Anyone cast 1/2" blanks?

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KCW

KCW

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I am curious, because I have been turning slimline pens, and it seems very wasteful to turn a 3/4" blank all the way down to those dimensions. Would there be any problems with making the blank that small? I understand that drilling becomes slightly more difficult and it may take a little longer to cure (without adjusting the MEKP).
 
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KCW said:
I am curious, because I have been turning slimline pens, and it seems very wasteful to turn a 3/4" blank all the way down to those dimensions. Would there be any problems with making the blank that small? I understand that drilling becomes slightly more difficult and it may take a little longer to cure (without adjusting the MEKP).
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Are you going to do it or are you looking for someone else to do it??? If you are doing it go ahead. you don't need anyone's approval. If you are looking for someone who does it I think most will make the 3/4" at least because it appeals to more of the mass and is more economical for them. The amount of resin saved is minimal at best. As far as adjusting Mekp, it goes by ounces of resin used not size of blank. Good luck. Have a great day.
 
Janster said:
Contact Bob at Blanks Slabs and Boards!
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I am looking to cast my own, sorry for the confusion.

jttheclockman said:
KCW said:
I am curious, because I have been turning slimline pens, and it seems very wasteful to turn a 3/4" blank all the way down to those dimensions. Would there be any problems with making the blank that small? I understand that drilling becomes slightly more difficult and it may take a little longer to cure (without adjusting the MEKP).
Click to expand...


Are you going to do it or are you looking for someone else to do it??? If you are doing it go ahead. you don't need anyone's approval. If you are looking for someone who does it I think most will make the 3/4" at least because it appeals to more of the mass and is more economical for them. The amount of resin saved is minimal at best. As far as adjusting Mekp, it goes by ounces of resin used not size of blank. Good luck. Have a great day.
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I am surely not looking for approval, only the wisdom of those that have come before me. I was only asking if anyone had unforeseen issues with this. If you reduce the diameter of the blank from 3/4 to 1/2, it would cut the amount of resin in half, plus some, that is if my math is correct. It was my understanding that the MEKP, sets off a chemical reaction, which induces heat into the material, causing a cure, and the smaller the object being cast, the less heat it would retain in the process. I have experienced this, when casting bottle stopper blanks, but I may be all wrong, I am pretty new to this.
 
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Your math is correct. For a 5" blank .5" diameter, it's about 1 cubic inch. For a 5" blank .75 diameter is about 2.2 cubic inches. As far as it being practical, I couldn't tell you, but I do know PSI sells 5/8" blanks.
 
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Take into account saw kerf

If you are going to do this do not forget to take into account saw kerf regardless if you are using a table saw or band saw if you are only making a 1 inch square you will not get 4 half inch blanks. Just be aware.


builtbybill said:
If you are making square blanks why not just make a 1" blank and cut it into 4 1/2" blanks.
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I've never had a problem casting 1/2" blanks from polyester resin (I live in a warm climate). I've cast as small as 1/8" diameter with no problems curing (I use the recommended 10 drops per oz in Silmar 41). If you found things taking too long to get to full cure in your conditions, you could always resort to heat to help the cure.

I found color swirls don't look as good on the outside as they do on the inside. If I cast too close to my finished size I don't turn away enough of the ugly / plain outside to reveal the good swirls on the inside. But that may have more to do with how I swirl my colors than the size of the blank. A different swirl technique could maybe eliminate the issue.

Drilling shouldn't be any more difficult if you have sharp drill bits with a good profile on them.

Good luck with your casting.

Ed
 
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I don't cast so I can't help with that, but I drill 1/2" square blanks for slimlines and styluses on my lathe with no problems at all. My guess is that it would be difficult to achieve the required accuracy on a drill press. Even if I have to start with 3/4" or 5/8" blanks, I saw them down to 1/2" just to save time turning off the waste on the lathe.
 
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Lenny said:
You could use 1/2 inch I.D. Pvc pipe as your mold. Perhaps a better way would be to get a Resin Saver mold, that way you don't have to drill the blanks as the tubes are already in place.
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That would be the plan (PVC) I have a good collection of molds going, including a resin saver for slims, but you can't get good swirls with them, or I can't at least.

Ed McDonnell said:
I've never had a problem casting 1/2" blanks from polyester resin (I live in a warm climate). I've cast as small as 1/8" diameter with no problems curing (I use the recommended 10 drops per oz in Silmar 41). If you found things taking too long to get to full cure in your conditions, you could always resort to heat to help the cure.

I found color swirls don't look as good on the outside as they do on the inside. If I cast too close to my finished size I don't turn away enough of the ugly / plain outside to reveal the good swirls on the inside. But that may have more to do with how I swirl my colors than the size of the blank. A different swirl technique could maybe eliminate the issue.

Drilling shouldn't be any more difficult if you have sharp drill bits with a good profile on them.

Good luck with your casting.

Ed
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Thank you, that is what I was wondering.
 
I used to slice down two sides of the full size blanks before drilling to save pieces for segmenting and custom center bands. I don't make many 7mm pens any more but occasionally I need one for a request. I use a 3/4" vertical round mold that makes a nice slender blank. Its not as wasteful as a square blanks because there are no corners to turn off. I got it a few year ago here from Fred Wissen, PTownSubbie.
 
JohnU said:
I used to slice down two sides of the full size blanks before drilling to save pieces for segmenting and custom center bands. I don't make many 7mm pens any more but occasionally I need one for a request. I use a 3/4" vertical round mold that makes a nice slender blank. Its not as wasteful as a square blanks because there are no corners to turn off. I got it a few year ago here from Fred Wissen, PTownSubbie.
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That is an interesting idea John, most of my blanks are 3/4" round (started with PVC, then went to one of Fred's vertical molds). I also have the 7/8" x 7/8 x 5 or 6, I might have to use that idea on those.
 
Dan, I have cast 1/2" blanks using PVC pipe with no problems. Since you are dealing with smaller blanks a good idea is to drill them on the lathe to assure a perfect drilling. Good luck.
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turncrazy43 said:
Dan, I have cast 1/2" blanks using PVC pipe with no problems. Since you are dealing with smaller blanks a good idea is to drill them on the lathe to assure a perfect drilling. Good luck.
___________________________________________
Everyday I'm vertical is a great day
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I do drill on the lathe, but my lathe is kind of a piece of junk, so it is not guaranteed that it will drill straight.
 
I tried 1/2 PVC and wasn't real happy with the results. My tip, for sure use some mold release. The polyresin doesn't seem to shrink as much in the 1/2 pipe and can be a bear to get out.
 
79spitfire said:
I tried 1/2 PVC and wasn't real happy with the results. My tip, for sure use some mold release. The polyresin doesn't seem to shrink as much in the 1/2 pipe and can be a bear to get out.
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Those are the things I was curious about, thank you for your reply.
 
When I started casting my own blanks, I made smaller blanks with the same idea you have. The issue I had was most often not having enough material to correct a mistake either when turning or drilling. The extra bit of resin saved was not worth the extra time wasted fixing a blank or starting again. I only make 3/4" blanks now
 
MikeinSC said:
When I started casting my own blanks, I made smaller blanks with the same idea you have. The issue I had was most often not having enough material to correct a mistake either when turning or drilling. The extra bit of resin saved was not worth the extra time wasted fixing a blank or starting again. I only make 3/4" blanks now
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Thanks for your response Mike. I still have not decided if I will waste my time with casting the smaller blanks, I like the idea of having a blank that I can make into any pen I want. It was just an idea that came to me, when I was turning a recent batch of slimline pens (which are not my favorite to turn) and noticed that I was turning more than half of the material away, before I even got to the relative size I was looking for. I will keep this in mind.
 
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