# Trouble with cracking Corian



## hump3366

I have turned some corian pens and and have a crack were the transmission is located.  Not there when made but was there after delivery to my first customer.  Luckily a friend who works with the product commercially.  CA or filler can be used but not after delivery to the customer.  Maybe having a larger hole in the material at the top? Any help would be great as a local countertop company would like to use these as gifts for clients.  Thanks.


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## denaucoin

I only have trouble with the cracking you describe when I put the transmission in, I think because it is not lined up straight.  I also have been making the transmission end a little thicker and this seems to help.


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## nativewooder

Many materials, while being drilled (especially with dull bits) will heat up and expand.  Over time, I have learned to double check after cooling to make sure the bit will still clear the hole.  If the hole seems a little too big, epoxy glue will solve that problem.  Many experienced pen makers do not use the suggested drill sizes but instead measure the parts with calipers and pick the next size drill bit to work with.


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## jd99

I have found, that if you pre-assemble the components before you turn it reduses the cracking after they are turned and assembled.

In other words drill the blank glue in the tube, and square the ends, then I assemble, and disassemble the nib, and final and use a plug I made to size the end for the trans, then turn and polish and do final assembly


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## PTownSubbie

JD brings up a point I never thought of before. Sounds like something that can be done. 

Another thing to do is chamfer the ends where the parts get pressed in. Even though the crack doesn't happen immediately, a chamfer reduces the stress at the end and hopefully that prevents a crack from forming on the ends.... It works for me.

The cracking a brittleness also depends on the corian style. It could be that it is not even corian but some other solid countertop material.....


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## reiddog1

Yea, I totally agree with PTown, but would also watch out for any glue that may be hiding inside the tube.  A small round file works wonders.  Hope this helps.

Dave


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## hump3366

Thanks all of the suggestions help.  I new the group would help.


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## ghostrider

I really haven't anything to add to what the others have said. 

I've done quite a few solid surface pens (most of them 7mm pens), and this has happened on my fair share of them. Sometimes I'll glue it, some times I'll take a little more off the end if I initially cut it long, other times I'll just start over. I do know that it's important to check for any glue residue before mounting any of the hardware, and then there is the issue of not pressing them in straight. 

Solid surface materials tend to be very hard, and this can result in them being a bit on the brittle side, however, this can happen with any acrylic or even wood. It's just another one of those things we have to watch out for.


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## jd99

I'm working on a new method for corian pens; its just a theory right now, but here's my thinking.

99% of the corian pens I do are 7mm also (Streamlines).

When I do the next batch, I'm going to make a tube clamp so I can hold the tube with out damaging it, and I am going to try assembling then disassembling the Nib, Final and sizing for the trans. as I mentioned above. but it will be before I glue the tube into the blank. Hence the need for the tube clamp.

My thinking is that this will hopefully size the tube and still leave it small enough after disassembly for the components to still be press fit enough to hold together.

I'm thinking that because the press fit on the components can some times be more then other times it is the expansion of the tube during the assembly that is cracking the corian, if the tube is already sized close to the the size that it will be expanded to before gluing into the blank there will be no cracking. 

But on the flip side the components might be loose. I won't know until I try this theory. I guess I could use loctite.

I'll post my findings after I do a few.


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## randyrls

Danny;  When I am doing 7mm corian, I use a transfer punch on the last 1/4" of the bare brass tube and with a twisting motion, I expand that portion of the tube.  I make a sliding fit with the components.   I glue in the tube, turn, and polish as normal.  Then when assembling, I put a drop of medium or thick CA on the inside (IMPORTANT!) of the tube  and put the pen together.  You can insert the transmission and ink cartridge at the same time because the pressure needed is slight.  Put it in with a twisting motion.  The Corian doesn't crack and the assembly is easy.


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## Wood Butcher

Corian, or any other solid surface material, will not flex when sized as thin as we do it.  If the parts are tight it will crack. DAMHIKT.
WB.


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## Ruby pen turning

reiddog1 said:


> Yea, I totally agree with PTown, but would also watch out for any glue that may be hiding inside the tube.  A small round file works wonders.  Hope this helps.
> 
> Dave


If it is a 7mm tube, a 1/4" drill bit will fit inside the tube to get rid of any glue in there. any glue in the tube of any pen could and usually will crack the blank.


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## jd99

randyrls said:


> Danny; When I am doing 7mm corian, I use a transfer punch on the last 1/4" of the bare brass tube and with a twisting motion, I expand that portion of the tube. I make a sliding fit with the components. I glue in the tube, turn, and polish as normal. Then when assembling, I put a drop of medium or thick CA on the inside (IMPORTANT!) of the tube and put the pen together. You can insert the transmission and ink cartridge at the same time because the pressure needed is slight. Put it in with a twisting motion. The Corian doesn't crack and the assembly is easy.


Thats sounds good, but I'm hopping to not have to use any glue or loctite for assembly, I hope that the tube will size enough to leave a slight press fit, I've measured the nib and Final's and on some of them there is a .005" to .007" pressfit, thats a lot of press fit, Corian wont stretch at all let alone that much.

Just thought of this...... 
Another thing to try might be to counter drill the ends down about 1/4" 7mm is .2756" maybe counter drill with a K .2811" or 9/32 .2812". Might be enough room to let the glue compress , but not put pressure on the corian.

I have a full set of reamers (Number, Letter and Fractional), I think I'll try that also but instead of drill just ream the ends out down a 1/4" from the top. Never know that might work, and the tube sizing before gluing won't be required.


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## PTownSubbie

Oh...Just remembered one more thing I do when I press fit the parts.....

I press the part very slowly! Press just a little bit...very little movement....rotate the piece 1/4 turn and press again....just a very little bit....rotate the piece 1/4 turn and press again....just a very little bit..... until fully inserted.

I think this gives the material a chance to slowly accept the changes that we are forcing upon them with the press fit that takes place. 

Whether or not this makes a difference, you have to prove to yourself but I can tell you I haven't cracked a blank since I started using this method. I make many slims for a guy that owns a countertop business so I have made many and until I decided to press them with this method, I cracked a couple with each batch....YMMV


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## jd99

I haven't had one crack since I've started doing the preassemble before turning either, but I would like to not have that step as it is time consuming. 

I think the counter-drilling might be a good trick, but I'm out of Streamlines right now I need to get another order in to try it.

Let you know

Oh and I move a lot of Corian also, they are good sellers, I'm on my second order of 200 blanks. :biggrin:


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## DonWood

I have problems with corian cracking when I use Gorilla Glue to glue in the tubes due to the expansion of the Gorilla Glue - So now I just use Epoxy or CA (prefer Epoxy since it gives me some working time before it sets).


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## timhoman0351

Have worked with Corian counter tops for a few years,fabricating and installing.Corian is a very brittle acrylic that can be thermal formed and glued.Expanding glue should only be used in tube to body assembly and left to cure for a day(until expantion has stopped).Flaring tube ends and sanding out tube hole to fit for flared tube is the best.Its the pressing to a tight fit that makes them crack.This is the only time I would use CA for assembly of parts.Corian will soften with heat and will become brittle and shrink a little when cooled.May try soaking in hot water before pressing to fit if not using the flaring method.Just a thought...


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## randyrls

jd99 said:


> When I do the next batch, I'm going to make a tube clamp so I can hold the tube with out damaging it, and I am going to try assembling then disassembling the Nib, Final and sizing for the trans. as I mentioned above. but it will be before I glue the tube into the blank. Hence the need for the tube clamp.



Danny;  I don't do many Corian pens any longer, but I developed a technique that works.

Insert a close-fitting transfer punch about 1/4" into the tube end and twist the punch in a circle until the fittings are a slip fit.  Drill blanks with a slightly larger bit than normal.  Use PU or other expanding foam glue.  Turn as normal.  Put a drop of CA or Loctite inside the tube and put the fitting on with a twisting motion.  CA can cause fogging during the out-gassing process, so make sure you leave the pen open.

Hope this helps.


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## Drstrangefart

I found the just tapping the transmission in gently with a vinyl hammer lets me adjust it and straighten it during assembly and doesn't introduce too much stress at once. You can also cut the lip on the inner edge of the tube down a bit with a razor before pressing the transmission in to kelp keep the stress load down.


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