1 Topic by philpem

  • philpem
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Topic: Modified Solidoodle 2 Pro suffering Y-axis shift -- help!

Hi,

I have a heavily modified Solidoodle 2 Pro:

* Standard controller board (Sanguinololu) -- fitted with TI DRV8825 drivers and a 60mm 12V fan for cooling
* Keenovo silicone mat bed heater (the heater resistor was one of the first things to fail!)
* Horizontal filament spool mount on the back panel (Tarwin's -- https://www.thingiverse.com/thing:34284)
* Several Lawsy mods -- extended filament guide, XY carriage, cable chain
* E3D V6 extruder and Jigsaw (Mdroman/Wardjr/Lawsy version -- https://www.thingiverse.com/thing:431363) with carriage-mount part cooler fan
* Direct drive Y axis -- http://tomhorsley.com/hardware/solidood … irect.html
* GT2 belts throughout, 20 tooth gears

(This is just a summary -- there's a full list of mods on http://wiki.philpem.me.uk/3dprint/solid … ent_setup)

I was running at 250000 Baud for comms to the controller, but had a lot of "checksum error" messages and printing stalls (printing stopping dead mid print), so I've switched back to 115200.

I'm running 1/32 microstep on the TI drivers. Current for the X and Y axes is up against the motor limits (as defined by Vref at least).

Now, while this setup (on a good day) will produce lovely parts, with perfect circles where demanded, I have a problem where the Y axis will suddenly skip during printing. This is markedly worse when the filament spool (E3D ABS filament, 750g) is less than half full -- the E3D spools seem to be tighter towards the centre.

I've found that the Y axis still binds slightly at four points in its travel, but nothing I've done has helped with that (not even the linear bearings on the Lawsy XY carriage). The 6mm back rod is brand new (the original had rust spots).
Do the two pulleys which carry the Y belts need to be in a specific position (rotationally with respect of the grubscrews) to each other? The binding seems to line up with times when the Y-shaft is in a specific position. I can disconnect the motor shaft coupling and still have the same binding.


I'm at my wits end now... I have a printer which prints almost perfectly (at the cost of losing 15mm of Y travel for the part fan), but I can't leave it alone because half the time it

What should my next step be to fix this?
Reduce microstepping?
Increase Vref (motor current)?  (I'm already up against the motor specs)
Different filament mount?  (does a top mount put less stress on the carriage?)

Thanks
Phil

2 Reply by Tin Falcon (edited by Tin Falcon 2018-07-01 11:24:51)

  • Tin Falcon
  • Tin Falcon
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Re: Modified Solidoodle 2 Pro suffering Y-axis shift -- help!

you may try a y axis tuning procedure



http://wiki.solidoodle.com/fix-axis-shifting

reducing the micro stepping   may help

you may try backing off the vefer .

the motor or driver may be getting hot. add a fan

Is the motor getting hot do have a themometer to check it with ?
or you may need a new driver chip. /board
the link gives a list.

Soliddoodle 4 stock w glass bed------Folger Tech Prusa 2020 upgraded to and titan /aero extruder mirror bed
FT5 with titan/ E3D Aero------MP mini select w glass bed
MP Utimate maker pro-W bondtech extruder
Marlin/Repetier Host/ Slic3r and Cura

3 Reply by heartless

  • heartless
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Re: Modified Solidoodle 2 Pro suffering Y-axis shift -- help!

dont really need a thermometer to check if the motor is getting hot - just touch it - if it is too hot to hold your finger on it for more than a second or two, then it is overheating.

even in the stock configuration of my SD4 with the motor inside the chamber, mine is barely lukewarm.
The X motor however likes to get burning hot without a fan on it, and it will skip steps if it gets too hot.

the binding issue, however, is definitely something you need to resolve. there should not be any binding throughout the travel. This is most likely a major part of you problems.

SD4 #1 & #2 - Lawsy carriages, E3D v6, Rumba controller board, mirror bed plate, X motor fan, upgraded PSU & Mica bed heater
SD4 #3 - in the works ~ Folgertech FT-5, rev 1
Printit Industries Beta Tester - Horizon H1

4 Reply by philpem (edited by philpem 2018-07-01 21:20:09)

  • philpem
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Re: Modified Solidoodle 2 Pro suffering Y-axis shift -- help!

I've just had the machine in pieces again (or at least the Y-axis shaft and assorted parts).

I didn't replace the original bronze bushings when I fitted the Y direct-drive kit as I didn't have any on hand. As it turned out, this was my undoing. The bushings were completely shot -- if I'd looked inside, I'd have seen the heavy scoring and scratches.

Here's a HOWTO for replacing them:

You will need:

  • One M6 socket screw

  • A couple of M6 penny washers

  • A fairly sturdy M6 nut

  • A hex socket, 15mm or larger (but not too much larger)

  • A suitable Allen key or driver for the bolt, and a suitable spanner for the nut.

  • Two new SF686ZZ type 6x13x5mm shielded, flanged bearings

  • A tapered reamer to enlarge the bearing holes to just shy of 13mm

  • Optional: Bearing retaining compound (Threadlock may work)

Feed the bolt through the bushing from the inside of the case (the bushing flange is on the outside). Put the socket on the end of the nut and line it up with the bushing's outer flange. Now load the penny washers and nut onto the rod and set them finger tight. Make sure the bushing and socket are still aligned. Use the Allen key to stop the bolt from rotating, then use a ring spanner to tighten the nut. Keep going until the tension on the nut suddenly releases (there will probably be a 'thud' sound). Remove the bushing, dismantle your makeshift bearing press, and repeat the process for the other bearing.

Before you fit the new bearings, you'll need to slightly enlarge the holes Solidoodle made. Use a tapered reamer and regularly check the new bearing for fit. You're aiming for a tight sliding fit -- you should be able to push the bearing in with your fingers, and it should require force to push out. If the bearing is too loose, a small amount of bearing retaining compound (e.g. Loctite 641) on the outer rim of the bearing may help -- loosen the bearing, apply retaining compound and push the bearing home. Wipe off any excess but don't let it enter the bearing!

Now refit the drive rod, pulleys and so on, and readjust the belt tension.


End result: the binding has completely gone (I can move the carriage with light fingertip pressure when the motor coupling grubscrews are loose) and the loud rattling noise of the printer has been replaced with the subtle whine of the motor driver's PWM frequency.

Next on the job list: replace the Z-axis. I have a lovely new trapezoidal leadscrew, stepper motor, anti-backlash nut and pillow blocks just waiting to be installed!