will1384's Ord Bot Hadron

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Re: will1384's Ord Bot Hadron

Postby will1384 » Fri Apr 04, 2014 10:57 pm

TLHarrell wrote:I assume this to mean that you are powering your Mega from 5v on the USB? Why not wire it to 12v power from the power supply? Or is that a potential noise issue?


The way it is now:

The Arduino Mega 2560 and LCD gets power from USB, when the ATX power supply is turned off.
The Arduino Mega 2560 and LCD gets power from the ATX power supply, when the USB cable is removed.

To turn off the Ord bot I have to turn off the ATX power supply and disconnect the USB cable.

Both D1 and D2 1N4004 rectifier diodes are installed on my Ramps 1.4 board, so the Ord bot can be used without a computer, also someday I want to try wireless printing.

I now have another problem

Image

I have the temperature set to 230, and it drops to 173 right after a few layers, just started happening yesterday, I hope its just a lose cable, I had a print just crumble in my hands, today I heated the workshop to 90°F and tried the same print again to see if it was just cold air.

I am going to make and enclosure for my Ord Bot, I have some scrap 80/20 Extrusion, and some Plexiglass/Lexan.
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Re: will1384's Ord Bot Hadron

Postby will1384 » Sat Apr 05, 2014 3:00 am

I started making this elarler this morning

Image

I used a bunch of scrap 80/20 10 series extrusion and what I think was scrap Lexan, I had gotten both at an auction cheap, it was used in some medical laboratory equipment, I did not want to cut any extrusion so I tried to use the pieces the way I got them, I ran out of small pieces when I got to making the door so I just used a sheet of Lexan as a door.

Image

I think later I will cut a piece of MDF for the bottom of the box, I also want to seal it, and make a hole for wires, maybe even an external control panel.

I printed a small part in the enclosure, the hot end started at 230, and stayed at 230 for good long time before the print, but then the fan kicked on and the temperature dropped to 185, the print only took 10 minutes, in that time the hot end temperature started rising and was 195 at the end of the print, I believe the box trapped enough heat to help raise the hot end temperature, I also think my fan may have been moved and started blowing on the hot end in a way that made it colder than before, I will change the fan location to try and get a better hot end temperature.
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Re: will1384's Ord Bot Hadron

Postby will1384 » Sun Apr 06, 2014 1:23 am

I cleaned up the wires, I want to cover the Ramps board and the wires with a box and fan later, but this looks OK for now.

Image

I tried moving the fan, and I was able to have the fan blow on the plastic and the hot end stay at 230, I only just slightly moved the fan, I put a digital thermometer on the outside of the enclosure, and a another digital thermometer on the inside, and there was a 10 degree difference.
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Re: will1384's Ord Bot Hadron

Postby flickerfly » Sun Apr 06, 2014 1:21 pm

I don't know if you've put the bottom in yet, but I was thinking of putting a drawer in the bottom of the enclosure to hold "printy stuff". Just thought I'd pass that thought along. Looks like a nice go of it. Also, thanks for pointing out the stl for the belt clamps you are using. I've been meaning to find another solution. The ones I got in my ATI kit are a bit loose.
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Re: will1384's Ord Bot Hadron

Postby will1384 » Mon Apr 07, 2014 5:36 am

flickerfly wrote:I don't know if you've put the bottom in yet, but I was thinking of putting a drawer in the bottom of the enclosure to hold "printy stuff". Just thought I'd pass that thought along. Looks like a nice go of it. Also, thanks for pointing out the stl for the belt clamps you are using. I've been meaning to find another solution. The ones I got in my ATI kit are a bit loose.



Thanks, a drawer or some sort of storage does sound nice, I will just have to see what will work, I may later cut a enclosure out of MDF on my Shapeoko 2 CNC router, and save the extrusion for something else, or at the least make a door with a window for the enclosure I have now.

My prints look pretty good, but I have noticed vibration artefacts, so I am going to try flexible couplers on my Z-Axis, and try vibration dampers on the stepper motors, I have already tried foam under the Ord Bot's feet with no effect.
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Re: will1384's Ord Bot Hadron

Postby will1384 » Tue Apr 08, 2014 3:38 am

I have been noticing vibration artifacts in my prints, so the first thing I tried was foam pads under the Ord Bot's feet,

I printed this test object

http://www.thingiverse.com/thing:277394

Image

foam did not help.

The second thing I tried was flexible couplings, I used a ball bearing like this,

Image

I remember reading about using a ball bearing like this in a forum and it sounded like a good idea so I decided to try it, I also tried NEMA 17vibration dampers,

Image

I used M3 6mm screws

Image

Image

I had to raise the Ord Bot up a tad after installing the NEMA 17vibration dampers, so I printed this up

http://www.thingiverse.com/thing:213262

Image


The top test was done with just flexible couplings, the bottom was done with both flexible couplings and NEMA 17vibration dampers

Image

What I believe now is that the only way to remove vibration artifacts is to lighten the load on the X-Axis and maybe Y-Axis, I will start with a Bowden type extruder to help remove weight from the X-Axis.
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Re: will1384's Ord Bot Hadron

Postby cvoinescu » Tue Apr 08, 2014 8:54 pm

What you're seeing are vibration artifacts: when an axis starts or stops moving suddenly, something (the extruder, the bed?) wobbles a little. I would check that all the belts are firmly tightened, and that the V-wheels are tight too, and that the extruder is firmly attached to the carriage. I would try to eliminate any springiness in the attachment of the bed surface to the Y carriage. You can try to adjust the current of the X and Y drivers, too, just in case it's the stepper itself that does not hold the position firmly enough (not likely, but worth a try just to eliminate it as a possibility).

I think the Z axis is fine. I would focus mostly on the Y axis, because that's the one where I can see a problem. Does the face labelled 'Y' look the same, or better?
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Re: will1384's Ord Bot Hadron

Postby will1384 » Wed Apr 09, 2014 2:51 am

cvoinescu wrote:What you're seeing are vibration artifacts: when an axis starts or stops moving suddenly, something (the extruder, the bed?) wobbles a little. I would check that all the belts are firmly tightened, and that the V-wheels are tight too, and that the extruder is firmly attached to the carriage. I would try to eliminate any springiness in the attachment of the bed surface to the Y carriage. You can try to adjust the current of the X and Y drivers, too, just in case it's the stepper itself that does not hold the position firmly enough (not likely, but worth a try just to eliminate it as a possibility).

I think the Z axis is fine. I would focus mostly on the Y axis, because that's the one where I can see a problem. Does the face labelled 'Y' look the same, or better?


Yep, the belts are tight, but not over tight, the V wheels are the same, the extruder is bolted down good, the leveling springs on the bed are well compressed, I have the StepStick A4988 drivers set to 1 amp, and the test object has vibration artifacts on all sides.

I found this web page

http://wiki.arcol.hu/blog:printing-reasonance

His fix was:
Feet pads - But that failed to work for me.
Vibration damping on stepper and idler plates - I only tried on the stepper motors, but it had no effect.
Using vibration damping on the extruder/hotend - Have not tried yet, thats why I want to try the Bowden type extruder.
Tightening the V wheels - I have my V wheels pretty tight already.

I may try rubber washers with the extruder/hotend and idler plates, but if that fails I will have to lighten the load.
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Re: will1384's Ord Bot Hadron

Postby flickerfly » Wed Apr 09, 2014 1:28 pm

I was just looking over your feet picture and the ones you linked. It looks like the linked ones included a bunch of dampening material. Maybe that image you have up is before tossing some cork into the mix, but I thought I'd just mention it to be sure. :-)
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Re: will1384's Ord Bot Hadron

Postby OliverK » Wed Apr 09, 2014 2:37 pm

Try two things:

1. Mounting the (at times rapidly oscillating) build plate and PCB on springs, held in tension by four loose M3 screw and nut assemblies always struck me as introducing excess movement (due to jerk/lurch) into the system. Get rid of the springs and replace them with Nylon (PA) PCB spacers. Obviously they don't have the same adjustment range as a spring, but they compress (and bounce back) enough to allow perfect build surface leveling. For grosser adjustment they can be packed with M3 washers. This makes for a very rigid assembly. I expected the heat bed to warp due to being fully constrained, but nothing happened. Head crashes are taken care of by Barts' excellent Z-wobble fix.

2. Reduce moving mass as much as possible. The standard Y carriage assembly (carriage plate, heated bed, glass, V-groove wheel assemblies, etc.) weighs more than 900g. I made a Y carriage plate with lots of holes that's half the weight of the original. It doesn't just reduce vibration because there is less mass being thrown around (less jerk/jolt during changes of direction), but it's also gentler on the whole drive system. This would also let you drive things faster, or reduce the stepper power.
Attachments
OrdBot-Y-Carriage.jpg
OrdBot-Lite-n-Rigid.jpg
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