Reed Slot Cutter?

[Steve Schulteis]

Anyone have a good source of router bits for cutting reed slots? I've experimented with a common 1/4" dovetail bit, but the tips of my reeds are 5.7mm (i.e. less than 1/4"), so the reeds end up getting pinched along the vent, potentially causing issues. I've found 3/16" mill bits and a router collet that should fit them, but I'm unsure about whether they're safe to run at my router's minimum speed (8000 rpm). I suppose I could stick with the 1/4" bit, route each slot oversized, and glue in a shim along one edge, but I'd like to avoid that if I can.

 

I'm not overly concerned about shaft length or diameter. I'm planning to glue the chamber walls in place after routing the reed slots, so I won't need to avoid them during that step. (Feel free to inform me if that's a bad idea.)

[Steve Schulteis]

I looked again and realized the page for the 3/16" bit I mentioned has a link to speeds and feeds, which specifies SFM values that translate to the full range of my router's speeds. So I guess that should work. I'm still curious if anyone else has found better/cheaper solutions that don't involve a proper mill.

[Chris Ghent]

Not quite sure what you mean about your reeds pinching if the cutter is wider than the reed tip width, but one issue if you are using old reeds is the cutter you link to is 10°. You could get a 1/4” dovetailing bit at 7.5° ( such as this one, look at the table at the bottom, its the first listed https://www.timbecon.com.au/torquata-dovetail-jointing-router-bit) which would be a better side angle, and shorten the end of the carbide inserts, leaving the cutter with a smaller diameter. You would need a cutter grinder to do this well but there are people who do this as a service. They would also make you one from scratch.

Edited November 22, 2021 by Chris Ghent

[alex_holden]

I wouldn't worry about 8000 RPM with a small diameter solid carbide bit - they can probably cope with tens of thousands. There's a potential issue with it overheating and burning the wood if you don't use a high enough feed rate for the spindle speed (because it's rubbing rather than cutting), but it may not matter if the cutter is sharp enough. Presumably the collet is rated appropriately for the router it's meant to go in.

 

The only problem with gluing the wall in after you cut the slot is that the slot can't undercut the wall, which means the chamber has to be wider than it would be otherwise, so you can't fit as many chambers into the pan, and higher pitched reeds respond better if the chamber volume is as small as possible.

 

I made my own custom shaped dovetail cutter from silver steel (drill rod), which has its pros and cons. It took three attempts before I made one I was really happy with. The reason it's so long is so it can reach down into a deep bass chamber after the walls are in place. I'm convinced Wheatstone must have used a cutter with a similar shape, having examined some of their reed pans.

 

 

 

[Steve Schulteis]

9 hours ago, Chris Ghent said:

Not quite sure what you mean about your reeds pinching if the cutter is wider than the reed tip width

 

When I cut a test slot, I cut most of it the correct width, but the slot at the tip of the reed is too wide, so the tip of the reed frame doesn't contact the slot on one side. The first point of contact on that side is along the vent, so the frame can flex slightly and interfere with the tongue. I did encounter some reed buzzing as a result.

 

9 hours ago, Chris Ghent said:

one issue if you are using old reeds is the cutter you link to is 10°.

 

I'm using new reeds, but your point remains valid. I'm operating on the assumption that as long as the angle isn't too sharp, there only needs to be contact between the reed and the slot at the top edge. I believe Alex Holden described doing this intentionally at one point.

 

9 hours ago, Chris Ghent said:

They would also make you one from scratch.

 

Thanks, I'll look into custom cutters.

 

6 hours ago, alex_holden said:

I wouldn't worry about 8000 RPM with a small diameter solid carbide bit - they can probably cope with tens of thousands.

 

Thanks. I haven't done any real machining since I was a teenager, and I obviously don't have great intuition about that sort of thing. I encountered one bit that stated a max speed of less than 1000 RPM, which was what got me thinking about that in the first place. They probably assumed you were cutting a specific material.

 

6 hours ago, alex_holden said:

The only problem with gluing the wall in after you cut the slot is that the slot can't undercut the wall, which means the chamber has to be wider than it would be otherwise, so you can't fit as many chambers into the pan, and higher pitched reeds respond better if the chamber volume is as small as possible.

 

I'm planning to glue the walls to the surface of the reed pan rather than routing channels to fit them into. It's a weaker join, but I don't see why it would be subject to stresses that would cause it to fail. I'm also not doing this in a production situation, so making templates to route those channels wouldn't save me any time. As long as I cut the reed slots just barely deeper than the frames' thickness, I should be able to glue a wall right over the edge of a reed slot, as long as I mind the excess glue.

[alex_holden]

11 minutes ago, Steve Schulteis said:

I'm planning to glue the walls to the surface of the reed pan rather than routing channels to fit them into. It's a weaker join, but I don't see why it would be subject to stresses that would cause it to fail. I'm also not doing this in a production situation, so making templates to route those channels wouldn't save me any time. As long as I cut the reed slots just barely deeper than the frames' thickness, I should be able to glue a wall right over the edge of a reed slot, as long as I mind the excess glue.

 

I see; I guess that should work. Let us know how it turns out.

[Don Taylor]

I find this topic interesting as I have always wondered how the reed pans are created and I might have a need to replace one myself this winter.

 

Do you rout the reed slots out by eye, or do you make up a set templates for the router bit to follow?

 

Don.

[Steve Schulteis]

7 minutes ago, Don Taylor said:

I find this topic interesting as I have always wondered how the reed pans are created and I might have a need to replace one myself this winter.

 

Do you rout the reed slots out by eye, or do you make up a set templates for the router bit to follow?

 

Don.

 

Maybe some exceptional individual out there has a steady enough hand to do it without a guide, but I sure don't. Here's a picture of the jig I'm using. Somewhere there's a video from one of the old factories that shows a more sophisticated version of the same concept.