Removing blanks from PVC

[Daddy1]

Is there a trick I'm missing? I can't get the PR blank out of the PVC. I have tried using a hammer and punch with no success. IT WON'T BUDGE! What am I missing?

 

[TBCbushings]

Hmmm, I have had no problems knocking them out...You can use cooking spray as a mold release from what I have heard...

 

[Daddy1]

I'll give it another shot tonight and see. Does thecooking spray go on before I cast or used after as I try to get them out?

 

[KenV]

Cooking spray or other mold release is used BEFORE casting.

 

[Brian G]

Pound harder? I use a 3/4" dowel to push them out, but most of the time the cooking spray release doesn't require much effort.

I spray a sheet of paper towel with cooking spray and then pull it through the PVC. You don't need much for it to work as a release.

 

[PSNCO]

How long after pouring went by before you tried to pound them out?

How cool was the area that you let them set up in?

How many drops of MEKP per ounce?

 

[SDB777]

I'm betting the tube is slightly bent from the heat during the cure.....how many castings in the tube you used?



Scott (it's not sticking to the PVC) B

 

[Dan26]

Maybe you could put it in the freezer for an hour then take it out to warm up. I don't know how much difference in shrinkage of materials there would be but if all else fails...

Another option, although I use it as a last resort, is to lay it on a concrete floor and tap along the pvc as you roll it. I've lost a couple of bkank this way but, again, if all else fails...

 

[pianomanpj]

If all else fails, mount the mold between centers or in a collet chuck and turn the PVC off the blank inside!

 

[ed4copies]

Kevin,

If it makes you feel any better, I never did have great success with PVC. AND I have tried turning it off---NOT FUN!

Thankfully, Dawn was willing to cast in square molds and I cut them apart with the bandsaw.

LOTS of people have said PVC works great!! NOT for US!!

Hope you find a solution.

 

[BSea]

Try using a heavy screw driver to tap the sides of the pvc (I use a hammer handle without the hammer attached). You can tell by the sound when the PR releases from the pvc. At 1st it sounds very solid, but when it releases, it sounds different. Sort of like the difference a clear bell sound, and a cracked bell. This works for me more than 95% of the time (probably around 98 to 99%), and I've done thousands.

And how long did you wait till you tried to get them out? If you did it too soon, you may have slightly expanded the blank in the pvc. This is just speculation on my part. Normally I have no trouble, but there have been times that I've had to split the pvc using a dremel to get the blank out.

Another method I've used is to use a clamp with a small piece of split pvc in line with the pvc with the blank in it. Then using a short piece of dowel, I've pushed out the blank by tightening the clamp. I hope that makes sense. If not, let me know, and I'll take a picture of how I do it.

I don't have a good explanation of why this happens. It seems to have something to do with the temperature when the blanks cool. I seem to have more trouble in the colder months.

 

[Daddy1]

Went home last night and beat the hell out of the PVC and it eventually came out. I am using a Michael's boxed set of PR. I will try the cooking spray next time. I can't wait to get the silicone molds. Here's the finished product. My first Steam Punk pen I posted it on face book late last night and got two orders right away! I guess it was worth it.
The PVC was new and straight, It was cast in approx. 70 degrees, and I tried to remove in about 70 degrees.

 

[gabriel-rivera]

Not trying to hijack the thread, but I had the same problem with not being able to get the blanks out of the PVC, and I did notice that the PVC was slightly bent as well... I thought that I may have used the wrong casting resin, still not sure I didn't..lol...after 2 days I finally got one of the blanks out of the PVC and it bends, is that normal or did I do something really wrong. YouTube made it look so easy.... Any help would be greatly appreciated.

 

[PSNCO]

If the tube is bent you may have to leave it out in the sun/heat for a long enough time to try to bend by hand the PVC straight. Or, you can try to cut the PVC off or turn it off.

 

[its_virgil]

I am not a fan of PVC used for molds. Some have good success while others do not. I never did. I am a big fan of silicone rubber molds (or what ever they are made from). Using the correct tools makes jobs much easier: molds made for casting polyresin and colorants formulated for use with polyresin are just two examples. Seems that a majority of the casting questions deal with what to use for molds and what to use for coloring...will this work? what about that? Anyone tried this stuff? Just saying.
Do a good turn daily!
Don

 

[BSea]

Not trying to hijack the thread, but I had the same problem with not being able to get the blanks out of the PVC, and I did notice that the PVC was slightly bent as well... I thought that I may have used the wrong casting resin, still not sure I didn't..lol...after 2 days I finally got one of the blanks out of the PVC and it bends, is that normal or did I do something really wrong. YouTube made it look so easy.... Any help would be greatly appreciated.

Are you saying the blank bends? If so, you may have used something to color the blanks that doesn't work well with the resin. My 1st question is what resin did you use?. Next, what did you color it with?

I have had some blanks that would be soft right after getting them out of the tubes, but not after 2 days.

 

[gabriel-rivera]

Are you saying the blank bends? If so, you may have used something to color the blanks that doesn't work well with the resin. My 1st question is what resin did you use?. Next, what did you color it with?

I have had some blanks that would be soft right after getting them out of the tubes, but not after 2 days.[/QUOTE]

Yes, the blank itself would bend, like a noodle. the ends were fairly hard, but the rest of the blank was soft.
I bought the resin at Hobby Lobby and it's called
"Amazing Clear Cast - 2 Part clear coating and casting resin" as for the type of dye/pigment, I used Jacquard Pearl EX Powdered Pigment.
I was finally able to get one of the blanks out of the PVC, and it was soft. I could press my thumbnail in and it would leave an indention, but would relax and even out after a few minutes. I read in another thread to go to Wood Whimsies and just buy the casting resin he sells by the gallon. I think I may do that...not really happy with the results I have gotten so far, but hey you have to start somewhere...

 

[Skie_M]

Is it the stuff that's meant to imitate water, for a tabletop plant still-life feature? That doesn't harden up very well ...

If not, then perhaps you didn't use enough hardener, or didn't mix it in long enough? The pearlx shouldn't really affect your resin's curing.

 

[ironman123]

I use Simlar 41 in PVC tubes and punch them out one end with a wooden dowel with a tap from a mallet.

 

[SSobel]

For those of you having trouble with PVC and want to make your life easy...you need one name. Fred Wissen, aka PtownSubbie. His Silicon molds are THE best!

he has a 6 hole 3/4 vertical round, and a 6" square mold if you wanna cut them up...and a hundred in tube molds!

PTownSubbie.com - Silicone Molds