Andrew Scott's tilting router lift
Andrew Scott writes:
Hi Matthias,
Here are some pictures of my modified tilt router lift. I hope my wife's checkered table cloth doesn't cause too much of a moiré pattern on your screen.
The first obvious change is the 18:16
gearing. I'm quite comfortable
with metric, imperial or decimal inches but the 16 turns per inch is
real convenient for me with 64ths available with a quarter turn.
The next easily visible addition is the angle crank. The angle crank
turns a 1/4 by 6 in. lag bolt "worm gear" that advances the angle one
crank per degree. This feature is really important for me. I looked at
1/4, 5/16 and 3/8 in. screws but the 10 tpi of the 1/4 worked out the
best to keep the quadrant radius close to your design. I got lucky with
my math and bandsaw work; the full 45 degrees is exactly 45 cranks.
I wanted the ability for quick setting so a cam engages the worm by pressing on an oak spring that forces the worm into the trunnion. Releasing the cam allows for a quick set.
The trunnion threads are created by
temporarily marking the quadrant with another lag bolt. The bolt is just
tapped with a hammer to leave a thread impression. Teeth are shallowly
cut with a bandsaw at the appropriate angle. It's easier to do this at
the back of the saw, pulling the stock towards you.
The worm gear construction is a bit fiddly but seems to work well. The worm is housed in a block of maple with an arch cut out to expose the threads to the trunnion. To make the worm I first cut the head off the lag bolt. Then the bolt is chucked in a drill and 1/2 in. of the pointy end is ground down with a bench grinder to 3/16 of an inch. I threaded the end with a 10-24 die and about a 1/2 inch of the head end with a 1/4 x 20 die. The 3/16 end is held in place in the worm block with an old router bit bearing, 1/2" O.D. x 3/16" I.D. The bearing is countersunk into the end of the maple block with a forstner bit and is held in place with a lock nut. The lag bolt passes through a 1/4 in. hole in the block and the 1 in. of the clear shank that's left glides pretty smoothly in the maple.
The crank is extended with a store bought
rod coupler and I bolted an old pencil sharpener crank on the end.
Other minor changes are double bearings in the gearing and lifting rod. I realize that roller skate bearings aren't thrust bearings but there is little axial pressure put on them, just snug. If they're left proud a hair it aids clearance as well. I liked your idea of a long carriage bolt to tighten the angle but, like you, I couldn't find one. Maybe they don't make longer ones? Anyway, I made my own coupler by threading the inside of a piece of light fixture hardware. It's a bit of a pain to assemble and disassemble but hopefully I won't need to do that much.
Matthias comments:
I was able to find an 8" (20 cm) long 3/8" carriage bolt at The Home Depot,
but it was a bit bulky. Then I realized I could eliminate that part
by just using the leftover 5/16 (or M6) threaded rod from the lift mechanism
for the angle clamp.
The tilt router lift is now happily in my workshop and my wife
is happy it's off the dinner table. I threatened that if I could find
a couple places to put candles, it's pretty enough to be a
centerpiece.
One other benefit of gearing the angle selector that I came across was that when you dry fit an angled router cut joint and you need to tweak it a fraction of a degree, even with a bit of backlash it's pretty easy to adjust by a fraction of a degree -- possibly even to the eighth.
Andrew Scott
See also:
Making curved molding