Questions with inlays using a router

[SDMF1984]

I just started doing some inlay work with a friend of mine. His has the turnlock system that i believe uses a 17mm and a 11.1 mm busing for inlay work. The Turnlock system is okay but I would like to stick with the standard PC bushings and my good old 690. My question is has anyone used the regular PC bushings for this? I will be using a 1/8 inch spiral bit. I may be wrong but would a 5/16 o.d. and a 7/16 o.d. bushing work? It is an 1/8 inch offset. It still sounds a little funny.
I am aware that PC sells an inlay bushing kit http://www.amazon.com/gp/product/B00...lance&n=228013
and that may be a future purchase, but for the time being i can barely afford my lumber so i would like to stick with my standard bushing kit.
For anyone that is interested the turnlock inlay system gives very good results. There are a few tricks though. The base in the spirocrafter kit gives you the necessary room to clamp the template down, my friend got one for free. You also need to check the centering often, because the turnlock system is univerisal there is a lot of slop in the screws. We had to keep checking the center. Other than that it was easy to use and made some clean inlays.
Thanks for any help.

[JimD]

Good choice of router.

I have a set for the PC baseplate that I have never used. Should try it sometime. The diameter with the ring snapped on is 9/16 (.562). The diameter with the ring off was just under 5/16 (.310 versus .3125). I think the 1/4 inch difference is the critical part. Possibly the extra .0025 is to allow the inlay to go in easier?

Jim

[bmyers]

I have not used regular PC bushings, I have the inlay kit from Milescraft and a Freud inlay kit. It won't matter though, you can't change math. It should work just fine though you've selected the wrong size. The only thing the has an effect on the fit is when the guides or router bit are not exactly the demension they say they are. But you are talking about small corrections here, some sanding of the inlay going into the recess maybe.

The Offset Math: subtract bit dia. from the bushings outside dia. and divide by 2.
Take the large dia. bushing, measure to the bit from the outside of the bushing.
Take the small dia. bushing and measure to the other side of the bit tip.

1/8 " bit = 9/16" big bushing. 5/16" small bushing = 5/32" offset
or
1/8 " bit = 11/16 big bushing, 3/16 small bushing = 9/32 " offset

1/4 " bit = 7/8 big bushing, 3/8 small bushing. 5/16" offsest

Big bushing routes the recess. Small bushing routes the inlay.


Remember that with setup like that, the small bushing dictates your tighest corner you can route, that is, with a 5/16 bushing you can't router a corner smaller than 5/16 so adjust accordingly in your template.

If you do have the Milescraft inlay kit, try getting a Spirocrafter and use it with your inlay kit to make concentric inlays like the ones attached.

In general, use the largest diameter bit/bushing that you can. The small bits break more and are costly to replace. If the inlay doesn't have a corner tighter than your small bushing then you can use it. If not you have to go 1/8" bits. Routing 1/2 way down into a recess and then full depth helps bits last a little longer but is a slow process.

The flower pattern was done by doing the inlay of ever other leaf and then going back over it doing ever other leaf again, offset from the first, removing a portion of the first inlay set.

Bill