Hi
I’ve managed to get a variable font working with 3 axis before but having applied the same set-up to a new font it keeps telling me on export that the “‘a’ is incompatible”. Have checked in the fix compatibility tab and all seems ok. Any common problems or issues I should look out for?
Thanks a lot!
Tom
Make sure your anchors match and that there are no stray points hiding in your outlines.
Have you read the Multiple Master tutorials? https://glyphsapp.com/tutorials/multiple-masters-part-2-keeping-your-outlines-compatible
Have made sure of this but still no blue lines connecting the instances 
Yes have been through but and it should be working but I havn’t even got the blue node lines. Is there anywhere i can send a screen or file. Confused why this doesn’t work but others do.
You need at least on interpolating instance or add the “Force compatibility” custom parameter to the font.
I have ‘enforce compatibility check’ in use but can see the ‘force compatibility’. I also a have the font interpolating fine with 2 axis (width/height) but when i add the third (weight) they all break.
Thanks for the help guys 
I’ve managed to get it working with 3 axis but illustrator crashes when using them everytime. Is this a common 3 axis problem in its own right or a problem when using in illustrator.
Thanks
Tom
yes i’ve seen that and it’s a great tool. unfortunately what i’m doing has to remain confidential
Axis-Praxis is not uploading anything. It is all in browser.
Or use the variable font tester script from mekkablue
Have no working knowledge of Python so when I get to run the script in the macro window what then? Thank you
You run the script after you have exported the variable font. Then you should find a test.html file next to the variable font.ttf.
There are installation instructions on the page. And explanations for every script.
The explanation also appears as tool tip when you hold your mouse a second over the menu entry of a script.