Trick for cutting/engraving acrylic

[bryan henderson]

Hello all

I was wondering if anyone can enlighten me on cutting engraving acrylic. Leave paper on/off, power,speed, air pressure, thickness. I am using a 30W Speedy Trotec with a 2" lense.


Bryan Henderson

[Scott Shepherd]

Engraving or cutting? Engrave with paper off, vector cut with paper on. To vector cut with paper on, you might have to peel paper off, engrave, apply transfer tape, vector cut. You can get away with vector cutting without the paper, depending on what you are trying to do and what your quality requirements are.

[Ross Lowry]

Why vector with the paper on?

[bryan henderson]

What about all the other setting for a 30W machine using 1/8" acrylic for an example????????

[Scott Shepherd]

Why vector with the paper on?

Sometimes without the paper on, depending on what you're doing (thickness, complexity of shape, proximity of next line to burn), the paper will help keep the top surface from getting contaminates on the surrounding area. Nothing worse than burning 45 minutes worth of product only to pull it out of the machine and see the smoke residue has left it's mark all over. Then it's a matter of having to polish that off or clean every single piece.

With the transfer tape on it, you finish cutting, peel the tape off and it's done.

Can't tell you the power/speed for a 30 watt, I don't have one, but my guess would be you could raster it (if it's cast, not extruded), at 100S, 20-25 power, and vector, probably in the 40-50 power, with 5-10% speed. Just a starting point. I'm sure someone with a 30W can give better numbers.

[Mike Null]

I always leave the paper on the under surface to minimize all kinds of marks including bounceback from the grid. This is especially important if you're working with clear acrylic.

Marks and scratches can be polished out but that's a lot of unnecessary work

[bryan henderson]

Mike

Can you give me some starting for settings on this Trotec speedy 30W

Bryan

[Joe Pelonio]

I always leave the paper on the under surface to minimize all kinds of marks including bounceback from the grid. This is especially important if you're working with clear acrylic.

Marks and scratches can be polished out but that's a lot of unnecessary work
I never get any discoloration on the face of clear, but do leave the paper on the back or will have a honeycomb pattern on it.

[Anthony Welch]

Using Dlevies acrylic. I leave both sides paper on. The engraved side is usually color filled.

Where my problem lies is, the tiny ridges on the sides of cuts. I've gotten less of it doubling my speed.

Anthony

[Darryl Hazen]

The lines your talking about are caused by the beam bouncing back up after hitting the honeycomb. Try placing sacrificial material between the honeycomb and the acrylic to have the acrylic stand off from the honeycomb.

[Bob Cole]

Lifting the acrylic off the table .25" will also work.

[Frank Corker]

I always engrave with the paper off. If I am cutting set sizes with no engraving, I leave it on, stops that liquid residue remaining. I also lift my piece off the honeycomb table like Bob has suggested, results in no ticks from the bounceback.

[bryan henderson]

I understand that the foucs point should be approx. 1/3 in from the top of the acylic. Is this what everyone does?

Bryan

[Mike Null]

Bryan

I focus at my lens distance which is 2". It is extremely rare that I take my machine out of focus for my work.

If I'm vectoring thick material I may focus into the material on the second pass.

I know there are a number of members who believe cutting must be done in one pass. I am not one of them.

[Doug Bergstrom]

Bryan,
Do you have a focus tool or autofocus on your laser? Focus varies depending on the lens you are using.

The best answer for your setting question is to test the acrylic with your laser. We all laser the same materials at different settings. Your laser might be slightly different even though the watts are the same, so the setting need to be different.

We take the paper off the top side but leave the paper on the bottom.

[Mike Null]

Bryan

If you're using auto focus double check your focus with the tool to be sure it's accurate.

If it's not accurate call Trotec and they'll tell you how to re-set it.

I manually focus everything.

[Andy Wingfield]

Hi Bryan,

I have some questions for you.
What type and brand of Acrylic are you utilizing?
Have you ever used Rhome Acrylic this is a fantastic product.
What do you have the hertz set at on your Speedy?
What were the power and speed settings you started with?
If you are getting burn back from your honey comb table lower your power it is set to high.
Also you may want to lower your air assist power pressure for a better vector cut result.
If you would like information emailed to you on how to adjust your air assist pump email me please.

Regards,

Andy

[Dave Johnson29]

I understand that the foucs point should be approx. 1/3 in from the top of the acylic. Is this what everyone does?


I have been focusing at the middle of the material. To my thinking the out of focus is shared equally toward the top and bottom.

I am not an expert by a long stretch.

[Jerry Beltramo]

We cut and engrave lots of acrylic. We remove the paper from both sites and have our settings as to minimize any smoke residue or flame up (we have a larger laser so settings will most likely not work for you). A trick we have used for over a year now is that we have cut steel rods to raise the acrylic off of the honeycomb table. These rods are sized to fit through the table. This keeps from marking the acrylic from the under side and has reduced the majority of flame up. This at least works well for us.

[Ray Rouleau]

Can anyone recomend a good adhesive for securing Acrylic?

[Scott Shepherd]

Securing it to what? Acrylic to Acrylic, the Weld-On products are excellent.

[Ray Rouleau]

Sorry Acrylic to Acrylic trying to build up a multi staged plaque.

[Scott Shepherd]

Weld-On #3 (unless someone corrects me). You'll need the applicator for it. It's thinner than water (or as thin), so it takes something with a super fine tip to apply it without making a mess of your project.

[Colleen Williams]

I notice that someone mentioned that you can polish out nicks and scratches from acrylic. Can you tell me what you would use for that and how would I go about it. I have one piece that has a light scratch at the upper edge of it that I can't sell as is but would like to be able to salvage if I can.

Thanks!

Colleen

[Joe Pelonio]

The same places that sell the Weldon also have acrylic polishing materials.

I use the Novus products.

http://www.novuspolish.com/

[Bill Jermyn]

Also, cast is much nicer to cut than extruded. I tend to get a little fire going cutting extruded.

[Doug Griffith]

Also, cast is much nicer to cut than extruded. I tend to get a little fire going cutting extruded.

From my experience, extruded cuts better than cast.

[Levi Chanowitz]

I am deep reverse engraving green edge cast acrylic now and I did not remove the paper. So far it seems ok. I do not see any problem.

Can I paint fill with the paper on?

[Mike Null]

Levi

In my view that's the best way.

[Larry Bratton]

Sorry Acrylic to Acrylic trying to build up a multi staged plaque.
OR Weldon #16. Sixteen is about as thick as syrup. I bought a couple of restaurant style mustard/catsup bottles with the tips. The #16 does not react with the plastic bottle and you have a handy tip for application. #3 is also good, but sometimes you need to put some adhesive down without using the water thin stuff. I keep both on hand. (Sixteen comes in gallon cans for about $75, so you can refill your bottles as needed.)

[Scott Challoner]

I've never had luck color filling reverse engraved cast acrylic. The frosted look of the cast doesn't let the color come through the other side very well. Maybe its just me. Did it turn out Levi?

[Mike Null]

Joe Hayes says he's able to get almost a clear result by defocusing his laser.

[Scott Challoner]

Joe Hayes says he's able to get almost a clear result by defocusing his laser.

I do that with extruded, but didn't realize it would work with cast too. Looks like I have a test to run today.:)

Thanks

[Joe Hayes]

Scott - depending on the acrylic you can get a clear engraving by pulling out of focus as Mike Null said. One example is yesterday I do some that required me to pull out of focus .125" I used two pieces of .0625 stacked on top of my acrylic to focus on. It was crystal clear engraving that I then color filled. The key is to get the beam wide enough and correct power to smooth out the laser lines. It takes a little testing to do this but the results are very good. I also need to remind you that you should refocus before vector cutting your material. You will be out of focus enough that it may not cut well.

Good luck

[Scott Challoner]

Thanks Joe. I'm definately going to give that a shot.

[Levi Chanowitz]

It came out super!!

But remember, I colour filled it with gold and my letters were close to an inch. If I would have done it in black the frostyness would show. I just had a job of reverse colour fill that specks of light that showed through the black. It was a nightmare.

Joe, you said that you took the lens out of focus .125. Dont you find that the letters come out much thicker (bolder)?