Modifying a vintage Craftsman insert plate to accept modern insert rings
I’ve needed a Router Table (RT) only a few times in my life, so I have relatively little experience using them. I recently purchased a 189-year old house, which I’m now remodeling, and I’d like to re-use some of its more-than-a-century-and-a-half-old quarter-sawn and rift-sawn Southern Yellow Pine tongue-and-groove flooring. In some cases, this will require trimming-down some relatively wide planks--5 ¼” wide—to smaller widths—3 1/4” wide and 2 ¼” wide--which, in turn, will require cutting new tongues or new grooves in the trimmed-down pieces, hence my current need for an RT.
My son is giving me his 1995-vintage, homeowner-quality, Craftsman 171.25490 RT for this purpose. Unfortunately, the insert rings--which were of the plastic, snap-in type--got lost at some point during my son’s ownership. The manufacturer of the RT, Vermont American (VA), tells me it no longer makes the insert rings, so I’m considering the feasibility of using insert rings from some other manufacturer.
My Craftsman/VA insert plate is made of steel and is 9/64” thick x 7-11/32” wide x 7-11/32” long. (Yes, it’s square...made of steel...and much thinner than modern insert plates. Arrgh!) Its existing center hole is 2 1/8” in diameter plus a 9/64” wide rabbet that’s 1/16” deep. My impression that the center hole in most modern insert plates--and therefore the diameter of most modern insert rings--is somewhat larger than what I currently have. On the other hand, it seems technically feasible to me—although the cost is currently unknown--to make the center hole in my existing insert plate as large as necessary to accommodate some manufacturer’s modern insert rings. So my first question for the forum is, “What brand insert rings would experienced forum contributors recommend, if it proves to be cost-effective to enlarge the insert plate’s center hole to accommodate such insert rings?”
“The devil is in the details,” as they say, so here are some of the be-deviling details:
Having a steel insert plate suggests that I’ll have to go to a local machine shop to get the plate modified, which, in turn, suggests a significant--possibly deal-breaking--cost. On the other hand, I won’t know whether the cost to modify the plate is a deal-breaker until I know what I want to ask the machine shop to do, hence my question about the preferred brand of insert ring. My plan is to buy a set of the preferred-brand insert rings then bring one of the rings with me when I go to the machine shop so the machinist will know exactly what my end goal is.
In case you're wondering why I don't simply drop-in a modern insert plate:
While my steel plate, and hence the rabbet in the cast aluminum table top, is only 9/64” thick/deep, I gather from reading the forum that most modern insert plates, whether aluminum or phenolic, are ¼” or 3/8” thick, suggesting that I can’t simply buy a modern, off-the-shelf, insert plate, cut it down to the width and length of my existing steel plate, then drop it into the 9/64” rabbet in my aluminum top, as the new plate would protrude at least several 64ths of an inch above the surface of my existing top. Note, too, that it's infeasible to increase the depth of the rabbet in my cast aluminum table top to 1/4" or more, as doing so would require removing at least 7/64" of aluminum from four insert plate support flanges that are currently only 10/64" thick: The remaining 3/64" thick flanges would be too thin to support the weight of a modern insert plate plus the router that would be attached to it.
So, if I want to continue using the RT for its intended purpose, I think my best option is to consider enlarging the hole in my existing insert plate to accommodate modern insert rings.
My impression is that, to accommodate modern insert rings, I’ll have to “laminate” something to the bottom of my existing insert plate to bring the thickness around the center hole to whatever the new insert rings require—1/4” or 3/8”--but I don’t see that as a show-stopper, just a necessary additional step to be aware of.
From previous posts, my impression was that it would be desirable to use insert rings compatible with Porter Cable (PC)-style guide bushings, so I gave my local PC dealer a call to see if he had such an insert ring in stock, or could get one. He didn’t have one in stock, but said he could order one and it would cost me a quite reasonable $5.99. On the other hand, as he looked to see what PC had available, he mentioned that PC was no longer making RT’s and an older version of PC’s insert ring had already been discontinued, so he wasn’t sure how much longer PC would be making the new version of its insert ring and, by extension, how long PC would be making the guide bushings to go with it. Given that, at this point, I can choose whichever insert ring manufacturer I want, do forum contributors believe I should invest in modifying my existing insert plate to accommodate PC-style insert rings…or is there a smarter move for the long haul?
If you made it this far in my long post, thanks for taking the time to read it…and I look forward to receiving your reply!