Hi,
I have measured very good Zaccel vibrations with this mounting system. It consists of a suspended acrylic base plate (3mm thick) on which a silicon pad (6mm thick) is placed. The APM case is placed on it with a little pressure from a velcro band.
The O-rings go through holes on each corner of the acrylic plate and are attached to the black nylon spacers. In order to avoid that the o-rings would move up/down the nylon spacers, I used flat metal nuts to block the o-ring (it is screwed between the first 10mm spacer and the bigger 30mm spacer).
The acrylic plate is suspended about 2mm above the fiberglass mounting plate. In order to shield the EMI interferences that could come from the PDB/ESCs, I added special EMI tape on this bottom fiberglass plate.
I show below the obtained results with motors 100% throttle:
This AccelZ measurement in the logs show an average of maximum 0.5g deviation, which is I guess quite good!
Other pictures:
Hugues
Comments
@LTMNO, yes it is an EMI shield (sorry for a year old late answer)
Just a question, is the grey cable covers, a shield?
Hello,
I have modified still the anti vibration " APM mount" and I think I have found my definitve setup. Here is an accelZ result in flight with UNBALANCED props and motors:
another one:
I replaced the four silicon pads under the APM by "ear plugs" pads (i just cut ear plugs in two otherwise it is to thick) and I press down the APM on them with a simple rubber band (much more elastic than the other rubber strap I used previously).
Here a picture of the setup:
@Daniel,
Yeas this looks very good indeed and similar to what I have purchased at Sertim. Sertim is only interessant for Europeans (like me). If you live in the US you'd better find a more local reseller indeed.
Do not forget the blog post of Maxbotix if you use a sonar : your shield cable between the sonar and APM should be shielded of course, but further the metallic part inside the shrink tube should be grounded on the side of APM.
I wil post a blog shortly about what I did to shield the sonar against EMI (it looks like a McGyver solution but it works !)
Hugues
The product references for the EMI cable wraps are:
-Z SST (then you have different diameters)
What you see glued on the bottom plate is :
-ZIPMESH 25mm Al (shields APM from PDB radiations)
Graph in flight corresponds to my post more or less. I can't post any new ones for now since I have crashed and broke two propellers thanks to this stupid collet mounting system |@@##.
Hello,
yes very effective against EMI. In fact I purchased this at a company called SERTIM in France.The metal braided thing you see cmies from the inside of a EMI heat shrink tube (i removed the heat shrink part to have a very flexible wire wrap (not to convey vibrations).
Hugues
@Chris : you can balance the motors by sticking on the side a piece of tape (alu tape or copper tape or even standard plastic tape, so long as it has enough weight). The position of the piece of tape on the circonference of the engine case must counter act the weight inbalance. To find the right position, you must do trial and errors by moving the piece of tape by 90° (quarter of a turn), then you fine tune in the quarter you found reduces best the vibrations.
@Dave, not flyed yet. I'm now ready to try it in flight after having fixed my throttle issue thanks to Randy. Will keep you posted.
Yes I agree with you that the O-ring suspension is cumbersome and probable not the best mechanical option. I have another issue with my setup here : as I have cut the silicon pad in four little cubes, I have less friction between the already slippery silicon pads and the also slippery acrylic plate =>I risk having my APM case move in case of shocks. I tried different glues and/or double sided tapes but nothing seems to stick on that silicon. I moulded this silicon pad myself mixing pure liquid silicon with a catalyser (purchased on a crafting/hobby web site : www.artificina.com). I would be very interested to replace this by fixed absorbing grommets.
I also wonder if I could not isolate/dampen now my motors by adding some o-rings on the screws ?
@Jim : yes this is a bench test I did, not a flight. The props are balanced , not the motors.
I will later balance also the motors with a laser test I saw on a forum : motor by motor you attach a small mirror on the active copter arm. You then project a laser (presentation pointer for example) at this mirror to have a reflexion of the laser dot on a distant enough surface (for example the wall of the room). Then you start the engine of that arm and check if the laser dot stays a dot or if it becomes rather a segment. If it remains a dot, the motor is balanced. Otherwise you stick some tape (random I guess) on one side of the motor and check the dot again. As long as the laser projected segment does not reduce its size to a dot, you move the piece of tape around the motor (I would say by 90° each time). You repeat the procedure for all other motors individually.
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