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By bugbear
#1195248
Have you priced water jet cutting?

That would cut brass, tufnol, nylon, steel, and can be very accurate.

I have NO IDEA on the cost.

BugBear
By J-G
#1195303
Deadeye wrote:Hi
Yes - I do have a smallish drill press and a 4" vice. I think I can do the bores pretty accurately. The issue is the teeth

If I could buy blanks with the right numbers of teeth I'd be sorted.


If you can take pre-cut gears with just a mark to indicate the centre and drill them on a drill-press with the accuracy of 0.01mm "you're a better man than I Gunga-Din" !!

MOD 1 gear teeth are only 2.4mm deep so if you are (say) 0.1mm out of centre with your bore you'll get less than a quarter turn before binding - unless of course you increase the nominal centre distance between meshing gears by (say) 0.4mm and that would lead to 'sloppy' mesh for most of each turn. Not only that there would be a sinusoidal variation in the speed of the driven gear.

It may well be acceptable (though inaccurate) for your application if it involves only forward motion (ie. clock or Orrery) but normally the bore and PCD should be absolutely concentric - and that is difficult to achieve without cutting the bore first.

You could use straight sided teeth and 'lantern' pinions which would negate all issues about bore concentricity and accurate centre distance of course!
By Inspector
#1195308
Being as I live across the pond I added England to a search "plastic gears" and got the following.
http://www.hpcgears.com
https://www.bearingboys.co.uk/Plastic-- ... ars-3314-c
https://www.gearsandsprockets.co.uk
http://www.motionco.co.uk/gears-c-32.html

Plus what comes up on eBay, Amazon and Aliexpress.

I also had a quick look on Alibaba.com and tons of companies have plastic gears of all sizes with many having the MOQ starting with one part. If you know the gears sizes and specs you can provide them with a list of them with the quantities you want and they will come back to you with a price and shipping options. I've done the same buying LED lighting for my workshop and a VDF to run a 3phase dust collector.

Once you get the gears from any of these places you will only need to put them on your machine and not have to futz with the bores.

Pete
By Deadeye
#1195320
Hi

I can centre by getting a pin the right size in the chuck and then clamping the gear whilst changing to a bit of the target bore diameter. A little "slop" isn't the end of the world.

I have found loads of sites that sell gears of the right sizes - at £5-25 per gear it's going to cost me hundreds of pounds for a proof of concept project!

I looked at water jet cutting. In terms of cost/cm, approximately it seems: water jet >> CNC > 3D print > laser >> moulding > cut your own (ignoring time).

People seem not to build much geared stuff these days!
By Inspector
#1195323
If you had written in your first post the steps you had already taken and the conclusion you've come to I would not have spent any time searching for possible sources and I suspect some others might not have either. Maybe if you have been good Santa will put them under the tree for you.
By Deadeye
#1195340
Inspector wrote:If you had written in your first post the steps you had already taken and the conclusion you've come to I would not have spent any time searching for possible sources and I suspect some others might not have either. Maybe if you have been good Santa will put them under the tree for you.


Golly! Sorry to have offended you; unintended.

I'm genuinely exploring the options and all the posts have been helpful in that. I hadn't looked at water jet, but now have (as a consequence of this thread) - and it's expensive.

To summarise:
- I'd like to do this as inexpensively as possible because, well, because.
- I tried laser cutting. It produced a technical issue, although I'm not sure whether this is a feature of lasering meltable material or poor operation
- CNC is expensive
- I have researched (following this thread) 3d printing (£1 for 8cc seems the best I can find so quite costly) and water jet (expensive)
- The ready made options are frustrating as they either have bores too wide or limited size range or cost ten quid a go.
- I can cut wood ones, but they need to be modulus 3 and up really and it makes it very big.

Sometimes on things you don't know about, someone has a great tip or insight, or a website that is perfect but is on page 20+ of the search results.

On your post specifically I have not come across Alibaba before ... and have now raised a query. It's rather a daunting site though!

Thanks again for your help.
By Deadeye
#1195432
profchris wrote:Could you buy the gears with the oversize bore and bush them down to your desired bore? Brass tube is available in 1mm increments with each size fitting inside the other. A little slop, but not too bad.

That's a good idea - thank you
By RobCee
#1196639
You may find that somewhere like 3D Hubs enables you to find a more competitive 3D-Printing service. You do have to register with them, but they enable you to pick the elements which are important to you for your job and match you with folks who have the capability.
I ended up matched to a local teenager with a 3D-Printer and the time to run a job for a very competitive price. You will need a 3D model of your gears though.
By dickm
#1196832
Thinking along the same lines, there is a place in Aberdeen called Make, which is community focused and has all sorts of printers and similar kit available for use. There are certainly other branches in Mainland Europe, so may be also elsewhere in UK.