Hi Tom - "not made to be centered" Sounds like B*S** to me.
I haven't got the PC but if I remember my friends, the bushing relief is molded into the base. I assume you tried loosening the sub base and and adjusting it. If you can't get it that way, try removing the subbase screws and rotating the subbase around. .020 is a long way off. I'm pretty sure the 690 uses the same base as my friends and I haven't had any problem using bushings on his router.
Is this the first time you have used bushings with it?

If you can't get any satisfaction from Porter Cable, you may want to look at this guy:
Amazon.com: Milescraft 1201 Base Plate / Bushing Set for Routers: Home Improvement
Fits right on your router, centers up nicely and you don't need to fool with the lock nuts.

 

Router base

i have the Milescraft 1207 Router Design Inlay Kit My 690 is right on with the centering pin that come's with this The base is the same So may be worth getting It will fit lot's of routers It may be of plastic Or some hard stuff I don't belive you will ever have any problum I use the Milescraft 1207 Router Design Inlay Kit Every day and it is still like new A easy way out I have the plung base and it is right on If you bought it from a box store take it back and get another unit Of course the plung base is sold seperate I have 2 set up One is new in the box Just don't need it Have a life time of routers and base's good luck

Amazon.com: Milescraft 1207 Router Design Inlay Kit: Home Improvement

Amazon.com: Milescraft 1201 Base Plate / Bushing Set for Routers: Home Improvement

 

Hi Tom,
John is right. What the guy from PC told you is B***S***! I have the 6931 base and I use it with both my PC 690 and my PC 9290 battery operated router. You must use a centering kit and it will allow you to use the baseplate that came with your router.
You loosen the screws on the base plate, install the centering kit, tighten the centering pin(by hand), lower the base so that the pin is captured in the bushing and then tighten the baseplate screws and the base will be centered.
Baseplate centering kit link:
Buy Base Plate Centering Kit 2 at Woodcraft.com

Jack

 

Thanks guys. I thought what the guy told me was a load... and it sounds like that's the consensus.

Will pursue the centering device and will post back when I've resolved this issue. THANKS again.

 

One more with a PC 693 I have never had the fixed base in it and I use guides and the inlay kit often. The PC tech is lying or an idiot.

 

Hi Tom

Sorry to say the guy from PC is right, if you take a hard look at the bases you will see why he said that .the standard base has split in the case and the plunge router base must have the room to get the motor in free and easy and slide by the motor line up pins..
But he didn't go the extra mile and tell you how to fix the problem ..

But the Milescraft base plates takes that error out in a heart beat plus it will let you use 1 3/4" OD bits without taking off the base plate and many of the profile bits are that big..


======

 

Thanks for the additional info. What about a standard ol' plunge router... not the interchangeable base one? Would that be better? I'm using this to make mortises, and need it to be accurate. Being this far out makes it extremely difficult to make a good fit at the accuracy I want.

 

one other thing when putting the motor in the base Don't let go all the way down Bring it un 1/4" so that when you tighten the allen bolt to hold base to the motor If you need to take it out You just losen the allen bolt it will come loose But if it is all the way to the bottom Their is no place for the motor to slide down and loosen You will have to take the bolt out to get to loosen up

 

Scroll Wood's solution is correct up until he said to retighten the baseplate screws. I have the same router and had the same problem. Porter Cable in their infinite wisdom put tapered holes in the baseplate, so guess what? When you retighten them with the factory screws, the baseplate goes right back to being misaligned.

What I did was to take a 5/16 brad point bit and very carefully counterbore the baseplate screw holes. Then go down to your local hardware store and buy panhead (aka binderhead) head screws (they are metric) to replace the tapered screws used by PC. That way when you center the baseplate using the centering tool, it won't shift when you retighten the baseplate.

I used the fastest speed available on my drill press and used a hit and release method so as to not get the phenolic base plate too hot.