Biopowered - vegetable oil and biodiesel forum
General => Wiki and forum discussion => Topic started by: julesandtash on March 29, 2015, 01:05:10 PM
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We have a DVD disc cleaning machine which has stripped a couple of teeth on one of the gears in it's little plastic gearbox
It is a 20mm diameter (to the outside of the teeth) gear with 30teeth, with a small 10 tooth gear on top of the main gear and a small extension shaft out of the back. It has a 2mm hole for the axle right through the centre.
I know you are all experts at printing things but can you print something that small and accurate ?
I would be forever if your debt if someone can make one for me
If not, does anybody know where i might get one - dont say a local model shop as I cant find any locally. Years ago I remember a shop called model engineering which was great but I think they are long gone.
Some photos
The side with the smaller gear on (the stripped one)
(http://i471.photobucket.com/albums/rr79/julesandtash/Biodiesel/20150329_130702_zps7izs5pou.jpg) (http://s471.photobucket.com/user/julesandtash/media/Biodiesel/20150329_130702_zps7izs5pou.jpg.html)
the other side with the small extension piece
(http://i471.photobucket.com/albums/rr79/julesandtash/Biodiesel/20150329_130738_zpsipeaybj6.jpg) (http://s471.photobucket.com/user/julesandtash/media/Biodiesel/20150329_130738_zpsipeaybj6.jpg.html)
and the side view showing the damaged gear
(http://i471.photobucket.com/albums/rr79/julesandtash/Biodiesel/20150329_130908_zpsejqqaimh.jpg) (http://s471.photobucket.com/user/julesandtash/media/Biodiesel/20150329_130908_zpsejqqaimh.jpg.html)
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there is something that you can rebuild broken gear teeth with. it is american and does work. can't remember the name but it is is used by repair shops for just what you need. try on the other channel. sort of thing HC would have kicking about.
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Thanks Bob, I have cross posted it there too.
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Love to give it a go, Jules, but as I think you half guessed stuff that small is tricky especially when you consider the size of the gear teeth and the mesh area they will have with other gears.
Whack up the photos and, if you can some dimensions of the teeth ... primarily exact OD of both and root to peak dimension (might need a caliper!), we should be able to work out gear dimensions from those.
What OD is the extension? Will it be taking any lateral force or does it act as a spacer on the shaft?
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So it's only the small gear that's damaged. That would be the trickiest to print.
How about cutting the small gear off and only printing that? That way the tooth profile could be cleaned up with a file (it couldn't if it was printed in piece) and the new gear glued and hot wire pinned to the existing large gear. A 2mm rod could be used to ensure alignment.
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post a pic of the whole machine please.
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Julian, that was a good idea.
I have cut the broken bit of cog off with a dremel no problem. I then discovered it is exactly the same size as the motor drive pinion, namely 8mm 10 tooth
They are quite easy to get so I will buy some (£3 for ten, delivered) and see how that goes.
If it works, it will be a lot easier than getting you to print one. If it doesn't then I will be asking for your efforts
This is the device we have
(http://ecx.images-amazon.com/images/I/51MFUFOqmfL._SY300_.jpg)
It is a Skip Doctor, sold by Amazon here... http://www.amazon.co.uk/SkipDr-Blu-Ray-Repair-Cleaning-System/dp/B00432ZSHG
It does work surprisingly well and has resurrected unreadable discs
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I have a 0.2mm extrusion nozzle for just this type of job, I also have 0.3, 0.4 and 0.5mm.
I'm like one of those scouty boys, be prepared, know wot r meen.
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nah, cant help.
sorry
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That's it, Jim's got the job ... I've only got a 0.4 and 0.5mm nozzel.
Happy to have a go at drawing it though.
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Thank you both. I will wait for the new cogs to arrive and see what they are like.
If they dont work then I will send the existing cogs to whichever one of you feels most comfortable at drawing them. I dont have any kit more accurate than a ruler to measure things so best that I send them to one of you.
Assuming that the new cogs do work, I will need to glue to the top of the old cog. Keeping them aligned will be easy enough with the axle through them but I need to know what to use.
The advert for the cogs says they are made of plastic acetal which appears to be this stuff http://plastics.ulprospector.com/generics/2/acetal
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Glueing plastics I've found Pound land Soopa glue, the 4/5 little bottles in a pack take some beating, they even have very narrow extension nozzles so you can apply a very small amounts at a time.
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That's it, Jim's got the job ... I've only got a 0.4 and 0.5mm nozzel.
Happy to have a go at drawing it though.
Okee dokee, you draw it I'll print it.
I'll even carry the cost of postage though I am a poor ragged arse pensioner struggling to make ends meet, too much month at the end of the money, pauses to wipe a tear or two, but I'll go without a meal for one day to cover the postage and get the gear down to Kernow.
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I can't see the pics cos I'm at work but there's millions of types on the bay eg
http://www.ebay.co.uk/itm/Qty-5-16mm-Dual-Plastic-Cog-Wheel-30-10-Gear-Teeth-for-Model-Gearboxes-/120850531768?pt=LH_DefaultDomain_3&hash=item1c2340c5b8
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You are very kind Jim. Ebay says that the cogs I ordered have been dispatched so I will see soon whether they do the job. If not then the old parts will be on route to Julian's drawing office
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Just thinking ahead, even with a 0.2mm nozzle and the "hand of Jim" driving it, I still think printing the little gear (now not in existence ... hope you measured it carefully before attacking it with the Dremel!) separately might be a good idea. Can the spacer on the opposite side of the big gear be a larger diameter?
If so the little gear can be made longer and embedded into the big one. The little gear could then be filed to size if required and it would allow the big gear to be printed with little or no support.
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The little 10 tooth motor pinions turned up today and are a perfect fit and mesh with the other gears.
Jims suggestion of superglue worked to bond the pinion onto the big cog that i cut the stripped one off of
Gearbox reassembled and the machine is working again. Hopefully i wont need the printing services for the time being but many thanks for the offer.
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Never mid Jim and his bloody glue ... where's the credit for the poor bugger who suggested cutting the small gear off in the first place?
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Never mid Jim and his bloody glue ... where's the credit for the poor bugger who suggested cutting the small gear off in the first place?
Oi, just 'cause I have superior technical knowledge on the glue subject there's no need to get grumpy.
Mind you cutting the small cog off was blindingly obvious.
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Mind you cutting the small cog off was blindingly obvious ... once some brainy chap had pointed it out!
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Mind you cutting the small cog off was blindingly obvious ... once some brainy chap had pointed it out!
So who was that?
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Thank you both for sharing some of your great intellects :)
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Thank you both for sharing some of your great intellects :)
No probs Jules, if you need anything in the future don't be afraid to ask.
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No probs Jules, if you need anything in the future don't be afraid to ask.
... and the "Pritt Stick Kid" will fix it!
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No probs Jules, if you need anything in the future don't be afraid to ask.
... and the "Pritt Stick Kid" will fix it!
Don't put yourself down Julian.