PDA

View Full Version : Routing 1/4" plexiglass edge...What am I doing wrong?


yoki32
12/13/2009, 05:39 PM
Hi there,

Alright here is my problem. Hope anyone can give suggestions. I started cutting some plexiglass pieces for my overflow box today and ran into a problem with trying to trim plexiglass with a router. My router is a 3 1/4 HP and is table-mounted. I had to cut two pieces that were less than 3 inches long so I had to drop the option of using my jointer to trim the edges so I decided to try my router instead.

The router bit I used is a 3/8" Bottom Flush trim (Freud #42-100). As soon as I started pushing my piece towards the bit, the plexiglass started to be trimmed but with splinters spitting here and there and not the usually hairy white hair like on my table saw. I finished cutting the piece and what a disaster!!! The edge was all irregular and not smooth at all. Now I'm wondering wheter I don't have the right bit or my router speed is set too high. I scraped that piece and don't wanna to scrap my other pieces once i'm done bonding my pieces. I took a look at melevsreef.com and the router bit he was using was the same that i'm using. I'm fairly new in using a router so I would appreciate anyone's suggestion on what I may be doing wrong.

Thanks again, much appreciated. :rolleyes:

Hilken
12/13/2009, 05:43 PM
I hope this isn't a stupid question cause it sounds like you know what your doing with a table mounted router, but could you have fed it from the wrong direction? Is this a bit with a bearing on the bottom?

Paul B
12/13/2009, 05:45 PM
It is a carbide tipped blade isn't it?

troylee
12/13/2009, 05:47 PM
couple of things...the first has been mentioned running it the wrong way...second is taking to much off at a time...run it threw your table saw with a 1/16th left to trim on the router then it will come out nice and smooth...
the third is it might be crappy material that is a big factor...;)

yoki32
12/13/2009, 06:04 PM
OK the bearing on the bit is on top and no I did run it the right way :) Humm....I tried trimming off 2/8". Should I be trimming in multiple passes then and less wide?

yoki32
12/13/2009, 06:05 PM
I forgot to mention that the edge on my other pieces come out perfectly shiny with my bench jointer so I think the quality of the plexiglass is okay...

yoki32
12/13/2009, 06:07 PM
I left 1/2" on the front and back pieces of my box. I mean:

1/2" trim + size of piece + 1/2" trim

Should I be using a 1/2" Flush trim bit instead?

TAB
12/13/2009, 06:19 PM
Sounds like your trying to take off too much at a go or your going the wrong direction. I tend to cut things a 1/8" over sized so I can remove about a 1/16" of a inch from each side. the feed direction is the opposite what it if your using a router in the normal position as it is now upside down. on a clockwise turning router, in the normal position you move it from left to right. In a router table, you move it right to left( as now the bit is spining counter clockwise from your perspective)

tat2shawn
12/13/2009, 06:20 PM
Sounds to me like you are tring to take too much material off at once. 1/8th overall would be fine to work with then you can take off 1/16th off each side.

iamwrasseman
12/13/2009, 06:21 PM
dont depend on the router to remove alot of matieral but precut the plexi and then trim with the router .troylee has it right and i would follow his or my instructions . one other thing ,always inspect your bit and be sure its sharp and not chipped or deformed in any way .

yoki32
12/13/2009, 06:27 PM
OK tomorrow I will try that...it's a brand new bit btw. Yes, I did run it from right to left. I'll try to get some pictures if it still doesn't work on how I am setup...

Thanks guy, much appreciated!

yoki32
12/13/2009, 06:27 PM
OK tomorrow I will try that...it's a brand new bit btw. Yes, I did run it from right to left. I'll try to get some pictures if it still doesn't work on how I am setup...

Thanks guys, much appreciated!

yoki32
12/14/2009, 09:09 AM
One other thing...I don't think the blade is carbide tipped...is carbide tipped meant for plastic?

Paul B
12/14/2009, 10:04 AM
Yes it is, it makes a big difference. Steel router bits are made for wood, plexiglass is much harder and will ruin a steel bit in no time. A carbide bit is probably 4 times the price. I built a lot of my furnature including my bed from plexiglass and carbide bits make a nice smooth cut

Acrylics
12/14/2009, 11:01 AM
I dunno, I'd need to see the set-up before drawing any real conclusions. With that router, you should be able to take off more than the 1/8". I'll commonly take off far more than that, but I'm also using much bigger cutters (1.5" diameter.)

Off hand, I'd say your router bit itself is too small. Shavings will often bind in a cutter that small causing some chatter, simply because a bit that small cannot clear that much in the way of chips/shavings. And if the amount being cut off is more than half the diameter of the cutter (3/16" in this case) - it can start to grab. If you have a larger diameter cutter - might help.
FWIW, IMO leave the router speed as fast as you possibly can - usually 21,000rpm or so on a 3+hp router.

If you could post a pic of your set-up plus the finished product, it would be helpful.

James

yoki32
12/14/2009, 05:44 PM
Hey Acrylics!

You are correct!!! I've tried 3 bits this morning...I retried the 3/8" flush trim bit and same result. So I decided to try the 1/2" bit and noticed that the edge was much smoother so I decided to try the 1/2" and the edge was very smooth just like using my jointer! The wider the bit the better edge you get. What if I buy a 1" Top Bearing Flush Trim bit, will it be even more smoother?

Now I have another question, my bottom piece of my overflow is 1/2" wider and 1/2" longer. My front and back pieces are 1/2" longer. Once all assembled, I will need to trim away the 1/2" edge. Can I do this on a table mounted router or do I have to use the router by hand. Should I remove the fence on my table router and move my overflow box by hand around the bearing of the bit? What would be the best method to do this? I really don't want to scrap my box!! Any pictures would be appreciated!!

Acrylics
12/14/2009, 05:59 PM
What if I buy a 1" Top Bearing Flush Trim bit, will it be even more smoother?I'd say no, don't buy a large diameter flush cutter. IME, once they get above 1/2" - the balance is all out of whack and the cutters are awful. If you want a 1" diameter straight cutter, just get a 1" diameter straight cutter :)

Now I have another question, my bottom piece of my overflow is 1/2" wider and 1/2" longer. My front and back pieces are 1/2" longer. Once all assembled, I will need to trim away the 1/2" edge. Can I do this on a table mounted router or do I have to use the router by hand. Should I remove the fence on my table router and move my overflow box by hand around the bearing of the bit? I'd do it on the router table, I do it all day, every day. A little trick for you though is to wrap a piece of masking tape (double thick if you like) where the bearing would go and make a rough cut that way. Then, when finished with this, unwrap the tape and then flush cut with the bearing directly on the plastic. Just keep certain the bearing is spinning freely on the cutter before flush cutting. Bearings can freeze and scar the plastic if you're not careful.

HTH,
James

yoki32
12/14/2009, 06:34 PM
Great tip!! I didn't even think about that! Do you remove the router fence when you flush trim the edges on the router table?

Acrylics
12/14/2009, 06:56 PM
Great tip!! I didn't even think about that! Do you remove the router fence when you flush trim the edges on the router table?
You got it, remove the fence when flush cutting this stuff :)

yoki32
12/14/2009, 06:57 PM
Many many thanks man!!!

shikhyung
12/15/2009, 08:26 AM
A little trick for you though is to wrap a piece of masking tape (double thick if you like) where the bearing would go and make a rough cut that way.
James
Don't get it. Can you show a pic? Thanks.

Acrylics
12/15/2009, 08:44 AM
Don't get it. Can you show a pic? Thanks.No pics, sorry. But here is the brief rundown:
Before you flush trim your parts, place a piece of masking tape on the work where the bearing would ride. This way the bearing is rolling on the tape rather than the acrylic. When finished with this, remove the tape and flush cut as normal. This last cut will only be about .005" so there won't be as many shavings getting in your way.

Hope this makes sense,
James

hebygb
12/15/2009, 09:03 AM
That last tip was as good as gold. Thanks James.