Author Topic: Metric internal gear supplier  (Read 6156 times)

Offline petertha

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Metric internal gear supplier
« on: October 08, 2014, 02:53:32 AM »
The engine plans I have call for an internal gear (ring gear): 40-teeth, mod-1.0, 20-deg PA, steel.
They reference a supplier called Maedler in Germany (which coincidentally is also referenced by a completely different plans provider for their gears as well).
I easily found corresponding part number 224- 440-00 from their website, plus other desirable goodies from what appears as an excellent selection of metric gears.
http://info.maedler.de/product/1643/1618/260/innenzahnkraenze-stahl-modul-1?result=22444000

The only problem is, so far no reply to my email inquiry about prices or possible shipping to Canada. I'll try again, but maybe its the situation where they only do larger accounts, or domestic, or just cant be bothered. I'm finding this to be a real tough size to locate in North America. Unfortunately the engine design kind of revolves (pun!) around this gear for cam ring cluster. Anyone have any dealings, experience or suggestions of other potential suppliers for onsey-twosey type orders?

Offline Jasonb

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Re: Metric internal gear supplier
« Reply #1 on: October 08, 2014, 07:45:24 AM »
These people will do single gears, used them several times. not sure about overseas but should be OK

http://www.hpcgears.com/n/products/6.internal_gears/internal_gears.php

Do Boston Gears not do them in the States?

Offline dieselpilot

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Re: Metric internal gear supplier
« Reply #2 on: October 08, 2014, 03:40:11 PM »
I quoted some gears from Maedler two years ago. They were using DHL or similar carrier so shipping cost was high but they do accept paypal. It took a couple days to get a reply. I didn't end up ordering however.

Offline Roger B

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Re: Metric internal gear supplier
« Reply #3 on: October 08, 2014, 08:03:34 PM »
If you can't find another source I can contact Mädler and see if I can help.
Best regards

Roger

Offline petertha

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Re: Metric internal gear supplier
« Reply #4 on: October 08, 2014, 08:35:34 PM »
Well I am happy to report some good news. Coincidentally I received an email reply this morning & turns out they sell them through amazon.com of all places. Which is ironic because I searched there specifically but must not have used the magic permutation of words in search criteria. However I typed in the Maedler part# & bingo, there it was (and for a good price). And similar PN queries turned up some complimentary mod-1 spur gears also needed. The USA to Canada looks a bit stiff, but that's familiar territory to me, I already have 'ways' around that. I'm just tickled I found the bugger & can get going on the project.

http://www.amazon.com/Internal-steel-module-outside-diameter/dp/B0087EDTMM/ref=sr_1_2?ie=UTF8&qid=1412796212&sr=8-2&keywords=internal+gear+40+teeth

Offline gmac

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Re: Metric internal gear supplier
« Reply #5 on: October 08, 2014, 11:45:42 PM »
...... or if you've got some time on your hands and not much cash;

<a href="https://www.youtube.com/watch?v=qSnWINtDAfs" target="_blank">http://www.youtube.com/watch?v=qSnWINtDAfs</a>

<a href="https://www.youtube.com/watch?v=4QLftRlHxj4" target="_blank">http://www.youtube.com/watch?v=4QLftRlHxj4</a>

<a href="https://www.youtube.com/watch?v=BgGXQUeYNKw" target="_blank">http://www.youtube.com/watch?v=BgGXQUeYNKw</a>

Cheers Garry

Offline petertha

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Re: Metric internal gear supplier
« Reply #6 on: October 09, 2014, 12:38:12 AM »
Fascinating videos, good score. I'll have my plate full just constructing the engine, but always good to have a plan B. In fact the spur gear video was also of interest because part of required assembly is mod-1 10 tooth. According to my tool catalog, a #1 cutter is sized for 12-13 teeth, #2 for 14-16 etc. so 10-tooth is ...? So if I couldn't adapt a commercial 10-tooth spur width wise, I suspect it was going to be a 'roll your own' exercise & figuring out how the cutter profile is developed.

Offline gmac

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Re: Metric internal gear supplier
« Reply #7 on: October 09, 2014, 12:51:05 AM »
Well if you don't have much time, want custom and have lots of money.......

<a href="https://www.youtube.com/watch?v=3LrkWl_kYCg" target="_blank">http://www.youtube.com/watch?v=3LrkWl_kYCg</a>

Cheers Garry

Offline gmac

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Re: Metric internal gear supplier
« Reply #8 on: October 09, 2014, 01:25:42 AM »
Peter;
It's an old memory from my engineering days, but I seem to recall 12 teeth being the lower practical limit for mating gears. Probably from a strength/durability point of view - although Boston Gear does mention 10 tooth; see pg 142

http://www.bostongear.com/pdf/gear_theory.pdf

http://www.khkgears.co.jp/en/gear_technology/pdf/gear_guide2.pdf

Although some manufacturers do mention 10T, a quick check of KBC's catalog shows what you found #1 cutter is for 12-13 T, so you may well be rolling your own.

Garry

Offline petertha

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Re: Metric internal gear supplier
« Reply #9 on: October 09, 2014, 04:19:03 AM »
This particular engine is a 50cc (total displacement), 5-cyl radial, 4S glow. I'm guessing the gear cluster load wont be too onerous as its purpose is driving the cam lobe ring. It goes 15-15-10-40 (crankshaft-idler-idler-internal ring), so I guess the 10 tooth would see 3700 rpm at rated 5500 rpm crankshaft. But basically I'm putting full faith in the designers experience! :)

One thing, this exercise has given be better appreciation & understanding of radial cam gear guts. I had this (naïve) thought I should be able to substitute imperial gears without much drama & modify a few bits to suit. But its actually kind of a sequential house of cards. You have to simultaneously juggle gear combinations to yield 4:1 ratio, coincident pitch circles using available tooth count gears & matching pitch/PA series... Turns out there are only so many combinations that satisfy & maintain a relatively compact package inside the nose housing. If you go too fine, it conflicts with things like requisite crankshaft diameter. If you go too big, the whole crankcase inflates. The closest imperial match I found was 24-24-16-64 in 32DP, but kind of mixed bag combination of brass & steel with available sizes. And amazingly more expensive ring gear! Turns out the prescribed metric combination is overall very good from what I can see & presumably mod-1 is a relatively strong tooth. Well, I'm hoping that's the case.

Back to the 10-tooth spur, is there any reason to think it might be any less precise fit to the ring gear based on low tooth count? Or do they work that magic into the tooth profile itself on commercial gears?

Offline dieselpilot

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Re: Metric internal gear supplier
« Reply #10 on: October 09, 2014, 03:01:16 PM »
12T is a practical limit before undercutting teeth becomes excessive. Often the addendum is modified when making gears smaller than 12T to avoid weak teeth. Yes, picking gears is tricky. I've been working with a similar tight arrangement, though I don't have to use an internal gear, for a while. That engine is in redesign stage because just as I was to start making parts I realized it can't be assembled, even though I checked and checked during design. In a smaller design I gave up and went to timing belt. 2:1 ratio, but  to get the right center distance with two gears they are too large.

Does the designer say anything about backlash in the gears? That arrangement 15-15-10-40 is pitch line to pitch line with no clearance. Clearance must be provided in the gears because center distance can't be changed, most likely in the 15/10 pair.

Greg

Offline gmac

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Re: Metric internal gear supplier
« Reply #11 on: October 09, 2014, 06:01:50 PM »
Perhaps a bit late at this stage but for reference;

http://www.sdp-si.com/D805/D805cat.htm

Garry

Offline petertha

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Re: Metric internal gear supplier
« Reply #12 on: October 09, 2014, 07:28:08 PM »
Does the designer say anything about backlash in the gears? That arrangement 15-15-10-40 is pitch line to pitch line with no clearance. Clearance must be provided in the gears because center distance can't be changed, most likely in the 15/10 pair.-Greg

Hmm.. that's a good thought. I'm going to go back & check verbiage but suspect short answer is no. I think all I did was spot-validated the 15/10 idler pair axle position, which was just tangent pitch circles as you say. I'm new to this but don't see a lot of wiggle room:
#1 15-tooth = concentric / integrated with crankshaft
#2/#3 15/10-toothed mated idler pair cluster = positioned on nose plate on pitch circle dimensions as mentioned)
#4 ring gear 40 tooth = sits inside of cam cup, also concentric with crankshaft via bearings

So dimensionally kind of locked down from what I can see. I know what you mean though from my amateur RC heli gear backlash fiddling, although that's more make it run vs designing. How can I get a handle on 'how much' or what to do about it? I guess the only consolation is I see this as common arrangement across a few similar (running) engines. This is an Ohrndorf varietal, but same gear train layout as Jung & Edwards & possibly one other.

Offline Jasonb

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Re: Metric internal gear supplier
« Reply #13 on: October 09, 2014, 07:37:06 PM »
On teh engien I've just finished I put a strip of fag paper between teh gears and then spotted through the idler position, you should just be able to make out the paper in this pic


Offline dieselpilot

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Re: Metric internal gear supplier
« Reply #14 on: October 09, 2014, 09:45:32 PM »
Exactly, in this case you can only provide clearance by shifting the teeth. There is nothing wrong with the arrangement, you just have to allow for backlash. If you are purchasing gears, this will mean custom gears for the 15/10 pair or just the ring gear (and move the 15/10 outward slightly) to allow backlash.

http://qtcgears.com/Q410/Q420Cat.html

I guess the sdp-si link is the same information.

Offline petertha

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Re: Metric internal gear supplier
« Reply #15 on: October 10, 2014, 06:50:13 AM »
Thanks JassonB. If I understand what you are showing, one can 'set' gear position with appropriate (paper thickness) gap by slightly tweaking the intermediate gear center position to suit? I think what dieselpilot is bringing up in the radial cam arrangement, there is no equivalent way to similarly 'offset' the idlers because its contained (confined) within internal gear... pitch circle tangent to pitch circle.... So pictorially instead of a slight (red triangle) its a single 'line'. Which therefore means a modification to tooth form? Hmm.. the plot thickens

I noticed in the one ring gear spec example an identified backlash amount.
http://qtcgears.com/KHK/newgears/KHK133.html

But I didn't see that specified in the Madler gear I require. Is there some sort of implied standard or ISO-type spec I could inquire about I wonder?
http://info.maedler.de/Article/22444000

Good points raised & new learnings to me. I just hope I land on an answer or solution!

Offline dieselpilot

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Re: Metric internal gear supplier
« Reply #16 on: October 10, 2014, 06:58:56 PM »
I had to look around. It appears that the standard method for providing backlash is in tooth profile (JIS, ISO, etc.). It seems as though you have nothing to worry about as it should be built into the gears. If you were making gears you'd have to be sure to cut them accordingly. The KHK site calls out backlash for every gear. I worked at a place that custom made every gear they needed and they were always modifying profile to make their gear ratios fit and reduce undercut on small gears. Sorry to make you worry about nothing.

When the situation allows, doing like Jason suggests is certainly applicable.

Greg

Offline petertha

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Re: Metric internal gear supplier
« Reply #17 on: October 11, 2014, 12:31:27 AM »
Thanks Greg. This is both good news and educational!

And just some additional info on the Madler front. The purchasing via amazon.com is pricey to NAm because of the business relationship. An order placed through amazon is basically just deflected & fulfilled through Germany behind the scenes. No stock or dealer physically resides in USA. So what I'm in the process of confirming is combined shipping of multiple-items from Madler direct to Canada, which they seem set up for & receptive to do by common couriers & e-payment methods. So that's good & hopefully all goes well.

Offline petertha

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Re: Metric internal gear supplier
« Reply #18 on: October 12, 2014, 04:55:07 AM »
If you can't find another source I can contact Mädler and see if I can help.
Forgot to say thank you for your kind gesture Roger, much appreciated. If I run into insurmountable problems ordering direct, you'll get an email!  :cheers:

 

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