Uniwidth font: no linked LSB/RSB over masters?

Hi, another special question about uniwidth fonts: Linked metrics f. e. LSB are practical, if bold versions get more space than smaller styles. In uniwidth fonts the width must not change over all masters/instances.
Is it possible, to say LSB =(n) in regular and LSB =(n**+10**) but only in bold?

Some glyph positions needs to be corrected in bold, but by setting LSB manually the value in regular changed too.

Thank you!

Bildschirmfoto 2024-03-03 um 22.09.52

I think it might be easier to use the width metric key instead of the sidebearing.

By running this script in your Macro Panel, it will for each glyph, take the width of the selected master and use it to create a width metric key.

selected_master = Font.selectedFontMaster
for glyph in Font.glyphs:
	width_value = glyph.layers[selected_master.id].width
	glyph.widthMetricsKey = f"={str(width_value)}"

You can have metrics keys per layer. Add a double equal sign at the start.

To be clear, what do you mean by “uniwidth” font. That each glyph in all masters has the same width, or that all glyphs are the same (that would be a monospace font).

If it is the former, then add a link “Link Metrics With First Master” to all but the first master.

Thank you @HugoJ i‘ll try it.
@GeorgSeifert yes, it‘s uniwidth, not monospaced.

You mean, you go from light to bold and the widths don’t change? This is usually referred to as “duplexed”.

Stop focusing on sidebearings. Instead focus on widths. The best way to handle this are the Link Widths custom parameters in File > Font Info > Masters.

Ok, the script works, and yes we can call it a duplex font @mekkablue .
“Link Metrics With First Master” was set before and it worked well.

I´m not sure, if this was what i searched for. I think we talk about finetuning now.
Maybe the picture shows the ‘problem’ with spacing: Like n and n there should be the same space between n and m, because the RSB of n should be the same as m. In regular (1st master) it is, in bold (2nd master) there should be more space at right of m (but the width can’t change) - What would be the best solution?

(Picture shows the black style instance)

Thank you all!

Then you need to change the outlines until the sidebearings match.

Ok, that would be my next step. Thanks.