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Old Jul 08, 2009, 12:04 PM
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flypaper 2's Avatar
Kingston, Canada
Joined Jun 2004
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Hi; Brand name of the gear bought at the local hobby shop, is Robinson Racing Products on the label. Says RRP 1113 48P metric 13 T. I actually use a 12 tooth, this was for testing. On the back of the label is a STICK ON STICKER that says, 1113 13T 32pitch metric(6mod) Then a bar code. Doesn't refer to the numbers on the front. I think they're using the sticker on the back simply for the pricing on the bar code. I'm using the same gear on two HK450s with no problems. By the way, these are steel gears.
If your ever down in the Kingston area on the weekend, drop in at the local hobby shop to find out where our club field is, or check out (krcm.org) As long as you have your MAAC membership your welcome to join the carnage. ..... Not all that bad.

Gord.
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Old Jul 08, 2009, 12:15 PM
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Glasswalker's Avatar
Ottawa, Ontario, Canada
Joined Jun 2009
131 Posts
Awesome! so that confirms the gear is correct! (I was getting worried there for a minute).

Ok perfect, did yours chew up the main gear a bit in the beginning as well? because I'm getting noticable plasic dust and fibers on the gear, the chasis and the wire (as shown in my photos)

So basically I just need to work at re-aligning it and I should be fine.

That helps make me feel better!

(and since it's not raining today I might be able to align it and get out for a maiden flight tonight! lol)

Thanks!
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Old Jul 08, 2009, 12:23 PM
Canadian Bacon
flypaper 2's Avatar
Kingston, Canada
Joined Jun 2004
13,050 Posts
I used to run a small motor shop so I've been playing with gears for years.Sort of like, everybody's been giving me the gears Take it easy on it as it is a virgin Let us know how you made out.Heading for the field myself. Sunny and no wind, so might as well make use of it.

Gord.
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Old Jul 08, 2009, 02:15 PM
How does it work? How did it?
mareklew's Avatar
Karlsruhe, Germany
Joined Mar 2009
1,155 Posts
Quote:
Originally Posted by Glasswalker
What is the pitch of the main gear in the HK450?
all Trex compatible main gears are on 0.5 module. So your 0.6 Pinion is off and will chew the gear.
BTW#1: don't buy main gears from HK, get Trex gears w/o the one-way, they cost like $6.50 a pack of three.
BTW#2: your noise was very characteristic for too tight a mesh on any gears.
BTW#3: never had any plastic dust on any of my gears or around. But I use 0.5 pinions...
Marek
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Old Jul 08, 2009, 02:34 PM
How does it work? How did it?
mareklew's Avatar
Karlsruhe, Germany
Joined Mar 2009
1,155 Posts
By the way: to figure out what module gear you have do the following:
1) measure the reference diameter of a gear. When gears mesh, the teeth touch at some point between tip and base, Reference diameter is diameter of circle passing through these points.
As doing this measurement is tricky, a good approximation can be obtained as following: measure the OUTER diameter of a gear (easy with calipers) and subtract the height of a tooth (again, easy with a caliper.
2) divide the diameter by number of teeth.

For Trex main gear, which is metric, the reference diameter is 75mm.
If you go the simplified way, you will find:
- outer diameter 76.22mm
- tooth heighy = 1.22mm
so approximate is 76.22-1.22 = 75mm = exactly the reference diameter.
If you divide 75 by 150 you get m=0.5.

If this gear was 0.6 module, it would have, at 150 teeth, about 90mm diameter.

EDIT: here: http://www.khkgears.co.jp/en/gear_te...pdf/module.pdf you can find some nice pictures and formulas compatible with what I wrote above.

Marek
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Old Jul 08, 2009, 03:02 PM
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United States, LA, Houma
Joined Jun 2008
1,399 Posts
i had the same problem last week,i bought a used trex 450 xl frame converted to v2 setup,i didnt know it at the time but it had a 0.6 pinion on a 0.5 main gear....the pics show the results.
it flew for a min then lost lift due to no more teeth on the main gear.
have a look!

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Old Jul 08, 2009, 03:27 PM
Excellence is Expected
MakMov's Avatar
Aurora, Colorado
Joined Nov 2005
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something don't look right about that gear set up...
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Old Jul 08, 2009, 03:29 PM
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Glasswalker's Avatar
Ottawa, Ontario, Canada
Joined Jun 2009
131 Posts
Ok but according to flypaper, the gear I have is in fact the right pitch (he has the same model of gear from the same manufacturer which also has the dual labeling) and he is using it with 2 HK450s with some success... So is that not enough that I an safely assume I'm just over-tightening?

Sorry getting conflicting info from different people so I'm confused if I should:
A) Adjust the tightness and fine tune it to be better, then any remaining noise should work itself out as the gear wears.
B) Replace the gear immediately because I don't want to chew up my entire main gear as shown in the photos by igotit

Thanks!
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Old Jul 08, 2009, 03:40 PM
Canadian Bacon
flypaper 2's Avatar
Kingston, Canada
Joined Jun 2004
13,050 Posts
Marek: The 6 mod is the one one the back of the label and the mistaken one at 32 pitch. Correct one is on the front of the label at 48 pitch and the one to use. So you have the right gear Glasswalker.

Gord
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Old Jul 08, 2009, 03:46 PM
How does it work? How did it?
mareklew's Avatar
Karlsruhe, Germany
Joined Mar 2009
1,155 Posts
> Ok but according to flypaper, the gear I have is in fact the right pitch

He's wrong (edit: or not, depending what's really in the pack, it HAS to be m=0.5).
Thing is, small pinions can mesh even if the pitch is slightly off. They will be noisy and may - depending on tooth shape - chew gears. They will definitely reduce efficiency and be weaker (properly meshed gear transfers force over more than one tooth at any time, bad mesh leads to only one tooth stressed at once).
His pinions may have been mislabeled, or they are of epicyclic teeth and thus less likely to damage gears too. If so, your pinions could also have been mislabeled, but I think it's not the case - see below.

> So is that not enough that I an safely assume I'm just over-tightening?

You get plastic powder around your mesh point. I have gone through 6 gears and never had any.
Also, a proper module pinion will let you install a 15T pinion and not run out of motor adjustment. You are on 12T and from what you write, you are now about where 15T should be.
15T m=0.5 is 7.5mm ref dia
12T m=0.6 is 7.2mm ref dia

> A) Adjust the tightness and fine tune it to be better, then any remaining
> noise should work itself out as the gear wears.
> B) Replace the gear immediately because I don't want to chew up my
> entire main gear as shown in the photos by igotit

You may do
C) adjust mesh for least noise, meanwhile order Trex main gears and proper pinions (get a set of steel pinions in few sizes) and hope they arrive before your HK main gear gives up.

Marek
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Old Jul 08, 2009, 03:48 PM
How does it work? How did it?
mareklew's Avatar
Karlsruhe, Germany
Joined Mar 2009
1,155 Posts
Quote:
Originally Posted by flypaper 2
Marek: The 6 mod is the one one the back of the label and the mistaken one at 32 pitch. Correct one is on the front of the label at 48 pitch and the one to use. So you have the right gear Glasswalker.
If it's so, then you are right, but see that he had problems backing out the motor to loosen the mesh? That would suggest a 12T/0.6, it has similar size like 15T/0.5.
Marek
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Old Jul 08, 2009, 04:13 PM
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Ottawa, Ontario, Canada
Joined Jun 2009
131 Posts
Part of the problem with backing out might be because the motor mounts are farther apart than the motor mount holes in the airframe.

As in when the motor is mounted in there, the 2 screws aren't 100% perpendicular to the rest of the frame, one sits just a little ahead of the other. When putting the screws in I have to have the motor at nearly 10 degrees angle to get them in easily. The holes are wide enough for the screws but the holes might not be far enough apart. I know on previous versions of the heli they were too small, looks like they widened them but slightly off center.

So I could likely get the motor another half mm or more back if I could get it 100% perpendicular, but I can't. but I didn't figure that mattered much, the motor is still centered, and it appeared at the time I could get the distance right so it didn't matter. But now I might have to pop the motor out and bore out the holes a little to give me more adjustment travel in the motor mount.

I think the LHS carries align pparts (they had a bunch of align helis in stock) so I should be able to get an align branded main gear there. I'll try it as-is, adjust for the best noise ratio and hope for the best. If it eats up the gear I guess I'll have to replace the gear/pinion then.
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Old Jul 08, 2009, 04:27 PM
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United States, LA, Houma
Joined Jun 2008
1,399 Posts
Quote:
Originally Posted by Glasswalker
Part of the problem with backing out might be because the motor mounts are farther apart than the motor mount holes in the airframe.

As in when the motor is mounted in there, the 2 screws aren't 100% perpendicular to the rest of the frame, one sits just a little ahead of the other. When putting the screws in I have to have the motor at nearly 10 degrees angle to get them in easily. The holes are wide enough for the screws but the holes might not be far enough apart. I know on previous versions of the heli they were too small, looks like they widened them but slightly off center.

So I could likely get the motor another half mm or more back if I could get it 100% perpendicular, but I can't. but I didn't figure that mattered much, the motor is still centered, and it appeared at the time I could get the distance right so it didn't matter. But now I might have to pop the motor out and bore out the holes a little to give me more adjustment travel in the motor mount.

I think the LHS carries align pparts (they had a bunch of align helis in stock) so I should be able to get an align branded main gear there. I'll try it as-is, adjust for the best noise ratio and hope for the best. If it eats up the gear I guess I'll have to replace the gear/pinion then.
just keep an eye on that gear,if in flight the noise gets alot quiter,id prepare for a landing. mine was making a gear noise,i flew her anayway after about a min the noise quited down then engine rpm started picking up as the heli lost lift,resulted in a crash damaging a few other parts.
id keep the heli close to me during flight,and listen very carefully to it!
good luck bro,i hope your flight ends better than mine did!
i flew 20 min ago and had a unexpected landing causing a boom strike.
and my lhs doesnt carry parts for my heli.
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Old Jul 08, 2009, 04:30 PM
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Glasswalker's Avatar
Ottawa, Ontario, Canada
Joined Jun 2009
131 Posts
Yeah, since I'm brand new, I'll be flying with training gear on, and keeping it likely only a foot or two off the ground for the first several batteries...

So if the gear's gonna go I suspect it will go long before I get the heli into the air far enough to cause damage in a crash
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Old Jul 08, 2009, 04:44 PM
Registered User
United States, LA, Houma
Joined Jun 2008
1,399 Posts
Quote:
Originally Posted by Glasswalker
Yeah, since I'm brand new, I'll be flying with training gear on, and keeping it likely only a foot or two off the ground for the first several batteries...

So if the gear's gonna go I suspect it will go long before I get the heli into the air far enough to cause damage in a crash
id run 1-2 packs with the heli in my hand or weighted down,if it will blow out on you it should do it then.
looks like a nice heli bro!
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