Grizzly makes 3 router tables that I know about you may want to check the manual to see if they show how to mount the router to the table, they may have a tricky way of doing it so you can use standard router bits.
BUT if not see below.
Extension are not cheap. the norm is about 50.oo bucks, but below you will see one at a great price.
Router Collet Extension 1/2" shank at 30.oo bucks http://www.sommerfeldtools.com/closeouts.asp
Plus this link below http://www.mikestools.com/productinf...001.00&affid=6
at 23.oo bucks
this one is 25.oo bucks with free shipping http://www.mlcswoodworking.com/order...outcollet.html
The MLCS Router Collet Extension
NEW! Extension for 1/4" bits works with 1/2" collet routers! Give your router bits an additional 2-1/4" (or 2" for #9468) when you extend them through the router table top with our router collet extension.
Eliminate the dangerous temptation of withdrawing the shank from the collet in order to raise the bit and to “provide the full depth of cut.” The router collet extension makes it possible to use all diameters of 1/2" and 1/4" shank bits safely. Place the router collet extension shank in the 1/2" router collet and the router bit shank in the extension collet and tighten both.
Use with 1/2" collet routers only. FREE INSTRUCTIONS available for the Router Collet Extension. http://www.mlcswoodworking.com/order.../instruct.html
Fine Woodworking featured the MLCS Router Collet Extension in the Tools & Materials section of issue #159 from December 2002.
Here are some quotes from the article:
“Collet Stretcher. The router collet extension from MLCS adds about 2-1/4” to the length of a router collet, a handy feature in the router table for above-the-table bit changes."
"When a router is mounted in a table, the collet of the router often ends up positioned well below the surface of the table, even after the motor has been raised to its maximum height. That means some bits are not able to reach far enough above the table to provide the full depth of cut.
Recently, MLCS began selling a router-collet extension that quickly remedies the problem. Also, as I quickly discovered, the extension makes bit changing a lot easier because the extension, which adds 2-1/4" in length, allows the collet to be raised well above the table. With the collet exposed it becomes relatively easy to work a pair of wrenches and change a bit."
“If you use a router table a lot and regularly struggle to install bits, the router extender might be worth a closer look."
From Wood Magazine's Shop Proven Products section in the March 2003 issue:
"Bit won't go high enough? Extend it.
Sometimes, especially with my table mounted plunge router, the combination of the router's limited plunge depth, the table insert's thickness, and a short shanked router bit cause me to tempt fate by pulling the bit farther out of the collet than I like, creating a safety hazard.
It is for such situations that MLCS sells the Router Collet Extension...
...it installs just like a router bit. Once it's mounted, you insert your bit into the collet, tighten it as you normally would (you'll need a 1-1/16" open or adjustable end wrench), and begin routing.
I measured .006" of runout (wobble), but detected no increase in vibration or chatter when routing red oak (the router itself contributed less than .001" of runout). As a bonus, with the Router Collet Extension installed,
I found it was easy to change bits from above the table.
A few words of caution: extending your router's collet puts extra stress on the tool and its bearings, so take multiple passes on stock, especially with large diameter bits (MLCS recommends using bits no larger than 3-1/2"). "