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Old 11-07-2015, 06:13 AM   #1
PasteMan

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Default Pattern and Plug Building - Epoxy vs Polyester

As the product manager for an extrudable epoxy paste or seamless modeling paste (SMP), I'm always interested in industry feedback on plug and pattern building. More importantly, the pro's & con's debate on polyesters vs epoxy....

And.....go!
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Old 11-07-2015, 04:14 PM   #2
sammymatik

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No real debate is there?

Epoxy is better in every aspect except for price.

Polyester is cheaper and is room temp cure, has high shrinkage, weaker and less durable.

Still I'm sure we've all used polyester. Though epoxy is a better performer if you don't mind added cost.

So your company makes epoxy paste for mold making? Never used that sort of thing except for a small demo thing we did in class. Could be handy stuff for a quick mold.
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Old 11-07-2015, 07:41 PM   #3
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For plug building I would argue that epoxy isn't necessarily superior. Of course if you're just comparing properties then epoxy is better every time, but if we are talking about plug building specifically then I think there's more to it than just the resin properties.

When I'm building plugs I am generally trying to work as quickly and easily as possible. Not only is epoxy more difficult to sand, but it takes a (relatively) long time to cure, so you are drawing out the process. With polyester (ok to be honest I use vinyl ester, but polyester has the same advantages) you can catalyse it hot and get it cured hard enough to start working with again in half an hour. You don't have to worry about measuring out specific quantities, just get as much resin as you need and tip in some catalyst. It's quicker to mix up and you normally have an indicator in the resin so you can tell when it's properly catalysed. It's easier to sand, so shaping is a quicker process.

Its all about speed for me, so the last thing I want to be doing is getting the scales out and wasting time measuring resin and hardener (especially if only mixing a tiny amount where the accuracy needed to stay within 1% becomes excruciating), then spending 5 minutes making sure it's properly mixed, then having to wait at least overnight before I can move on. I'm getting impatient just thinking about it all!
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Old 11-08-2015, 09:10 AM   #4
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Quote:
Originally Posted by sammymatik View Post
So your company makes epoxy paste for mold making? Never used that sort of thing except for a small demo thing we did in class. Could be handy stuff for a quick mold.
Yes sir we do...versions for large and small projects. Feel free to PM to discuss further.

Your point is spot on in terms of speed, durablility, etc....the cost is more up front, but have had experiences that show where the epoxy system saves overall in post rework (labor, time, etc).


Quote:
Originally Posted by Hanaldo View Post
For plug building I would argue that epoxy isn't necessarily superior. Of course if you're just comparing properties then epoxy is better every time, but if we are talking about plug building specifically then I think there's more to it than just the resin properties.

When I'm building plugs I am generally trying to work as quickly and easily as possible. Not only is epoxy more difficult to sand, but it takes a (relatively) long time to cure, so you are drawing out the process. With polyester (ok to be honest I use vinyl ester, but polyester has the same advantages) you can catalyse it hot and get it cured hard enough to start working with again in half an hour. You don't have to worry about measuring out specific quantities, just get as much resin as you need and tip in some catalyst. It's quicker to mix up and you normally have an indicator in the resin so you can tell when it's properly catalysed. It's easier to sand, so shaping is a quicker process.

Its all about speed for me, so the last thing I want to be doing is getting the scales out and wasting time measuring resin and hardener (especially if only mixing a tiny amount where the accuracy needed to stay within 1% becomes excruciating), then spending 5 minutes making sure it's properly mixed, then having to wait at least overnight before I can move on. I'm getting impatient just thinking about it all!
I'm specifically referring to a 1:1 thixotrophic paste thats applied by a metered dispensing machine....large tools (wind, aero, marine, etc). Shore D hardness and really isnt that difficult to sand once (if) machined properly. What kind of epoxy tooling system are you using for your plugs?
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Old 11-08-2015, 07:12 PM   #5
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I think the scale of the patterns being made is the difference here. I do automotive things; radiator ducts, intake plenums, bonnet scoops/bulges etc. Things where I build them on the car.

I can imagine that for the large scale patterns that you would see in the wind/aero/marine industries, epoxy is probably more efficient. Especially if it's being shaped by machine anyway.
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