Servo grommets -

I think they should go down (between the rubber grommet and the wooden mounting rail/plate). That will prevent the "sharp" end from cutting into the wood if you tighten the screws too much. Just my opinion, though.

They go with the shoulder down against the mounting plate or rail.

Always insert the brass grommets up from under the rubber shock absorber so rounded end is flat against the surface the servos is being mounted on - screw with washer from other side. This method forms an "I" beam so as not to crush the rubber. (similar to engine mount in your car or m/cycle). If grommet is inserted from same side as screw, then the screw will drive the sharp end of grommet into the wood, or plastic mount, compress the rubber and there will be no shock absorption/play left - end result broken gears/cracked IC boards/broken leads, pressure fracture of plastic mount = servo fails and perhaps a doomed model. Example = most Hitec & Futaba manuals have a page on installing servos, RX antenna etc e.g Optic 6 manual page 3

no part of a servo case should be in contact with the mounting plate. side mounting servos in glider wings or similar applications may be installed using a rubber double sided tape. regards Alan T. Alan's Hobby, Model & RC Web Links

Hitec? If so the instructions tell you shoulder down onto the mounting surface.

I've come across some people who swear blind the brass bushes are either useless or should be installed from the top. Those people are talking rubbish.

The manufacturer designed them to be used a particular way and if they didn't offer some benefit they'd drop them to save a few cents on manufacturing. Hence, they are beneficial and need to be installed correctly. You paid for them, they work, so use them correctly.

Sorry for the rant, I get annoyed at those that constantly think they know better than the people who spent all the money on R&D to produce the product. Manufacturers don't design in non-functional features if they can help it.

Shoulder should be at the bottom -- the screw will then contact the hon-shoulder end and form the I-beam mentioned before -- cuts down on over-tightening the screw and compressing the grommet to the point that it no longer isolates vibration.

BTW, make sure that the grommet is nice and squishy (like a nougat or jelly-worm). If in doubt, chuch it out and get new ones.

Of course, if you're running electrics, it's probably over-kill as there is no vibration from the motor unless something is out of whack.

The inserts go in from the bottom so that the flared (big) end mates with the mounting surface. The screw head makes for the flair on the other side. The rubber inserts have a front and back side. Look in the grove and you should see a tab. It goes to the outside of the servo.

Happy Landings, Skyhawk

Lee:

I don't know the answer to the question, but I went over and looked at Mr Akimoto's servos. On the Airtronics, the shoulder in on top, and the Futaba on the bottom - so much for observing!

Common sense says either way will work. What is really apparent is that over compressing the rubber grommet with too much tightening will reduce its shock absorber cushioning effect.

Anyway perhaps there will be a spirited debate over his issue much like the 3 rubber bands per each side of the wing? In short, I wouldn't spend much time thinking about these trivial concerns.

Mr Billy

Correct!!

Mr. Billy If you Google on this subject you will find there was a debate. Flange up or down. Me... I install flange up. " Trivial concerns" ???? Naaa. It boils down to " I will install it MY way, you install YOUR way."

Flange up??? or down?? It really does not matter as long as you DO NOT OVER TIGHTEN THE SCREW. If you install it flange down make sure you add a washer on top so you have extra surface area, then the screw will not distort the bushing. Flange up, add a washer to the bottom. Or , I cut brass tubing slightly undersize in relation to the height of the rubber and install a flat washer top and bottom......makes a nice vibe free "sandwich".

Mike R Reading Pa.

You got it :-)

Mike

Lee:

The shoulder MUST be on the bottom. Rationale for this is that with the shoulder UP (which is wrong) the screw can and will drive the insert into the wood below with no problem. This in turn compresses the rubber grommet, which in turn negates the vibration isolation properties of the grommet. With the shoulder down, use a screw with a WASHER (this is a must). This combination will prevent overtightening as the washer will contact the top of the brass insert (the sharp end) and prevent you from torquing down on the screw.

Dubro manufactures servo mounting screws (hex head) that come complete with captive washers, these are great for servo mounting.

Or you can order good ones from MicroFasteners. They have a multitude of uses other than just holding servos in place They will cost about $5 for

100 with probably $5 for shipping...