Lee

I wanted to route a 10 inch square to a depth of 1/4 inch on a workbench. Having never done anything like that I had some problems. I ended up using a lexan plate mounted to my Bosch plunge router which was not ideal. My first problem was that the plate was not large enough to have all four sides remain on the top ( non routed) surface - one corner would be unsupported as I moved the router to the opposite edge resuting in some "divots" in the bottom. The second problem was the lexan tended to sag when the router was in the middle of the square resulting in a cut deeper in the middle than the sides.
I got the job done but wondered how the "pros" would do it so the bottom would be glass smooth and even.
Is there a better way to do this other than buy a big expensive piece of lexan?
Thanks!
Lee

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bmb in ab

I would suggest starting in the middle and working in a circular motion toward the perimiter. This should maximize the available support for the router.

reible

A couple of thoughts for you...



Rather then lexan an acrylic sheet of let’s say 3/8" thick is very stiff and cheaper in general then lexan. (Of course if you drop it does not act like lexan.) I have a post that you might find interesting so check out:
www.routerforums.com/showthread.php?t=395


(I use it to do some lettering where the letters are left and the other area is in relief.)


You didn’t say how you controlled the cutting process, template guides or ????? but making a pass around the outside first then as another answered starting at the middle and working out is a good idea.

The third part of this is the bit you are using. It should be one that has a bottom cutting edge, a plunge type bit will work better then a plain straight bit.


Ed

reible

Thought of a couple of other hints:

Stop and clean out the chips often and if you're using a plunge router do the plunge near the edge where more of the router is supported.

Ed

template tom

Make yourself a template which will be greater than the square size required (This will depend on what template guide and cutter you have available) Insert two rods through the base of the router where the side fence is usually attached. Approx 2-3 feet long then insert two supports either side to keep your router level and of you go
Tom

Lee

Thanks for all the good ideas.
This was my methodolgy (for good or bad): 1. used 1/4 " upcut spiral bit to define the edges of the square in two passes of 1/8" each. That worked great. Used a straight edge as a guide. 2. Switched to a 1/2" straight bit to remove the remaining center in 1/8" increments (two passes).
Comments or questions:
bmb: Wouldn't I quickly end up with only 1/2 the base supporting the router as I moved out from the center? A tough balancing job with my Bosch plunge router.
tom: I'm with you on the long rods through the edge guide holes (clever) but you lost me when you talk about two other supports. Please explain.
reible: Thanks for the info on acrylic. Also read your referenced post. Got to hunt around for one of those base making kits. I did think about using 1/2 ply for a base but I would have to make a lot of holes in it to see and I was afraid the rigidity would suffer.

I thought it wise to only take 1/8" passes but maybe I made my problem much worse having 3 depths (surface, 1/8", and 1/4") to contend with. Should I have done 1/4" in a single pass?
Thanks again, Lee

reible

OK, first I would make the outside pass in maybe two steps the first being deeper then the second. I would make sure the cutter has a cutting edge on the bottom. Otherwise a std straight bit has only a cutter on the edges and will leave swirrely (sp?) marks. I would then go to the center of the square or about so and make plunge to the full depth. From this I would work out towards the edges in a spiral pattern with the bit at full depth and take off just a small amount of the edges as you go. You want to go so the bit cuts into the wood and does not get pulled along. As you get closer to the outside make sure you keep the pressure on the supported side.

This is a lot like when I do free hand signs except the letters are always left to add support. The larger sub base I made allows the smaller lighter trim router to work very well for me.

If you have a "dish cutter" they do a really nice job. They might have another name but it has a flat bottom and a radius on the edges so they don't dig in.

Ed

reible

Tom have you tried this and if so what dia of rod does your router use?

I had a simular idea maybe 10 years ago with a Sear router and crs but the rods turned to to move all over the place. I then threaded the ends and tried to pull them tight in the box I had made. This worked better but I gave up on the idea. The Porter Cable routers I now have use a much thicker rod so maybe I should revisit this next spring when my workshop opens again.

If you have a working model could you post a picture?

Ed

Mike

Lee, if you need a larger base plate for a special job try making it out of 1/4" Masonite. This is far cheaper than either of the plastics. Just cut your inside clearance hole so its within your mounting screws and you will have plenty of view to see your edges. This is only a guess but perhaps you are making a tile inlay table?

Mike

reible

This is off topic but after reading Tom idea I posted but I'm not sure it is clear what I was talking about so I did a couple of sketches. Please keep in mind this was what I tried to do but it DID NOT work well. DO NOT make one of these based on what I did but you are welcome to resolve the problems and do as you like....... BTW this was done some years ago so the details may not be as shown......

Ed

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