Options to reduce memory footprint to increase buffer.

I have a delta printer....with Arduino Mega 256, .when printing small circles it really slows down....to the point it stutters. ...
I notice that the buffer (currently set to 15) runs low and maybe out....
I know comms is fixed at 115k so is there any options I could turn of in the configurator that would allow
a smaller footprint for the app that would in turn allow me to increase the buffer size?
if I could get to 32 steps or something I suspect the problem would e greatly reduced.
I do not use any of the dynamic software level and bed correction only constants to correct for frame alignment.

Is there a better board recommendation for the deltas?  I bought a 32 bit smoothy clone but decided I didn't want to mess with Smoothieware, especially now that my delta is running well.


  • Problem is that a mega2560 ha sonly 8kb ram for all the buffers. So with deltas you can reduce subsegments per move to increase the number of moves buffered. That of course only works for small moves otherwise you need more lines to store move.

    For deltas I advice the RADDS board with arduino due. Repetier-Firmware runs on it, the board is 10 times faster and we have 96kb instead of 8kb ram, so 32 lines with even more subsegments is no problem. I even run 600 calculation per second on it for smoother movements.
  • Thanks for the advice...was hoping I could remove the leveling or some other unused feature to get more buffer but I will try to find a RADDS board, it sounds like just the ticket....sadly I got my delta mechanically all dialed in and due to some dumb decisions I made in the design I expect changing the board will mean some painful recalibration and tweaking.
  • Actually you should store your calibration values and set them exactly the sam ein new firmware. Due and AVR version are 100% identical except hardware handling and available memory. So with same correction values I expect same result.

    Removing features more frees flash memory but RAM is the limiting factor here.
  • Four Months later.......My budget and the RADDS board availability are finally in sync...so I will probably order the setup (would love to try the diamond hot end but that will have to wait).... Anyway one big factor in moving to the RADDS Due set up are the step sticks....are the 128 step units worth all the extra money do you think?  I understand they are quieter but that isn't a big deal...if they noticeably improve smoothness, resolution or speed well for that I will pay.  Hoping smoothness will in part be helped by the Due being more powerful so less delta stuttering.  Also hoping this change will maybe reduce the crashing problems I have if while printing I try to adjust anything from the printer LCD/control knob.

    My previous comment about the calibration is not due to the firmware calibrations it is the result of the stupid way I put the printer together...I expected I could move the calibrations to the new CPUas you suggest, however the problem is I have to partly disassemble the frame / bed mountings to change the electronics which will possibly require all new settings once it is reassembled...:(

    Any suggestions where best to purchase the electronic components in the US?
    RADDS seems more popular in with the Euro Vendors which isn't a problem but does increase the shipping etc.

    Thanks for all the work with Repetier and help here.
  • Have a look at the reseller list:
    should be available in US as well, but yes it is a german company that produces them so eu is better covered.

    Higher resolution also always means slower maximum speeds. Expect the radds to handle 100KHz on deltas without problems. In V2 firmware I think 150000 will also possible. Tests with my delta looked fine. Regarding resolution I think 100-150 steps per mm is fine. Higher resolution might a bit smoother and more silent. My big delta has even only 80 steps per mm. So if I take that with double resolution I would like it. Maybe one day I replace the external drivers with higher resolutions:-)
    So yes you can use 128 microstepping but it is not necessary. I think it gives a minimal improvement in quality and maybe a bit more silent moves.
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