 6-TPI blade.  Stay inside the line.

To fine-tune the cut, I alternated between test-fitting the collar halves to the column, and sanding them on my oscillating belt sander.  A drum sander would also work great for this.  Just take your time, sand to the line slowly, test your fit.  I probably test-fit ten times for each half of the collar, and stopped once the collar halves nicely fit the column with no gaps.

Now drill the holes for your carriage bolts.  I used a saddle square to transfer the lines I had made on the top of the collar back in step #9 to the INSIDE of the two collar haves (the sides that will be TOWARDS the column).  And then I found the center of the edge using my combination square set at half the thickness of the piece, and making two marks.  The difference between the two marks is the center.  I drilled 5/16" holes through each half of the collar.

If your drill press has a rack for raising/lowering the table, you need to accommodate it by notching the block.  I did this on my table saw, nibbling enough material away from both halves of the collar so the rack wouldn't interfere.

Now we can do our first test tightening.  Install the two carriage bolts through the holes (I seated the heads with a hammer) and assembled the collar around the column, and used a couple of knobs to snug everything up.  I found I get the best results with one smaller knob and one larger ratcheting knob.  I snug the little knob, and then crank the ratcheting knob a bit.  Once snug try moving the collar by grabbing it with both hands and twisting it.  It shouldn't budge.

Now take it all apart again and drill your 5/16" holes for the t-bolts.  There are four holes (two in each collar half) and two more in the subfence.  Just center these both length and width-wise in the dadoes.  A good trick for finding marking the center of the dado is to use a 3/8" gauge block and draw two lines and divide those by eye.

You will need to drill two holes into the edge of the subfence for the t-bolts that hold the actual fence.  I can't remember where I placed these, I will update this page if anyone actually tries building one of these.

Make a fence.  I make these from 1" thick wood and I route a t-slot into each side.  The one I'm using now is 1" plywood (actually a piece of 3/4" and 1/4" scrap glued together).  The t-slot on back allows for mounting the fence to the subfence.  The t-slot on front allows me to add a stop-block.  To route a t-slot, I use a 3/8" straight bit to remove most of the material, and then a Rockler or Whiteside t-slot bit to finish it off.  A router table is invaluable for this.

Now reassemble once again.  You need a couple of 1' long pieces of t-track, some t-bolts (four to hold the t-track in the dadoes on the collar, two sets to hold the t-track to the subfence, and two to hold the fence to the subfence.

 

Random notes...

The t-bolts I used in the collar didn't extend much below the bottom, I was concerned the knobs wouldn't get much purchase on them.  I ended-up adding a 1" counterbore (you can use a Forstner bit, I used a piloted counterbore).  I went 1/4" deep.\

The 5/16" holes can be a little tight for 5/16-18 t-bolts and carriage bolts.  My 5/16" drill bit may be a few thousandths undersized, too.  So when I was all done, I reamed-out all my 5/16" holes to 21/64" (this is 1/64" larger than 5/16").

I didn't write-up anything on making a stop-block, but I'll picture mine here soon.  I use this same stop block for both my drill press and table saw sled fences.  It has a ridge which rides in the t-slot so the block doesn't twist, and a t-bolt and knob snug it up.

You may notice I used some wingnuts and some knobs on my jig.  I didn't do this for any other reason than I was out of knobs and the prices on those things is about $1.50 each.  A recent PayPal contribution was used for the t-track, and there wasn't enough left for knobs, so wingnuts it was.

 

If you spot any errors or there is any confusion, please let me know so I can update this page.  I plan on updating it to get rid of the red.  This has been sitting on my hard drive, unpublished, for a couple of months now.  Sometimes the best way for me to get in gear is to just get in gear, so I'll fix the missing parts soon.  Here is a <link> (soon) to a file with my SketchUp file for the collar.  I haven't drawn the subfence and there is no way my skills are currently up to adding carriage bolts or t-nuts or t-track, sorry.  I think there is plenty there for the builder, though.

 

--Phil
phil@cgallery.com

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