Problems with PRE-echo on models

[ednisley]

problem with setscrew then we should get the model smaller size than it should.

The relative motion between the shaft and pulley caused by a loose setscrew depends on far too many factors for that to be always true. The effect isn't necessarily linear and definitely not predictable.

I know, because I once thought I understood what was going on and was totally wrong. [grin]

Have you taken the pulleys off, verified that the shafts aren't scarred, and secured the setscrews with threadlock?

you can't get the pre-echo in this way.

Any disconnection between the commanded motor rotation and the actual platform motion will cause inconsistent results as the platform accelerates and decelerates, because that will put the nozzle in the wrong position. Because the motors continue to have the proper position, the overall model will be correct, but the details will come out wrong.

The most obvious cause is a loose pulley setscrew, but that's not the only possible mechanical problem.

Check for:

• Loose belts: if they're not taut, they're too loose
• Loose belt clamps
• Loose / sticking idler pulley
• Loose or binding linear slides (unlikely, but possible)

Look at it this way: other people have successfully printed your model on MakerGear M2 hardware, using similar software and firmware, without encountering the same problem. The G-Code shows nothing that would indicate a model defect, so there's almost certainly a hardware problem between the motors and the platform on your printer.

I have a small poster above my workbench to remind me how to find problems:
http://debuggingrules.com/?page_id=40

In my experience, the most important rule is Quit thinking and look. I can always find a reason to avoid testing an inconvenient section of a circuit, because it can't possibly have any effect, but that's usually where the problem lies.

Keep looking... [grin]

[DenysNazarenko]

Hi Ed,

Please read forum more carefully, other people also has the same problem. Please take a look at the photos with red arrows. I assume that your printer is tuned fine and should print without problems?

If so, please find the model in attach , rotate it by -90deg by X to make the holes horizontal and print as slow as possible to avoid machine vibration.
I waiting your photos of the details. This will helps define reason of the problem.

Happy holidays to everyone

[jimc]

The echo that you pointed out on my pictures is totally different. You will not fix that and you will find that on almost any 3d printer to some degree. as i said previously,its the vibration from a direction change which travels through the hardware. If you are seeing some type of artifact BEFORE the move then that is not an echo. It is a totally different issue.

[ednisley]

other people also has the same problem.

You have shown that the problem on your M2 occurs shortly before the nozzle reaches a corner. That's not the same as the slight mechanical resonance / ringing that occurs after the nozzle goes around a corner, which is what appears in the photos of models printed by other people.

I've suggested several causes of the problem you're seeing. Let us know what you find as you work down through the list; well-focused closeup photographs will be helpful to show mechanical details.

Other than that, I have nothing further to offer...

[DenysNazarenko]

Hi Ed,

Our discussion is difficult since I try to provide evidence, photos, theory but from your side I see only your opinion. You even don't want to print the model to understand that you also has the same problem. On given moment I find the solution - I ask for refund for the printer. But we can continue the discussion since I'm very interesting to find the reason of the problem but I need the prof not the words.

The relative motion between the shaft and pulley caused by a loose setscrew depends on far too many factors for that to be always true. The effect isn't necessarily linear and definitely not predictable.

I use very simple model of line and square and it's complicity predictable at last for engines.

You have shown that the problem on your M2 occurs shortly before the nozzle reaches a corner. That's not the same as the slight mechanical resonance / ringing that occurs after the nozzle goes around a corner, which is what appears in the photos of models printed by other people.

No. Other people also has the problem before every corner but they think that "mechanical resonance".

Please explain how mechanical resonance can create this picture, step by step please -

Echo2.jpg (57.5 KiB) Viewed 8996 times

The true is that all you have problems with pre-echo and close the eyes on this and think that is the mystical "mechanical resonance" but you can't proof that is mechanical resonance with slow printings. btw. other printers models don't have this problem and any mystical "mechanical resonance". Of course I see the true "mechanical resonance" that appears on very height speed and it's looks bit different.

[jimc]

Well i have printed the model and what you are pointing to in the pictures i will repeat again is very common with most printers. Some more than others. Unless you plan on paying $4-5k for a well built core xy machine you are goig to get this. Again if its happening before the move then its completely different problem and not what the arrows are pointing to. I think you need to look around a bit and see the prints from other machines in person. You will see it on all of them unless the print is specifically printed super slow to make a print to avoid this in pictures. You are going to be quite disapponted with whatever printer you get. Good luck to you.

[DenysNazarenko]

Hi Jim,

Sorry but problem not related to the well built. I think the problem related to firmware that try to stop extruder before the finish of the line to avoid "mechanical vibration" but M2 not tuned correctly and printer do this before it really should do this. Some other printers don't has this problem. I will prof this on the next week. (even cheap Chinese)

My prof (not _words_) -

Pre-Echo prof1.jpg (90.93 KiB) Viewed 8988 times

Pre-Echo prof2.jpg (85.68 KiB) Viewed 8988 times

[DenysNazarenko]

Hi Everyone,

My explanation of well built and setscrew problem. as you can see you will get completely other picture in result.

Pre-Echo prof3.jpg (127.92 KiB) Viewed 8984 times

[jimc]

Ok for the 4th and last time. The extruder stopping to extrude before the end of the line is mot an echo and has nothing to do with the arrows you pointed on my print. The firmware is marlin and the same firmware most printers use. The only thing that stops an extrusion before the end of a line is a setting in s3d called coasting.

[DenysNazarenko]

Hi Jim,

seems you even don't _want_ understand me I don't tell about extrusion. I tell about movement of the extruder as coordinate point.
Just open your mind and step inside ©fight club

yes. we try connect M2 to Arduino Mega instead RAMBO and get the same problem. But we use same firmware - marlin. The company who use other firmware have a different results. Why MakerGear don't want to finish tuning of own printer and continue tell the story about vibration and well built I don't know

I can bet 300$ that other printer that cost less than 1700$ will print this model without problem