... . Mine use the base of the chair (timber top) I have used the rail top as a reference for everything. However I can easily make it an option for the blocks. Give me a chance to eat some roast beef and Yorkshire pudding, and I will then post another file. *TurboCAD Deluxe 20.2 64-bit cheers, Martin. posted: 30 Jul 2018 01:13 from: Martin Wynne Hi Andy, Here's another file attached, this time with the blocks referenced from the timber tops: 2_291954_550000000.png 2_291955_200000000.png Note that these blocks don't actually touch the timber top, but they are referenced from it: 2_291956_360000000.png The template is for 4-SF gauge (16.2mm). The actual Z offset from the rail top is set to 5.23/32" (BS-95R bullhead rail)+ 1.3/4" (chair seat thickness). At 4mm/ft scale= 2.4896mm (0.0980"): 0 INSERT 2 S1L 8 CHMARKER 10 0.8988 20 0.9449 30 -0.0980 41 1.0000 42 1.0000 43 1.0000 50 0.000 Here's the ...