Drilling in winter

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ed4copies

ed4copies

Local Chapter Manager
Joined
Mar 25, 2005
Messages
24,757
Location
Racine, WI, USA.
Last year, we got a few questions about blanks, mostly polyresin, cracking from the inside.

As time went on, we kind of isolated the cause to cold weather drilling and the effect cold has on polyresins.

Anyone who wants to "chime in" here, it will help others THINK about the temperature differential and perhaps save them a few blanks.

Also, we should accentuate the importance of sharp DRILL BITS, too. We talk about "scarey sharp" tools, then drill with very dull bits that can ruin the blank before it gets to the lathe!!

Comments welcome both personal experiences and scientific explanations.

Thanks!!!
 
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I have a cold shop. I do run a construction heater while I am in the shop, but I keep my supplies in the house where it's warm. I bring my blanks out to the shop, cut to size and drill in groups no bigger than 10 pens. I do all m gluing in the house. I take out to the shop what I can turn in one hour, leaving the rest in the house. The shop heater takes the edge of the extreme cold, but I seldom get it warmer than 40-45F.

Hope that helps
 
My only cracking and breaking incidents with PR has been when I rushed the glue curing. It cures much slower in cold weather...

Once I started turning the blanks the next day or so (usually a week, actually) after gluing them, and using sharper tools, I haven't had much troubles...

Given that my house is set to 58, and my shop is in the much colder basement, I doubt you'll find anyone turning at colder temperatures than me, but as Ed says, YMMV
 
I also have to wonder if the age of the blank affects the tendancy to crack in colder weather. Does Pr become more brittle with age?
 
mredburn said:
I also have to wonder if the age of the blank affects the tendancy to crack in colder weather. Does Pr become more brittle with age?
Click to expand...

I don't think so. I have some blanks I purchased when acrylester was "new", probably 1998???

The problem with answering your question is, I was not a great turner when I did them at that time. So, if I turn them now, I would expect no difficulty---will try it in the next couple weeks.
Thanks for the suggestion!!
 
I am with you Tom (tbfoto). It has dropped into the LOW 70's in my shop lately. I had to close the garage door! I will get through. No problems with PR cold cracking, even in this harsh environment!
 
Ed,

I've never had a problem with cracking. I don't store my blanks out in the cold shop though, but instead in the turning dungeon that is around 55-58 degrees in the winter.

I would think that a blank being drilled, whether cold or warm, is still generating rapid heat build up, but with a cold blank, the rapid heat increase would be like dropping an icecube in hot water... it's going to crack.

If anyone wants to send me some of the blanks in question, I would be happy to run some unbiased tests. :biggrin::wink:
 
when it is cold here in TX I lay my blanks out on a table that has an infrared heater above it and let them warm up for 1 hr. by this time they may be hot in the hand but they will drill with no problem
 
Unless you have a few thousand more blanks than I have, you can make a nice "pen blank" cigar humidor for just a few dollars. A few sheets of OSB, a Halogen work light (maybe 2, up north) and a cheap thermostat set at 70 degrees will take care of most pen blank weather issues, IN THE WINTER.

IT GETS A LITTLE MORE EXPENSIVE in the summer in the South, trying to keep them under 100 degrees and under 80 percent humidity.
 
My pen shop is about 50-60 in the winter and I have never had any problems with PR. I usually let the CA set for at least 12 hours before doing anything ( although I do not think I would have any problems other than perhaps the tube slipping)
 
Ed, here is my thinking. We need to find out form the manufacturer that at what temp. the PR will mess up or if after it's processed to a casted item at what temp. would tooling will effect it then maybe we can try to bring the blanks to that temp before we start drilling or tooling them. In many threads in the past I've read that avoid excessive heat to PR blanks as that would cause blow out or cracks, so those temps. were experimental as the members tried them in their shops and never any actual temp was mentioned, now we need that answer for the opposite spectrum so we know at what temp. they will crack, and what's the ideal temp for working with them. Now, Dozer mentioned that if it's too cold and you start drilling and the heat generated form the friction will cause the cracking like ice in a hot water.
 
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