I'm wondering if anyone can help me? I recently tried to use a
dovetail jig and found that my dovetail joints were consistently
sloppy on one side of the pin by about 1/16". Everything else fit
snuggly when viewed from the side but at the top of each pin there was
this 1/16" gap. (and, yes, I tried extending the bit a little but the
joint was still sloppy)
After checking everything out, I've concluded that because the bit is
off-center in the guide bushing, the bit is allowed to travel a little
deeper on one side of the cut. Looking at the bit in the bushing, it
is obvious that this is where my slop is coming in.
I removed the bushing and checked the distance from the bit to the
edge of the baseplate and then checked the opposite side. There is a
1/16" difference. I tried removing all the screws and rotating the
baseplate clockwise a couple of times, but the results are still
pretty much the same. (oh, sorry, didn't mention that I am using a
Porter-Cable 690 series router with the stock baseplate) I also tried
using a baseplate from my plunge router base. Almost the same
results. I would have thought that PC would have better tolerances
than that. Anyway, can you think of any way to correct this problem
so that I can use my dovetail jig?
Could I use a bearing in lieu of the guide bushing? My jig requires a
7/16" O.D. bushing so if a bearing is a possibility, do they come in
that size? What would hold the bearing on the shaft?
I'm a newbie to woodworking and not at all comfortable with the idea
of trying to make a new baseplate at this point. I'd just be happy to
be able to use my jig to make the drawers for the router table I'm
building. I know a little further on in the process I'll be pretty
much forced to make a baseplate for the table, but I'm just working on
little steps at a time. :)
Are you rotating the router when you use it? Try to keep the orientation the
same at all times. It's a good idea to mark one side of the baseplate with a
marking pen and always keep the mark facing you. Also, you will want to
remove the three baseplate screws and try rotating the baseplate over one
set of holes at a time until you find the holes that get the bit closer to
You rarely find a 690 that is dead-on concentric, but if you get it close,
and always orient the router the same way, you should be able to get better
cuts than you are getting on your jig.
Tried that with very little change in the results.
This advice will work well in general but when using a guide bushing
it doesn't help that much because when you are routing down a 1/2"
pair of dovetail fingers on a template, you can't really keep the same
edge against the pattern.
Thanks for your reply,
Swingman wrote, wondering if this is really what he meant?
You'd think that one of the top of the line routers, (Porta Cable) could get
a measurement right! Sure doesnt say much about Porta Cable when it comes
to getting their baseplates in line. Makes me a little leary about my next
You can lead them to LINUX
but you can't make them THINK.
Most of us have been confronted by your problem, I'm sure. In my case, I
did some modification of the holes in the plastic baseplate. Doesn't take
much (1/32) to compensate. Makes it necessary to check concentricity every
time thereafter, but you've seen that the results will justify the effort.
The counterbores are usually enough oversize; a bit of scraping might be
necessary if they're not.
I did everything mentioned in this string. I ended up purchasing a DW 610
for my dovetail work. It solved all my problems. :-)
I only use my 690 in a router table these days, along with a foot switch for
Some information on the collar/cutter centricity issue at the
http://www.patwarner.com/collarguide.html link. A very common problem.
Suspect your error is more like a 1/32nd x 2. As bad as it may seem,
doing a 180 with the router when the work is indexed on the right side
of the jig may cancel all of the error. Try sample on scrap.
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