Shenui cutting speed vs quality

[matthew knott]

On a biggish bed laser 1.2 x 1.8 meters, what sort of max cutting speed would you expect 10mm or .4' circles to still look like circles?
Cheers

[Rodne Gold]

Depends on the material and the system slop as well as backlash compensation and whether you use the small circle compensation..
Big bed size so even if there is a small % "error" , it can translate to a big number on small stuff..
Eg 1mm in one direction ..lets say the 1.8m size = 0.05% error
I would definitely not expect anything good at max speed like 500mm/sec..maybe 50-200mm sec would be in a sort of sweet spot..? Not too sure tho.

[Dave Sheldrake]

I can't speak for Shen machines (I don't have one) but on the HX 2.5m x 1.5m (2515) anything much over 175mm per second tends to loose shape on a radius, the biggest offender seems to be when shifting from a full speed straight line to a radius corner " U " that kind of shape.

My experience tends to be much the same as Rod's, 75mm PS gives nice sizes cutting with a max of 175 to keep the circles visually good (but not always perfectly accurate) if I'm just line burning the surface of a job. On the HX the gantry is a big chuck, a lot of weight to force into changing direction quickly, I'm told that the servo drive Chinese flatbeds are reportedly good but haven't tried it on one of those.

I can run some stuff on the 2515's if it's any good as a test Matt?

best wishes

Dave

almost forgot: corners <90 degrees also tend to "loose the tail end" above 175mm ps .

[john banks]

We use a max of 50mm/s and slightly slower than stock acceleration on our 1280 to avoid wobble and loss of quality.

[Jonathan Brown]

Where would this error be coming from? Is it following error in the servo motors? Perhaps you could tune the amplifiers to give a stiffer response?

If it is slop in the belts, maybe tighter tension?

I just finished an hour of tuning and testing on the x-y system I am building for my fiber laser and managed to get the error down to 2.5um at 150mm/sec running and 10um when reversing direction on an axis. This is of course with brushless motors, ground ballscrews and square type linear bearings.

[matthew knott]

Thanks guys, i get pretty ropey looking circles at 30mm/second, might need to have a play with the backlash settings, anyone any pointers on how to 'tune' one up, Im happy to just experiment and play working out what effects what, but my guess is you guys have already been through all this. Its not an issue just yet as we normally cut at 5-8mm second, but i want to get it set right! Shenui have asked for photos and say they will help me fix it! Main problem is im mega busy with other stuff right now, 10 minutes spent is 10 i dont have, bloody customers

[George M. Perzel]

Matt;
I have a Shenhui 1200x800 with dual heads so max single head is about 1100x800. Cut circles, about 5mm diameter, appear very round at 200 mm cut speed. can send pics if you need.
Best Regards,
George
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