Roughness of edges when cutting Corian sheets

[drodda]

I have been cutting corian and find that I need to sand the edges quite a bit to get them smooth enough to bond two pieces back together seamlessly. I am using an Alpha with a PC router. Is there any routines that you use to get the edges smooth enough to bond together without touching with a sander first? I.E. type of bit/speed of cut or conventional cut? This also goes for inlays in corian. I am not getting the tight fit that I would expect from Corian.

Any help besides buying a Spindle would be greatly appreciated.

Thanks,

Dave

[richards]

Dave,
What you're seeing may be the 'chatter' problem that has been discussed on the forum. Buying a spindle probably won't help much. (I tried that first. In my opinion, every Shopbot should have a spindle, but it won't cure 'chatter').

What finally worked for me was to add a belt-driven 3:1 gear unit to the X and Y axes. It didn't totally eliminate the 'chatter', but it minimized the problem to the point that I don't complain about 'chatter' any more.

[drodda]

Mike,

Do you have an pictures of your belt drive gear unit setup?

I was hoping that someone who cuts corian alot could help shed some light on cuting tools or speeds.

Thanks for the reply,

Dave

[jeff_guinn]

Dave,
The best way to cut a joint in any solid surface material is to align the 2 pieces on your table at a distance apart less than the diameter of your bit.Cut down the mlddle & make sure you have removed material from the entire surface of both joint faces.You can apply Magic Marker to both surfaces before cutting to ensure both surfaces are completely machined. This setup mirrors chatter or problems with bit not being perfectly at 90 degrees to table. I personally use Belin 0 flute bits & would not exceed 1"/sec on straight thru cuts.Corian contains filler materials & should never gum-up even at high RPM & slow move speeds.

[patricktoomey]

Dave, I cut quite a bit of Corian and unfortunately I have not been able to overcome the roughness of the cuts. I use a 5hp Colombo spindle and regardless of what cutter I use or how slowly I cut, the marks are always there. As Mike said, his gear reduction seems to solve this issue on his Alpha. I have a PRT and I'm changing to an alternate controller, probably the Ascension 1000 to alleviate the problem. I don't know about alternate controllers for the Alpha though, I think the alternate controllers just coming on the market are for the PR and PRT series. Although a few people claim to get perfectly smooth cuts from their stock machines, I haven't seen one that does not make pronounced jagged edges especially in materials like Corian. There have been many different motors, gearing combinations, drivers, etc. used over the years in ShopBots so some combinations must have been better than others. Due to the resolution that the stock controller is capable of creating with its step angles and frequency, this is just a limiation of the stock machine. I've spoken with several people with the new aftermarket controllers who now make perfect cuts requiring no sanding. For wood the stock resolution seems fine much of the time but in Corian it becomes a real issue.

I would say a spindle may be slightly smoother but probably not dramatically so. I use solid carbide cutters, usually compression spirals. The cutters must be used only while very sharp. Once they start to dull a little your joints aren't going to be great. One other thing I do for cutting edges to be seamed together is to use a wavy edge cutter.
http://www.amazon.com/gp/product/B00004T7LG/104-6736721-3672701?v=glance&n=228013
By cutting one side with the bit set at a given depth and then cutting the other side with the bit stepped down half of the wave pattern length, the two pieces can be pulled together and will hold flat together. It also gives more surface area for the adhesive. I do this in the bot and that works fine as long as you're cutting a straight line on the parts (only one axis moving)

[drodda]

The parts I am trying to cut are not straight. They are 8 pieces cut out of corian. If you took a solid round circle with the center gone and cut it into 8 different sections then wanted to glue them back together to get offsetting colors from each piece. So you are dealing with radial straight lines on each end but arcs on top and bottom that don't have to join anything. The joints are straight to each other. i hoope I explained this right? Thanks for the information. At least I know it's not just me.

Dave

[drodda]

The other problem that I am finding is the out of square even as little as is measureable is making cutting a theoreticly perfect circle into pieces and joining them and getting a perfect circle again. There always seems to be some error somewhere that makes the two ends not meet exactly. Any ideas on how to eliminate this?

Dave

[jeff_guinn]

Dave,
Why don't you post a drawing or pic of a finished project & we'll be better able to help?
Jeff

[drodda]

http://www.dkpokertables.com/images/60rnd-1-sm.jpg

The above link is of a table that I made using Wood instead of Corian. Imagine the walnut and ash being two differnt types of corian instead.

I have not gotten one in corian finished so far.

[patricktoomey]

Dave, that does complicate matters. I have my bot squared to the point where I'm a little less than 1/16" out measuring diagonally accross a 48" x 96" rectangle. Even this small amount out of square does indeed cause issues with large circle split into parts as you're doing. I did a segmented 48" table with glacier white and black quartz Corian. While the joints weren't perfect, they were close enough that using the black adhesive there was no visible gap after sanding. Depending on the colors of material you use there may be an issue with perfect matches using factory colors. I use Integra adhesives which are available in thousands of colors matched to any brand and can even be custom matched or you can mix colors yourself if you're brave. Here's a link to Integra if you're interested... http://www.integra-adhesives.com/solidsurface/index.htm

[drodda]

After a lengthy discussion with Jeff tonight we have come to the conclusion that the 12" Z on my Alpha is magnifying my chatter more than those without the 12" Z. Together we worked out a couple senarios that might help to remove some of the chatter. I will keep you posted once I have had a chance to try the fixes. I want to thank Jeff for his knowledge and insight that he has shared with me. People like Jeff are why I bought a Shopbot.

Patrick,

Thanks for the link to the adhesives. I will look into them also. I have been using the corian ones but am still really new to the solid surface world.

[gerald_d]

Dave, to elimate the 12" Z issue, put a (removable) false box on your table to raise the corian up near to the gantry.