Naw, this machine is still in the under-engineered phase. It still needs some more thought and improvements. I haven't reached the peak yet.
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Router Planing Fixtures
- Thread starter Bruce Johnson
- Start date
Naw, this machine is still in the under-engineered phase. It still needs some more thought and improvements. I haven't reached the peak yet.
I did that already, and it's still dragging and grabbing. I may even switch to UHMW plastic bars for the side rails, in place of the aluminum.
Going to try and flatten the edges of my maple boards for gluing together and realized my mdf rails aren't straight.
Will be trying to mount some aluminum pieces to the existing jig so I don't have to start over...
Can i drill holes in it with a sharp drill bit or am I asking for trouble?
Will be trying to mount some aluminum pieces to the existing jig so I don't have to start over...
Can i drill holes in it with a sharp drill bit or am I asking for trouble?
That's unfortunate, considering how useful the notch bar sounds to be. Wouldn't a second notch bar riding the opposite rail reduce the risk of binding?
So currently (sorry for the sketchiness) you have notches that are only slightly wider than the rail:
The twist allowed to the sled is a function of the tolerance of the notch over the rail:
There's no counteracting force preventing the twist from occurring, so it binds. If you widen the notch gaps, you also increase the tolerance, but you lose accuracy and there's still a risk of binding.
But if you both widen the notch gaps and add a second set of notches over the other rail, flanges to the insides of the rails:
You can increase the angle of twist before binding while retaining the precision of your current design.
Or you could put wide-gapped notches on all sides, which retains the precision of your original notch bar while minimizing both twist and binding, kind of how a railcar truck works:
But given you've said moving the sled onto and off the rails is unwieldy, this would probably make setting up for a planing session more difficult.
My sled is buried in preparation for the move, but I drilled large 2" and 3" holes in the tall sides to help reduce the weight of the sled somewhat. I'm pretty sure I did this on a recommendation from you @Bruce Johnson 
They have things called linear rails and stepper motors that I hear you can hook to a controller and program them to precisely move a router in any way you want. You should definitely add those!
I don’t produce enough to make CNC worthwhile, but there are a few operations where it would have come in really handy, like cutting perfect elliptical inlays! I’m fascinated by it, but not convinced it’s really quicker than traditional template methods for low output shops. In a pinch, there’s a local Maker space that has a CNC for hire.
So I finally got around to trying to flatten the edges of some boards for a little portable bass project I have kicking around in my head. As mentioned earlier today in this thread I wanted to add some aluminum straight edges to my jig to ensure for an even surface.
So I got that done:
Using my vacuum board as a large machined-flat surface I install the rails upside down so that they would be flat to the board, the jig MDF rails might not always be flat so this way it doesn't matter.
Yeah you can see a few places where it dips away from the metal rails...
I flip the jig rails upside down again and put ALL my pieces in. 12 1x4 home roasted maple boards.
Clamp to taste...
I *SAID* clamp to taste!
Now I flip it right side up and rest them between my two portable workbenches. The Pieces should be no higher than the rails and I have MDF insets on my jig to act as spacers so the router bit has room to move across all boards.
Time to go to work!
New 2" router bit I wanted to try for this job. (Spoiler alert! It worked well and left no "swirlies" like my other bit that has the angled blade tips)
You can see some leftover blue chalk I rubbed on to be able to keep track of any low/untouched spots. If the low spots were in the last 1-2" of the board at either end I didn't worry too much as that will be cut off later... probably... hopefully...
One set of edges done! Time to do the other... Unclamp, flip jig pieces back over (but not the boards this time!), reclamp, re-chalk and repeat the routing process.
Took maybe 45 minutes to do the job itself:
Okay, FULL DISCLOSURE: I know the boards edges aren't perfectly parallel. I never squared them up. I am not too worried as the deviation isn't that huge. None of them look trapezoidal. To me the important point is that the edges are flat and ready to be joined.
I still have to plane them to thickness so you can see lines easily simply because of surface coloration and height differences. The seams themselves are better than anything I've done before!
So I got that done:
Using my vacuum board as a large machined-flat surface I install the rails upside down so that they would be flat to the board, the jig MDF rails might not always be flat so this way it doesn't matter.
Yeah you can see a few places where it dips away from the metal rails...
I flip the jig rails upside down again and put ALL my pieces in. 12 1x4 home roasted maple boards.
Clamp to taste...
I *SAID* clamp to taste!
Now I flip it right side up and rest them between my two portable workbenches. The Pieces should be no higher than the rails and I have MDF insets on my jig to act as spacers so the router bit has room to move across all boards.
Time to go to work!
New 2" router bit I wanted to try for this job. (Spoiler alert! It worked well and left no "swirlies" like my other bit that has the angled blade tips)
You can see some leftover blue chalk I rubbed on to be able to keep track of any low/untouched spots. If the low spots were in the last 1-2" of the board at either end I didn't worry too much as that will be cut off later... probably... hopefully...
One set of edges done! Time to do the other... Unclamp, flip jig pieces back over (but not the boards this time!), reclamp, re-chalk and repeat the routing process.
Took maybe 45 minutes to do the job itself:
Okay, FULL DISCLOSURE: I know the boards edges aren't perfectly parallel. I never squared them up. I am not too worried as the deviation isn't that huge. None of them look trapezoidal. To me the important point is that the edges are flat and ready to be joined.
I still have to plane them to thickness so you can see lines easily simply because of surface coloration and height differences. The seams themselves are better than anything I've done before!
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I saw this in a guitar building facebook group and figured this crowd would get a kick out of it:
And when you're done, it can be flipped over and used as a work bench, drafting table or to eat lunch.
Frikkin genius.
Frikkin genius.
So in my last post, you saw how my jig hangs between two work benches? I momentarily considered doing a price check on ikea table that had removable leaves so this guitarist ain't far off!
That's clever and funny and a good practical idea. Once you understand the principles of router planing, there are many things that can be adapted into a fixture.
I understand what you are getting at, but I think adding more notch bars and tightening up the clearance would make it worse. It would jam at a smaller angle off square and want to chatter as I pulled the bridge.
I see two approaches to solving this:
The first, simplest way would be to replace the notch bar with a row of roller wheels. The wheels would be mounted flat, axis vertical. I could find some ball bearings with an OD about 1", and mount them in a row with about 7/16" gap between them. They would roll on the sides of the aluminum rails. That would prevent any jamming and dragging.
The more complicated approach would be to add a mechanism that controls the two ends of the bridge and keeps it square across the rails. For example, using small steel cable and pulleys on both sides, linked together. Actually not that complicated to build. And, if I built that, it could be powered to help drag the weight of the bridge. I could use a hand wheel on the pulleys to get a better mechanical ratio. Or, power the cables with a pneumatic cylinder or an electric motor.
I'll probably do the wheel bar thing for the short term, but start planning out the cable rig for the future. Right now, I need to move on to other machine projects (and, you know, building basses!). Overall, this machine is working well and shown that it can do the router planing that I need.
My sled is buried in preparation for the move, but I drilled large 2" and 3" holes in the tall sides to help reduce the weight of the sled somewhat. I'm pretty sure I did this on a recommendation from you @Bruce Johnson
In my machine, I need the bridge to be heavy. When I'm making heavy cuts, the bridge is actually slightly floating and lifting up off the rails. I'm pretty sure that's why I was getting those slight steps in the surface sometimes. Experimenting with this rig has made me appreciate that there's some significant force and horsepower involved in routing a path 1 1/2" wide x 1/8" deep. It takes some muscle to pull the bridge along, and that same power is trying to lift the bridge up.
There's a reason why my big pin router has a 3000 lb frame. And why John has to pay attention to the rigidity of the frame of his CNC router. There are forces involved.
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They have things called linear rails and stepper motors that I hear you can hook to a controller and program them to precisely move a router in any way you want. You should definitely add those!
Nah, that would be cheating. I don't want any dang computers running my machines!
Marketing HP. Miniature horses. Smoke and mirrors and outright lies.
120V motor that has a 15-amp plug on it = 1800 watts maximum input = 2.4 HP at 100% efficiency, and no motor is 100% efficient.
Those draw 15A, supposedly. The Boring old 690 draws 11 amps, currently claimed 1-3/4 hp . Ergo, they are not "nearly twice as powerful" and both are bovine excrement-ing about their power output. But the 690 is only slightly delusional (only claiming 98.9% efficiency), while the "big ones" are blowing a lot more smoke (134% efficiency as claimed.)
Real world you might see 80-85% efficiency without the marketing department's herd of male buffalo. I do believe the 690 used to claim a somewhat more plausible 1.5 HP. Which would lead a more plausible figure of "about 2" for the bigger one. So 25% more powerful, in real life.
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Yeah, that's true. The higher HP rating that they claim is calculated from "instantaneous torque", where they include the inertia of the spinning mass of the motor at the instant the cutter touches the wood. A "3 1/4 HP" PC 7518 router does have a lot more cutting power than a "1 3/4 HP" PC 690, but it's not really 3 1/4 true horsepower continuously.
Before they left the cheap end, ShopBot used (first) a separate parallelization cable and drive cable, and (then) an upgraded system with the drive cables also doing the parallelization cable function (they were, at first, "plotter-based" CNC and inexpensive - that quickly went out of fashion with them, but it's what I own.) That system is easily and inexpensively done with a few sliding glass door bearings and such-like. I might be able to find the drawing from when I changed mine from version 1 to 2. They also do cute things with unistrut and glass door bearings if you want to prevent uplift.
Obviously, you'd power yours some other way, not with steppers or servos. Hand cranks or steam rams or hydraulics (or miniature horses on treadmills, or walking around a capstan.)
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I need to get a couple things off my plate, then:
I have 2 sets of linear rails and a thick sheet of clear rigid polyesther to support the router. I have a dust port and shoe "skirt" to keep the dust in control.
Basically a CNC without the steppers and computer.
I'll mount it to 1" MDF, on hinges to tuck away when not in use.
The sled/router base will be mounted in such a way that I 'should' be able to joint up to about 4" thick down to about 1/4" thick. Primarily to thickness bodies.
I may end up using it in conjunction with templates too.
I have 2 sets of linear rails and a thick sheet of clear rigid polyesther to support the router. I have a dust port and shoe "skirt" to keep the dust in control.
Basically a CNC without the steppers and computer.
I'll mount it to 1" MDF, on hinges to tuck away when not in use.
The sled/router base will be mounted in such a way that I 'should' be able to joint up to about 4" thick down to about 1/4" thick. Primarily to thickness bodies.
I may end up using it in conjunction with templates too.
Yeah, I can totally see the usefulness of a sled using linear rails and just manually moving it along the rail path rather than trying to drive it. I know John originally started down that path and quickly fell down the world's deepest rabbit hole. But I think the linear rail would solve a lot of issues regarding rigidity and smooth operation while not solving that one issue of liberating every single dollar I've ever made in my life.
