Cutting letters out of sintra with the router leaves edges that won't easily paint acceptably. Any secrets?
Posted by Mark M. Kottwitz (Member # 1764) on :
I wipe the edges with MEK, lightly sand the faces with 220 grit paper, and prime with a good quality fill primer. I let that cure, then paint. No problems as of yet with anything I've done.
Posted by Dave Sherby (Member # 698) on :
Ok, I'm just a beginning routerer but could the wrong bit be the problem?
Posted by goddinfla (Member # 1502) on :
We're cutting 1/2 inch sintra with brushed aluminum faces. The customer wants the edges silver also. The edges are rough and porous and don't look good when painted. Filling and sanding all the small letters is a pain. Looking for alternate bits, speeds, or any other tricks.
Posted by Graham Parsons (Member # 1129) on :
Is the porousness (?!) not a feature of Sintra - it is, after all, a pvc foamboard? I don't think even another bit will ever give a perfectly smooth edge due to the cells in the material?
Posted by Donald Thompson (Member # 3726) on :
I use my electric chainsaw with water in it instead of oil.
Posted by David Harding (Member # 108) on :
I don't have lots of expertise with this, but in my experience, acrylic leaves a better edge. What is saved in materials using PVC is eaten up in labor. Of course, if the letters are already cut, my advice is useless.
Posted by Rene Giroux (Member # 4980) on :
Hi Dennis, if the customer wants painted edges, it might just be the wrong material for the job. Or get the customer to pick a color in your Sintra pallet and stick with it just like picking a color of vinyl.
I'm cutting a black Sintra right now and the face of the letter needs to be nice and sharp but the edge touching the wall is less important so I will be using a "downsheer" bit. Cut and blow some air and they're ready to go !
Personnally, I think brushed aluminum faces would look better with black returns. But maybe you can find gray Sintra and the final result would probably be close enough...
Posted by Tim Whitcher (Member # 685) on :
Hey, Dennis. This was posted on the Shopbot Forum:
"I cut 1/2" & 3/4" PVC with .040 brush aluminum as well as painted aluminum all the time.
My favorite bit is the Belin O. Depending on the size I will us a 1/8" to 1/4" CED.
For 1/8" CED single spiral flute: 18,000 RPM @ .4 IPS
1/4" CED spiral single flute 12,200 RPM's @ 1 IPS
Hold down with Home Double Faced Engraving tape. You'll get a nice clean finish.
If you want a clean edge, you don't want to use a down spiral bit because it will trap the chips on your cutting and you will get gouges on the sides of your letters."
Don't know if this is B.S. or not....
Posted by goddinfla (Member # 1502) on :
THe letters are already cut. Didn't know the customer didn't want black edges until the install.
Posted by Dave Sherby (Member # 698) on :
Ouch, that kinda screws things up.
The Belin O flute spiral is a great bit. I just finished cutting 18 four foot letters, three six foot letters and a 19' tall tree out of 11 sheets of Alumalite. The Aluminum edges are perfect. We only had to sand of some loose pieces of the core. DiBond comes off the router with no help needed.
I use the Belin up cut spiral O flute. After cutting all that Alumalite and some DiBond previously, the bit is still sharp as a surgeon's scalpel. The bit has a highly polished spiral backside to the cutting edge.
But I think the others are right that PVC is an expanded foam so the core will not be super smooth with any bit. So now all you have to do is figure out how to paint it.
Posted by Ray Rheaume (Member # 3794) on :
Foam brush and some tapping motions.
Posted by Gregg Parkes (Member # 7710) on :
About the only thing I could suggest is mask with a application tape over the letters and (razor to shape) brush or spray the edges. Then remove the tape.
![[Rolling On The Floor]](graemlins/rolf.gif)
but could the wrong bit be the problem?
![[Cool]](cool.gif)