[JillB99]

I have designed a Celtic knot, being a triquetta with a circle interwoven, the circle being in the centre of the triquetta, as per attached .pdf file drawing.

I made each of the 6 sections of the triquetta a separate profile, T1 to T6. These were engraved first on the MDF with a 1.5mm milling bit with a single pass depth of cut 1.0mm.

The 3 sections of the circle C1- C3 were cut immediately after T6 was finished.

The problem is, the circle is way off centre, having dropped down about 10mm, as shown in the cut picture attached.

The Celtic knot was designed with AutoCAD, then the tool paths and the G.code generated on Vectrix Aspire. The simulated cut is shown attached.
The G.code was imported into UGS to run the OEM controller.

Prior to this, I ran a test piece of a 40mm diameter circle , cut along the inside, and a 70mm squate surrounding the circle, cut from the outside with square corners. The cut result was a perfect circle of 40mm diameter and a 70mm square. You can see this on the picture showing the cut results.The machine feed rate , to get a decent circle was only 30mm /minute with a 1.5mm bit and a 1mm depth of cut. I had previously done a 40mm circle using 60mm/min feed rate, 1mm depth of cut, and ended up with a 37.5mm diameter circle

������������ ������������������������������������������������ ������������: Can anyone please advise why after the 6 profiles T1-T6 are engraved 1mm deep at 20mm/min feed rate, the circle C1-C3 profiles are way out of alignment, not even making a circle, as shown in the attached photo.
I am using a Chinese 3040 500W CNC table. The X & Y stepper motors are 2A rated, and the new Z stepper 4A rated. The table is quite sturdy

Hoping someone can point me in the right direction please

regards to all,
Jill