HELP - router makes incorrectly shaped radiuss

good afternoon
My self-made MACH3 router makes incorrectly shaped roundings ~ 0.25 mm. Have any of you encountered such a situation. This is shown in the connected image.
Sorry for the language - I translate with GOOGLE
Indulis Attachment 29854

Maybe it's because of back lash, or the machine is not squared properly. Can also be caused by the software sending the step signals or even in the g-code. Are you using accurate steps or rounding corners? Can you post the g-code?

The axes X Y are perpendicular.
Baklash is not larger than 0.05 mm
I use Hybrid Servo Drive HBS86H for drive.
I use POKEYS 57E for control.
I also added control from the LPT port, but the error did not decrease
(Toolpaths used in this file:)
(Profile 1)
(Tools used in this file: )
(1 = End Mill {12 mm}kokam)
N100G00G21G17G90G40G49G80
N110G71G91.1
N120T1M06
N130 (End Mill {12 mm}kokam)
N140G00G43Z20.010H1
N150S16000M03
N160(Toolpath:- Profile 1)
N170()
N180G94
N190X0.000Y0.000F2000.0
N200G00X-39.000Y-37.000Z20.000
N210G00Z2.000
N220G1Z0.000F2000.0
N230G1Y-7.000Z-5.000
N240G1Y37.000
N250G2X-37.000Y39.000I2.000J0.000
N260G1X37.000
N270G2X39.000Y37.000I0.000J-2.000
N280G1Y-37.000
N290G2X37.000Y-39.000I-2.000J0.000
N300G1X-37.000
N310G2X-39.000Y-37.000I0.000J2.000
N320G1Y-7.000
N330G00Z20.000
N340G00Z20.010
N350G00X0.000Y0.000
N360M09
N370M30
%

This is my third construction.
The first is with servomotors and LPT port control.
It has everything in order with precision.
The second is with collector servomotors and AKZ250 CONTROL from USB.
It also has no problems with accuracy.
But now I am using servo steppers and problems with accuracy are starting ...

Could it have anything to do with path blending

G61 G64

There is currently a constant velocity in the settings.
I switched to exact stop, nothing changed from it ??? ... Attachment 29855

My guess would be movement or deflection of some part of the router.I would suggest you try cutting two identical parts-one using conventional cutting and one using climb cutting and see how they compare.

The direction of rotation does not affect the result.
But with increasing processing speed the error increases.

the servostepper has 200 steps per revolution, the encoder 1000 pulses per revolution.
HBS86H I have selected 1000 PULSES PER RPM
There are 250 pulses per mm displacement along X and Y.