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Offset Router

Not a LAN on the edge of your desk
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The typical router is a really useful woodworking tool, but it's top-heavy. I use mine all the time and this one fact is the one that screams itself at me whenever I use the router to put an attractive edge on a workpiece. Besides being top-heavy, the center of mass is beyond the edge of the workpiece, so careful control is the name of the game, lest you damage something expensive.

My idea is for a router that would be used specifically for edge work but one that could be adapted to other uses.

The router's motor is mounted rigidly to the base of the router, right at the bottom. It can be a typical router motor, it still rotates counterclockwise looking at the shaft end. I can even imagine this being a base that would accept one of the removable Porter-Cable router motors.

The motor's shaft end is a gear that engages another gear that is the top end of collet shaft. They're same-size gears so the motor's shaft speed is the collet shaft speed. You could conceivably make them different sizes so there could be speed adjustments, but variable speed routers are already out there, and they don't require you keep a bag of gears handy.

Height-adjustment mechanisms would have to either lift and and drop the motor with them, or there would have to be a compressible linkage that permitted the collet shaft to change length under load. That's not impossible, but I'd avoid the extra moving parts if I could. Looks like the motor's going for a ride!

The downside is that this necessarily makes the router fatter at the base, but since my gripe is about tippy routers, I'll take that pill. It somewhat cancels reaction torque - the motor and collet shafts are counterrotating.

It would be about 66% wider than a current router of similar capacity, but only about 66% as high, with the wider base that would make it rock-steady on edge work. This is the router you dig out for working on $5000 granite countertops. It'll also get much closer to a closed end than a conventional router - the minimum distance from a wall is limited by the radius of the driving mechanism at the top of the collet shaft, or the radius of the base around the collet end, whichever is greater.

elhigh, Sep 02 2007

better solution http://www.patwarne...offset_subbase.html
[zeno, Oct 09 2007]


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Annotation:







       + Bun for the poetry of //removable Porter-Cable router motors// Also, a great idea!
csea, Sep 02 2007
  

       Sounds good to me. Although letting //the collet shaft... change length under load// sounds kind of iffy to me - unless I'm not understanding you, that's going to let your tool jump around. Spline the collet shaft to let it slide up and down, and put another collet-like collar at the top to grip it at the desired location.   

       My pet peeve is the reaction torque you mentioned. After routing the backs of rails and stiles for glass cabinet doors for 6 hours, my hands would barely keep a grip on the stupid thing when starting. I was tempted to lay it on the floor and hold it with my foot. A selectable soft-start option would not be amiss.
lurch, Sep 02 2007
  

       I decided not to recommend a collet shaft whose length can change under load, for exactly the doubts [lurch] has in mind. The motor rides up and down with the height changes just like before, but now the motor is underslung - at maximum shaft extension, the motor barely is above the base of the tool.   

       Any feature that is currently available with an existing router shouldn't be too difficult to incorporate into this router, especially those involving the motor, like soft-start and variable speed electronics. Like I said, this could almost be achievable with an existing router motor, but the Porter-Cable units have the collets on their ends, which would ultimately make using them as drop-ins on an aftermarket base like this unwieldy. This would be better realized as a ready-made tool.
elhigh, Sep 02 2007
  

       Static lead weights on bolt on arm to shift gravity ? Abit like ones used on competition bows . A large G shaped arm could take weight under the work . work with any router , more setup time though .
wjt, Sep 03 2007
  

       I routinely put larger bases with right angle guides on routers to add stability.   

       A bevel gear arrangement would enable a router to be made in the shape of a barrel type jig saw with a lower c/g and a long, relatively narrow base for maneuverability.   

       [lurch], get a shaper or make a router table.
nuclear hobo, Sep 03 2007
  

       So you want to run a shaft with the collett at one end parralell to the motor spindle? Driven at the top by gears? The motor is fixed to the router base as low as possible. So run your driven shaft with depth adjustment - locked by thrust races either side of fixed plate on the shaft- but no need for keyway etc. if your gear on the collett shaft is four(or so) inches in depth- so will mesh constantly with gear on top of motor as you slide it up and down. Have a nice day.
the dog's breakfast, Sep 03 2007
  

       Thank you, [tdb], for making me realize that [elhigh] is talking about motor parallel to but offset from shaft - I, for some reason, no fault of his, was thinking of a setup like an angle grinder. I'm awake now.   

       The gears will need to be of radius equal to half the motor offset; they'll be pretty good sized. My first thought was that making one of them //four (or so) inches// long would be far to heavy. But on second thought, if the driven shaft moment of inertia matches that of the motor shaft, start-up reaction torque not just //somewhat// cancelled - it's gone. Virtual second bun.
lurch, Sep 03 2007
  

       I misrepresented the idea in the original post - the collet shaft wouldn't be the part that changed length under load. It would be mounted rigidly to the height-changing mechanism that would permit different depths of penetration of the bit into the workpiece. It would have to be the motor's shaft whose length could change under load. Or, as [breakfast] described, the engagement changes. It all comes out in the wash.   

       I'm sticking with the relationship between the collet and the motor being constant - both are attached the adjustment, and they ride up and down together.
elhigh, Sep 03 2007
  

       I have been thinking about this idea since you first posted it. I didn't like it very much. I Think it makes the machine more complicated than it is and should be. Yet I recognise the problem you describe. I couldn't bun, couldn't bone.   

       Now I found this, see link. I much prefer this to your solution so bone for you. What do you think about this link and the solution?
zeno, Oct 09 2007
  

       Oh, and I also found that many routers have the soft start option.   

       But I guess my reactions come to late.
zeno, Oct 17 2007
  

       [zeno] This idea is for the router head to be offset. In your link, can you see the diameter of the router base plate? It is not good for getting the cutter into tight internal corners. The idea here is that the head is offset from the centre of the baseplate -think of the handle on the plate pictured in your link as being a driven spindle. The tighter radius at that end of the plate would allow access to tight internal corners.
the dog's breakfast, Oct 17 2007
  

       The getting into corners is only a positive side effect. The problem solved here is tippy routers, which is solved better in my link, I think.
zeno, Oct 17 2007
  

       [zeno], the source of the tippy router problem isn't addressed in your link at all. In fact, in that example, the router is now even taller.   

       My idea places the drive motor down low, riding parallel to the collet. I've known about those offset bases for al ong time, and all the do is provide a handle off to one side and give a somewhat larger base. What it really does is go a long way toward preventing accidental lift or tipping of the router while in use on an edge.   

       My offset router would have the router's motor down over the wide part of that subbase, and the collet projecting down through the narrow end. That keeps the vast majority of the mass of the tool on top of the workpiece while still providing the larger base that helps prevent tipping and lifting.   

       My solution isn't perfect - it sacrifices the compact footprint for a low CG and advantageous mass distribution. But if I did an awful lot of freehand edge work, I'd be sorely tempted to pony up for one like this.
elhigh, Oct 17 2007
  

       Ah, I assumed they would solve the tipping problem with a wider base and a better way to hold the machine. But I just looked at the pictures, never worked with one. I except your explanation and will remove my fishbone fortwith.
zeno, Oct 18 2007
  


 

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