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A DIY micro adjust for a router fence - inexpensive but precise

Ever gazed at the Incra router fence with the LS micro positioner? $537. Oh and you'll need a huge router table to hold all that… Well, here's my shop-made substitute. $26 if you make your own thumbwheel, or $35 if you opt for a steel one. I'll probably change out these thumb-screw tighteners on the fence with cam clamps for another $14, so finally I'll end up spending $50 on this. I should note that I already invested in my own handmade router table table, which gives me about 12" of table behind the fence to build this on.

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I have a 20+ year old Craftsman router table/fence that I've set into a 2.5×6' table. The fence has always been a pain. It wants to sit cockeyed, then moves/straightens when you tighten it. And with a horrid stiff 2.5" vac hose coming out the back, it was a constant hassle to set. $537 isn't in my budget, and I came across a nice youtube video on "DIY Thumb wheels" which showed how these were used for, I think, a stop adjustment. That was all I needed and I was off. I found a steel bar from a previous life as a garage door opener, and bought a 3/8-16 8" hex bolt and nut along with a ¼" threaded rod and nuts. Also I had this small "toggle" clamp I bought direct from China on eBay.

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The clamp is a quick release to allow the approximate positioning of the fence, quickly sliding the bolt under the quick release clamp. Once that clamp is locked, the thumbwheel gives a genuine micro adjustment. With 16 threads per inch, this setup moves 1/64" for each quarter turn. Really allows precise positioning, and holds the fence while it is tightened to the table. Since the fence likes to twist, I added the wooden guides on the outside of the sliding part of the micro adjust. This keeps the fence perfectly aligned as it moves, even with nothing else tightened. It's an astounding improvement on a cheap table and fence. I might even keep it!

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In the old configuration, with the hose straight out the back, the hose constantly fought the positioning. I had to reroute it to give access to the micro adjust. But a double benefit: using an elbow means that the hose is flexing as the fence moves, not sliding on/off the table across its ribs (eh!!!!) , and it presents MUCH less resistance and does not stick.

The above pics show my final setup with the metal thumbwheel, but I hurried a "prototype" with a DIY wooden one - a hex nut mortised into the cutting from a circle cutter. These are in the next two pics.

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Obviously this is still clamped. Once I have a few miles on it and I'm comfortable with the position, I'll probably screw it on and give back the clamps.

Construction: As you can see, the thumbwheel sits tight between two wooden supports. I fudged my hollow chisel mortiser to work as a (poor excuse for) a drill press and drilled and cut one double-thick support, then sliced it in half on the band saw. The clamp presses down into a block cut with a 90deg chisel router bit. There is nothing magic about this, but mounting the parts on top of the ply base had to be done with a lot of care so everything lines up. Also, I found that the mortised nut had hysteresis - I think the nut pushed deep into the mortise in one direction, but then slid in the mortise before hitting tight against the support and starting to move in the other direction. The metal thumbwheel is one piece of steel, and with the surrounding supports tight to it, there is almost no hysteresis. The fence moves instantly back and forth when you reverse direction of the wheel.

Parts: (June 2022) The metal bar was saved from an old garage door opener. I think you can buy bar in any big box if you don't have it. The other hardware came from the big box. The vac elbow was hard to find. Originally this was simply the end of a shop vac hose stuck in the fence. Most of the elbows you find are not for this, but connecting two hoses, I guess for dust collection ducting(??). This one works perfectly. I found it on Amazon: Flexaust 231 Tuec Plastic 90 Elbow. I see the price went up since I bought it 3 days ago. Inflation. It's now $11.43 The clamp is from eBay. Search "toggle hold down clamp". I see some for about $10. At that price you'll wait for an express packet from China, which is usually under 2 weeks. The metal nut is also from eBay "Zoro Select Z0285 Lock Nut,3/8-16,Steel,Black Oxide". About $9 with shipping. (I have no financial interest in any of this.)

Lots of words for a small project but I was so frustrated with fence that constantly fought me trying to position it. I'm so delighted with outcome, I wanted to share it. I know, there is nothing new under the sun, and I'm sure this has been done before. But I can offer an update and pointers to get the parts in today's world.


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