Buttom-up dlp firmware complication

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Herant
Posts: 2
Joined: Thu Jun 30, 2016 1:39 pm

Buttom-up dlp firmware complication

Postby Herant » Thu Jun 30, 2016 8:18 pm

Hello,

I'm currently working on Buttom-up DLP printer for my school project. I've been doing some reasearch for a while now and simply step by step ordering the parts i need for this project. Finally i just finished the mechanical built of the machine, well not great looking one but you its a prototype so its supose to be fast and ugly.
After uploading Marlins firmware to my arduino shield ramps 1.4 (The DLP version of course) and enabling z-min i saw that the movement were really strange. I'm currently using CreationWorkshop and when i ran some dry tests with it the z-axis went up until it hit the z-min, after that the image were projected to my screen for about 10sec or so then it went down for about quart of an inch and then back up but not all the way to the z-min. Trough the whole test it went up and down like this until it finished and went up til it hit the z-min(home position).

From its behavior it seemed to me like the code were meant for a Top-down system and not Buttom-up, even tho the z-axis went to z-min which is the upper limit in my case and started to print right after which is kinda strange. I went through the code to see if i activated the wrong end switch but after playing with it for while i realized that the z-max is doing nothing even if it's set as "true" and activated in code.
I had another thought about this, maybe i positioned the stepper motor that drives acme-rod in the wrong position according to the code, mine is placed at the buttom which means when i drive motor to the Z-home in CreationWorkshop it goes counter-clockwise which means up. For this i tryed to invert the stepper motor inside the code but it still was wierd with all that jogging up and down thing it did.

From what i've seen in others people projects or the retail printers the process with Buttom-up printing supose to go down to the vat until it hits the endstop so it knows that the printing bed all the way down, then it starts to project the image for awhile and after that it goes up and down minus the layer hight until the process is finished and then all the way up to the upper limit switch. Correct me if i'm wrong here, but that what seems to be the logical operation for me atleast.

Since I'm at very beginning stage of learning c++ so i only went through the code i recognized, maybe there is something else i had to change i don't really know, thats why i came to you guys.

I was also thinking about writing my own very short version of the code but it seemed rather impossible because of how complicated Merlin code looks, i know alot there is made in general for loads of different boards and parts but even finding right pins to run Stepper_oneRevolution made my head hurt.

So what do you think i should do?
Last edited by Herant on Mon Jul 25, 2016 9:34 am, edited 1 time in total.

Herant
Posts: 2
Joined: Thu Jun 30, 2016 1:39 pm

Re: Buttom-up dlp firmware complication

Postby Herant » Sat Jul 02, 2016 8:53 am

Here i made a video to give you guys a better understanding what i am struggling with

https://www.youtube.com/watch?v=F42rNil1iwU&feature=youtu.be