I've seen these flex curve templates before. Never used one, but it seems like it would work here. Just a bendable piece you screw onto wood and use it as a router template. If you want your template to be symmetrical, you could use one of these to make the curve on a piece of scrap, and then use the scrap as a template on each side of this template. You can probably find a cheaper one that this with some searching.
Oh man! This is so me and my problem. I haven’t ordered it yet, but wouldn’t an edge guide work for getting these inside cuts?
I believe that’s the correct answer, here is another similar one so you can see it from different angles
https://www.amazon.com/Bosch-Deluxe-Extraction-Adapter-RA1054/dp/B00005RHPP/
Maybe there is missing part for the edge?
So, I have this thing
I have the same router and mounted it to a table using the Kreg plate and levelers - Kreg Tool Precision Router Table Insert Plate w/Level-Loc Rings predrilled for Bosch & Porter Cable Routers (PRS4036) https://www.amazon.com/dp/B01M2X1447/ref=cm_sw_r_cp_api_glt_i_RXJKVEVFM6RW9NYM3841?_encoding=UTF8&psc=1 and Kreg PRS3040 Precision Router Table Insert Plate Levelers, Medium https://www.amazon.com/dp/B000VRML54/ref=cm_sw_r_cp_api_glt_i_S2SHS4AR13A3SBB1P0TH?_encoding=UTF8&psc=1. A lift would have been nice but personally couldn’t justify the expense for that yet since I dont use the router too often
Well you know what to get him for his birthday
They go in the plate of your router and allow you to use any router bit you choose. You have to account for the bushing diameter but that's easy once you get used to it.
Get a circle cutting jig and use routet (example: https://www.amazon.com/Milescraft-1219-Circleguidekit/dp/B07VNGTGMV) . You will get much better result and it will be much faster.
The edge guide is a great addition for this item.
https://www.amazon.com/gp/product/B00002242B reviews are spot on, the installation is kinda "figure it out" but it's been nice to use. The center rings were very tight and hard to remove/insert but sanded down ok to fix that.
If you’re wondering how you’re going to get the curve on your template to be smooth...consider this: CMT TMP-1200 Flexible Template for Curved and Arched Routing, 15/32 X 15/32-Inch https://www.amazon.com/dp/B008AXXH54/ref=cm_sw_r_cp_api_glc_fabc_48d2Fb43RP3HG?_encoding=UTF8&psc=1
I second investing in a circle cutting jig. I tried the template approach on a few projects and while a big improvement over freehand (wasn't nearly as successful as you were OP BTW), the template still resulted in a pretty wonky circle cut, because I of course free hand cut the circle template too. I just invested in the Milescraft Circle Jig and have loved it. Just built my first cutting board / serving platter which I wanted to be a circular and the jig was phenomenal.
Using the circles as their own patterns seems like a good idea, but it wouldn't work exactly: you can't just offset the circle and use a pattern bit, because the resulting cut circle will have a different center and a radius increased/decreased by the diameter of the bit.
You can cut patterns with the right radii, or use the circle jig directly, with no pattern, if you can find the relative position of the two centers.
Also, that bit looks too long for this. If you end up using a pattern, you can use a bushing to follow the pattern with a spiral bit and cut exactly however deep you need.
That is rad. Might have just made my track saw decision for me too. Here is a link for the kit on Amazon. Thanks for this OP!
https://www.amazon.com/dp/B004Z55E9I/ref=cm_sw_r_em_apa_i_Zq1vEbYBQJXZD
If you have a regular router, a flush trim bit would be the solution here. Attach the aluminum plate to a piece of mdf, and trim the mdf down so it's the exact shape of the plate (this first step is somewhat optional, but you don't have a lot of height to work with so it will make the rest easier). Set your template on another piece of mdf, and use a fairly thin bit (like a 1/4") and a template guide (this is what I have - https://smile.amazon.com/gp/product/B01IMORJHM/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1).
You follow the top piece of mdf EXACTLY, keep the bushing against the top template the entire time. Once you do this, the cutout on the lower sheet will give you the exact shape you need (using the same bit and bushing). You can set that template on whatever and just get your depth right and it will fit spot on.
This plate looks very similar and is the first result for router table plate on Amazon.
Just got this finished up last night - looking forward to my next project where I'll need it!
I picked up a rock-solid custom router table off of CL back in December that looked similar to Norm Abram's Ultimate Router Table design. The door was off and missing a hinge, a drawer was missing, and even though it looked to have been pre-routed for a plate, the router plate insert was missing.
After taking some careful measurements and looking around, I purchased this router base insert, which looked to be the exact fit for the original routing. Using a drill press I picked up for free off of Next Door, I carefully drilled the holes in the plate, installed the undertable router base for my router (The Bosch one everyone recommends), and got it all working.
Router tables may not seem sexy or cool, but I am so beyond happy I got this set up!
I'm not sure if it's the same as what you linked, but I have the dust collection attachment that came with the edge guide. It attaches either to the edge guide or to the plunge base in place of the plastic shield. I haven't actually used it so I can't comment about whether it's effective.
look for the bosch edge guide. That's been a champ.
don't try to get it to work with a Craftsman router table. You'll just be disappointed.
edit for link