Cracking Corian.

[Chief Hill]

Ok Well I have turned 3 corian pens lately. 1 Sierra. Turned out great.
And 2 Slims. BOTH slims cracked right where the Nib and the Final get press fit.
So here is my question.
WHY???
Tubes are with kits 7mm of course. Light sanding on outside, Med Ca to glue in. Insides clean and clear of any debris before fitting. And they still cracked. Not just a little crack a tiny blow out crack where the corian fell out.
Anybody else have issues like this with corian?

 

[hewunch]

Yep, because there isn't any give with corian. I usually get it where the transmission inserts in the lower barrel. Here is what I do.
1. I do not put glue on the part of the tube that will be closest to the middle. I do this by inserting the first part of the tube, applying glue to the tube and not backing the tube out as I insert it.
2. I also ream out the part of the blank closest to each end. By making the hole a little bigger it gives room for expansion.
3. You may want to use Gorilla glue or Sumo to glue the tubes in and or sand down the parts that insert into the tubes a little.
hth

 

[ZanderPommo]

for corian and only corian I use a chainsaw file to loosen the fit and CA in the parts

 

[mick]

Rob, what size drill bit are you using for the 7mm slimlines?. IMHO if you're using a 7mm bit there just isn't enough expansion room and since corian just doesn't give it ends up cracking. I use a 9/32 bit for all my 7mm pens and this gives enough room if there's any expansion of the tube when inserting the fittings. If you feel this hole is too big use a ploy glue and it will expand to fill any gap and still give you some give.

 

[hewunch]

Another option would be to press the parts into the tube before you glue the tube in that way it would be "pre" expanded. Then knock them back out before you glue it up.

 

[workinforwood]

Now, I disagree with CA for corian. I drill corian at a relatively slow speed because it is plastic, but regardless, the hole is always just a hair larger than the tube..it's the nature of the beast. But, since the tube is a hair larger, when the tube expands from pressing in a part, the tube doesn't expand enough to hit the corian. Now if you use CA glue and that completely fills the cavity, then you have a completely hard unforgiving situation. I use Gorilla glue with corian blanks. The gorilla glue expands to fill the cavities for a solid bond and at the same time, the glue has flexibility, so it can be crushed without blowing out. So..CA is possible cause of failure.
Another possible cause is that you are simply not getting a straight push, so if the nib goes in on even a slight angle, it cracks the corian.
Possible cause #3, you have a slight bit of CA getting into the tube, the glue causes the nib to push sideways, cracking the blank
Possible Cause#4, you don't have corian, you have alternate corian..some other brand of similar stuff. Not all corian is the same. Actual corian has a bit of give to it..it's like it has more bondo in it. Many off brand products that pretend to be corian are more brittle, like they have more stone or something in them that causes them to crack easier.
Posssible Cause #5, is a mish mash of all the above.

 

[AceMrFixIt]

I agree with the not getting a straight push. I had to redo one last week due to a crack. Also make sure the ends are trimmed or sanded to the sleeve. I delivered the pen today and the guy dropped it on cement 20 seconds later. He paid and I left, but I think I will fix it if its broke.

 

[seawolf]

I had a similar problem. Now I take the fresh drilled blank and put it in a small pan of water then re-drill it seems the heat of drilling may cause a shrink when the blank cools.
Mark

 

[randyrls]

I mentioned this in another thread, but I had corian slimlines crack on me.

I expand the last 1/4" of the brass tubes. Put a close-fit transfer punch in the tube and twist sideways until the fitting is a slip fit in the tube. Only takes a few seconds. Drill the hole in the blank and check the brass tube fit. Use Polyurethane (Gorilla) glue to glue the blank in. Make sure the glue does not push the brass tube sideways out of the blank. After turning and finishing the blank, put a small dab of Epoxy inside the tube and insert the fittings with a twisting motion. Put vasoline on the joint and upper portion of the transmission so you don't glue the transmission fast. DAMHIKT!

 

[CSue]

I've done a bunch of slimlines from corian over the last 3 years or so. I only use CA to glue in the tubes. I use 7mm or 9/32" drill bit - whatever is handy at the time. There are only two instances when my slimline blanks have cracked or blown. One instance is when I've done segmenting with the corian. The second is when I haven't actually squared the ends. If even a fraction of an inch is overhanging the tube, its going to crack or blow because it can't "give."

I always sand the ends carefully to make sure the ends are squared.