Bondable machinable material...

whoizrob · 24th August 2006, 17:51

My materials knowledge is pretty limited to what I can find on-line but I need help with a starting point.

I'm looking for a nice material that is easily machinable, cheap, and bondable with good properties for use in the loop. Delrin is a good mainstay of machinable parts but bonding with epoxy seems to yield marginal shear strength at best.

Any pointers?

Rob

Dutchy · 24th August 2006, 20:14

http://www.plasticsportal.net/wa/pla...inkpage_public

This page will tell you what the specific qualities of a certain plastic are... Please do not only consider the Engineering plastics. You'll have a wonderfull cadidate in PS (PolyStyrene). You know in in it's foamed state as a packaging material, but it can be used as a pure material as well. It can be bonded by certain solvents (e.g. acetone).. The Nylons are too sensitive to expansion because of moist. Although I liked machining nylons you'll need to be carefull whever small tolerances are needed and adjust your design to allow for such variances. (e.g. use radial o-ring iso axial o-ring etc etc)

plazma · 26th August 2006, 20:33

Quote: (Originally Posted by whoizrob)

My materials knowledge is pretty limited to what I can find on-line but I need help with a starting point.

I'm looking for a nice material that is easily machinable, cheap, and bondable with good properties for use in the loop. Delrin is a good mainstay of machinable parts but bonding with epoxy seems to yield marginal shear strength at best.

Any pointers?

Rob

PVC is cheap, easily machined, good bonding (with Tangit) and also a pretty good thermal insulator.

-Pasi

Dutchy · 26th August 2006, 22:54

Quote: (Originally Posted by plazma)

PVC is cheap, easily machined, good bonding (with Tangit) and also a pretty good thermal insulator.

-Pasi

Yup and there are a few UV resistant types out there... If you can't be bothered (or expensive) then consider priming and coating.... With a good primer the well loved black coat is going to stick.......

cool_hardware52 · 27th August 2006, 01:12

Quote: (Originally Posted by plazma)

PVC is cheap, easily machined, good bonding (with Tangit) and also a pretty good thermal insulator.

-Pasi

PVC is readily available, easily solvent welded, and like most thermoplatics is a good insulator.

I would not call it easy to machine. In part due to it's poor thermal conductivity, PVC can do nasty things when you machine it. The relative low melting point leads to well melting. Grabs drill, distorts, poor finish, and dimensional changes due to heating are all real problems.

Basically I hate cutting the stuff. If you go slow, have very sharp tools, and allow plenty of cooling time between passes or cuts it can be done.

Tobin

Dutchy · 27th August 2006, 07:27

Quote: (Originally Posted by cool_hardware52)

PVC is readily available, easily solvent welded, and like most thermoplatics is a good insulator.

I would not call it easy to machine. In part due to it's poor thermal conductivity, PVC can do nasty things when you machine it. The relative low melting point leads to well melting. Grabs drill, distorts, poor finish, and dimensional changes due to heating are all real problems.

Basically I hate cutting the stuff. If you go slow, have very sharp tools, and allow plenty of cooling time between passes or cuts it can be done.

Tobin

Iow don't use hard-metal (sintered) schissels but use the old fahioned ones and reduce industrial cutting speeds to a tenth and you should be fine. Cooling and lubrication help a lot.

whoizrob · 28th August 2006, 01:05

There was a thread on here not too long ago discussing how PVC (esp the bonding/etching chemicals) offgas some pretty nasty stuff... Opinions?

Rob

nurseling · 28th August 2006, 02:24

Quote: (Originally Posted by whoizrob)

There was a thread on here not too long ago discussing how PVC (esp the bonding/etching chemicals) offgas some pretty nasty stuff... Opinions?

Rob

I would think after 24 hours the offgassing should cease. My saltwater reeftank never had a problem with it. I would not think we would

narked at 90 · 28th August 2006, 02:36

PVC dose of gas for some time but it dose subside after a wile, but is a bitch to machine!
personaly i would prefer ABS if you can get it in the sizes your after and it still welds very nicley like pvc.
regards john routley

Skipbreather · 28th August 2006, 03:37

I’ve had excellent results building cool dive toys w/ PVC- everything from BOV’s to radial scrubbers. Chief reason in all cases for the particular material choice was that I could reliably bond parts. My best results have been w/ 3M Scotch Weld 2216. As others have mentioned, keep your tools sharp, your speeds & feeds reasonable, and there will be few problems.

24th August 2006, 17:51	#1 (permalink)
whoizrob New Member Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Apr 2006 Location: Sacramento Posts: 72	Bondable machinable material... My materials knowledge is pretty limited to what I can find on-line but I need help with a starting point. I'm looking for a nice material that is easily machinable, cheap, and bondable with good properties for use in the loop. Delrin is a good mainstay of machinable parts but bonding with epoxy seems to yield marginal shear strength at best. Any pointers? Rob
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24th August 2006, 20:14	#2 (permalink)
Dutchy Rene Warries Current Rebreather/s: Sport Kiss Other Rebreather/s: Join Date: Apr 2006 Location: Nieuwegein (The Netherlands) Posts: 844	Re: Bondable machinable material... http://www.plasticsportal.net/wa/pla...inkpage_public This page will tell you what the specific qualities of a certain plastic are... Please do not only consider the Engineering plastics. You'll have a wonderfull cadidate in PS (PolyStyrene). You know in in it's foamed state as a packaging material, but it can be used as a pure material as well. It can be bonded by certain solvents (e.g. acetone).. The Nylons are too sensitive to expansion because of moist. Although I liked machining nylons you'll need to be carefull whever small tolerances are needed and adjust your design to allow for such variances. (e.g. use radial o-ring iso axial o-ring etc etc) __________________ = This post is environmentally friendly. It is composed of 100% recycled electrons only. =
(Online)

26th August 2006, 20:33	#3 (permalink)
plazma Just add ice & water Current Rebreather/s: Home Build Other Rebreather/s: Inspiration Classic Home Build Join Date: Feb 2005 Location: Oulu, Finland Posts: 154	Re: Bondable machinable material... Quote: (Originally Posted by whoizrob) My materials knowledge is pretty limited to what I can find on-line but I need help with a starting point. I'm looking for a nice material that is easily machinable, cheap, and bondable with good properties for use in the loop. Delrin is a good mainstay of machinable parts but bonding with epoxy seems to yield marginal shear strength at best. Any pointers? Rob PVC is cheap, easily machined, good bonding (with Tangit) and also a pretty good thermal insulator. -Pasi
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26th August 2006, 22:54	#4 (permalink)
Dutchy Rene Warries Current Rebreather/s: Sport Kiss Other Rebreather/s: Join Date: Apr 2006 Location: Nieuwegein (The Netherlands) Posts: 844	Re: Bondable machinable material... Quote: (Originally Posted by plazma) PVC is cheap, easily machined, good bonding (with Tangit) and also a pretty good thermal insulator. -Pasi Yup and there are a few UV resistant types out there... If you can't be bothered (or expensive) then consider priming and coating.... With a good primer the well loved black coat is going to stick....... __________________ = This post is environmentally friendly. It is composed of 100% recycled electrons only. =
(Online)

27th August 2006, 01:12	#5 (permalink)
cool_hardware52 RBW Member Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Mar 2005 Location: SoCal USA Posts: 399	Re: Bondable machinable material... Quote: (Originally Posted by plazma) PVC is cheap, easily machined, good bonding (with Tangit) and also a pretty good thermal insulator. -Pasi PVC is readily available, easily solvent welded, and like most thermoplatics is a good insulator. I would not call it easy to machine. In part due to it's poor thermal conductivity, PVC can do nasty things when you machine it. The relative low melting point leads to well melting. Grabs drill, distorts, poor finish, and dimensional changes due to heating are all real problems. Basically I hate cutting the stuff. If you go slow, have very sharp tools, and allow plenty of cooling time between passes or cuts it can be done. Tobin __________________ www.deepseasupply.com
(Offline)

27th August 2006, 07:27	#6 (permalink)
Dutchy Rene Warries Current Rebreather/s: Sport Kiss Other Rebreather/s: Join Date: Apr 2006 Location: Nieuwegein (The Netherlands) Posts: 844	Re: Bondable machinable material... Quote: (Originally Posted by cool_hardware52) PVC is readily available, easily solvent welded, and like most thermoplatics is a good insulator. I would not call it easy to machine. In part due to it's poor thermal conductivity, PVC can do nasty things when you machine it. The relative low melting point leads to well melting. Grabs drill, distorts, poor finish, and dimensional changes due to heating are all real problems. Basically I hate cutting the stuff. If you go slow, have very sharp tools, and allow plenty of cooling time between passes or cuts it can be done. Tobin Iow don't use hard-metal (sintered) schissels but use the old fahioned ones and reduce industrial cutting speeds to a tenth and you should be fine. Cooling and lubrication help a lot. __________________ = This post is environmentally friendly. It is composed of 100% recycled electrons only. =
(Online)

28th August 2006, 01:05	#7 (permalink)
whoizrob New Member Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Apr 2006 Location: Sacramento Posts: 72	Re: Bondable machinable material... There was a thread on here not too long ago discussing how PVC (esp the bonding/etching chemicals) offgas some pretty nasty stuff... Opinions? Rob
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28th August 2006, 02:24	#8 (permalink)
nurseling New Member Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Jan 2006 Location: pensacola, FL Posts: 33	Re: Bondable machinable material... Quote: (Originally Posted by whoizrob) There was a thread on here not too long ago discussing how PVC (esp the bonding/etching chemicals) offgas some pretty nasty stuff... Opinions? Rob I would think after 24 hours the offgassing should cease. My saltwater reeftank never had a problem with it. I would not think we would
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28th August 2006, 02:36	#9 (permalink)
narked at 90 John Routley Current Rebreather/s: Inspiration Classic Other CCR Dolphin Home Build Other Rebreather/s: Other CCR Dolphin Home Build Join Date: Feb 2005 Location: middlands uk Posts: 1,074	Re: Bondable machinable material... PVC dose of gas for some time but it dose subside after a wile, but is a bitch to machine! personaly i would prefer ABS if you can get it in the sizes your after and it still welds very nicley like pvc. regards john routley __________________ *WWW.NARKEDAT90.CO.UK* *http://www.grpservices.com/pursuit/* Supporting Shearwater Research Products in Europe Narked at 90 Go Military
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28th August 2006, 03:37	#10 (permalink)
Skipbreather Reads the fine print Current Rebreather/s: Megalodon Home Build Other Rebreather/s: Not Bought Yet MK 15.X Home Build Join Date: Mar 2005 Location: Chicago, Illinois, USA Posts: 584	Re: Bondable machinable material... I’ve had excellent results building cool dive toys w/ PVC- everything from BOV’s to radial scrubbers. Chief reason in all cases for the particular material choice was that I could reliably bond parts. My best results have been w/ 3M Scotch Weld 2216. As others have mentioned, keep your tools sharp, your speeds & feeds reasonable, and there will be few problems.
(Offline)

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