Author Topic: Could one of you 3D printing Gurus print me a small plastic gearwheel please? (Read 9721 times)

julesandtash · « **on:** March 29, 2015, 01:05:10 PM »

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)

the other side with the small extension piece

and the side view showing the damaged gear

photoman290 · « **Reply #1 on:** March 29, 2015, 01:11:34 PM »

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.

julesandtash · « **Reply #2 on:** March 29, 2015, 01:21:40 PM »

Thanks Bob, I have cross posted it there too.

Julian · « **Reply #3 on:** March 29, 2015, 01:21:43 PM »

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?

Julian · « **Reply #4 on:** March 29, 2015, 01:28:18 PM »

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.

GedsJeep · « **Reply #5 on:** March 29, 2015, 02:23:33 PM »

post a pic of the whole machine please.

julesandtash · « **Reply #6 on:** March 29, 2015, 02:36:03 PM »

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

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

Jamesrl · « **Reply #7 on:** March 29, 2015, 02:41:54 PM »

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.

GedsJeep · « **Reply #8 on:** March 29, 2015, 03:01:48 PM »

nah, cant help.

sorry

Julian · « **Reply #9 on:** March 29, 2015, 03:13:00 PM »

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.

julesandtash · « **Reply #10 on:** March 29, 2015, 03:30:34 PM »

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

Jamesrl · « **Reply #11 on:** March 29, 2015, 03:58:03 PM »

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.

Jamesrl · « **Reply #12 on:** March 29, 2015, 05:25:24 PM »

Quote from: Julian on March 29, 2015, 03:13:00 PM

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.

Keef · « **Reply #13 on:** March 30, 2015, 03:03:56 PM »

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

julesandtash · « **Reply #14 on:** March 30, 2015, 03:05:35 PM »

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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Could one of you 3D printing Gurus print me a small plastic gearwheel please?