MIMF

Yes, you have to cut the slot in the sled.

Do you have blade stabilizers for your slotting blade? Otherwise square to the arbor of the motor is square to the arbor of the motor.

I didn't make myself clear...too many thoughts at once. so the slot in the sled will have to be cut with a wide blade to allow the slotting blade with stiffeners to rise through to the extent that a fret slot will be cut. so it's not a zero clearance set up.

I guess i'm worried about chip out...with ebony say..will that be an issue?

and ..after squarting everything up with the wide blade to make the cut in the sled...after fixing the fence.. i wouldn't want changing the blade to alter thes et up.

I'm sorry I was so un clear, but I have no experience iwth the process and am at the stage now where I will fix the fence after a squaring routine.

If it's that close you could always dado the bottom of the sled to clear the stabilizers and then cut a zero clearance slot for just the cutting section. I like to build my sleds with 1/2 bottoms, so that means the blade is a quarter inch less high than a 3/4 bottom, might be enough to forgo a dado? (I don't know, I'm having a custom blade made by grinding just the toothed section of a normal thickness, carbide blade down for my fret slotting setup, so haven't seen the stabilizer setup firsthand).

Chip-out has never been an issue for me with the Stewmac blade. I keep mine clean and I sharpen it and set the teeth every year or so as needed. Soap and hot water do wonders to soak the accretions off it.

I appreciate all the tips.

By my calculations I have an error of 0.0019" per inch of cut out of square. Over a fretboard width that would be < 0.0038" (0.0965mm).
Can anyone tell me if that's in the ball park and if not what is?

Also if the fret slots are going to be parallel wouldn't one scribe the centreline after all the slots are cut and then end up square anyway?

sorry i think that's 0.0019"

So I went and checked on that carbide fret slotting blade the other day, I'd talked a few times with my saw guy about it, and he finally gave me a price. $400. So looks like I won't be getting that carbide fret slotting blade after all!

HSS (high speed steel) is a great saw blade material.

I doubt very much if the SM blades are anything but high carbon, perhaps with a little Cr in the mix. The one I have certainly isn't hardened as I can sharpen it quite handily with a 3 corner file. If I get 40-50 fingerboards per 10 minutes of sharpening that seems good enough.

McMaster - Carr has a HSS 6" metal slitting blade with a 1/2" hole and .025" width for about $60. You need 5" stabilizers to keep it from flexing as it's only .025" thick. I have been using one for a while and it works fine as long as you don't force it.

You know, a lot of folks are using the StewMac and LMII blades quite successfully.

Yeah I don't have a problem with HSS, I'd just been talking to my saw guy for awhile about it and he's been saying he could do it for a decent price. Dunno, maybe he was in a bad mood that day or maybe the actual thickness I've told him I needed didn't click before. My main reason for looking for one is I don't have any experience sharpening blades or setting teeth. I know I can have it sharpened but I've read a lot of people talking about resetting their teeth to get the proper kerf width. I guess I'll just have to add that to the old bag of tricks!

Sharpening and setting teeth is not exactly rocket science. If you can hold a file I think you can handle it. Setting is totally unnecessary unless you are using very hard fingerboards like phenolic and African blackwood.
Understanding that the solid carbide saw blanks are incredibly expensive and the fact that they can only be ground efficiently with diamond grinding wheels should help you see why the cost is so high. You would probably do better buying an off the shelf blade from a place like this:
http://www.malcosaw.com/ecom/category/18/
There are many other places that sell solid carbide blades. Just know that not all carbide is created equal. Some of it is junk and some of it is really good but it has to be formulated for what you are trying to cut as I'm sure you know.
http://robbjack.com/search?Search-Type= ... %5D=coarse
It looks like 4" dia is about the maximum you'll find out there in that thickness and the 1" arbor is your only choice.

Don't think I'm going to try and reinvent the wheel here, I'll just pick up the stewmac blade and call it a day. Sorry to hijack the thread!