making "complex" mouldings

I am making the baseboard mouldings for my new home and am getting "rough" results from my router. I hope somebody out there can tell me what is wrong with my technique.
The current rooms I am working on are to be painted so I am using poplar. The moulding starts with a 1x4 at the bottom. On top of the I want a decorative moulding. I have picked a Bosch edge moulding that has a 1 5/8 inch long cutter. The wood piece is 1/2 inch thick by 1 3/4 inches high ( the extra height is to reach the bearing, and will be cut off later). I have built an inverted U shaped jig that is about 3 feet long and is attached to my router table. It centered with about 1 1/2 feet on each side of the bit. For routing I slide the wood through the inverted U where it passes over the bit (vertical).
The bit is new, and sharp. The router is a PC 7519 running at full speed.
The bit sounds like it is chewing off chips instead of making a clean cut. The resulting moulding is rough and when held up to an oblique light appears to have divots in it. They can be sanded out, but due to the complex shape I would need to fit a lot of different curves along the length of each board.
I tried using two passes per board - the first wihere the board does not quite touch the bearing and the second at full depth with contact to the bearing. The results were the same for each case.
Am I expecting too much from the bit - I expected a smooth cut in poplar. If so, do I just bite the bullet and make a Bondo mold to do the trim. Is there something I can do to my technique to make the thing work for me. I need to make well over 1000 feet of this stuff.
Thanks, Len
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snipped-for-privacy@uiuc.edu wrote:

Bag the jig and use featherboards to hold the stock against the cutterhead.
Make a few passes, raising the bit/moving the fence each time rather than taking it all in one swipe
Orient the grain properly so you can avoid tearout.
Or
Buy a shaper
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snipped-for-privacy@uiuc.edu wrote: ...

Good idea for the jig, but does it hold the work firmly in contact w/ the bearing surface at the point of the cut? If not, perhaps the problem is that the work "jumps" slightly as it passes by. W/ poplar and a truly sharp bit you should indeed, be able to get a nice finish. Also, if you slow the feed rate down, does the quality of cut improve? If not, that again makes me think of not holding the work firmly against the bearing. Is the piece of material you're putting the profile on thick enough to be essentially rigid? If not, the importance and difficulty in solving the above problem is increased. For hand-fed routing or shaping, I like to make a "hidden" cut where I can use force directly over the cutting point if at all possible.
Other thoughts include the smaller the cutting diameter, the slower the feed needs to be so the circular cutting path isn't visible. For this much material, you might want to consider the investment in a power feeder that can help.
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wrote:

That sounds like a lot of bit for that particular router. You said you tried 2 passes but you might try 4 passes. I would do that buy just raising the bit a little more each time and always run against the bearing and fence. Also check your grain orientation. Poplar should be easy enough to run but running against the grain can cause problems even with softer woods. You might also make your last pass just taking a small amount to clean things up. Before that pass check to be sure you don't have any burrs that might run between the wood and the bearing.
Mike O.
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Get your setting correct on the bit and fence...
Stack up a series of plates made out of hardboard that cover the router top. Use several...maybe 4-5.
Make a pass..remove a plate Make a pass..remove a plate
This will allow the cutter to remove a little a time and not chip out.
This also keeps you from moving the fence or bit after initial setup.
A 7518 is powerful router but it is not a shaper...
snipped-for-privacy@uiuc.edu wrote:

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The bit is recutting it's own chips. Use a vacuum the get them out of there.
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