Home |
Search |
Today's Posts |
|
Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
Reply |
|
LinkBack | Thread Tools | Display Modes |
#1
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
My low tech pencil sharpener has a drive that uses a 2.2" gear to drive the
mechanism from the motor. The gear broke into 3 pieces. I can probably repair it but am unsure of the composition and what to use for cement/ strengthening. It is an Amber waxy looking/feeling material and it scrapes like wax. What is this?? TIA |
#2
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
In article ,
Splork wrote: My low tech pencil sharpener has a drive that uses a 2.2" gear to drive the mechanism from the motor. The gear broke into 3 pieces. I can probably repair it but am unsure of the composition and what to use for cement/ strengthening. Cut a groove around the perimeter, deep enough to get past the gear teeth. Wrap a steel wire around the gear in the groove, and twist the ends to make it tight. If cyanoacrylate will stick to the plastic, use that to get the pieces assembled before you add the wire. Isaac |
#3
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
On Sat, 27 Oct 2012 20:47:30 -0400, Splork wrote:
My low tech pencil sharpener has a drive that uses a 2.2" gear to drive the mechanism from the motor. The gear broke into 3 pieces. I can probably repair it but am unsure of the composition and what to use for cement/ strengthening. It is an Amber waxy looking/feeling material and it scrapes like wax. What is this?? My guess(tm) would be Molybdenum disulfide lubricated nylon gears. Search google for "self lubricating plastic gears". However, glue is not going to help. No glue will stick to a plastic gear that is impregnated with some manner of wax or grease. Your best bet is to temporarily stick the gear together with some manner of cyanoacrylate adhesive (super glue), and make a lost wax plaster mold in order to clone the gear. http://en.wikipedia.org/wiki/Lost-wax_casting -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#4
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
isw wrote in message
]... In article , Splork wrote: My low tech pencil sharpener has a drive that uses a 2.2" gear to drive the mechanism from the motor. The gear broke into 3 pieces. I can probably repair it but am unsure of the composition and what to use for cement/ strengthening. Cut a groove around the perimeter, deep enough to get past the gear teeth. Wrap a steel wire around the gear in the groove, and twist the ends to make it tight. If cyanoacrylate will stick to the plastic, use that to get the pieces assembled before you add the wire. Isaac Are you saying cut a slot through the middle of the teeth into the bulk under the teeth? I suspect a .4mm saw in a Dremmel would end up as a melted mess and not a slot, perhaps a heated scalpel blade in a jig Or perhaps use some nicrome wire with some silone sleeve at the overlap, apply a weight and some adjustable current. Hope the wire melts into the bulk of the plastic and perhaps ypu can ignore twisting off of the wire. May need to recess 3 pins into the disc part , then swathe in hotmelt or something, if the 3 sections have failed with smooth edges, before doing the wire job |
#5
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
N_Cook wrote in message
... isw wrote in message ]... In article , Splork wrote: My low tech pencil sharpener has a drive that uses a 2.2" gear to drive the mechanism from the motor. The gear broke into 3 pieces. I can probably repair it but am unsure of the composition and what to use for cement/ strengthening. Cut a groove around the perimeter, deep enough to get past the gear teeth. Wrap a steel wire around the gear in the groove, and twist the ends to make it tight. If cyanoacrylate will stick to the plastic, use that to get the pieces assembled before you add the wire. Isaac Are you saying cut a slot through the middle of the teeth into the bulk under the teeth? I suspect a .4mm saw in a Dremmel would end up as a melted mess and not a slot, perhaps a heated scalpel blade in a jig Or perhaps use some nicrome wire with some silone sleeve at the overlap, apply a weight and some adjustable current. Hope the wire melts into the bulk of the plastic and perhaps ypu can ignore twisting off of the wire. May need to recess 3 pins into the disc part , then swathe in hotmelt or something, if the 3 sections have failed with smooth edges, before doing the wire job on second thoughts as its 2.2 inch there is probably quite a thickness of bulk material. Wire and twist around the teeth to act as an alignment jig , then 3 pins and generally hotmelt "soldering" along all the joins, cut away the wire. Precede with a test that the plastic and hotmelt are compatible in the first place. |
#6
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
The Lady from Philadelphia advises you to purchase a new pencil-sharpening
instrument. |
#7
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
William Sommerwerck wrote in message
... The Lady from Philadelphia advises you to purchase a new pencil-sharpening instrument. You've just posted that 'reply' to a thread with repair in the title on a board with repair in the title |
#8
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
Jamie t wrote in message
... N_Cook wrote: isw wrote in message ]... In article , Splork wrote: My low tech pencil sharpener has a drive that uses a 2.2" gear to drive the mechanism from the motor. The gear broke into 3 pieces. I can probably repair it but am unsure of the composition and what to use for cement/ strengthening. Cut a groove around the perimeter, deep enough to get past the gear teeth. Wrap a steel wire around the gear in the groove, and twist the ends to make it tight. If cyanoacrylate will stick to the plastic, use that to get the pieces assembled before you add the wire. Isaac Are you saying cut a slot through the middle of the teeth into the bulk under the teeth? I suspect a .4mm saw in a Dremmel would end up as a melted mess and not a slot, perhaps a heated scalpel blade in a jig Or perhaps use some nicrome wire with some silone sleeve at the overlap, apply a weight and some adjustable current. Hope the wire melts into the bulk of the plastic and perhaps ypu can ignore twisting off of the wire. May need to recess 3 pins into the disc part , then swathe in hotmelt or something, if the 3 sections have failed with smooth edges, before doing the wire job what is a waxy plastic gear? I can't picture any gears being made of wax or material soft like wax? Jamie I've come across them but don't remember where, glossy looking as though covered in oil , hard white material but not PTFE , and slippery to the touch but no oil film. IIRC quite coarse teeth and pitch as though not very structural plastic. |
#9
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
N_Cook wrote:
isw wrote in message ]... In article , Splork wrote: My low tech pencil sharpener has a drive that uses a 2.2" gear to drive the mechanism from the motor. The gear broke into 3 pieces. I can probably repair it but am unsure of the composition and what to use for cement/ strengthening. Cut a groove around the perimeter, deep enough to get past the gear teeth. Wrap a steel wire around the gear in the groove, and twist the ends to make it tight. If cyanoacrylate will stick to the plastic, use that to get the pieces assembled before you add the wire. Isaac Are you saying cut a slot through the middle of the teeth into the bulk under the teeth? I suspect a .4mm saw in a Dremmel would end up as a melted mess and not a slot, perhaps a heated scalpel blade in a jig Or perhaps use some nicrome wire with some silone sleeve at the overlap, apply a weight and some adjustable current. Hope the wire melts into the bulk of the plastic and perhaps ypu can ignore twisting off of the wire. May need to recess 3 pins into the disc part , then swathe in hotmelt or something, if the 3 sections have failed with smooth edges, before doing the wire job what is a waxy plastic gear? I can't picture any gears being made of wax or material soft like wax? Jamie |
#10
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
On Oct 29, 7:42*am, "N_Cook" wrote:
William Sommerwerck wrote in message ... The Lady from Philadelphia advises you to purchase a new pencil-sharpening instrument. You've just posted that 'reply' to a thread with repair in the title on a board with repair in the title But common sense has a place even in a repair group. |
#11
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
You've just posted that "reply" to a thread with repair in the title
on a board with repair in the title. You're rather missing the point. The reference is to a character in Lucretia Peabody Hale's short stories "The Peterkin Papers". Said lady was a fountain of common sense, giving simple solutions to what appeared -- to the Peterkins -- to be complicated problems. http://en.wikipedia.org/wiki/The_Peterkin_Papers |
#12
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
In article , "N_Cook"
wrote: isw wrote in message ]... In article , Splork wrote: My low tech pencil sharpener has a drive that uses a 2.2" gear to drive the mechanism from the motor. The gear broke into 3 pieces. I can probably repair it but am unsure of the composition and what to use for cement/ strengthening. Cut a groove around the perimeter, deep enough to get past the gear teeth. Wrap a steel wire around the gear in the groove, and twist the ends to make it tight. If cyanoacrylate will stick to the plastic, use that to get the pieces assembled before you add the wire. Isaac Are you saying cut a slot through the middle of the teeth into the bulk under the teeth? Yup. Exactly. I suspect a .4mm saw in a Dremmel would end up as a melted mess and not a slot, perhaps a heated scalpel blade in a jig Just use a coping saw. Or perhaps use some nicrome wire with some silone sleeve at the overlap, apply a weight and some adjustable current. Hope the wire melts into the bulk of the plastic and perhaps ypu can ignore twisting off of the wire. May need to recess 3 pins into the disc part , then swathe in hotmelt or something, if the 3 sections have failed with smooth edges, before doing the wire job Something to hold it together long enough to get the groove cut would make it easier. Even clamping the pieces between a couple of washers might do it. Isaac |
#13
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
On Mon, 29 Oct 2012 10:37:59 -0500, Jamie
t wrote: N_Cook wrote: isw wrote in message ]... In article , Splork wrote: My low tech pencil sharpener has a drive that uses a 2.2" gear to drive the mechanism from the motor. The gear broke into 3 pieces. I can probably repair it but am unsure of the composition and what to use for cement/ strengthening. Cut a groove around the perimeter, deep enough to get past the gear teeth. Wrap a steel wire around the gear in the groove, and twist the ends to make it tight. If cyanoacrylate will stick to the plastic, use that to get the pieces assembled before you add the wire. Isaac Are you saying cut a slot through the middle of the teeth into the bulk under the teeth? I suspect a .4mm saw in a Dremmel would end up as a melted mess and not a slot, perhaps a heated scalpel blade in a jig Or perhaps use some nicrome wire with some silone sleeve at the overlap, apply a weight and some adjustable current. Hope the wire melts into the bulk of the plastic and perhaps ypu can ignore twisting off of the wire. May need to recess 3 pins into the disc part , then swathe in hotmelt or something, if the 3 sections have failed with smooth edges, before doing the wire job what is a waxy plastic gear? I can't picture any gears being made of wax or material soft like wax? Jamie Thanks to all the replies!! The unit is at least 20 years old. The gear is brown Bakelite in color. I say waxy because it has a soapy feel and I can scrape the material with my thumbnail and get some to come off. Like very hard wax. Odd for a drive gear material so I suppose it changed in nature over time. The exterior seems most changed so perhaps there is some material strength remaining. The teeth are about twice as wide as the body and none have broken off. A clean 3 way break. The body is too thin for making a groove around the perimeter. Adhesive would be required in and around the breaks for adequate strength. I cannot think of an adhesive for this material so I posted here hoping for anyone familiar with it to chime in. As an alternate to a lost wax reproduction, I thought of reassembling the gear and wiring it to stay put, some holes could be drilled through the disc (several on each segment) and a 2 operation repair then be undertaken. On one side a layer of JB Weld between hub and teeth, then a repeat on the other side. Would give a metal sandwich with the holes ensuring the teeth remain in roper position and are driven. Will look over the unit to see if any special clearance need be observed. Likely the best option in hand. Just discovered someone who has cloned the gear and is selling them $12 or so. |
#14
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
Splork wrote:
On Mon, 29 Oct 2012 10:37:59 -0500, Jamie t wrote: N_Cook wrote: isw wrote in message ]... In article , Splork wrote: My low tech pencil sharpener has a drive that uses a 2.2" gear to drive the mechanism from the motor. The gear broke into 3 pieces. I can probably repair it but am unsure of the composition and what to use for cement/ strengthening. Cut a groove around the perimeter, deep enough to get past the gear teeth. Wrap a steel wire around the gear in the groove, and twist the ends to make it tight. If cyanoacrylate will stick to the plastic, use that to get the pieces assembled before you add the wire. Isaac Are you saying cut a slot through the middle of the teeth into the bulk under the teeth? I suspect a .4mm saw in a Dremmel would end up as a melted mess and not a slot, perhaps a heated scalpel blade in a jig Or perhaps use some nicrome wire with some silone sleeve at the overlap, apply a weight and some adjustable current. Hope the wire melts into the bulk of the plastic and perhaps ypu can ignore twisting off of the wire. May need to recess 3 pins into the disc part , then swathe in hotmelt or something, if the 3 sections have failed with smooth edges, before doing the wire job what is a waxy plastic gear? I can't picture any gears being made of wax or material soft like wax? Jamie Thanks to all the replies!! The unit is at least 20 years old. The gear is brown Bakelite in color. I say waxy because it has a soapy feel and I can scrape the material with my thumbnail and get some to come off. Like very hard wax. Odd for a drive gear material so I suppose it changed in nature over time. The exterior seems most changed so perhaps there is some material strength remaining. They call it micarta http://en.wikipedia.org/wiki/Micarta Jamie |
#15
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
Jamie t wrote in message
... Splork wrote: On Mon, 29 Oct 2012 10:37:59 -0500, Jamie t wrote: N_Cook wrote: isw wrote in message ]... In article , Splork wrote: My low tech pencil sharpener has a drive that uses a 2.2" gear to drive the mechanism from the motor. The gear broke into 3 pieces. I can probably repair it but am unsure of the composition and what to use for cement/ strengthening. Cut a groove around the perimeter, deep enough to get past the gear teeth. Wrap a steel wire around the gear in the groove, and twist the ends to make it tight. If cyanoacrylate will stick to the plastic, use that to get the pieces assembled before you add the wire. Isaac Are you saying cut a slot through the middle of the teeth into the bulk under the teeth? I suspect a .4mm saw in a Dremmel would end up as a melted mess and not a slot, perhaps a heated scalpel blade in a jig Or perhaps use some nicrome wire with some silone sleeve at the overlap, apply a weight and some adjustable current. Hope the wire melts into the bulk of the plastic and perhaps ypu can ignore twisting off of the wire. May need to recess 3 pins into the disc part , then swathe in hotmelt or something, if the 3 sections have failed with smooth edges, before doing the wire job what is a waxy plastic gear? I can't picture any gears being made of wax or material soft like wax? Jamie Thanks to all the replies!! The unit is at least 20 years old. The gear is brown Bakelite in color. I say waxy because it has a soapy feel and I can scrape the material with my thumbnail and get some to come off. Like very hard wax. Odd for a drive gear material so I suppose it changed in nature over time. The exterior seems most changed so perhaps there is some material strength remaining. They call it micarta http://en.wikipedia.org/wiki/Micarta Jamie In that case, known as Tufnol in the UK . But as those are cloth reinforced I would not have expected the material to split , has it got fibrous mat reinforcement? |
#16
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
Jamie t wrote in message
... Splork wrote: On Mon, 29 Oct 2012 10:37:59 -0500, Jamie t wrote: N_Cook wrote: isw wrote in message ]... In article , Splork wrote: My low tech pencil sharpener has a drive that uses a 2.2" gear to drive the mechanism from the motor. The gear broke into 3 pieces. I can probably repair it but am unsure of the composition and what to use for cement/ strengthening. Cut a groove around the perimeter, deep enough to get past the gear teeth. Wrap a steel wire around the gear in the groove, and twist the ends to make it tight. If cyanoacrylate will stick to the plastic, use that to get the pieces assembled before you add the wire. Isaac Are you saying cut a slot through the middle of the teeth into the bulk under the teeth? I suspect a .4mm saw in a Dremmel would end up as a melted mess and not a slot, perhaps a heated scalpel blade in a jig Or perhaps use some nicrome wire with some silone sleeve at the overlap, apply a weight and some adjustable current. Hope the wire melts into the bulk of the plastic and perhaps ypu can ignore twisting off of the wire. May need to recess 3 pins into the disc part , then swathe in hotmelt or something, if the 3 sections have failed with smooth edges, before doing the wire job what is a waxy plastic gear? I can't picture any gears being made of wax or material soft like wax? Jamie Thanks to all the replies!! The unit is at least 20 years old. The gear is brown Bakelite in color. I say waxy because it has a soapy feel and I can scrape the material with my thumbnail and get some to come off. Like very hard wax. Odd for a drive gear material so I suppose it changed in nature over time. The exterior seems most changed so perhaps there is some material strength remaining. They call it micarta http://en.wikipedia.org/wiki/Micarta Jamie I suspect its this material , upper left cog but I don't know what its called http://www.rennbay.com/pics/928insta.../Fig.%2050.jpg from http://www.rennbay.com/odotutorial.html structurally poor but decouples vibration from a gear train |
#17
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
N_Cook wrote:
Jamie t wrote in message ... Splork wrote: On Mon, 29 Oct 2012 10:37:59 -0500, Jamie et wrote: N_Cook wrote: isw wrote in message ]... In article , Splork wrote: My low tech pencil sharpener has a drive that uses a 2.2" gear to drive the mechanism from the motor. The gear broke into 3 pieces. I can probably repair it but am unsure of the composition and what to use for cement/ strengthening. Cut a groove around the perimeter, deep enough to get past the gear teeth. Wrap a steel wire around the gear in the groove, and twist the ends to make it tight. If cyanoacrylate will stick to the plastic, use that to get the pieces assembled before you add the wire. Isaac Are you saying cut a slot through the middle of the teeth into the bulk under the teeth? I suspect a .4mm saw in a Dremmel would end up as a melted mess and not a slot, perhaps a heated scalpel blade in a jig Or perhaps use some nicrome wire with some silone sleeve at the overlap, apply a weight and some adjustable current. Hope the wire melts into the bulk of the plastic and perhaps ypu can ignore twisting off of the wire. May need to recess 3 pins into the disc part , then swathe in hotmelt or something, if the 3 sections have failed with smooth edges, before doing the wire job what is a waxy plastic gear? I can't picture any gears being made of wax or material soft like wax? Jamie Thanks to all the replies!! The unit is at least 20 years old. The gear is brown Bakelite in color. I say waxy because it has a soapy feel and I can scrape the material with my thumbnail and get some to come off. Like very hard wax. Odd for a drive gear material so I suppose it changed in nature over time. The exterior seems most changed so perhaps there is some material strength remaining. They call it micarta http://en.wikipedia.org/wiki/Micarta Jamie In that case, known as Tufnol in the UK . But as those are cloth reinforced I would not have expected the material to split , has it got fibrous mat reinforcement? Micarta is the trade name for the company that created the process. I guess you can use a wide range of material to make it, you need to be specific in its use, which dictates the composites better suited for the jobs. People that make knife handles could use micarta composite and what they mostly do is use layers to clothe soaked in a resin and compressed in a bundle until hardened... I've seen them use all sorts of different materials over the years, including hemp. Jamie |
#18
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
"Splork" wrote in message ... My low tech pencil sharpener has a drive that uses a 2.2" gear to drive the mechanism from the motor. The gear broke into 3 pieces. I can probably repair it but am unsure of the composition and what to use for cement/ strengthening. It is an Amber waxy looking/feeling material and it scrapes like wax. What is this?? TIA Knackered, I'd say ... Arfa |
#19
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
On Sun, 4 Nov 2012 09:00:35 -0000, "N_Cook" wrote:
Jamie t wrote in message ... Splork wrote: On Mon, 29 Oct 2012 10:37:59 -0500, Jamie t wrote: N_Cook wrote: isw wrote in message ]... In article , Splork wrote: My low tech pencil sharpener has a drive that uses a 2.2" gear to drive the mechanism from the motor. The gear broke into 3 pieces. I can probably repair it but am unsure of the composition and what to use for cement/ strengthening. Cut a groove around the perimeter, deep enough to get past the gear teeth. Wrap a steel wire around the gear in the groove, and twist the ends to make it tight. If cyanoacrylate will stick to the plastic, use that to get the pieces assembled before you add the wire. Isaac Are you saying cut a slot through the middle of the teeth into the bulk under the teeth? I suspect a .4mm saw in a Dremmel would end up as a melted mess and not a slot, perhaps a heated scalpel blade in a jig Or perhaps use some nicrome wire with some silone sleeve at the overlap, apply a weight and some adjustable current. Hope the wire melts into the bulk of the plastic and perhaps ypu can ignore twisting off of the wire. May need to recess 3 pins into the disc part , then swathe in hotmelt or something, if the 3 sections have failed with smooth edges, before doing the wire job what is a waxy plastic gear? I can't picture any gears being made of wax or material soft like wax? Jamie Thanks to all the replies!! The unit is at least 20 years old. The gear is brown Bakelite in color. I say waxy because it has a soapy feel and I can scrape the material with my thumbnail and get some to come off. Like very hard wax. Odd for a drive gear material so I suppose it changed in nature over time. The exterior seems most changed so perhaps there is some material strength remaining. They call it micarta http://en.wikipedia.org/wiki/Micarta Jamie I suspect its this material , upper left cog but I don't know what its called http://www.rennbay.com/pics/928insta.../Fig.%2050.jpg from http://www.rennbay.com/odotutorial.html structurally poor but decouples vibration from a gear train Color looks about right. Will get a scan of it tomorrow and post it. I saw a number of posts on web sites referring to odometer repair while looking for info on this gear. Also found a site where there are dozens of people with this same problem asking for some reason: My post "Boston Model 18 Lg Gear Needed" http://www.merchantcircle.com/busine.../shoutout/list There is no binder or substrate to it. Heft in the teeth and hub, body half as thick. I see that the center hole of the hub which is keyed to the drive shaft may have worn a bit allowing the shaft some slack and instead of all force delivered to driving the gear, some was directed against small points on the hub surface. The drive has a 15 degree or so pitch and this slack would allow the gear motion off axis which would also work to crack it. A little slop may be what killed it. If I go with a JB Weld repair I will grease the shaft and use JB weld on the hub also. Thanks to all for the conversation. |
#20
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
Micarta is the trade name for the company that created the process.
The original micarta was developed by George Westinghouse. As a laminate, Westinghouse sold it well into the 1960s. GE had a similar product, textolite, which was used for countertops, gears, etc. Both are similar to Formica. |
#21
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
On Mon, 5 Nov 2012 03:51:30 -0800, "William Sommerwerck"
wrote: Micarta is the trade name for the company that created the process. The original micarta was developed by George Westinghouse. As a laminate, Westinghouse sold it well into the 1960s. GE had a similar product, textolite, which was used for countertops, gears, etc. Both are similar to Formica. Micarta is also know generically as "Phenolic". However, phenolic does not always mean it is made with phenolic resin. The first Micarta was made with Bakelite, a phenolic resin, but for years now a very common phenolic is G10, which every one here would recognize as fiberglass filled epoxy circuit board material. I have machined several different types of phenolic over the years, linen filled, fiberglass filled, carbon fiber filled, paper filled. etc. G10 is quite strong and is easy to glue with epoxy if the surface is roughed up a bit first. Eric |
#22
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
|
#23
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
On Sun, 4 Nov 2012 09:00:35 -0000, "N_Cook" wrote:
Jamie t wrote in message ... Splork wrote: On Mon, 29 Oct 2012 10:37:59 -0500, Jamie t wrote: N_Cook wrote: isw wrote in message ]... In article , Splork wrote: My low tech pencil sharpener has a drive that uses a 2.2" gear to drive the mechanism from the motor. The gear broke into 3 pieces. I can probably repair it but am unsure of the composition and what to use for cement/ strengthening. Cut a groove around the perimeter, deep enough to get past the gear teeth. Wrap a steel wire around the gear in the groove, and twist the ends to make it tight. If cyanoacrylate will stick to the plastic, use that to get the pieces assembled before you add the wire. Isaac Are you saying cut a slot through the middle of the teeth into the bulk under the teeth? I suspect a .4mm saw in a Dremmel would end up as a melted mess and not a slot, perhaps a heated scalpel blade in a jig Or perhaps use some nicrome wire with some silone sleeve at the overlap, apply a weight and some adjustable current. Hope the wire melts into the bulk of the plastic and perhaps ypu can ignore twisting off of the wire. May need to recess 3 pins into the disc part , then swathe in hotmelt or something, if the 3 sections have failed with smooth edges, before doing the wire job what is a waxy plastic gear? I can't picture any gears being made of wax or material soft like wax? Jamie Thanks to all the replies!! The unit is at least 20 years old. The gear is brown Bakelite in color. I say waxy because it has a soapy feel and I can scrape the material with my thumbnail and get some to come off. Like very hard wax. Odd for a drive gear material so I suppose it changed in nature over time. The exterior seems most changed so perhaps there is some material strength remaining. They call it micarta http://en.wikipedia.org/wiki/Micarta Jamie I suspect its this material , upper left cog but I don't know what its called http://www.rennbay.com/pics/928insta.../Fig.%2050.jpg from http://www.rennbay.com/odotutorial.html structurally poor but decouples vibration from a gear train Here are 2 scans. One lighter to show some detail, the other both sides, one which easily reassembles. I think JB weld must might do a good job after each piece has a couple of holes to the other side to form a clamp. http://users.rcn.com/healer//Gear1.jpg http://users.rcn.com/healer//Gear1a.jpg |
#24
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
On Wed, 07 Nov 2012 08:22:31 +0000, Charlie+ wrote:
On Tue, 06 Nov 2012 22:57:02 -0500, Splork wrote as underneath my scribble : Crack on the left is the original, the gear has been running eccentric some time, wear on the right teeth is considerable, if you do a repair pay considerable attention to concentric-icity(!!) to the centre. Is the equipment worth it? A dirty repair might be to use hot glue for thin metal or fibre washers in the rebates... try first to see if hot glue will stick to the soft gear material, might have to abrade. http://users.rcn.com/healer//Gear1.jpg http://users.rcn.com/healer//Gear1a.jpg That's the word I was looking for yesterday. Concentric. This is a pencil sharpener. When I reach to use it and it is gone . . . Yeah, worth it. The only repair that I think worthwhile, which is potentially long lasting, is on each piece, to place 2 holes halfway between hub and teeth, 3 holes on the largest, to allow jb weld (Strong metal bearing epoxy) to join obverse and reverse of the gear (2 operations). Once sandwiched between the "weld", being restrained and driven by the pins that form through the holes, I can place the gear on the drive shaft and greasing the gear end to prevent adhesion, make a third gluing operation for a strong tight fit around the shaft end. So the cracks will not be repaired, but the pins/vias that form in the holes will keep it together, sandwiched between plates which prevent it from divergence in any axis. The 3 segments held and driven separately. Now if laziness prevails........ :-) |
#25
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
Charlie+ wrote in message
... On Wed, 07 Nov 2012 20:49:51 -0500, Splork wrote as underneath my scribble : On Wed, 07 Nov 2012 08:22:31 +0000, Charlie+ wrote: On Tue, 06 Nov 2012 22:57:02 -0500, Splork wrote as underneath my scribble : Crack on the left is the original, the gear has been running eccentric some time, wear on the right teeth is considerable, if you do a repair pay considerable attention to concentric-icity(!!) to the centre. Is the equipment worth it? A dirty repair might be to use hot glue for thin metal or fibre washers in the rebates... try first to see if hot glue will stick to the soft gear material, might have to abrade. http://users.rcn.com/healer//Gear1.jpg http://users.rcn.com/healer//Gear1a.jpg That's the word I was looking for yesterday. Concentric. This is a pencil sharpener. When I reach to use it and it is gone . . . Yeah, worth it. The only repair that I think worthwhile, which is potentially long lasting, is on each piece, to place 2 holes halfway between hub and teeth, 3 holes on the largest, to allow jb weld (Strong metal bearing epoxy) to join obverse and reverse of the gear (2 operations). Once sandwiched between the "weld", being restrained and driven by the pins that form through the holes, I can place the gear on the drive shaft and greasing the gear end to prevent adhesion, make a third gluing operation for a strong tight fit around the shaft end. So the cracks will not be repaired, but the pins/vias that form in the holes will keep it together, sandwiched between plates which prevent it from divergence in any axis. The 3 segments held and driven separately. Now if laziness prevails........ :-) Good luck with it, hot glue has some 'give' in it which would provide the required flexibility. What I call hotmelt string is more convenient in this sort of operation. With the gun hot, squeeze out a long run of hotmelt over clean metal sheet. When cold , use like soldering operation with an old soldering iron, melding original material and the string. |
#26
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
On Thu, 8 Nov 2012 08:19:11 -0000, "N_Cook" wrote:
Charlie+ wrote in message .. . On Wed, 07 Nov 2012 20:49:51 -0500, Splork wrote as underneath my scribble : On Wed, 07 Nov 2012 08:22:31 +0000, Charlie+ wrote: On Tue, 06 Nov 2012 22:57:02 -0500, Splork wrote as underneath my scribble : Crack on the left is the original, the gear has been running eccentric some time, wear on the right teeth is considerable, if you do a repair pay considerable attention to concentric-icity(!!) to the centre. Is the equipment worth it? A dirty repair might be to use hot glue for thin metal or fibre washers in the rebates... try first to see if hot glue will stick to the soft gear material, might have to abrade. http://users.rcn.com/healer//Gear1.jpg http://users.rcn.com/healer//Gear1a.jpg That's the word I was looking for yesterday. Concentric. This is a pencil sharpener. When I reach to use it and it is gone . . . Yeah, worth it. The only repair that I think worthwhile, which is potentially long lasting, is on each piece, to place 2 holes halfway between hub and teeth, 3 holes on the largest, to allow jb weld (Strong metal bearing epoxy) to join obverse and reverse of the gear (2 operations). Once sandwiched between the "weld", being restrained and driven by the pins that form through the holes, I can place the gear on the drive shaft and greasing the gear end to prevent adhesion, make a third gluing operation for a strong tight fit around the shaft end. So the cracks will not be repaired, but the pins/vias that form in the holes will keep it together, sandwiched between plates which prevent it from divergence in any axis. The 3 segments held and driven separately. Now if laziness prevails........ :-) Good luck with it, hot glue has some 'give' in it which would provide the required flexibility. What I call hotmelt string is more convenient in this sort of operation. With the gun hot, squeeze out a long run of hotmelt over clean metal sheet. When cold , use like soldering operation with an old soldering iron, melding original material and the string. Thanks for the suggestions. Sounds interesting to me. Never used hot glue so I find the use of it like solder intriguing, and I like cleverness. Perhaps I am over estimating my need for strength. Rarely successful at repairing plastic gears and one of this size seems an unlikely candidate for glue. I do have a glue gun here somewhere. There is a lot of force applied to the shaft via the hub. Lots of torque needed to turn the sharpener blades. Manually un-movable. Will probably use the idea I had using JBWeld to create the least amount of give, but will experiment with hot glue to experience it's usefulness, and use it when I attempt small plastic gear replacement. Good stuff! Thanks again |
#27
Posted to sci.electronics.repair
|
|||
|
|||
waxy plastic gear repair
Splork udtrykte præcist:
My low tech pencil sharpener has a drive that uses a 2.2" gear to drive the mechanism from the motor. The gear broke into 3 pieces. I can probably repair it but am unsure of the composition and what to use for cement/ strengthening. It is an Amber waxy looking/feeling material and it scrapes like wax. Perhaps you can find somebody with a 3D-printer who will print a new gear? Somebody who has made their own 3D-printer might be looking for interesting stuff to print. But then again, get a new one, unless you have lot of free time and no money. Leif -- Husk kørelys bagpå, hvis din bilfabrikant har taget den idiotiske beslutning at undlade det. |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Bond fridge glass shelf to plastic/repair plastic clip | UK diy | |||
How to Glue Plastic Gear on Ice Maker? | Home Repair | |||
Plastic gear on a metal shaft | Metalworking | |||
Repair vcr crack gear??? | Electronics Repair | |||
replace plastic gear on powerfeed | Metalworking |