A60 motor shaft broke on bench? - RC Groups
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Jul 02, 2012, 12:06 PM
Registered User

A60 motor shaft broke on bench?

Hi guys,

I thought I'd reach out for some assistance and advice.

I just woke up to find a problem with my new Hacker A60 18L, just installed in a ESM pilatus PC21. (It sat in the box for 8 months while I've been building.) Now I'm worried.

I ran it up on sat night (12s, 5200 lipos and a castle HV120), then removed the prop to re-install the cowl. after re-installed the prop I put the the fuselage back on the workbench and woke up to find this. Literally, the prop was on the bench and had fallen off in the middle of the night!

Only put 56A/2300w in it for 2 minutes as a test. With a very expensive ( 5 bladed varioprop and spinner) setup- I'm a bit nervous.

Does you have any advice or a similar experiences? I don't think I over tightened the prop as the aluminum varioprop hub is in perfect condition.
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Jul 02, 2012, 09:01 PM
Average Joe 2 Semi-Pro n Back!
I am sorry to see this problem, although fortunately it happened on the bench, rather than in flight.

This is definitely a case of too much tightening, causing a fracture at the C-Clip groove. The tell-tale sign is the groove in the front plate of the motor from the c-clip. This happens when too much prop adapter clamping pressure is applied back against the clip, which deforms it and pushes it into the front plate when you run it.

Please send it in to us at Aero-Model, and we will replace the shaft, as well as make sure everything is cleaned up and fits together properly. An electric doesn't need as much tightening on the prop as a gas engine does!

If you have any questions, please PM me, or give me a call at the office (480) 726-7519

Jul 02, 2012, 09:08 PM
Registered User
Thanks Mike! I didn't think i was adding that much torque- I've had electrics for a while now (20 years) but I'm sure it's possible with such a large prop/plane (this size motor is new to me). I'll reach out to you tomorrow.

In the meantime is there a specified torque setting I should be using when setting the prop adapter?
Aug 15, 2012, 12:48 PM
Hacker Brushless USA
As a (late) update to this question.

Hacker sent over some torque specs on there larger motors:

A60: 15Nm
C50: 15Nm
Q80XS and S : 15Nm
Q80-M and L : 20Nm

I will also post this as a sticky at the top of this forum.

Aug 16, 2012, 03:48 AM
Registered User
Thank you Mike! I appreciate the attention to detail in following up to my post and the fact that Hacker provided this great information!

This confirms one of the reasons I chose Hacker in the first place- quality, performance, parts and support. After investing so much time a project- details like this are critical to safety and success of a new project. This adds to my confidence in Hacker and aeromodel.

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