Router Table Sub-Fences

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Router Table Sub-Fences:
We explain how to make and use them.

We explain how to make and use them

Any dedicated router user has probably got a router table or aspirations to own one. I maintain you can make a better one than you can buy, because it can be customised to suit you. A manufactured table will invariably be deficient in one way or another, the straight fence often being the culprit. The biggest area of concern is how the workpiece runs across the cutter and in the majority of cases it will be against the fence, but that may not be enough. Here’s why… 

Height
Most table fences aren’t really high enough for my liking. I like plenty of work support, which if you are machining vertical components, can be problematic if they don’t lie truly flat against the fence as only
the bottom area is supported. Usually the fence opening can be altered by sliding the facings in or
out and then locking them in position. However, they cannot give continuous support as the workpiece runs across the cutter. 

Adjustments
This is where a sub-fence comes into its own. So long as you can attach it securely to the fence behind, it gives a continuous running surface and extra height support. If a cutter has a bearing you need to cut a slot to accommodate it. Screw or clip the sub-fence to the main fence making sure it is in front of the cutter. Switch the router on and slowly push the fence assembly back so the running cutter can break through the sub-fence. A key time to do this is when making scribing cuts. With a fence opening the component can get pushed into it as it moves forward damaging the end and giving the operator a fright. 

You can fix a sub-fence with double-sided carpet tape if you don’t want to spoil the fence surfaces

Push the fence backwards on to the revolving cutter until the right amount is projecting, switch off and lock the fence

If you need ultimate control, clamp a board on top and in front of the sub-fence to form a tunnel

Making the grooves in this solitaire board would not be possible without a sub-fence

A continuous sub-fence and a square push piece make scribing and tenoning cuts easy

Advantages
Another advantage is that any slight difference between the infeed and outfeed fence facings disappears
when the sub-fence smooths over the gap effectively. Big or tall cutters can be rather scary to use, having half the cutter hidden behind the sub-fence is more reassuring to work with and less danger of a ‘catch’. Panel raising normally requires a large diameter expensive cutter but a vertical type is smaller and cheaper. However, unless it is used with a sub-fence the edge or the raise will splinter and breakout.

My own router table has a high fence to start with, so I can machine vertical workpieces

Another example where a fence opening would make this task impossible

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