Every now and then people get to complaining about things not being quite right and never again will they use anything but the right tool for the job 

Here then is a list of things which work as fret saws and some that don't and the width of the kerf they leave. There is a short bit of fret in the kerf of those that worked.

1. Jack dovetail saw 0.6mm - my regular fret saw - works

2. Record tenon saw 1.0mm does not work

3a Double sided Irwin pull saw crosscut (fine hardened) side 0.8mm -works

3b                Rip (coarse unhardened) side 0.6mm - works - tearout danger

4 Red frame Junior hacksaw 0.6mm works

5 Blue $2 shop hacksaw blade 0.8mm works

6a Legion brand $2 shop hacksaw blade - wavy blade. 1.0mm does not work.

6b        hammered flat 0.7mm works

7 Coping saw fine blade 0.7mm works but blade bends and wobbles so not recommended.

Also in the top photo is a rig to use a hacksaw blade - a pair of bits of pine bolted together - for rigidity  and as depth stop.

The Dovetail saw effectively has a built in depth stop as you stop cutting when you can not see light "under " the blade.

With some of the thicker blades that work I would use a bit more superglue to hold the fret in or just give the saw a light tapping with the hammer or rub with a file to make it thinner.

When I first got that Irwin pull saw I tried it as a fret saw and it didn't work I think it must have worn a little narrower over the years of abuse it has had to put up with.