Benbox Laser Machines/CO2 Lasers/3D Printers

General Category => Projects => Topic started by: Agastar on October 22, 2016, 01:01:39 PM

Title: House Elves On Strike
Post by: Agastar on October 22, 2016, 01:01:39 PM
Well, I think I finally got it dialed in to something acceptable. Now, to go replace all the wood that ended up being test pieces lol.

Feed Rate: 1800
Resolution: .1
Width: 149mm
Height: 115mm
Power: 0-255

Image Processing: I removed the white background from the text and cut out the house elf leaving a transparent background. The house elf's contrast was adjusted to -20 to bring out some of the lighter tones and the image was saved as a png file.

Wood processing: I forgot to sand the wood before engraving but I will do that on the rest of the pieces. A light sanding will bring out a little more detail.

Hardware: The laser module was custom built with an M140 laser diode that is currently set to 2000mW and is being driven by the PWM/TTL laser driver I designed.

Other Notes: The house elf was engraved separately from the text but the machine and T2L settings were the same for both.
Title: Re: House Elves On Strike
Post by: Zax on October 22, 2016, 01:56:57 PM
Looks very nice!
Title: Re: House Elves On Strike
Post by: ggallant571 on October 22, 2016, 02:47:16 PM
Go to Wal-mart and get some of the 4x6 neon index cards. About $0.88 for 100. They are perfect test material. The surface color burns off with very low power. You still have to adjust for the wood in the end but they sure save a lot of wood.
Title: Re: House Elves On Strike
Post by: Agastar on October 22, 2016, 03:04:31 PM
Thanks!

I'll grab some of those cards. Only problem is wood is hard to get right unless you have the same wood to dial in the settings with.
Title: Re: House Elves On Strike
Post by: ggallant571 on October 22, 2016, 03:19:26 PM
I am etching the elves at speed 1800 and power setting 6 out of 255 with unfocused beam. This is my second attempt, first failed because the text was backwards. Never noticed that x direction invert was asserted. Don't use the grbl firmware very much anymore and everything else apparently didn't matter.
Title: Re: House Elves On Strike
Post by: Agastar on October 22, 2016, 04:57:47 PM
Cool, I'd like to see what you come up with.
Title: Re: House Elves On Strike
Post by: ggallant571 on October 22, 2016, 06:29:11 PM
She Who Must Be Obeyed likes it. I took your original and tried to clean up around the lettering. Gave up and erased the existing letters and then used the text entry on gimp to replace the words. Looks ok on the screen up not etched, at least on cardboard. Took about 20 minutes. I think the pixel to mm conversion is wrong plus the power was too strong.
Title: Re: House Elves On Strike
Post by: Agastar on October 23, 2016, 04:50:32 PM
Yeah, I didn't even think about cleaning up the lettering. Before I took out the background I adjusted the brightness a little and that helped make the lettering darker.

Here are the final two images I used combined into one. You can see how much I darkened up the house elf lol.
Title: Re: House Elves On Strike
Post by: ThothLoki on January 14, 2017, 11:21:58 AM
ok. So I tried to do this one.
Last night, I took my engraver apart, flipped my x axis, greased up the wheels, tightened all bolts and tightened all of the belts. I did focus the laser as well. If you look at the picture labeled "full picture", you will see the difference between when I has the x axis going in reverse and when I finally found the setting to correct that.

The other two pictures are closeups of the lettering that shows the difference between the two burns.

For timeline purposes, I started the reversed burn and then found the menu. I stopped the burn, reversed the x axis in T2L and started again.
My questions is, why are my lines so wavy?
Title: Re: House Elves On Strike
Post by: nottingham82 on January 14, 2017, 11:37:27 AM
I had wavey lines once. Switched to diagonal engraving and it went away.
Title: Re: House Elves On Strike
Post by: ThothLoki on January 14, 2017, 11:43:39 AM
I will give that a shot and report back.
Title: Re: House Elves On Strike
Post by: nottingham82 on January 14, 2017, 12:09:17 PM
It happened when I went to a new firware.  .9 is still my favorite.  although When I'm testing its nice to be able to up the speed on the fly.
Title: Re: House Elves On Strike
Post by: Zax on January 14, 2017, 12:13:51 PM
The wavy lines are most likely caused by incorrect belt tension or some slop in the axis.

Diagonal engraving and using 0.9g will both mask the problem. Grbl 1.1 is faster with the motion so makes it appear worse, in the same way diagonal actually moves slower since 2 axis are being used to get the same feed rate.
Title: Re: House Elves On Strike
Post by: nottingham82 on January 14, 2017, 12:14:59 PM
sure blame the craftsman and his tools and his lack of tool maintenance and the computer next to his tools....

he is not wrong though.

You would be proud zax.  Just yesterday I re-tightened all the belts and screws.
Title: Re: House Elves On Strike
Post by: Zax on January 14, 2017, 12:18:05 PM
Well my first thought was his machine got in the alcohol cabinet.
Title: Re: House Elves On Strike
Post by: ThothLoki on January 14, 2017, 12:23:45 PM
no Zax, my machine is too young. That cabinet if for ME!

I was going at 1800 horizontal. theoretically, slowing the speed down should help. I will try that and diagonal.
should I go back to 0.9 then instead of 1.1?
Title: Re: House Elves On Strike
Post by: nottingham82 on January 14, 2017, 12:26:59 PM
soo yeah 1800 could be the culprit along with a loose belt. 

I like my engravings to actually remove about a mm of wood.  So I go slow.  Usually 750 with air assist so it wont catch fire and tape so the smoke doesnt burn the edges.  But that's just me.  I like it to look almost like I routered it.
Title: Re: House Elves On Strike
Post by: ThothLoki on January 14, 2017, 12:36:11 PM
The belts don't feel loose. I just tightened them. Outside of some tensioning instrument, what is the best belt tension guage method do use?
Title: Re: House Elves On Strike
Post by: Zax on January 14, 2017, 12:43:19 PM
Sorry, no scientific method. It's more of a feel thing, light finger pressure with around 1/4" deflection.

Are you sure the axis are tight, no side to side play or twisting?

You can slow down to see if it improves (it should) and also drop the acceleration / deceleration values which helps too, but all these are "workarounds" for an underlying mechanical problem.

If nothing else, get into that cabinet and the lines may look straight!
Title: Re: House Elves On Strike
Post by: ThothLoki on January 14, 2017, 03:42:03 PM
ok. so here is my second version. I think it turned out a lot better. You know how it is a good idea to make one change at a time? Well, here is what I did (all at once):


I think it turned out good. I plan to make a sign that will max out my A5 machine, but that won't be until next week. It is still -5* and a heat wave is coming. It will get up to 20-30*F (yay) so I should actually be able to stand it in my garage.
Title: Re: House Elves On Strike
Post by: Zax on January 14, 2017, 03:46:30 PM
It still looks a bit drunk, try reducing the accel/decel.

Enable debug mode so you can send manual commands, then type:

$120=200.000 [press enter]
$121=200.000 [press enter]

If it's a belt tension issue you should expect improvements, if not then it's something to do with the axis or the laser is loose etc.
Title: Re: House Elves On Strike
Post by: nottingham82 on January 14, 2017, 03:46:51 PM
you might consider doing the sign in slate.  I did one for my gf's sewing room door.  I think it turns out cool.  Wood is a good medium too.   
Title: Re: House Elves On Strike
Post by: ThothLoki on January 14, 2017, 04:28:43 PM
@Zax I agree. It still is a bit drunk. I will look into it a bit more and see what happens. It may have to wait until later this week. What "wheels" do you use for your axis? The ones I have are the basic white wheels that came with the machine. I wonder if that could be part of the problem.

@nottingham82   That sounds like a great idea! now if I could just get my laser engrave to stop getting into my liquor cabinet!!!
Title: Re: House Elves On Strike
Post by: nottingham82 on January 14, 2017, 04:32:51 PM
only thing with slate is that its dark so make sure its in a well lit area.  In a dark hallway its not very noticeable.
Title: Re: House Elves On Strike
Post by: ggallant571 on January 14, 2017, 05:08:03 PM
I stated etching the plant leaves. Nice aroma and it keeps them in their pot.
Title: Re: House Elves On Strike
Post by: Zax on January 14, 2017, 06:13:12 PM
Mechanically my machine is stock, so the same white wheels.

@ggallant571, I think you're confused. The leaves were pot!
Title: Re: House Elves On Strike
Post by: ggallant571 on January 14, 2017, 06:56:58 PM
I will have to add them to "what can be cut" list.
Title: Re: House Elves On Strike
Post by: ThothLoki on January 14, 2017, 07:26:40 PM
Pot and lasers.......sounds like the makings of a rave
Title: Re: House Elves On Strike
Post by: ThothLoki on January 15, 2017, 12:13:09 PM
It still looks a bit drunk, try reducing the accel/decel.

Enable debug mode so you can send manual commands, then type:

$120=200.000 [press enter]
$121=200.000 [press enter]

If it's a belt tension issue you should expect improvements, if not then it's something to do with the axis or the laser is loose etc.

I am going to do this today. What are the default values?
Title: Re: House Elves On Strike
Post by: Zax on January 15, 2017, 12:40:22 PM
I use 800 as defaults, but 200 was the default in previous versions (Grbl 0.9).
Title: Re: House Elves On Strike
Post by: ggallant571 on January 15, 2017, 03:04:20 PM
I use home-brew firmware with zero acceleration at 900 to 1200 mm/min. If it needs acceleration, I modify at the host application to start early and overshoot on the horizontal lines.
Title: Re: House Elves On Strike
Post by: Zax on January 15, 2017, 03:46:11 PM
I'm sure you're thinking of something else, as zero acceleration = no movement   :-\
Title: Re: House Elves On Strike
Post by: ThothLoki on January 15, 2017, 04:30:23 PM
Thanks. I made the changes. It did not have any noticeable effect. At high speeds my line is very wavy. At low speed, my line dips in the middle. I will post pictures and hopefully video of my x axis later. I am going to start a new thread for this as this is getting off topic from the thread name.

It is only my x axis that is having trouble. My Y is straight as an arrow.
Title: Re: House Elves On Strike
Post by: ggallant571 on January 15, 2017, 06:25:55 PM
I should have said it has no acceleration profiling. Start/Stop only. I have raster etched letters such as "H" and examined under magnifying glass. No visible deviation with the start/stop points. I guess this would be equivalent to a very high grbl accel value.