Looking for a hard durable plastic......
Looking for a hard durable plastic......
(OP)
Hello everyone,
I have been looking for a hard durable plastic for a few weeks now searching the internet and calling a few places and noone has been able to fully answer my questions so I figured I would try to pick your brains for a while.
What I want to build is an auger out of plastic that will be used to drill into sand by hand, simular to the one pictured below. I want it to be strong, stiff, and maybe a little flexable. I do not want it to be able to shadder, I would rather it flex and bend than shatter.
This will about a 5-6 foot shaft about 3"-4" in diameter with "threads" or "blades" like an auger on three feet of one side of the shaft. The auger "blades" will be about 4" wide and will be about 1/8" thick near the end tapering to about 3/8" where it spirals around the shaft.
It will be used to be temporarily set in the sand and will be spun by hand, only about 3'-4' of the shaft will be going down into the sand. The plastic needs to be durable enough to be able to drill though sand. If the ground is hard packed dirt or clay then the product should not be used in it.
From what I have learned so far I think I would prefer a thermaset plastic? (so that I do not have to heat it and pour it in)
Or maybe some sort of epoxy? Not sure about epoxy, because the epoxy that I have used (to build a small wooden sailboat) was very hard and didn't have any flex to it.
What I hope to do is make a mold of a current metal auger out of a silicone rubber like GI-1000 (http://www.silicones-inc.com/gi1000.pdf). Then use that rubber casting as a form to pore my plastic/epoxy into to make my plastic auger.
So can anyone give me a suggestion or point me in the right direction?
Any advice or guidance would be greatly appreciated!
I have been looking for a hard durable plastic for a few weeks now searching the internet and calling a few places and noone has been able to fully answer my questions so I figured I would try to pick your brains for a while.
What I want to build is an auger out of plastic that will be used to drill into sand by hand, simular to the one pictured below. I want it to be strong, stiff, and maybe a little flexable. I do not want it to be able to shadder, I would rather it flex and bend than shatter.
This will about a 5-6 foot shaft about 3"-4" in diameter with "threads" or "blades" like an auger on three feet of one side of the shaft. The auger "blades" will be about 4" wide and will be about 1/8" thick near the end tapering to about 3/8" where it spirals around the shaft.
It will be used to be temporarily set in the sand and will be spun by hand, only about 3'-4' of the shaft will be going down into the sand. The plastic needs to be durable enough to be able to drill though sand. If the ground is hard packed dirt or clay then the product should not be used in it.
From what I have learned so far I think I would prefer a thermaset plastic? (so that I do not have to heat it and pour it in)
Or maybe some sort of epoxy? Not sure about epoxy, because the epoxy that I have used (to build a small wooden sailboat) was very hard and didn't have any flex to it.
What I hope to do is make a mold of a current metal auger out of a silicone rubber like GI-1000 (http://www.silicones-inc.com/gi1000.pdf). Then use that rubber casting as a form to pore my plastic/epoxy into to make my plastic auger.
So can anyone give me a suggestion or point me in the right direction?
Any advice or guidance would be greatly appreciated!






RE: Looking for a hard durable plastic......
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Looking for a hard durable plastic......
Regards
Pat
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RE: Looking for a hard durable plastic......
Thank you very much for your reply. Just did a quick search on Cast Nylon and I find that it doesn't do well fully submerged. For my application the plastic auger will probably be sumbmerged a pretty good deal. It states that it can swell as much as 5% in fully submerged applications.
Not sure if this is a problem or not, does it loose it's strenght when it is swollen?
Also where I find it, it can only be puchased in a solid state. Not in a liquid so that it could just be poured into a mold and a hardener be added. I would like to try and avoid having to heat the material in the process.
When you say it may be a problem controling the glass fiber placementduring curing, do you mean that the strengthening particles in the mixture may settle to the bottom?
Thanks again pat.
RE: Looking for a hard durable plastic......
I seemed to have missed your post when I was scrolling down the page (I am new to this forum layout). I will check out garden tools, great suggestion.
RE: Looking for a hard durable plastic......
The submerged thing is a new twist that seems to have been overlooked in your previous posts.
Nylons absorb water and swell and soften and toughen. They absorb a fixed amount then stabilise so long as the humidity remains constant. The absorption process is quite slow with thick section. Some glass fibre can offset the change of properties.
I still think cast nylon 6 is your best bet, unless you have another surprise announcement.
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
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RE: Looking for a hard durable plastic......
Dan - Owner

http://www.Hi-TecDesigns.com
RE: Looking for a hard durable plastic......
The auger wouldn't be left in the water for any more than 24 hours and would normaly be left in the water/sand for 4-6 hours.
pat, you said that nylons absorb a fixed amount then stabilize if the humidity remains constant. So lets say one day the auger was left in the water/sand for 6 hours and then again the next day for 4 hours. Would cast nylon 6 still be strong enough. Also, do you know about how much strength would be lost when the nylon absorbs it's maximum amount of moisture?
macgyvers,
You could be 100% correct. I intend to try it with a metal auger by hand before the plastic one is made. Good point.
RE: Looking for a hard durable plastic......
RE: Looking for a hard durable plastic......
How long is a piece of string?
You haven't really provided enough information on the loading etc to really tell you that.
(Pat, Nylon was my first guess but then I searched hand tools and the first few I found were ABS but your point on manufacturing is well taken)
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Looking for a hard durable plastic......
I agree the shaft will need to be thicker than if it were steel. I can't comment on the force required to turn the auger.
Another option is to have a steel shaft with small arms sticking out then casting over that.
I presume you want plastic rather than metal is so that it does less damage to the boat if it is dropped or handled roughly against the deck or hull or people for that matter.
Regards
Pat
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RE: Looking for a hard durable plastic......
But, it seems we must play guessing games.
RE: Looking for a hard durable plastic......
RE: Looking for a hard durable plastic......
When tested to destruction, the metal drive dog is the part that normally fails.
Regards
Pat
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RE: Looking for a hard durable plastic......
I have used small augers that drill into the sand for umbrellas and they went in without a whole lot of effort. So I figre is something that small can be driven into the sand then why not a larger one where you could put a bit more power behind it if needed.
RE: Looking for a hard durable plastic......
The plastic one will be harder to drive as it will have a thicker shaft and blades
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
RE: Looking for a hard durable plastic......
Dan - Owner

http://www.Hi-TecDesigns.com