Image shrinkage SOLVED when moving SVG from the GIMP to Inkscape

As a longtime GIMP user, I start my scaled CNC design projects in the GIMP, then export SVG files and import them into Inkscape to do the conversion to G-code. That raw code gets integrated into a custom program, then run by LinuxCNC with a custom Glade panel that can choose depth of cut, which path, etc. This process chain has cut many beautiful electric guitars' pickguards.

I recently was working on a CNC project (an acrylic guitar pickguard), needing to change an edge detail, and happened to upgrade Inkscape. Inkscape's GcodeTools module now seems to have a bug in it for imperial measure projects (0.92.4 in 2019), and in figuring out a way around that... (do the orientation points in mm, then change the "100" (mm) to a "1" (in) using text edit before creating the G-code file)...

I found out why my routed output had mysteriously shrunk recently. According to: graphicdesign.stackexchange.com/question...g-and-viewbox-values "The CSS specification describes that absolute length units are fixed in relation to each other: 96px = 1in Inkscape v0.92 uses a relation of 96px/in, Inkscape v0.91 and earlier used a value of 90px/in" ...Of course I used to use 0.48, updated in the past year to 0.92, then a few weeks ago to 0.92.4, and I was still assuming the old default of 90px/in, and so all my designs were coming out a bit small. (A couple months ago, I was pulling my hair out trying to figure out what I had bungled, as I need high precision.) Yah, updating software can cause horrible problems... I was unable to find a setting for SVG creation resolution in the GIMP, but fortunately Inkscape has an import resolution setting.

TLDR; When moving an .SVG file from the GIMP to an Inkscape newer than 0.91, make sure that Edit / Preferences / bitmaps / (Import) Default import resolution is set to 90. (The installed default is 96.) This avoids shrinkage of the image.

as I need high precision.

why not SVG 2 DXF on inkscape
then using a REAL CAD like librecad or the just testversion of Qcad to REAL SCALE and Dimention the PART
and a REAL CAM like the Free versions of FreeCAD,Heekscnc,Sheetcam........

i know it is one step more But it is a Increce of precision
and BEST of ALL you got CRC ((Cutter Radius Compensation)))
so you can take your tooltable some ofset to Rouph and go to fine as you like
first cut 5mm off contour
second 1mm off contur
messur and give it the final

also you can use bits you like from Fine to Roughing Reshaped
and the final gets a new one
Guitar building s quite alot of here in Germany Hobbyists

Thanks for your suggestions. I'm working with a homebuilt router table (photos on facebook.com/Volectar-joystick-guitars-422091631204144), so my idea of high precision is not terribly strict in the machinists' sense. The pickguard really does need to fit properly, though, to match pickup cavities and avoid overlap of body contours. LinuxCNC's gcode can do radius compensation, which I have been playing with, however, most of my cuts are with conical bits so my depth of cut controls the radius, too. Chucking bits in and out is imprecise with the current setup, so I do a lot of measuring. I created a GIMP file to give me stickers with 100ths of inch marked (yes, imperial measures, hah), so I have made rulers of many lengths to measure from the bit point to the table surface. Note that acrylic stock is difficult to shave finely; it tends to melt and ripple if I cut too thin a layer or too slow. My current setup is adequate, and took months to get working, so I'm inclined to stick with it for now. Maybe when we build or buy a bigger, more rigid table I'll work on a new, better process. CNC is wonderful for electric guitar work - consider building a volector joystick control instrument; I can be a resource on the project.