Author Topic: Getting started  (Read 970 times)

ggallant571

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Getting started
« on: July 31, 2016, 09:45:44 AM »
I am very new to lasers. Purchased a 5.5W from GearBest. Unit arrived and was assembled with few problems. Test cuts are not very good, actually very poor. Quite comforting to find users on this site experiencing similar problems and then reporting success.

My initial purpose in purchasing was to cut 3mm ABS. Have since expanded goal to other plastics and wood.

I wrote a Linux (my primary environment) program that parses SVG files and generates gcode for the laser. It is OK for now. Work flow is openscad export to SVG then import to cutting tool.

I then found and downloaded BenCutLaser. Played with it without connecting to the laser. I have read the document at least 5 times and find the problems detected and solutions implemented quite interesting. Also have read the "what can be cut" forum posts and will order similar materials.

Observations/Questions:

1. What is the "ideal" distance from laser to work peice?
2. 3mm cuts thru ABS seem to melt and fill in the slot once past 1mm in depth.
3. W\Plywood is charring and the ash remains in the cut. Again at the 1mm depth.
4. Am considering modifying the grbl code to
    a. Automatically reducing the laser power during deceleration to avoid deep burns at 90 degree corners.
    b. Adjust the feed rate based on the angle to the next point (currently doing in host software).

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Zax

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Re: Getting started
« Reply #1 on: July 31, 2016, 10:01:57 AM »
Welcome, and great work on your solution so far. It sounds impressive, and your ideas / goals would be excellent additions too.

Lob0426

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Re: Getting started
« Reply #2 on: July 31, 2016, 10:30:40 AM »
Sounds like you need to play with the focus.

The charring indicates you have too wide of beam or are going too slow. Possibly both. I had similar until I got the focus set properly.

There is no fixed focal length. You have to focus by hand. That is what the "weak" button is for. It is easier to focus using BenCutLaser. It has a focus function in the second tab from the left. It cuts a line then you readjust, cut again, until you get the smallest line possible. You need to do this with a piece the same thickness as the piece you are cutting. It will take several runs to cut through 3mm. You will need to change the focus deeper for each run. There is tool in the forum that connects to the focus ring so you can focus easier during work. @Ralph the writer of BenCutLaser and the Admin of the forum designed the tool.

From what I read some plastics melt back and reattach. A fan may help to cool the plastic during cutting. There should be more info in the forum about cutting for you to read. I am new to this too. Until I played with the focus I had problems too.

Richard
Richard
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Lob0426

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Re: Getting started
« Reply #3 on: July 31, 2016, 10:35:55 AM »
I found the post about focusing tools.

http://benboxlaser.us/index.php?topic=69.0
Richard
A5 2.5W w/homing switches on L7
A5 2W diode self upgraded from stock 500mw
Printrbot Play. Ext bed, integrated tablet control.
Printrbot Simple Metal

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Re: Getting started
« Reply #4 on: July 31, 2016, 11:05:00 AM »
Welcome...!!!
Admin -- Ralph -- support @ BenCutLaser dot us
http://www.BenCutLaser.us/BenCutLaserSetup1.8.6m.exe.zip
BCL Paid license: $39.95
via Paypal to bclpp@primemail.com

ggallant571

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Re: Getting started
« Reply #5 on: July 31, 2016, 12:07:27 PM »
I think the focus is set OK because if I do a single pass with low laser power there is a sharp narrow line cut in the work piece. Plus there is a lot of smoke.

I asked about the distance between laser and work piece because it seems to me the further away the better.

Adjusting the focus between passes is iffy on my setup as the laser dot moves in both X  & Y. I have built a slide mechanism (no motor yet) that holds the laser and I can "adjust" the laser height manually. Controller does not have a Z Axis option but have ordered one that does.
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