Warning: Loctite 248 and damages on AX-12A/AX-18A cases

Bioloid robot kit from Korean company Robotis; CM5 controller block, AX12 servos..
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Warning: Loctite 248 and damages on AX-12A/AX-18A cases

Post by PedroR » Thu Mar 29, 2012 6:41 pm

Post by PedroR
Thu Mar 29, 2012 6:41 pm

Hi all

We've been assembling a Bioloid GP for our office (it's our second :) ) and the GP kit ships with Loctite 248.

As you may know Robotis has updated their popular Servos from AX-12+ to AX-12A and AX-18F to AX-18A and this kit has shipped with these updated models.

When building the Bioloid GP, we found that Loctite 248 melts the plastic of the servo case on AX-12A and AX-18A. . (Loctite 248 is thread locking glue)

The most severe damage has been to the location where nuts are inserted: the Loctite melted the palstic around the nut so when we tried to remove the screw the whole set of screw+nut would turn freely and the screw would not come out.
We had to aggressively damage the servo case to be able to release the screw and metal frame from the servo.

This problem does not seem to happen with the older AX-12+ and AX-18F. We have an older Bioloid GP with these servos (also assembled with the help of Loctite 248) and it is fine.
Thread locking glue is a good idea to use in this type of kits.

I don't know why Robotis still ships Loctite 248 with the upgraded Bioloid GP kits (that have the new AX- 1xA servos) but we have reported the issue to them and are waiting for their reply.


If you recall a similar issue with certain types of Locatite has also been reported when Bioloid PREMIUM was released (see here http://robosavvy.com/forum/viewtopic.ph ... &view=next )

This is mainly a heads up for other users.

We'll also post back some pictures of assembling our Bioloid GP in the next days (we've customized it with some additional DoF).

Regards
Pedro.
Hi all

We've been assembling a Bioloid GP for our office (it's our second :) ) and the GP kit ships with Loctite 248.

As you may know Robotis has updated their popular Servos from AX-12+ to AX-12A and AX-18F to AX-18A and this kit has shipped with these updated models.

When building the Bioloid GP, we found that Loctite 248 melts the plastic of the servo case on AX-12A and AX-18A. . (Loctite 248 is thread locking glue)

The most severe damage has been to the location where nuts are inserted: the Loctite melted the palstic around the nut so when we tried to remove the screw the whole set of screw+nut would turn freely and the screw would not come out.
We had to aggressively damage the servo case to be able to release the screw and metal frame from the servo.

This problem does not seem to happen with the older AX-12+ and AX-18F. We have an older Bioloid GP with these servos (also assembled with the help of Loctite 248) and it is fine.
Thread locking glue is a good idea to use in this type of kits.

I don't know why Robotis still ships Loctite 248 with the upgraded Bioloid GP kits (that have the new AX- 1xA servos) but we have reported the issue to them and are waiting for their reply.


If you recall a similar issue with certain types of Locatite has also been reported when Bioloid PREMIUM was released (see here http://robosavvy.com/forum/viewtopic.ph ... &view=next )

This is mainly a heads up for other users.

We'll also post back some pictures of assembling our Bioloid GP in the next days (we've customized it with some additional DoF).

Regards
Pedro.
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Post by Tyberius » Tue Apr 03, 2012 2:58 am

Post by Tyberius
Tue Apr 03, 2012 2:58 am

How much loctite are you using?

I have a pretty set 'dip & dab' method, meaning dip the tip of the bolt into a small spoonful of loctite, then dab on a paper towel. This seems to apply just the right amount of loctite and I've never had an issue melting any plastic like this.

Less is more when it comes to loctite, you really barely need anything for it to be effective. It shouldn't even be coming into contact with the surrounding plastic, if so you're using too much.
How much loctite are you using?

I have a pretty set 'dip & dab' method, meaning dip the tip of the bolt into a small spoonful of loctite, then dab on a paper towel. This seems to apply just the right amount of loctite and I've never had an issue melting any plastic like this.

Less is more when it comes to loctite, you really barely need anything for it to be effective. It shouldn't even be coming into contact with the surrounding plastic, if so you're using too much.
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Post by PedroR » Tue Apr 03, 2012 2:41 pm

Post by PedroR
Tue Apr 03, 2012 2:41 pm

Hi Tyberius

Thank you for sharing your experience.

To clarify, the purpose of my post is not to tell people to stay away from Loctite but instead to explain the fact that that Loctite 248 will melt the plastic of AX-12A and AX-18A.

As far as we know, this did not happen with the old servos (AX-12+ and AX-18F), so we believe this is relevant information to share with our customer base.

I agree that one needs to be careful with the amount of Loctite used.
Unfortunately this is not explained anywhere on the manual of the Robot neither are there any warnings about the possible damage.

As a side note, in our case the damages were caused on screws that had to be removed and reinserted (the first dis assembly was fine but after re assembling, the next dis assembly was problematic on a couple of screws. - in case you're wondering the reason to disassemble the robot was adding and tuning/upgrading DoFs).


Having said this we appreciate your advice on the best way to handle Loctite (I missed that part on my post).
We look forward to hear from Robotis as well (they're running their own tests after our report).

Regards
Pedro.
Hi Tyberius

Thank you for sharing your experience.

To clarify, the purpose of my post is not to tell people to stay away from Loctite but instead to explain the fact that that Loctite 248 will melt the plastic of AX-12A and AX-18A.

As far as we know, this did not happen with the old servos (AX-12+ and AX-18F), so we believe this is relevant information to share with our customer base.

I agree that one needs to be careful with the amount of Loctite used.
Unfortunately this is not explained anywhere on the manual of the Robot neither are there any warnings about the possible damage.

As a side note, in our case the damages were caused on screws that had to be removed and reinserted (the first dis assembly was fine but after re assembling, the next dis assembly was problematic on a couple of screws. - in case you're wondering the reason to disassemble the robot was adding and tuning/upgrading DoFs).


Having said this we appreciate your advice on the best way to handle Loctite (I missed that part on my post).
We look forward to hear from Robotis as well (they're running their own tests after our report).

Regards
Pedro.
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Post by petercohen » Sun Aug 05, 2012 9:13 am

Post by petercohen
Sun Aug 05, 2012 9:13 am

Does Loctite 248 damage the plastic of the MX series?
Does Loctite 248 damage the plastic of the MX series?
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Post by PedroR » Mon Aug 27, 2012 10:03 am

Post by PedroR
Mon Aug 27, 2012 10:03 am

Hi

Robotis never sent us further information about this issue on AX-18As (or MXs for that matter).

The method recommended by Tyberius - using VERY little amounts of Loctite - doesn't seem to cause any damage and can be safely used with AX-18As (and I would assume MXs).

Loctite is a really nice tool for easing maintenance in the long run.
The only thing you need to make sure is to use very little Loctite and apply it on the tip of the screw (and not the thread).
If you put it on the tip it should find its way into the thread of the screw and nut without overflowing (and touching the plastic).

You can test it yourself by applying a little bit of Loctite 248 on one of the flat surfaces and leave it for a 3 or 4 days.


I can't confirm if Loctite will damage the plastic on MX servos but if you choose to use it then make sure to follow Tyberius technique.

Regards
Pedro.
Hi

Robotis never sent us further information about this issue on AX-18As (or MXs for that matter).

The method recommended by Tyberius - using VERY little amounts of Loctite - doesn't seem to cause any damage and can be safely used with AX-18As (and I would assume MXs).

Loctite is a really nice tool for easing maintenance in the long run.
The only thing you need to make sure is to use very little Loctite and apply it on the tip of the screw (and not the thread).
If you put it on the tip it should find its way into the thread of the screw and nut without overflowing (and touching the plastic).

You can test it yourself by applying a little bit of Loctite 248 on one of the flat surfaces and leave it for a 3 or 4 days.


I can't confirm if Loctite will damage the plastic on MX servos but if you choose to use it then make sure to follow Tyberius technique.

Regards
Pedro.
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