Need advanced help with gantry problem

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JohnSays
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Joined: Tue Apr 26, 2016 2:42 pm
Location: Saint Petersburg, FL

Need advanced help with gantry problem

Postby JohnSays » Sat May 26, 2018 3:06 pm

I have two N2s. I have done the alignment procedure on both of them many times. Or to be more specific, on one of them ( call it P1) many times and on the other (P2) just twice. The P2 gantry moves beautifly -- free and easy. It just sort of skates over the build plate. P1 does not move like P2. It moves stiffly and will actually jam and has to be finagled to get it to resume movement. This after following the alignment procedures many times. I have used the printed blocks to align and I have used the gantry holders used to keep the gantry from moving during shipment to align. At no time even while trying to align the x-y gantry have I gotten P1 to move freely. It never has and as a result I get a very slight oblongness to round prints. During printing, the problem is noticeable mostly on the first layer where three quarters of the lines bind to each other and the other one quarter do not. If it were not for P2, I would not have known how freely a gantry can move. Also, I found it easy and rather intuitive to align P2. So I am pointing out that I have been succesfull in applying the alignment procedures.

I have found that a couple of drops of 10 weight oil on the rods (each of them) does make the printhead move easier, but does not stop the binding or make them move nearly as easily as th eP2.

Does anyone know what problem I may be running into? What else to look at? I say this because I do not think the problem is actually alignment per say. If it is, it would have resolved. Any suggestions on how to resolve this problem?
- John
2 Raise3D N2 Duals, V2 nozzles, Bondtech BMGs, adjustable table, Panucatt SD2224 drivers, run-out sensor, thermal overload protection resistors on motion controller board, Firmware 1.1.8ABH - with Lin_Advance, Palette+

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JohnSays
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Joined: Tue Apr 26, 2016 2:42 pm
Location: Saint Petersburg, FL

Re: Need advanced help with gantry problem

Postby JohnSays » Sun May 27, 2018 3:07 am

I may have fixed part of this problem. The X rod that runs through the printhead holder was sticking out of the back of the G2 holding block -- the one in the front of the machine. I believe it was actually scraping against the inside of the frame and thus dragging. Now that I have slipped the rod forward about an eighth of an inch, the printhead seems to be running very free indeed. Still not quite as free as P2, but significantly more freely. I'm now going to go through the alignment process to see if that completely fixes all the issues. I'm thinking that if it was dragging that would put some pressure on the entire gantry and perhaps push it towards being out of square -- even if just a little, that could make a difference. Also, that block had a screw in it that held the rod in place. It was tight against the rod so the rod could not move forward if it ran into something -- such as the side of the housing.
Last edited by JohnSays on Sun May 27, 2018 3:36 am, edited 1 time in total.
- John
2 Raise3D N2 Duals, V2 nozzles, Bondtech BMGs, adjustable table, Panucatt SD2224 drivers, run-out sensor, thermal overload protection resistors on motion controller board, Firmware 1.1.8ABH - with Lin_Advance, Palette+

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JohnSays
Posts: 595
Joined: Tue Apr 26, 2016 2:42 pm
Location: Saint Petersburg, FL

Re: Need advanced help with gantry problem

Postby JohnSays » Sun May 27, 2018 3:35 am

I did the alignment procedures again and got a little better ease of movement. I am satisfied with that part of things. What still concerns me is that the whole assembly will arbitrarily stick/lock. I cannot move it left, right, forward, or backward. Then it frees up and moves smooth as can be over the same spot. Weird. Something else weird: The printhead moves the same with the machine off or on. My other machine is not like that at all. So P2 does not move easy at all when off. P1 does, but P1 also does this weird thing which may be a clue to the problem: when P1 is off and I move the head around, the LCD screen comes on as if I am sending it electricity. Me thinks spinning the motors is back generating to the system. Is this normal? Shouldn't there be diodes or transistors in place to prevent this? I'm wondering if the extra resistance I am experiencing is the generation of electricity and that that in some way locks the motors until a capacitor discharges. I have no idea of the internal circuits, but something is not right and way over my pay grade at this point.
- John
2 Raise3D N2 Duals, V2 nozzles, Bondtech BMGs, adjustable table, Panucatt SD2224 drivers, run-out sensor, thermal overload protection resistors on motion controller board, Firmware 1.1.8ABH - with Lin_Advance, Palette+

MDVolle
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Joined: Fri Oct 20, 2017 9:00 pm
Location: Fullerton CA

Re: Need advanced help with gantry problem

Postby MDVolle » Sun May 27, 2018 9:34 pm

John,

I'm not an expert but when I move the gantry on mine, there are a few sung spots near the far right of travel but not anything more serious than slightly stiff.

As for the display trying to power when you move the gantry - sounds like something shorted in the electrical - yes, the motors could generate voltage while being moved and they would feel stiffer the faster you try to move them - they might feel loose at slow speeds and stiffer with speed.

I don't see any positive reason that they should be connected to a "load" when the unit is powered down, so something electrical seems like a reasonable place to look.

Have you identified if it is one or both motors doing this?

That might narrow your search. You could also try disconnecting the motors at the control board - if they are shorted somewhere in the wiring to the gantry, they will still generate resistance - if not, they will move freely.

Sounds like a genuinely interesting but probably frustrating problem.

Mark

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JohnSays
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Location: Saint Petersburg, FL

Re: Need advanced help with gantry problem

Postby JohnSays » Mon May 28, 2018 3:24 am

Thanks Mark. Good suggestions.
- John
2 Raise3D N2 Duals, V2 nozzles, Bondtech BMGs, adjustable table, Panucatt SD2224 drivers, run-out sensor, thermal overload protection resistors on motion controller board, Firmware 1.1.8ABH - with Lin_Advance, Palette+

ABH
Posts: 172
Joined: Sun Aug 14, 2016 7:31 pm

Re: Need advanced help with gantry problem

Postby ABH » Tue May 29, 2018 8:28 pm

Maybe you would like to read my post here:
http://forum.raise3d.com/viewtopic.php?f=4&t=6666&p=26601#p26601
I don't believe that I am the only one with a printer that suffers (suffered) from this.

Also, I like doing the gantry adjustment in a different way than what is recommended by Raise3D, by using these spacers:
https://www.thingiverse.com/thing:2778058

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JohnSays
Posts: 595
Joined: Tue Apr 26, 2016 2:42 pm
Location: Saint Petersburg, FL

Re: Need advanced help with gantry problem

Postby JohnSays » Thu Jun 21, 2018 8:47 pm

Thanks Mark and ABH. I do use the mold injected rod holders that shipped with the printer to keep the rod from moving. I think the spacers are a mistake as the collar pulleys may not be perfectly aligned with one another and you will start with an uneven base to square up from.

In my case, the problem with adjustment was that when I loosened the set screws in the collar pulleys, they were somehow stuck to the rods and so did not slip during adjustment. Thus, they did not adjust. Once I discovered this, I was able to free them and the adjustment proceeded normally and all is working well. I will now alwasy duble check for loose collars before proceeding with the adjustment.

Just a new unique problem I guess.
- John
2 Raise3D N2 Duals, V2 nozzles, Bondtech BMGs, adjustable table, Panucatt SD2224 drivers, run-out sensor, thermal overload protection resistors on motion controller board, Firmware 1.1.8ABH - with Lin_Advance, Palette+


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