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Greetings,
I'm trying to save a couple old plastic knobs that have stripped set screw threads, that don't have brass inserts. I remember reading someplace about a machinable potting material that is easily flowed into a mold. I've tried JB Weld, but it doesn't flow well. It has a tendency to leave void areas. I want to drill a new set screw hole and hand tap it for 4-40 set screw.
I remember seeing some discussion on potting material on one of the groups I read, so I'm asking for help. Any advice will be appreciated. I will also post this to some of the other groups I read.
TNX es 73 de WABAG ..
Paul K.
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JB weld works well for this.
Mike kd5rjz
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On Sat, Aug 18, 2018 at 4:55 PM, Paul Koretko <hglent@...> wrote: Greetings,
I'm trying to save a couple old plastic knobs that have stripped set screw
threads, that don't have brass inserts. I remember reading someplace about
a machinable potting material that is easily flowed into a mold. I've
tried JB Weld, but it doesn't flow well. It has a tendency to leave void
areas. I want to drill a new set screw hole and hand tap it for 4-40 set
screw.
I remember seeing some discussion on potting material on one of the groups
I read, so I'm asking for help. Any advice will be appreciated. I will
also post this to some of the other groups I read.
TNX es 73 de WABAG ..
Paul K.
|
Is the knob large enough to use a 6-32 set screw? If so make sure you use a correct numbered drill with the tap.
73,
Blll, WA2DVU
Cape Mah
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Paul Koretko Sent: Saturday, August 18, 2018 5:55 PM To: [email protected]Subject: [TekScopes] Machinable Potting Material ??? Greetings, I'm trying to save a couple old plastic knobs that have stripped set screw threads, that don't have brass inserts. I remember reading someplace about a machinable potting material that is easily flowed into a mold. I've tried JB Weld, but it doesn't flow well. It has a tendency to leave void areas. I want to drill a new set screw hole and hand tap it for 4-40 set screw. I remember seeing some discussion on potting material on one of the groups I read, so I'm asking for help. Any advice will be appreciated. I will also post this to some of the other groups I read. TNX es 73 de WABAG .. Paul K.
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Micromark has some low-temp casting materials <= 160 degrees F. (Metal)
R.
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----- Original Message ----- From: "Mike D" <vfd.ninja@...> To: < [email protected]> Sent: Saturday, August 18, 2018 4:16 PM Subject: Re: [TekScopes] Machinable Potting Material ??? JB weld works well for this.
Mike kd5rjz
On Sat, Aug 18, 2018 at 4:55 PM, Paul Koretko <hglent@...> wrote:
Greetings,
I'm trying to save a couple old plastic knobs that have stripped set screw
threads, that don't have brass inserts. I remember reading someplace about
a machinable potting material that is easily flowed into a mold. I've
tried JB Weld, but it doesn't flow well. It has a tendency to leave void
areas. I want to drill a new set screw hole and hand tap it for 4-40 set
screw.
I remember seeing some discussion on potting material on one of the groups
I read, so I'm asking for help. Any advice will be appreciated. I will
also post this to some of the other groups I read.
TNX es 73 de WABAG ..
Paul K.
|
Warming the JB Weld will decrease the viscosity. I used to pot solid state modules for the side-winder AIM_9H using Hysol epoxy, it was done in a vacum chamber, no voids or bubbles allowed. On Sat, Aug 18, 2018 at 5:21 PM, Richard L. Wurdack <dickw@...> wrote: Micromark has some low-temp casting materials <= 160 degrees F. (Metal)
R.
----- Original Message ----- From: "Mike D" <vfd.ninja@...>
To: <[email protected]>
Sent: Saturday, August 18, 2018 4:16 PM
Subject: Re: [TekScopes] Machinable Potting Material ???
JB weld works well for this.
Mike kd5rjz
On Sat, Aug 18, 2018 at 4:55 PM, Paul Koretko <hglent@...> wrote:
Greetings,
I'm trying to save a couple old plastic knobs that have stripped set
screw
threads, that don't have brass inserts. I remember reading someplace
about
a machinable potting material that is easily flowed into a mold. I've
tried JB Weld, but it doesn't flow well. It has a tendency to leave void
areas. I want to drill a new set screw hole and hand tap it for 4-40 set
screw.
I remember seeing some discussion on potting material on one of the
groups
I read, so I'm asking for help. Any advice will be appreciated. I will
also post this to some of the other groups I read.
TNX es 73 de WABAG ..
Paul K.
|
An alternate approach would be to hand machine delrin rod on a drill press.
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On Sat, Aug 18, 2018 at 6:05 PM, james morton <jrm38510@...> wrote: Warming the JB Weld will decrease the viscosity. I used to pot solid
state modules for the side-winder AIM_9H using Hysol epoxy, it was done in
a vacum chamber, no voids or bubbles allowed.
On Sat, Aug 18, 2018 at 5:21 PM, Richard L. Wurdack <dickw@...>
wrote:
Micromark has some low-temp casting materials <= 160 degrees F. (Metal)
R.
----- Original Message ----- From: "Mike D" <vfd.ninja@...>
To: <[email protected]>
Sent: Saturday, August 18, 2018 4:16 PM
Subject: Re: [TekScopes] Machinable Potting Material ???
JB weld works well for this.
Mike kd5rjz
On Sat, Aug 18, 2018 at 4:55 PM, Paul Koretko <hglent@...> wrote:
Greetings,
I'm trying to save a couple old plastic knobs that have stripped set
screw
threads, that don't have brass inserts. I remember reading someplace
about
a machinable potting material that is easily flowed into a mold. I've
tried JB Weld, but it doesn't flow well. It has a tendency to leave
void
areas. I want to drill a new set screw hole and hand tap it for 4-40
set
screw.
I remember seeing some discussion on potting material on one of the
groups
I read, so I'm asking for help. Any advice will be appreciated. I will
also post this to some of the other groups I read.
TNX es 73 de WABAG ..
Paul K.
|
He is wanting to replace stripped inserts in knobs, seems like a great
application for easily tap-able jb weld. No concern about viscosity in that
application.
I'm not sure Micromark's bismuth/tin allow would hold a thread for very
long though.
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On Sat, Aug 18, 2018 at 8:05 PM james morton <JRM38510@...> wrote: Warming the JB Weld will decrease the viscosity. I used to pot solid
state modules for the side-winder AIM_9H using Hysol epoxy, it was done in
a vacum chamber, no voids or bubbles allowed.
On Sat, Aug 18, 2018 at 5:21 PM, Richard L. Wurdack <dickw@...>
wrote:
Micromark has some low-temp casting materials <= 160 degrees F. (Metal)
R.
----- Original Message ----- From: "Mike D" <vfd.ninja@...>
To: <[email protected]>
Sent: Saturday, August 18, 2018 4:16 PM
Subject: Re: [TekScopes] Machinable Potting Material ???
JB weld works well for this.
Mike kd5rjz
On Sat, Aug 18, 2018 at 4:55 PM, Paul Koretko <hglent@...> wrote:
Greetings,
I'm trying to save a couple old plastic knobs that have stripped set
screw
threads, that don't have brass inserts. I remember reading someplace
about
a machinable potting material that is easily flowed into a mold. I've
tried JB Weld, but it doesn't flow well. It has a tendency to leave
void
areas. I want to drill a new set screw hole and hand tap it for 4-40
set
screw.
I remember seeing some discussion on potting material on one of the
groups
I read, so I'm asking for help. Any advice will be appreciated. I
will
also post this to some of the other groups I read.
TNX es 73 de WABAG ..
Paul K.
|
plastic is fairly soft compared to metal, normal thread is 70%, you can use a smaller tap hole to approach 95% thread, use a good sharp tap. plastic threads will hold better and longer with more thread contact.
I have used heli-coil in a few cases. moved to 5-40 or 6-32 in others.
¸é±ð²Ô¨¦±ð
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On 2018-08-18 04:27 PM, Bill Riches wrote: Is the knob large enough to use a 6-32 set screw? If so make sure you use a correct numbered drill with the tap.
73,
Blll, WA2DVU
Cape Mah
-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Paul Koretko
Sent: Saturday, August 18, 2018 5:55 PM
To: [email protected]
Subject: [TekScopes] Machinable Potting Material ???
Greetings,
I'm trying to save a couple old plastic knobs that have stripped set screw threads, that don't have brass inserts. I remember reading someplace about a machinable potting material that is easily flowed into a mold. I've tried JB Weld, but it doesn't flow well. It has a tendency to leave void areas. I want to drill a new set screw hole and hand tap it for 4-40 set screw.
I remember seeing some discussion on potting material on one of the groups I read, so I'm asking for help. Any advice will be appreciated. I will also post this to some of the other groups I read.
TNX es 73 de WABAG ..
Paul K.
|
Epoxy resin mixed with enough ground silica to make a stiff paste then rammed into the hole
Robin
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On 19 Aug 2018, at 05:45, ¸é±ð²Ô¨¦±ð <k6fsb.1@...> wrote:
plastic is fairly soft compared to metal, normal thread is 70%, you can use a smaller tap hole to approach 95% thread, use a good sharp tap. plastic threads will hold better and longer with more thread contact.
I have used heli-coil in a few cases. moved to 5-40 or 6-32 in others.
¸é±ð²Ô¨¦±ð
On 2018-08-18 04:27 PM, Bill Riches wrote:
Is the knob large enough to use a 6-32 set screw? If so make sure you use a correct numbered drill with the tap.
73,
Blll, WA2DVU
Cape Mah
-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Paul Koretko
Sent: Saturday, August 18, 2018 5:55 PM
To: [email protected]
Subject: [TekScopes] Machinable Potting Material ???
Greetings,
I'm trying to save a couple old plastic knobs that have stripped set screw threads, that don't have brass inserts. I remember reading someplace about a machinable potting material that is easily flowed into a mold. I've tried JB Weld, but it doesn't flow well. It has a tendency to leave void areas. I want to drill a new set screw hole and hand tap it for 4-40 set screw.
I remember seeing some discussion on potting material on one of the groups I read, so I'm asking for help. Any advice will be appreciated. I will also post this to some of the other groups I read.
TNX es 73 de WABAG ..
Paul K.
|
Just try a Helicoil first,
I just fixed some stripped bakelite knobs from a 1920's radio using 4BA Helicoils - worked great!
Adrian
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On 8/18/2018 10:55 PM, Paul Koretko wrote: Greetings,
I'm trying to save a couple old plastic knobs that have stripped set screw threads, that don't have brass inserts. I remember reading someplace about a machinable potting material that is easily flowed into a mold. I've tried JB Weld, but it doesn't flow well. It has a tendency to leave void areas. I want to drill a new set screw hole and hand tap it for 4-40 set screw.
I remember seeing some discussion on potting material on one of the groups I read, so I'm asking for help. Any advice will be appreciated. I will also post this to some of the other groups I read.
TNX es 73 de WABAG ..
Paul K.
|
Paul,
Devcon makes two metal filled epoxies which would probably not make great potting material because of conductivity. They are outstanding repair materials however. The original one is Devcon A. It is steel filled epoxy putty and is very similar to JB Weld. The two Devcon F compounds are aluminum filled epoxy. The original Devcon F is just like Devcon A except for the aluminum content. However, Devcon F-2 is POURABLE! It would probably work well for what you intend. I was told years ago that these materials were 80% metal although I do not know how they do it. I had a cracked injection mold years ago which we needed to get some parts out of before it went out for repair. High temp Devcon saved our butts!
Jack Reynolds
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Mike D
Bill Riches