Cutting 1 inch thick acrylic

[Walt Langhans]

Hey guys

Is anyone cutting 1 inch thick acrylic with their laser, and if so how powerful of a tube are you using? I've got a customer who is asking for some custom work that needs to be pretty precise, so I don't want to use a table saw.

Thanks!

[Joe Pelonio]

I can only tell you that with my 45 watts 1/2" takes 2-3 passes. I know someone with 100 watts that can cut it in one pass but he leaves the paper cover on both sides or it will discolor and there is a definitely noticeable angle to the cut.

[Rich Harman]

I cut 3/4" in one pass at about 4mm/sec. Edges are straight, but not as straight as you would get with a table saw. If it can be cut with a table saw I would do it that way slightly oversized then sand down. It doesn't really take long to get a polished edge.

[Braden Todd]

I cut 1" and was told I could do 1 1/2" thick if I wanted to push it. I am using 400 watts for this, gives a nice polished straight edge with my 5" lens.

[Kev Williams]

Cutting most any material 1" thick "precisely" with anything less than several hundred watts of laser power likely isn't going to happen.

Cutting 1" thick acrylic with a table saw isn't fun either!

I made some mold casting 'pushers' awhile back out of 1" thick delrin. Several different sized squares with different radius corners, and they had to be nearly a press fit within the molds. I used an 1/8" 2-flute endmill with a 1-1/4" cut height and cut with my tool machines. I had to run them in several passes but the final products turned out great.

I couldn't have lasered delrin anyway, but had they wanted plex, I would've used the same method...

[Walt Langhans]

Thanks guys! You always steer me in the right direction :D

[John Blazy]

come on Rick! you know very well that polishing acrylic is way more work than a laser cut edge! gotta razor scrape / and / or sand the edge, pull cords out for the disk sander, then change pads for the buffer, then follow with machine glaze, or just leave the white rouge edge with just wiping. WAYYY more work than our yummy laser edge !!!


Ive been buffing acrylic for years, and what a dream to have a laser to leave an edge you can ship "as is". No offense, Rich - just bustin yer net 'nads.

[Rich Harman]

... and what a dream to have a laser to leave an edge you can ship "as is". No offense, Rich - just bustin yer net 'nads.

I made about a dozen 3/4" thick acrylic name plates not long ago. The lasered edge was "acceptable" but not what I considered to be a professional look. After I was done (with sanding and polishing) they looked like blocks of crystal, the laser just can't do that - and it really didn't take as long as I thought it would.

[John Blazy]

You are so right about that Rich! After buffing, nothing compares. I have a 3/8" thick acrylic hall mirror right now that I want a polished roundover. It pains me to take my router to the laser cut edge, since that edge looks so nice as is, but nothing like after I polish the roundover.

Whats your method of polishing? I razor scrape the saw marks and/or wet sand with 800 or 1000 (or use 3M Trizact blue discs (about 1500 grit) - structure abrasive - cuts fast due to the grooves eliminating hydroplaning), then white rouge, then machine glaze (3M Perfect it - 40 bucks a bottle, but worth it). Sometimes I dry sand with 320, then use heavy cut compound on a cotton drum, then machine glaze. The heavy cut really takes sand scratches out.

[Paul Phillips]

When I have to polish Acrylic It's usually coming off the CNC with a nice clean finish pass, I use a 6" air DA sander and hit it with 400 grit and can then go right to my bench mounted 12" buffing wheel using plastic buffing compound, within a few minutes I can have it looking flawless, i.e., if your properly set up to do it, it should be quick and easy!

BTW, I can get through 1" Acrylic with my 120 watts and a 2.5" lens but the results are not acceptable, the edges are not clean and straight, I always use my CNC if I can.

[David Somers]

Hey everyone! Curious where flame polishing fits into your acrylic finishing? Sounds like it might not, at least for those of you who have posted in this thread so far?
I do little acrylic so far, mostly utility stuff rather than finished work for display so I am curious.

Thanks!

Dave

[Rich Harman]

Whats your method of polishing?

I rarely do anything that requires polishing. In that instance I just used a progression of sanding starting with 60 or 80 grit all the way down to 1000 or 1500, followed by some polishing compound (probably Meguiars) - using the machined surface of the table saw as a work surface.

[John Blazy]

I just today flame polished a bevel on a few mirror frames in exotic rope mottled Anigre veneer laminated onto 3/8" acrylic. I milled the bevel on my jointer (should have used my router table with a 45 degree chamfer bit), then scraped the edge with a utility knife blade, then flame polished for immediate results. Since the laser cut edge is essentially flame polished, the chamfer looked pretty good melted into the laser cut edge.

This post is in answer to Dave Somers about flame polishing. It is not nearly as perfect as abrasive polishing, but is plenty acceptable if done right. Sometimes I use my plastic welder to "flame" polish - it has plenty of heat to melt the face, but without the actual flame of propane, it comes out smoother, and doesn't bubble the surface.


Flame polishing also creates a bulged edge - the expansion of the melted surface creates a lip. Machining, then buffing will not deform the surface, to machine buffing is superior if the project allows this added time and expense. Otherwise, flame polishing is awesome.

Just remember to never clean the edge with any solvents besides mineral spirits.

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