# Posting arcs on a 1325: IJK or R, and does the retract difference matter? **URL:** \ **Category:** CAD/CAM Software\ **Created:** [October 14, 2026, 1:30pm UTC](https://cnc-routers.org/t/posting-arcs-on-a-1325-ijk-or-r-and-does-the-retract-difference-matter/90 "2026-10-14T13:30:46Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![mike1958](https://cnc-routers.org/user_avatar/cnc-routers.org/mike1958/32/49_2.png) [@mike1958](https://cnc-routers.org/u/mike1958)\ **Post date:** [October 14, 2026, 1:30pm UTC](https://cnc-routers.org/t/posting-arcs-on-a-1325-ijk-or-r-and-does-the-retract-difference-matter/90/1 "2026-10-14T13:30:46Z")
Trying to get a post processor I can trust for my RC1325 and arc output is where I keep stalling. The machine is fine, this is me not knowing which convention to standardise on. My current post writes arcs as IJK. If I flip the same file to R format it also runs, and the parts look the same to my eye, so I have no real basis for choosing one. What I have already been through: - Cut the same 600 x 400 pocket twice in 12 mm birch ply with a 6 mm compression bit at 18,000 rpm, once with IJK output and once with R. Edge finish looked identical, so that test told me nothing. - Re-checked the G54 work origin against the physical corner of the sheet twice, and both times it came back to the same number, so I do not think origin setup is the variable. - Turned the controller’s arc tolerance compensation off and on, which changed nothing visible. - Watched the Z moves in backplot. The IJK version enters the cut maybe 0.3 mm lower than the R version, which is small but repeatable. So how are people posting their 1325s for nested sheet work, and is that retract gap something I should actually care about or am I chasing noise? I have not got my head around how feed override behaves on the pendant yet either. ![image](https://cnc-routers.org/uploads/default/original/1X/33f655b2a3ce3f880f419a1f36f3082abe99973b.jpeg)