Why is it not possible to make a chanter with a tuning slide like we see on traditional flutes? It would make it easier for pipes to be in tune - no more tweeking the reed.
Who said it’s not possible??
There are several makers who insert a brass sleeve into the chanter so you can slide your reed for tuning.
Pipemaker Andreas Rogge is famous for his many different inventions for doing this type of thing, including an external slide connected to the reed staple on the inside for moving the reed in and out. The problem with a slide is that you are changing the length of the whole chanter in relation to the reed, but most directly affecting the notes closest to the reed. Micro-adjustments can be made, but because you are affecting the whole chanter, you put some notes out of tune at the same time you bring others into tune. That led Rogge to design hex bolts into the side of the chanter so you could tweak each note. Brian Howard has designed an iris that can be opened/closed to fix the bottom D.
Different pipemakers each have their own ideas about these kinds of fixes. You could easily start a war about whose ideas are right, and whose chanters wouldn’t need such fixes if they had a better reed/chanter design. There’s too much black magic associated with chanter design to get an accurate answer.
djm
Maybe you could put the flute-like tuning slide under the reed seat, about and inch or so above the back D. I know the internal bore is tapered but if it had to be straight for 3 or 4mm that could be enough scope for tuning.
Just a thought,
Tommy
The chanter doesn’t need any device for re-tuning because fiddles have pegs, and fine-tuners, and flutes have tuning slides.
But what to do if you play with a concertina? 
Tim Britton puts tuning slides in his chanters I think, in the reed seat.
DG
Peter Laban wrote
But what to do if you play with a concertina?
Maybe you would squeeze it in or squeeze it out 
Rogge chanter
concertinas have multiple flat sides at odd angles like the stealth bomber, so when you hurl it out the window, the boxplayer cannot use radar to quickly locate it again
I have fitted a slide very similar to the Rogge chanter to mine and a couple of other peoples chanters. It’s completely reversible, so if you don’t like it you can swap back. If anyone is interested I can describe how I did it in detail.
Although there is no denying that the reed has an optimum position set into the chanter, sometimes (when in a session or band situation) it can be very useful to be able to quickly and conveniently nudge the pitch of your chanter up or down a small amount.
David
David,
I quite agree. It has all the effect of adding and removing hemp without the hassle or risk of damage after 3 pints or a clumsy neighbour etc.,… I recommend it. If anyone is going to do this, make sure the sleeve is wide enough to accomodate a couple of layers of waxed hemp to allow a good seal/different o.d. staples.
Alan