Router fence micropositioner Q for Mr. Kirby

[linear]

Referring to this article:
http://www.bt3central.com/articles/files/rtrmicro.pdf
and this thread:
http://www.bt3central.com/showpost.p...02&postcount=8

My questions is how are you clamping the fence to the tabletop? What I think I'm seeing is that there are knobs threaded through holes in the ends of the aluminum angle where it extends beyond the edge of the tabletop. And what I surmise is that you have some kind of threaded block below the bottom of the tabletop that the knob snugs against the bottom when tightened.

Have I puzzled that out correctly? If so, what's it look like?

[RodKirby]

Hi Rob - sort of

The article was showing my original Woodhaven table/fence/clamps.

[Edit - just noticed your second reference is to my other router table - I used the same woodhaven clamping design on it as well]

These pics show how I had to "extend" the fence when I made my own, larger, table. The (Woodhaven) clamps are 1/4" thick aluminum angle, drilled/tapped for a 1/4-20 stud. I had to rout a slot in the "extenders" to let the angle grip - the table was not quite as thick as the woodhaven one. I also added some stick-on stair-tread (like heavy sandpaper), to provide better grip for the angle (not visible in the pic).

I think the pics will make sense...

[linear]

Thanks for an incredibly speedy reply (and a great original idea).

I don't have the nifty aluminum clamps, so here's what I have in mind, would you please tell me what you think? My table top is 3/4" melamine, and I have sourced a nice chunk of 2" aluminum L-channel which I'll use to secure my fence (Craftsman aluminum extrusion one that so many people got on clearance) to the table top. the L-channel will attach to nuts in T-slots on the back of the fence. I'm free to hang over the end of the table to any length I want.

then I aim to make a two-part clamp, with a spacer block at 3/4", and a "grabber" that has a soft rubber pad (maybe) to give a decent grip as I tighten the stud down via knob topside. Hopefully the attached drawing makes sense, my drafting teacher would be horrified. any curves indicated by the sketch should be straight lines.


Also, my daughter wanted to contribute this to the discussion:


(And in case it wasn't clear, feedback is welcome from all, thank you for reading)

[LCHIEN]

Thanks for an incredibly speedy reply (and a great original idea).

I don't have the nifty aluminum clamps, so here's what I have in mind, would you please tell me what you think? My table top is 3/4" melamine, and I have sourced a nice chunk of 2" aluminum L-channel which I'll use to secure my fence (Craftsman aluminum extrusion one that so many people got on clearance) to the table top. the L-channel will attach to nuts in T-slots on the back of the fence. I'm free to hang over the end of the table to any length I want.

then I aim to make a two-part clamp, with a spacer block at 3/4", and a "grabber" that has a soft rubber pad (maybe) to give a decent grip as I tighten the stud down via knob topside. Hopefully the attached drawing makes sense, my drafting teacher would be horrified. any curves indicated by the sketch should be straight lines.


Also, my daughter wanted to contribute this to the discussion:


(And in case it wasn't clear, feedback is welcome from all, thank you for reading)

Frankly I think there's a flaw there. The clamp would compress the spacer and put as much or more force into tilting it as it would clamping the soft pad. It might clamp but I don't think it would be effective.

My suggestion would be to put the spacer to the left of the tension screw, the tension screw in the middle and the compression pad on the
right. Making a lever arm with an outside fulcrum. You will of course need some way to retain the spacer (the fulcrum) and make it a little flexible since it will need to bend slightly.

[linear]

Spacer has to be "captured" somehow, I don't see how to do that if I have it outside the bolt.

Rod's top block captures the vertical part of his metal clamp arm.

I guess if my screw bore down on the tabletop (much like when I clamp the fence with a C-clamp) then I'd just need to make the equivalent of the body of the C-clamp. But at that point I'd rather just use a C-clamp. I had been using a short HF bar clamp to secure my MDF fence to my older table. I just was aspiring to higher levels of Kirbytude with this version.

[RodKirby]

I agree with Loring - and along with his comments, I think you can (just) see how woodhaven do it now - for variable thickness tops - "outside fulcrum" are the key words...

[linear]

Well, now that I brought up C-clamps...

What about just using a couple C-clamps, and making a "shoe" for the top side (fixed to the L-channel) that would have a hole that captures the round pad, and epoxying a clamping block to the mating side that would ride under the table top. The pads distribute the clamping force, and are "consumable" in case I overtighten and crack one. I can put some rubber spray-on grip coating on the face of the bottom pad that contacts the table.

Then my whole fabrication job is to make a couple 2-inch blocks, one with a hole in it, and one with spray-on tool grip on one face. I can make that in a couple jiffies.

I don't like the outside fulcrum, you have a mechanical disadvantage.

[LCHIEN]

...

I don't like the outside fulcrum, you have a mechanical disadvantage.

You have a force disadvantage but you have a distance advantage. You can reclaim all that by using a different screw thread (Yet another mecahnical tool - a rotated inclined plane). Use a finer thread to regain the mech force advantage.

To make the pivot, you can make the whoe fulcrum a hinge with an L-bracket.
Or put a loose rod through the spacer (the spacer will be under compression).

At least Rod likes my idea. That makes my day .

[linear]

Routing a quarter-inch slot in the table top would probably be easier than any of these options.

If I ever go and do some fool stunt like bolt a foot-high fence to the extruded fence, there could be a lot of torque around the left-right axis along the table top, and that would resist that torque more effectively than anything else I can think of.

[niki]

Hi Rob

This idea is very old, I made it some 10 years ago.

On the last pic, you can see my micro-adjuster

Hope it helps
niki

[niki]