file Frage Y Axis fun and games

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20 Nov 2018 02:48 #55172 von pev
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Hi all,

Im new to CNC but familiar with the concepts. I picked up a second hand SC600/2 (I believe!) which Ive been attempting to get going using UCCNC via an UC100. While familiarising, it seems that the Y axis gets half way along with a velocity 3000 and then makes a loud "wheeeee" noise with motion stalling but UCCNC still thinking position is changing. Dropping the velocity to about 1500 seems to solve this. However as Im wanting to machine acrylic, i really want to go around 2,500, not to mention the fact that it seems well below spec which I want to investigate.

Doing some reading and digging around the forums I found the excellent video from Stoney CNC about tuning the Y axis. So, I spent a few hours following the process and now seem to have improved things a bit. I then repeated the process (understanding it a bit better the second time!) but still not *that* much better, and having seen in the video the presenters success at 5000 - 6000 it makes me fairly sure something more significant is up.

Anyway, after looking at everything I could think of I cynically checked the Y stepper motor and lo and behold it seems that the previous owner has swapped the Y axis stepper for an "RB Step Motor 17HDC4023-24B" - when I understand this should be a Nanotec unit. Now google doesn't bring up any specs but it seems they're prevalent on Alibaba and previous experience tells me that things from Alibaba tend to use specs as a guideline as opposed to, well, a specification!

So, to my questions :
1) Am i likely right in my hypothesis that this stepper is likely to blame?
2) Should I just replace with direct replacement from Stepcraft or is there a marginally more powerful replacement I should use?
3) To prove my hypothesis, could I do something as simple as rotating the belt pulley with a torque wrench to see what torque it requires to move and see how that relates to the spec of the motor (assuming I can find it for the fitted & OEM one!)
4) any other ideas?
5) Has anyone got part numbers for ordering direct from Nanotec as the postage / courier cost from Stepcraft vastly outstripped the already marked up cost of the motor!

Thanks!

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22 Nov 2018 03:15 - 22 Nov 2018 03:16 #55212 von eiaro
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pev schrieb: So, to my questions :
1) Am i likely right in my hypothesis that this stepper is likely to blame?
2) Should I just replace with direct replacement from Stepcraft or is there a marginally more powerful replacement I should use?
3) To prove my hypothesis, could I do something as simple as rotating the belt pulley with a torque wrench to see what torque it requires to move and see how that relates to the spec of the motor (assuming I can find it for the fitted & OEM one!)
4) any other ideas?
5) Has anyone got part numbers for ordering direct from Nanotec as the postage / courier cost from Stepcraft vastly outstripped the already marked up cost of the motor!

So the hardest task on your router get a saggy 3D printer stepper.

1 - Yes, lack of torque make the sound. Remember that the sound is usually not a bad stepper but too much friction. But since you followed Stoneys video I assume your gantry is close to friction free.
2 - Original is better. By using the router you have wear even on a perfectly tuned machine. By not being overpowered you will notice if your machine gets untrammed and does excessive wear on your rails, and big motors would just let you continue (with more wear and bad tool marks as your cost of lazyness/"failing to make a good PM schedule").
3 - Not really, just buy the spec. I guess you could use your method, but why bother?
5 - Nope, but Sorotec sell them with, to me, acceptable markup and normal postage. I'm sure Stoney will too. Please remember this is brand name steppers and price cannot be compared to random China steppers.
https://www.sorotec.de/shop/stepper-motor-Y-axis--Pos--83.html

StepCraft 2 840 with HF500 spindle controlled by LinuxCNC
Last edit: 22 Nov 2018 03:16 by eiaro.

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31 Jan 2019 02:17 #55850 von Doug
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Dear pev,

It is likely that your Y axis will require mechanically tuned. Rory Stoney has produced an excellent video on this topic. I also wrote up some tips on this thread under the titles "Y Axis Mechanical Tuning/Excess Powder Coat in Bearing Rebates" and "Y Axis Gantry Alignment":

https://www.stepcraft-systems.com/en/forum/assembly-and-maintenance/4432-undocumented-assembly-steps-wheezes-and-advice#47348

I got mine mechanically tuned to run without any issues at 2,500 mm/min. Even at 3,000 mm/min, I still got some binding with the symptoms you describe. All of my cuts on wood, acrylic and aluminium were successful at feed rates up to this maximum. Please see my various threads and videos for parameters. I have cut both 1/8" cast acrylic and 2.5 mm PVC guitar pickguards with both 2 mm 2 flute end mill and a Trend 90 degree V-groove cutters successfully.

Regards.

Doug

Stepcraft 2/840, StoneyCNC industrial HF spindle, 4th axis, TurboCAD 2016 Professional 64 bit, MeshCAM, GWizard feeds & speeds calculator, UCCNC
Hobby use: guitar building (luthiery), https://www.facebook.com/DougShortGuitarBlog/

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10 Feb 2019 01:05 #55930 von Rory
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Clean of the STEPCRAFT grease and use light spray oil... 3in1 or WD...
this will make a big difference to top end performance

reapply regularly.

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