NEJE Diode laser success with Hobby Lobby FB

[hunterdave99]

After a good bit of experimenting, I finally had success with my diode laser and Hobby Lobby black foam board (black paper and a black core). My laser is the large Neje 3 Max with the A40640 laser head. I clean up the plans with Inkscape and burn with Lightburn software. The lightburn auto detects the different colors and sets up a different cut for each color. For a full cut I go 3 passes, 100% power, at 6000mm/min speed. For a score cut I go 2 passes at 70% power, same speed. For a shallow score (like a blue line on a wing) I go 1 pass at 50% power, same speed. If I just want to cut the paper (like for peeling it) I go 1 pass at 25% power, same speed. Finally, if I just want to leave a reference mark on the paper without cutting it I go 1 pass at 15% power, same speed. By keeping the speed real high, it prevents the laser from lingering and reduces melting. It only takes a couple minutes for a full sheet. All cuts are with air assist.
Cost: the hobby lobby foam is $2.99 per sheet but it is worth the cost for the convenience.
Weight: it is a little heavier. I weighed 5 sheets each of Hobby Lobby black, Dollar Tree black with white core, and regular DTFB. The DT black weighed 103.4 grams. The regular DTFB weighed 112 grams. The Hobby Lobby black weighed 158.2 grams. I made up some of the weight by adding holes to internal sheets such as wing spars and doublers (see pictures).
Strength: this HL foam seems a little stronger. The paper adhesive seems a little stronger as well. It also takes spray paint as long as you go multiple thin coats. See the picture of the canopy that I painted. Blue painters tape sealed well and was easy to peel off.
For my first plane I tried Airc-Pirate's 50mm EDF Goshawk. Overall it turned out pretty good. I call it the "Bat Jet" I will have to wait till spring for the maiden.
Here are quite a few pics.

 

[Old and rusty]

Wow, took a quick spin around the Internet today looking at foam board to see some of the other brands available...the vast variety, as well as the price differences were somewhat staggering. So far I've only used the Dollar Tree Adams foam board (white), but lately have been wondering if some brands were superior to others. Went from the Adams DTFB all the way to the 16.00 (on sale) per sheet Gatorboard, (which, hands down looked the best to me) and pretty much everything else in between. At one time had thought the different brands were all actually the same just carrying different labels...but couldn't have been more wrong about that.
I think I'll go middle of the road price wise next time and check out some of the Hobby Lobby black foam board at 2.99 per sheet and see how that goes.

 

[Mr NCT]

Wow, took a quick spin around the Internet today looking at foam board to see some of the other brands available...the vast variety, as well as the price differences were somewhat staggering. So far I've only used the Dollar Tree Adams foam board (white), but lately have been wondering if some brands were superior to others. Went from the Adams DTFB all the way to the 16.00 (on sale) per sheet Gatorboard, (which, hands down looked the best to me) and pretty much everything else in between. At one time had thought the different brands were all actually the same just carrying different labels...but couldn't have been more wrong about that.
I think I'll go middle of the road price wise next time and check out some of the Hobby Lobby black foam board at 2.99 per sheet and see how that goes.

I used the Hobby Lobby board on my first simple cub because you can get different colors. I didn't realize a the time the weight difference, the Hobby Lobby is almost twice as heavy per sheet. It didn't increase the overall weight by double but it did make it tail heavy.

 

[Old and rusty]

I used the Hobby Lobby board on my first simple cub because you can get different colors. I didn't realize a the time the weight difference, the Hobby Lobby is almost twice as heavy per sheet. It didn't increase the overall weight by double but it did make it tail heavy.

View attachment 244022 View attachment 244023 View attachment 244024

Like the idea of different colors...guess it would depend on the type of paint, but do you think the plane constructed of the HL heavier foam board would weigh more than a fully painted plane made with the Adams foam board? Did you use clear tape over the colored covering? Is the HL foam board much sturdier...I appreciate the info.
...the cub looks great, by the way
...

 

[Mr NCT]

Yes, the HL board plane was heavier than the DT painted plane.
Didn't use clear tape on the HL, somewhat sturdier.
The simple Cub is prone to tip stalls if you don't keep your speed up in turns and my first two (second was DT painted) died in dramatic manor this way. I skinned my third one with printed paper skins and finally learned to fly it.

Skin - Rasterize Skins for the FT Simple Cub

The FT Simple Cub is one of the most popular FT models out there. It's a great plane and fun to fly. And there is so much history to the Piper Cub and all of its variants. Here are seven cool skins for you to use and put some spice into your FT...

forum.flitetest.com

 

[TOMinSATX]

Found this thread looking for some leads on cutting foam for a build I'm busy designing parts and molds for. The refs in the lead post gave me some answers that I tested this evening. I've got a 12.5watt Creality Falcon 2 laser cutter and like others I've messed with cutting different foam boards including one experiment to black paint (water based) the Dollar Tree black papered white foam after stripping the paper. The result was a very messy cut through, at any power and speed settings. This last week I bought two sheets of the Hobby Lobby black foam and spent more that a little time stripping paper. I'll be doing some plug framing with the paper on, but the end product will not have paper so that's why the effort.

I'm attaching some photos of my second test run looking for the best speed and clean cuts. The first picture shows the results from the front and the second from the back after taping the pieces together and flipping over left to right. The results indicate that I can use 6000 mm/min at 60-75% with two passes and get a clean cut. I'm guessing I can increase the speed some and still be good. My measurements on the stripped foam get a .165"/4.20mm thickness. I'll be doing an accurate weight test later. I'm hoping that this information will help some others. BTW I do have a 300CFM exhaust system on the laser cutter hood that vents outside the garage.


Added Notes:

I weighed a panel of the HL foam that is 15.15" x 15.15" (229.5 SqIn)
(This was sized to fit my Laser cut limits)
and got these results..
60.61 grams with 2 sides w/paper
44.52 grams with 1 side w/paper.
28.42 grams with no paper.

In order to get a best assumption on weights for future estimates...
Actual weight measured on a 20"x30" piece was 158.4 grams or 0.264 g/SqIn.
Based on sample weights:
Full sheet (20x30) should weigh
With Paper = 158.4g
Subtract Paper = 84.1g
Net Weight = 74.3g (0.1238 g/SqIn)