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Plastic ring gear failure
Reminds me of a notorious generic fault with Philips car cassette
players of years gone by. A steel disc set in a hard plastic periphery, differential expansion with cold or heat (never discovered which with the Philips). In that case periphery was of pulley form taking a drive belt, this time cog form mating with a drive cog. Part of the take-up spool structure of Sony EV S700 video8 VCR from 1985 , used in 6 channel audio mode, so again a functioning m/c required to salvage audio from a tape archive (like the DAT m/c in recent thread here}. I placed the broken away quarter of the ring gear back with the remaining 3/4 ring and there is a stress-relieved gap of about half a tooth. Any advice? At the moment I intend grinding back a sliver from the steel, along its exposed quarter, to allow the bits of plastic gear to align again, and allow non-jamming tooth engagement. There is a bit of a ledge to the plastic cross-section to allow for some glue along the length as well as the broken ends. This spool drive assembly contains a magnet that "engages" with the steel disc , as a slip clutch |
Plastic ring gear failure
N_Cook wrote:
Reminds me of a notorious generic fault with Philips car cassette players of years gone by. A steel disc set in a hard plastic periphery, differential expansion with cold or heat (never discovered which with the Philips). In that case periphery was of pulley form taking a drive belt, this time cog form mating with a drive cog. Part of the take-up spool structure of Sony EV S700 video8 VCR from 1985 , used in 6 channel audio mode, so again a functioning m/c required to salvage audio from a tape archive (like the DAT m/c in recent thread here}. I placed the broken away quarter of the ring gear back with the remaining 3/4 ring and there is a stress-relieved gap of about half a tooth. Any advice? At the moment I intend grinding back a sliver from the steel, along its exposed quarter, to allow the bits of plastic gear to align again, and allow non-jamming tooth engagement. There is a bit of a ledge to the plastic cross-section to allow for some glue along the length as well as the broken ends. This spool drive assembly contains a magnet that "engages" with the steel disc , as a slip clutch I have no repair sugestions. This same crappy plastic gear molded onto sheet metal was a problem with the sony professional walkman lines. I finally trashed my last one after replacement parts were not accessible. Even if some are in a warehouse somehwhere, in yellowed plastic bags they're certainly cracked as well. The other problem is they used some sort of that bright white and very slippery plastic. Nothing seems to adhere to it, which is why I gave up. I really liked the WM-DC2 otherwise. |
Plastic ring gear failure
On 13/09/2013 23:16, Cydrome Leader wrote:
N_Cook wrote: Reminds me of a notorious generic fault with Philips car cassette players of years gone by. A steel disc set in a hard plastic periphery, differential expansion with cold or heat (never discovered which with the Philips). In that case periphery was of pulley form taking a drive belt, this time cog form mating with a drive cog. Part of the take-up spool structure of Sony EV S700 video8 VCR from 1985 , used in 6 channel audio mode, so again a functioning m/c required to salvage audio from a tape archive (like the DAT m/c in recent thread here}. I placed the broken away quarter of the ring gear back with the remaining 3/4 ring and there is a stress-relieved gap of about half a tooth. Any advice? At the moment I intend grinding back a sliver from the steel, along its exposed quarter, to allow the bits of plastic gear to align again, and allow non-jamming tooth engagement. There is a bit of a ledge to the plastic cross-section to allow for some glue along the length as well as the broken ends. This spool drive assembly contains a magnet that "engages" with the steel disc , as a slip clutch I have no repair sugestions. This same crappy plastic gear molded onto sheet metal was a problem with the sony professional walkman lines. I finally trashed my last one after replacement parts were not accessible. Even if some are in a warehouse somehwhere, in yellowed plastic bags they're certainly cracked as well. The other problem is they used some sort of that bright white and very slippery plastic. Nothing seems to adhere to it, which is why I gave up. I really liked the WM-DC2 otherwise. this m/c has been stored in the studio over the years, so no extreme hot or cold. So as no sign of rust , either the plastic shrinks with age or there is stress set into the plastic when formed around the steel and then the plastic weakens with age |
Plastic ring gear failure
N_Cook wrote:
On 13/09/2013 23:16, Cydrome Leader wrote: N_Cook wrote: Reminds me of a notorious generic fault with Philips car cassette players of years gone by. A steel disc set in a hard plastic periphery, differential expansion with cold or heat (never discovered which with the Philips). In that case periphery was of pulley form taking a drive belt, this time cog form mating with a drive cog. Part of the take-up spool structure of Sony EV S700 video8 VCR from 1985 , used in 6 channel audio mode, so again a functioning m/c required to salvage audio from a tape archive (like the DAT m/c in recent thread here}. I placed the broken away quarter of the ring gear back with the remaining 3/4 ring and there is a stress-relieved gap of about half a tooth. Any advice? At the moment I intend grinding back a sliver from the steel, along its exposed quarter, to allow the bits of plastic gear to align again, and allow non-jamming tooth engagement. There is a bit of a ledge to the plastic cross-section to allow for some glue along the length as well as the broken ends. This spool drive assembly contains a magnet that "engages" with the steel disc , as a slip clutch I have no repair sugestions. This same crappy plastic gear molded onto sheet metal was a problem with the sony professional walkman lines. I finally trashed my last one after replacement parts were not accessible. Even if some are in a warehouse somehwhere, in yellowed plastic bags they're certainly cracked as well. The other problem is they used some sort of that bright white and very slippery plastic. Nothing seems to adhere to it, which is why I gave up. I really liked the WM-DC2 otherwise. this m/c has been stored in the studio over the years, so no extreme hot or cold. So as no sign of rust , either the plastic shrinks with age or there is stress set into the plastic when formed around the steel and then the plastic weakens with age Probably both. As you're seen the crack starts at the bottom of the teeth where the stress is highest and it seems impossible to squeeze the gear back into shape, so it's not just a plain old crack, plus there's just not enough power on portable tape deck to split gears apart in the first place. On one forum I came across there is talk that the gear in the walkmen may have been polyethylene, matching the issue where you can't glue it. another person says delrin, which explains shrinkage over time. I even considered drilling holes into the area around the cracks and wiring them together to bridge the gap, but there just wasn't enough space, material and give to work with. Too bad "3d printers" can't make truly useful parts yet. |
Plastic ring gear failure
Cydrome Leader wrote:
Too bad "3d printers" can't make truly useful parts yet. They can, and you can get entire working setups for less than $500 these days. They are the bare printer, no fancy looking box or case that looks like an HP inkjet. They work so well that someone in Texas, where it is legal, made the lower receiver of an AR-15 assault rifle with one. His first attempts shattered from the forces of firing one round, he has YouTube videos of making one that lasted over 100 rounds. Sounds pretty "useful" to me. What somebody needs to build now is a 3d scanner, which will take an object, such as a cracked gear, and produce a file of commands to the 3d printer to get it to make a new one. It would need some fairly sophisticated software, so you could make multiple scans (such as one lying on the top and one lying on the the bottom) and combine and correct them. Geoff. -- Geoffrey S. Mendelson, N3OWJ/4X1GM/KBUH7245/KBUW5379 |
Plastic ring gear failure
Den 15-09-2013 10:39, Geoffrey S. Mendelson skrev:
Cydrome Leader wrote: Too bad "3d printers" can't make truly useful parts yet. They can, and you can get entire working setups for less than $500 these days. They are the bare printer, no fancy looking box or case that looks like an HP inkjet. They work so well that someone in Texas, where it is legal, made the lower receiver of an AR-15 assault rifle with one. His first attempts shattered from the forces of firing one round, he has YouTube videos of making one that lasted over 100 rounds. Sounds pretty "useful" to me. What somebody needs to build now is a 3d scanner, which will take an object, such as a cracked gear, and produce a file of commands to the 3d printer to get it to make a new one. It would need some fairly sophisticated software, so you could make multiple scans (such as one lying on the top and one lying on the the bottom) and combine and correct them. Something like this: http://www.youtube.com/watch?v=7ZrJsrTT4EA At work we have a 3D-scanner that can use reference dots that are placed on the object for combining multiple scans of the same object into one 3D model. -- Uffe |
Plastic ring gear failure
On 15/09/2013 09:15, Cydrome Leader wrote:
N_Cook wrote: On 13/09/2013 23:16, Cydrome Leader wrote: N_Cook wrote: Reminds me of a notorious generic fault with Philips car cassette players of years gone by. A steel disc set in a hard plastic periphery, differential expansion with cold or heat (never discovered which with the Philips). In that case periphery was of pulley form taking a drive belt, this time cog form mating with a drive cog. Part of the take-up spool structure of Sony EV S700 video8 VCR from 1985 , used in 6 channel audio mode, so again a functioning m/c required to salvage audio from a tape archive (like the DAT m/c in recent thread here}. I placed the broken away quarter of the ring gear back with the remaining 3/4 ring and there is a stress-relieved gap of about half a tooth. Any advice? At the moment I intend grinding back a sliver from the steel, along its exposed quarter, to allow the bits of plastic gear to align again, and allow non-jamming tooth engagement. There is a bit of a ledge to the plastic cross-section to allow for some glue along the length as well as the broken ends. This spool drive assembly contains a magnet that "engages" with the steel disc , as a slip clutch I have no repair sugestions. This same crappy plastic gear molded onto sheet metal was a problem with the sony professional walkman lines. I finally trashed my last one after replacement parts were not accessible. Even if some are in a warehouse somehwhere, in yellowed plastic bags they're certainly cracked as well. The other problem is they used some sort of that bright white and very slippery plastic. Nothing seems to adhere to it, which is why I gave up. I really liked the WM-DC2 otherwise. this m/c has been stored in the studio over the years, so no extreme hot or cold. So as no sign of rust , either the plastic shrinks with age or there is stress set into the plastic when formed around the steel and then the plastic weakens with age Probably both. As you're seen the crack starts at the bottom of the teeth where the stress is highest and it seems impossible to squeeze the gear back into shape, so it's not just a plain old crack, plus there's just not enough power on portable tape deck to split gears apart in the first place. On one forum I came across there is talk that the gear in the walkmen may have been polyethylene, matching the issue where you can't glue it. another person says delrin, which explains shrinkage over time. I even considered drilling holes into the area around the cracks and wiring them together to bridge the gap, but there just wasn't enough space, material and give to work with. Too bad "3d printers" can't make truly useful parts yet. Shaving back the steel allowed resetting the ends, a ring of heatshrink around and carefully heated the heatshrink , only, with soldering iron and glued around whole disc/plastic join. Looks a goood , non-jamming and non-oval repair, will see tomorrow, get it back in the deck I thought of one use for a 3D printer. Making false teeth. Taking dental cast, multi-scan and stitch to get a 3D computer model, patch in via copying sections for missing teeth, take negative mathematical casts wherever necessary. Break such a set of false teeth then easy to generate a replacement from the mathematecal model. Unfortunately a 3D printer cannot do what is so easy with a 2D printer, colour up the resulting false teeth to colour match. |
Plastic ring gear failure
As a 3D printer is about the cost of a set of false teeth, I can see
walk-in High Street agencies producing false teeth almost while you wait, perhaps in the next 5 years. Perhaps a secondary melt-mixing stage to add pc controlled dyestuffs to the melt to colour up the teeth/plate at the generation stage |
Plastic ring gear failure
On 13/09/2013 12:51, N_Cook wrote:
Reminds me of a notorious generic fault with Philips car cassette players of years gone by. A steel disc set in a hard plastic periphery, differential expansion with cold or heat (never discovered which with the Philips). In that case periphery was of pulley form taking a drive belt, this time cog form mating with a drive cog. Part of the take-up spool structure of Sony EV S700 video8 VCR from 1985 , used in 6 channel audio mode, so again a functioning m/c required to salvage audio from a tape archive (like the DAT m/c in recent thread here}. I placed the broken away quarter of the ring gear back with the remaining 3/4 ring and there is a stress-relieved gap of about half a tooth. Any advice? At the moment I intend grinding back a sliver from the steel, along its exposed quarter, to allow the bits of plastic gear to align again, and allow non-jamming tooth engagement. There is a bit of a ledge to the plastic cross-section to allow for some glue along the length as well as the broken ends. This spool drive assembly contains a magnet that "engages" with the steel disc , as a slip clutch Back to the original problem. Laces and unlaces and plays , FF and REW ok. Looks as though the gear broke over time in storage. The PCM legend flickers randomly and no sound out, no 6ch VU bargraph display , the original problem. Not tried playing a video tape but I expect no picture either. Other than cleaning all tape running surfaces , anything to check for? does not like PLAY+REW drops out. Reminds me of Beta video failure mode, usually slip clutch problems ISTR |
Plastic ring gear failure
I decided to inspect under the deck, easier than first seemed. Now with
a better viewing angle for the heads, one of the 3 is broken. |
Plastic ring gear failure
Geoffrey S. Mendelson wrote:
Cydrome Leader wrote: Too bad "3d printers" can't make truly useful parts yet. They can, and you can get entire working setups for less than $500 these days. They are the bare printer, no fancy looking box or case that looks like an HP inkjet. They work so well that someone in Texas, where it is legal, made the lower receiver of an AR-15 assault rifle with one. His first attempts shattered from the forces of firing one round, he has YouTube videos of making one that lasted over 100 rounds. Sounds pretty "useful" to me. You've obviously never seen these machines in person. The outputted parts are pretty horrible by an measure. No $500 piece of junk can make the usable gears for the OP's problem or a walkman. What somebody needs to build now is a 3d scanner, which will take an object, such as a cracked gear, and produce a file of commands to the 3d printer to get it to make a new one. It would need some fairly sophisticated software, so you could make multiple scans (such as one lying on the top and one lying on the the bottom) and combine and correct them. Geoff. this stuff exists, they had some at the MD&M show in Chicago last week. Still, no printer anybody could afford will produce usable intricate parts, and they won't be of the type that dribbles a plastic ribbon on a crooked warped table. |
Plastic ring gear failure
On 09/16/2013 12:48 AM, N_Cook wrote:
As a 3D printer is about the cost of a set of false teeth, I can see walk-in High Street agencies producing false teeth almost while you wait, perhaps in the next 5 years. Perhaps a secondary melt-mixing stage to add pc controlled dyestuffs to the melt to colour up the teeth/plate at the generation stage I like it! |
Plastic ring gear failure
On 17/09/2013 14:21, dave wrote:
On 09/16/2013 12:48 AM, N_Cook wrote: As a 3D printer is about the cost of a set of false teeth, I can see walk-in High Street agencies producing false teeth almost while you wait, perhaps in the next 5 years. Perhaps a secondary melt-mixing stage to add pc controlled dyestuffs to the melt to colour up the teeth/plate at the generation stage I like it! I watched a utube of them making false teeth the traditional way, no wonder with so many intermediary stages , they are so expensive. With such a mark-up I can see 3D printing come in there with a wallop, like the 2 bucks reading glasses that started coming in 10 or 15 years ago, wheras previously there was only expensive opticians scripped reading glasses |
Plastic ring gear failure
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