BAKELITE KNOB REPAIR

11/18/2009 12:33:05 PMBob Masse

:
:Hi! I have an old 1930's radio with bakelite knobs. The knobs have the indicator pointers broken off of them and I would like to repair them. I've seen everything from JB weld to fiberglass resin recommended for repairing bakelite. I would like to hear suggestions, from those having experience in this area, as to what works and lasts.Thanks for any info.
: Bob Masse
:
:

11/18/2009 6:59:58 PMBill G.

Hi Bob,
I work a lot with bakelite cabinets. I just use household glue. It holds and doesn't show. Not showing is important. I did one with JB Weld. It held all right but you could tell it had been repaired.
If you have a knob that is cracked down the middle, you may have to go with the JB Weld, though. Tensil strenght is important there.

Best Regards,

Bill Grimm

Best Regards,

Bill Grimm

11/18/2009 7:40:20 PMBob Masse

:Hi Bob,
: I work a lot with bakelite cabinets. I just use household glue. It holds and doesn't show. Not showing is important. I did one with JB Weld. It held all right but you could tell it had been repaired.
: If you have a knob that is cracked down the middle, you may have to go with the JB Weld, though. Tensil strenght is important there.
:
:Best Regards,
:
:Bill Grimm
:
:Best Regards,
:
:Bill Grimm
:
:
:
:Hi! Bill,
Thanks for reply.My knobs have the pointers missing completely so I can't just glue them back together.I have to build up the area where the pointers were and then shape them.It doesn't say anything about repairing plastic on the JB weld package so I was looking for advice of someone who experimented in this area. Do you think it would work well to actually add on to the knob? I appreciate your advice.
:Tks. Bob Masse
:
:

11/18/2009 9:15:58 PMTerry F

I used a product called PLASTEX. You can use it to fill gaps, repair stripped threads, or use the molding bar to repair/reproduce almost any plastic part. Various colors.

www.PLASTEX.net

Good luck.
terry F

11/19/2009 10:50:44 AMBob Masse

:I used a product called PLASTEX. You can use it to fill gaps, repair stripped threads, or use the molding bar to repair/reproduce almost any plastic part. Various colors.
:
:www.PLASTEX.net
:
:Good luck.
:terry F
:
:
:
:Hi! Terry,
Thanks for info.It looks like good stuff.
: Bob Massse
:
:

11/18/2009 9:25:15 PMBill G.

Hi Bob,
Before you go on a big project, you may want to consider getting another knob or pointer. I have purchased knobs from David Frush. His email ia parts2many@aol.com. Send a photo and what it came from. He may have it.

Best Regards,

Bill Grimm

11/18/2009 9:43:55 PMMarv Nuce

Bob,
You might consider gluing/epoxying a thin plastic disk to the back side of the knob. Lightly sand mating surfaces for good bond, trim to knob diameter, but leave a pointer where the original was, then build up the pointer area with clear epoxy, shape, sand and paint to match. Even acrylics can be built up in layers too, while matching color, then sanded/shaped. You can use craft acrylics to mix the desired color, then overcoat with polyurethane or lacquer in satin, semigloss or gloss.

marv

::Hi Bob,
:: I work a lot with bakelite cabinets. I just use household glue. It holds and doesn't show. Not showing is important. I did one with JB Weld. It held all right but you could tell it had been repaired.
:: If you have a knob that is cracked down the middle, you may have to go with the JB Weld, though. Tensil strenght is important there.
::
::Best Regards,
::
::Bill Grimm
::
::Best Regards,
::
::Bill Grimm
::
::
::
::Hi! Bill,
: Thanks for reply.My knobs have the pointers missing completely so I can't just glue them back together.I have to build up the area where the pointers were and then shape them.It doesn't say anything about repairing plastic on the JB weld package so I was looking for advice of someone who experimented in this area. Do you think it would work well to actually add on to the knob? I appreciate your advice.
::Tks. Bob Masse
::
::
:

11/19/2009 12:24:13 AMMarv Nuce

Bob,
You can also use acrylics to create a marbled effect with water and different colors. I also use it on wood end grain, where the finish is nearly opaque. After overcoating with lacquer/polyurethane, it looks good, and saves labor/$$ vs toning lacquers.

marv

::Hi Bob,
:: I work a lot with bakelite cabinets. I just use household glue. It holds and doesn't show. Not showing is important. I did one with JB Weld. It held all right but you could tell it had been repaired.
:: If you have a knob that is cracked down the middle, you may have to go with the JB Weld, though. Tensil strenght is important there.
::
::Best Regards,
::
::Bill Grimm
::
::Best Regards,
::
::Bill Grimm
::
::
::
::Hi! Bill,
: Thanks for reply.My knobs have the pointers missing completely so I can't just glue them back together.I have to build up the area where the pointers were and then shape them.It doesn't say anything about repairing plastic on the JB weld package so I was looking for advice of someone who experimented in this area. Do you think it would work well to actually add on to the knob? I appreciate your advice.
::Tks. Bob Masse
::
::
:

11/22/2009 11:56:59 AMBob Masse

:Bob,
:You can also use acrylics to create a marbled effect with water and different colors. I also use it on wood end grain, where the finish is nearly opaque. After overcoating with lacquer/polyurethane, it looks good, and saves labor/$$ vs toning lacquers.
:
:marv
:
:::Hi Bob,
::: I work a lot with bakelite cabinets. I just use household glue. It holds and doesn't show. Not showing is important. I did one with JB Weld. It held all right but you could tell it had been repaired.
::: If you have a knob that is cracked down the middle, you may have to go with the JB Weld, though. Tensil strenght is important there.
:::
:::Best Regards,
:::
:::Bill Grimm
:::
:::Best Regards,
:::
:::Bill Grimm
:::
:::
:::
:::Hi! Bill,
:: Thanks for reply.My knobs have the pointers missing completely so I can't just glue them back together.I have to build up the area where the pointers were and then shape them.It doesn't say anything about repairing plastic on the JB weld package so I was looking for advice of someone who experimented in this area. Do you think it would work well to actually add on to the knob? I appreciate your advice.
:::Tks. Bob Masse
:::
:::
::
:
:
:
:Thanks for all replies! I got a few ideas from them.
: Bob Masse
:
:

11/22/2009 1:59:00 PMThomas Dermody

Also, JB Weld does work very well for repairing bakelite. You can mix in oil paints for color. If you are adhering some JB Weld to the edge of a knob, you may consider filing into the underside of the knob so that the JB Weld has something to grab onto (or the disc method Marv suggested). A wire running through the addition will also help to strengthen it. Mould a basic form with clay, and then file to your desired appearance.

I have great luck repairing bakelite with super glue, though you say that parts are actually missing.

T.

11/22/2009 3:52:57 PMMarv Nuce

Bob/Thomas,
Craft shops also carry a clay like compound that can be shaped, then baked in a standard oven. Of course you'll need a mold of the orig with the pointer added. Regular parafin wax can be melted, then poured around the knob, then once hard, remove knob and carve the pointer. Press the clay into mold, remove and bake. I've also used latex molding (liquid) compound, but is water/ammonia based and takes days to dry, after applying several painted on layers. Craft acrylics of different colors and water can be used to create a marbled effect, then overcoat with appropriate finish. Craft casting materials are also an option for pouring a new knob. For an RCA 86BK I carved (wood) a model of the needed knob, but couldn't get the finish to look like an original, so used that dummy to make a mold from latex. Sat the mold in melted wax to retain it's shape. After wax cooled, poured in liquid state clear epoxy. Once hard, drilled a 1/4" shaft hole from the backside and installed a brass shaft retainer. Once again, used craft acrylics to duplicate the color/marbling of remaining knobs. Kept this process secret from the owner, and when delivered, asked him to pick one of 3 new knobs. He failed to find any difference.

marv

:Also, JB Weld does work very well for repairing bakelite. You can mix in oil paints for color. If you are adhering some JB Weld to the edge of a knob, you may consider filing into the underside of the knob so that the JB Weld has something to grab onto (or the disc method Marv suggested). A wire running through the addition will also help to strengthen it. Mould a basic form with clay, and then file to your desired appearance.
:
:I have great luck repairing bakelite with super glue, though you say that parts are actually missing.
:
:T.
:

11/22/2009 4:44:02 PMGeorge T

Hi, if it was me I would make a shallow mold of the knob. Hopefully would have one good knob with pointer intact. If not then I would use Plaster Paris make a mold, carve out the pointer. Then I would use epoxy glue and bakelite dust obtained from a parts cabinet with a file and mix it with the epoxy to get the correct color. Pour a little into the mold to fill the pointer with just a little to overfil. Then put the knob back in the mold and let dry. I have had excellent results doing this. It take very little sanding to make it look original. Good Luck, George T

11/22/2009 7:53:17 PMThomas Dermody

The marbling sounds fun. I have always liked that kind of plastic.

T.