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Jan 16, 2016, 12:41 PM
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Tacon Bigfoot 160 Bushing


Hi guys,
I searched around but didn't find an answer for what to do with the brass bushing that comes with the 160. I am using it "stock", ie, just as in the picture as received mounting in front of firewall. Does the busing have to go on the back shaft? (thats the only logical place it fits, but is it mandatory?) Or is it just included for using the motor a different way. Don't want any surprises....!
(interesting that it specs an 8mm shaft, but it is definitely 12m!)
Thx DSA
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Jan 16, 2016, 02:17 PM
Jack
jackerbes's Avatar
That bushing, if it has two set screws in it, is just to reinforce against the pulling forces on the shaft when it is used in the tractor mode and mounted on a firewall. It is intended that it be slid up against the Circlip and then locked in place there.

It is a good idea to have it there, if you have to make one you can use a wheel collar drilled out to 8mm. A 5/16" drill is slightly smaller than 8mm and could be used to drill one out:

8mm = 0.3149"
5/16" = 0.3125"

Most drills will drill a hole that is a little bit over sized and if you run it in the hole for a while it will get a little larger.

In use that bushing, the shaft, the Circlip, and the smaller thin bushing beneath the Circlip all rotate with the shaft and inner races. So you want to have a hole in the firewall that is large enough to clear all of those parts if the motor is not on an extended mount that gives is clearance.

The shaft in that motor has flats and Circlip grooves that allow it to be fit into the motor either for a firewall mount or a through the firewall mount. And it also allows it to be used with the supplied bolt on prop adapter or with the shaft extending out for a collet type prop adapter.

Jack
Jan 16, 2016, 03:07 PM
Registered User
Thread OP
Thanks Jack, thats what I figured like this.....
Problem is, there are no flats on the shaft, and the set screws from the bushing stick out ever-so-slightly and rub on the Xmount hole. I guess I can grind down the set screws a touch so they go in further and clear the outer margin of the bushing. Or try to widen the Xmount hole a tad, what a pain.
Thx again...DSA
Jan 16, 2016, 03:21 PM
Registered User
Doug Bartley's Avatar
I'd actually grind flats in the shaft to set the grub screws deeper and assure they lock the shaft in place. Id also reassure the screws stay put with a tiny drop of 242 Blue Locktite. The ciirclip and collar are all that prevents the rotor from moving forward or completely leaving its place.
fwiw Doug B
Jan 16, 2016, 05:31 PM
Ronaldo Nogueira
ronaldopn's Avatar
Quote:
Originally Posted by dsa44
Thanks Jack, thats what I figured like this.....
Problem is, there are no flats on the shaft, and the set screws from the bushing stick out ever-so-slightly and rub on the Xmount hole. I guess I can grind down the set screws a touch so they go in further and clear the outer margin of the bushing. Or try to widen the Xmount hole a tad, what a pain.
Thx again...DSA
I had the same issue in a NTM4258, my solution was to use 2 collars, the first one facing the circlip (or bearing) without a grub screw (just acting like a spacer) then a second one with the grub screw and a flat spot on the shaft.
When creating the flat spot, make a reasonably deep groove, don't rely on friction to hold the collar in place.
Make sure you apply Loctite to the grub screw.
Jan 16, 2016, 05:55 PM
Jack
jackerbes's Avatar
With all the pulling load on the Circlip, I would take some confidence from having the collar there so I would want it to be well engaged with the shaft. I would probably grind a couple of small flats on the shaft as it only takes a moment. You can see how easy it is here and I would do it with the motor in a bag and it would only take a moment.

Making and Replacing a Brushless Motor Shaft - www.rcgroups.com/forums/showthread.php?t=1240725

Jack
Jan 17, 2016, 10:10 AM
Registered User
Thread OP
Thanks guys, I like the idea of a second collar, but nothing handy! I will carefully grind some flats on the shaft and locktite the grub screws in. The tape over the motor housing is a great idea to keep the shavings out!! Just surprised with a motor of this size, that it had not already been done at the factory...
Cheers
Jul 10, 2017, 04:50 PM
"Discussion Always Welcomed"
Thomas Cummings's Avatar
I know this is an older topic but I bought a 160 myself so I was searching forums.

Just to play devil's advocate, wouldn't it take several hundred pounds of force in a press to pop that circlip?
Jul 11, 2017, 06:26 AM
Jack
jackerbes's Avatar
Quote:
Originally Posted by Thomas Cummings
I know this is an older topic but I bought a 160 myself so I was searching forums.

Just to play devil's advocate, wouldn't it take several hundred pounds of force in a press to pop that circlip?
If you mean to cause it to fail, yes, it would take a lot of pressure. The purpose of the collar is to reinforce the clip and prevent it from failing or popping out of the groove. For intentional removal there are plier like tools that will engage the two holes and let you expand the clip and lift if off.

And the circlips can be removed with a couple small screwdrivers if you are stubborn and know what you are doing, you have to expand it and then get it above the groove, then slide it off of the shaft.

I'm sort of surprised that the places that sell that motor don't offer a replacement Circlip in the accessories package, it there is a part that is likely to need replacing the clip is it because it is easily lost or damaged in removal.

http://www.nitroplanes.com/96m608-bi...335-245kv.html

http://www.hobbypartz.com/96m608-big...335-245kv.html

Jack
Jul 11, 2017, 06:57 AM
"Discussion Always Welcomed"
Thomas Cummings's Avatar
Quote:
Originally Posted by jackerbes
If you mean to cause it to fail, yes, it would take a lot of pressure.
Yes, that is what I was referring to.

I am assuming that these motors are re-purposed industrial motor designs that were probably intended to provide torque and not resist thrust but as anyone who has removed a circlip, even with the special tool for doing so, knows that little bugger isn't going to hop out of the groove on its own. The axial force that would cause the circlip to fail in sheer would probably be many times the weight of our planes ( I realize this is a static and not dynamic loading).

I can see where the bushing would be an insurance policy but I don't want to grind on or disassemble a brand new motor.

I have heard of motors failing due to bearing failure or magnets coming unseated but I haven't heard of the motor bell flying off.

Just because I haven't heard about it doesn't mean it hasn't happened though!

At the same time one of my personal engineering rules is, "On any large and or complicated assembly the part that costs 5 cents (The Nickel Part) will fail and take down the whole".

Interesting discussion, thanks for your thoughtful response!
Jul 11, 2017, 11:49 AM
Jack
jackerbes's Avatar
Quote:
Originally Posted by Thomas Cummings
Yes, that is what I was referring to.

I am assuming that these motors are re-purposed industrial motor designs that were probably intended to provide torque and not resist thrust but as anyone who has removed a circlip, even with the special tool for doing so, knows that little bugger isn't going to hop out of the groove on its own. The axial force that would cause the circlip to fail in sheer would probably be many times the weight of our planes ( I realize this is a static and not dynamic loading).
Actually they were developed specifically for RC and use in small car type vehicles airplanes. So they do have good torque and use it for either turning propellers and rotors or wheels through gearing. They are generally capable of handling loads that require an input power of 3-4W for each gram of motor weight or a little bit more. And will handle higher loads if they are time limited. At 645g I would consider that Tacon-160 motor a 2000W or so motor. And the input power would be the voltage under load x the Current in Amps at that load. So if you ran it on 16V that would be a load drawing 125A or so.

They rate it as a 2700W motor and say it can be run on up to 58V (that would be a charged and rested 14S LiPO pack) and at that input power it would be drawing about 4.2W per gram against it 645g weight. So it might be save to run it continuously at that load. It all boils down to how hot the windings are getting and if th temp is still rising.

As the limiting factor is the heat in the windings, when they get up to 155C to 200C (wire quality decides which) or so in the windings and have a still rising temperature, they are on their way to burning up. A simple procedures is the put your finger tip on the side of the metal base (the non-rotating part) and it that is too hot to keep a finger on it it is over 130F/54C is time to consider backing off and getting a watt meter to better evaluate your load because it will be quite a bit hotter in the windings. But the housing and magnets will stay cool on a running motor that has some cooling air flow. Magnets will start losing magnetism permanently if they get up 80C or so.

I have heard of motors failing due to bearing failure or magnets coming unseated but I haven't heard of the motor bell flying off.[/quote]

[quote]I can see where the bushing would be an insurance policy but I don't want to grind on or disassemble a brand new motor.

These motors are actually easy to work on and it is fun to rewind them to improve them and get more power and smoother running motors. The Tacon line is a little above average in price, and maybe in quality too. I have not had one of that brand. When you take the clip off if the shaft is a sliding fit in the inner races, the magnets are still holding the housing in place. And it can take a considerably strong pull to overcome the magnets and get the housing to lift up and come off. It has probably happened in flight but never to me.

Quote:
Just because I haven't heard about it doesn't mean it hasn't happened though!

At the same time one of my personal engineering rules is, "On any large and or complicated assembly the part that costs 5 cents (The Nickel Part) will fail and take down the whole".

Interesting discussion, thanks for your thoughtful response!
That is a good rule, I call it Murphy's Law. Good luck with your project, if you burn up your motor or damage it in some way, check back here with the details and maybe a photo or two and we'll help you with getting it rewound!

Jack
Jul 11, 2017, 06:11 PM
Ronaldo Nogueira
ronaldopn's Avatar
Quote:
Originally Posted by Thomas Cummings
Just because I haven't heard about it doesn't mean it hasn't happened though!
It happened
Check here

I bought this kit a long time ago and since then I replace the cir-clip every time I remove it from the motor. As a mechanical engineer who's been working in aviation for 20 years it makes total sense to me.
I follow Jack's tip on the collar too as a backup.
Ronaldo


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