Routing Lexan

[GAC05]

Hi all,
Looking for some tips on getting good results chamfering the edge of thin 1/8" or 3mm Lexan (Home Depot).
I need to put a clean 45-degree edge on it that I can use to join 2 pieces with some acrylic solvent cement.
I have a DeWalt cordless trim router with a carbide 45dg edge trimming bit set in a table I made, with a solid fence to guide the material into the bit.
With just trimming the edge and not cutting into material this thin, is the rule of thumb slow spindle and slow feed or go fast on the spindle rpm to get a smoother result?
I ran a few test scraps but I don't know what I am doing just yet. The Dewalt can go from pretty slow to scary fast. At high speed, I feel like I need to count fingers after each pass to make sure they are all still there.
The router seems to cut best when going from right to left with the bit poking up through the table. The other way wants to grab and launch the material off the table.
This is the end of the moon project so I don't want to screw up the faces with the finish line in sight.

Thanks for reading

 

[Gino]

According to how much you need to do, could you do it with a table saw ??

 

[GAC05]

According to how much you need to do, could you do it with a table saw ??

I dunno - I don't have a table saw but the seams are pretty short - 12" to 14" long. I need a tight fit so the glue doesn't run out of a gap & ruin the face. Once that acrylic cement burns into the face there's no do-over. Using a straight edge to edge butt joint seemed to work, was hardly noticeable but was not very strong. Figured the 45 would give more surface area for the solvent to weld the two together.
I just want to get this done so I can think about something else - like figure skating.....

 

[Gino]

How 'bout a table-mount disc/belt sander ?? Run it along the sander's table on a 45º angle.

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[GAC05]

How 'bout a table-mount disc/belt sander ?? Run it along the sander's table on a 45º angle.

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Might work, I do have a handheld Ryobi belt sander and some duct tape. Will think about this in the morning - thanks Gino.

 

[Rocco G]

While I've not done it with lexan that thin (scary thin almost), we used to often do a half-lap joint with a rabbeting bit in a hand held router on 3/16" and 1/4" acrylic and polycarbonate. Carbide cutters are a must but you said you have one. IIRC I spent $90 on three fluted rabbeting router bit about 25 years ago and it still cut cleanly the last time I did this. 45 degree or half lap, go into the direction of the bit turning, or it can get away from you. If the router wants to pull the material away from you, you are going the wrong way. Plus perhaps two/three passes are needed so you don't ruin the cut. And of course do some practice cuts to get the speed/feed rates dialed in. I don't have adjustable speed router so we did it full speed. YMMV As an alternative, maybe find someone with a CNC machine to do the cutting? Best of luck with it!

 

[GAC05]

While I've not done it with lexan that thin (scary thin almost), we used to often do a half-lap joint with a rabbeting bit in a hand held router on 3/16" and 1/4" acrylic and polycarbonate. Carbide cutters are a must but you said you have one. IIRC I spent $90 on three fluted rabbeting router bit about 25 years ago and it still cut cleanly the last time I did this. 45 degree or half lap, go into the direction of the bit turning, or it can get away from you. If the router wants to pull the material away from you, you are going the wrong way. Plus perhaps two/three passes are needed so you don't ruin the cut. And of course do some practice cuts to get the speed/feed rates dialed in. I don't have adjustable speed router so we did it full speed. YMMV As an alternative, maybe find someone with a CNC machine to do the cutting? Best of luck with it!

Thank you for the feedback.
Now that I am not holding the router by hand a tiny lap joint might be doable.

 

[Jester]

For speeds and feed rates on acrylic (or any other material) there are CNC calculators. They will give you an idea of where to start with your trim router. cnccookbook.com offers a free trial of their excellent calculator. Set it up as if you have a Shapeoko 3 router table, as this can use a Makita trim router.

 

[citysignshop]

I dunno - I don't have a table saw but the seams are pretty short - 12" to 14" long. I need a tight fit so the glue doesn't run out of a gap & ruin the face. Once that acrylic cement burns into the face there's no do-over. Using a straight edge to edge butt joint seemed to work, was hardly noticeable but was not very strong. Figured the 45 would give more surface area for the solvent to weld the two together.
I just want to get this done so I can think about something else - like figure skating.....

I'm not a pro fabricator, but done my share....first question is; what are you making? Sounds like you need this perfect joint. ok. Lexan comes in rolls, so perhaps it would make sense ( next time) to avoid the joint. A bevel on a 1/8" joint is not going to add much strength over a simple butt joint, so why bother? Route the edge clean and straight, put packing tape on the face so the glue CAN'T run thru, use a thickened glue like weld-on #16. Scrape off the excess ( squeeze-out) when dry. Stressing this thin joint past a few degrees is likely to crack any glue joint, so I hope it's supported while further fabrication/installation is going on? good luck!

 

[Raum Divarco]

Hi all,
Looking for some tips on getting good results chamfering the edge of thin 1/8" or 3mm Lexan (Home Depot).
I need to put a clean 45-degree edge on it that I can use to join 2 pieces with some acrylic solvent cement.
I have a DeWalt cordless trim router with a carbide 45dg edge trimming bit set in a table I made, with a solid fence to guide the material into the bit.
With just trimming the edge and not cutting into material this thin, is the rule of thumb slow spindle and slow feed or go fast on the spindle rpm to get a smoother result?
I ran a few test scraps but I don't know what I am doing just yet. The Dewalt can go from pretty slow to scary fast. At high speed, I feel like I need to count fingers after each pass to make sure they are all still there.
The router seems to cut best when going from right to left with the bit poking up through the table. The other way wants to grab and launch the material off the table.
This is the end of the moon project so I don't want to screw up the faces with the finish line in sight.

Thanks for reading

for smaller quantities on hand routers and table saws i often sandwich the material i want cut as best i can between "sacrificial" materials.
so i have firm pressure on both sides as i run it through.

 

[GAC05]

Thank you all for the feedback - some good stuff in here to consider.
As far as the how and why:
I pretty much had to work with what was available locally at the time. No oversized sheets of Lexan and only SCIGRIP #4 for the cement.
The client was in a hurry and didn't want to wait for materials to be shipped in by ocean. Then this little thing called Covid came up in the news and the bottom dropped out of our tourist industry.
We are just now starting to get visitors back in here and they want to get it done now.
Some issues:
I did glue up the panels' edge to edge and we took them to the site for a test fit and to check the lighting. I made a sturdy crate (heavy) to carry them to the frame (these are about 8x6). Due to a miscommunication, I did not know how far we would have to carry it to get to the top of the hill overlooking the ocean they put the moon on. It turned out to be a trek on par with the journey to Mordor in LOTR for the 4 of us. If I was 30 years younger I would have rachet strapped the crate to my back and run up the hill by myself, but those days are gone. A 3rd party snapped both joints on one of the faces moving the frame to set the slab. When I went back up the hill to recover them we walked them down without a frame (one guy for each face) without snapping the second one. My thinking was to try to make the joints a little stronger as it will be a prop for people to sit on and although the joints are high & low away from the seat I know the face is going to get bumped and most likely kicked. Not sure that I can add a brace as it is backlit and they want the seams as invisible as possible. I am thinking I will brace each end of each seam that will be hidden by the trim holding the panels in place. The machine shop is going to deliver the finished moon-can soon so I'll post up more (even if it is a disaster).

The interesting thing about the visitors - many of the first are coming here on vaccination tours from Asian countries.
Come in, get a shot, stay in our hotels - not sure if they are sticking around long enough to get the second dose but the hotels and restaurants are picking up. I am sure Guam is not paying for the vaccines so I don't know that selling/giving them to tourists is on the up and up but it is happening.

wayne