Steve Hargreaves - Moderator Posted April 25, 2009 Share Posted April 25, 2009 After some advise please.....I have a new Turnigy C35/36/1100 motor & have just run it up in my new project.....it initially span up OK but as the revs got over half throttle it started to vibrate & make a horrible screaming noise. I shut down & tried again withou the prop & as I get to 3/4 throttle & above the scream is terrible....it actually hurts your ears. There is also some slight vibration (even without the prop) through the airframe & this is in complete contrast to my other Turnigies which are turbine smooth. I have tried a different ESC & this makes no difference.....any thoughts??? Is it just a duff motor?? Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted April 25, 2009 Share Posted April 25, 2009 What timing have set on the ESC Steve - most outrunners prefer a hard setting. Quote Link to comment Share on other sites More sharing options...
Ron van Sommeren Posted April 25, 2009 Share Posted April 25, 2009 One possible explanation: squealing/jerking motors Prettig weekend Ron Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted April 25, 2009 Share Posted April 25, 2009 Thats a nice link there Ron Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted April 26, 2009 Share Posted April 26, 2009 Steve I am not sure the squeal you are getting is the same as that described in Ron's post. As you say you would expect the motor, particularly without the prop, to be turbine smooth. If your other motors don't do it then I suspect the motor is at fault. Quote Link to comment Share on other sites More sharing options...
Former Member Posted April 26, 2009 Share Posted April 26, 2009 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted April 27, 2009 Author Share Posted April 27, 2009 Hi all..... thanks for the responses. Timbo...yes I thought it might be that too but the ESC I was initially using is a cheapy & isn't programmable plus it spins up my other motors c/w prop no problem & the ESC I swapped it for also runs my other motors just fine. Also I would think the timing would become more relevant & have a greater effect when the motor is under load......it screams even when running with no prop Ron...thanks for the link but as Simon says the squeakl described is not the same as the one I am getting...I know the sound it is describing & this usually occurs as start up......this motor spins up fine & its only as it reaches top speed we get the screeching.... Eric....its more of an "electrical" scream than a mechanical one......I will slip a bit of 3-in-1 on the bearings though just in case. As Simon says I think it must be the motor....I've changed everything else!!! It cam from H.K. so its not so easy to send it back but I may do anyway.....I wonder if its been wound slightly wrong. I will try & capture some footage of it & post it up here later for more consideration.... Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted April 27, 2009 Author Share Posted April 27, 2009 OK here we go......not brilliant quality but you get the idea......note can of 3-in-1 in background Eric!!!. The camera seems to mute the noise somewhat...it doesn't sound too bad on the clip but believe me it's really ear piercing......... & yes I do know its bad practise to hold a motor in a ply former as I'm doing in the video but I had full body armour on & highly trained paramedics standing by just out of shot if anything went wrong... Quote Link to comment Share on other sites More sharing options...
Ron van Sommeren Posted April 27, 2009 Share Posted April 27, 2009 "Try a DROP of oil on the bearings ..." Careful with oil in greased bearings Eric, see posts http://www.rcgroups.com/forums/showthread.php?p=11907250&highlight=oil+oiling#post11907250 and post #15 here http://www.rcgroups.com/forums/showthread.php?t=1012048 Vriendelijke groeten Ron Edited By Ron van Sommeren on 27/04/2009 12:46:22Edited By Ron van Sommeren on 27/04/2009 12:48:22 Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted April 27, 2009 Author Share Posted April 27, 2009 Hi Ron.....the video was taken after the 3-in-1 was applied!!!!! Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted April 27, 2009 Share Posted April 27, 2009 I know what it is ! You have the throttle on the wrong stick Seriously, I cant actually hear anything to worry about TBH. I know you said the video sound lost a bit in translation, but it just sounds like a high revving motor to me. Does it do it with a prop on and under a bit of load.? Quote Link to comment Share on other sites More sharing options...
Ron van Sommeren Posted April 27, 2009 Share Posted April 27, 2009 You are too fast Steve, I had only typed the opening sentence and was looking for the apropriate links edit: guess it's lunchtime in the UK Edited By Ron van Sommeren on 27/04/2009 12:49:33 Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted April 27, 2009 Author Share Posted April 27, 2009 Timbo, yes it does....it,s fine up to about 2/3rd throttle & with the noise we get a sort of resonant vibration through the airframe....indeed it got so bad that it actually threw the prop & driver off bending the shaft in the process (now replaced). & yes the prop drver (collet type) was tight!!! My intial feeling was.."oops.....unbalanced prop..!" so I stuck it on my magnetic balancer & it was a fraction out but only a fraction......a quick rub with the sanding block against the heavy trailing edge & it was perfect......tried again....no different ....again it seemed to resonate at about 2/3rd throttle but I managed to shut down the motor before anything nasty happened!!!! One thing that does occur......in the model the motor is fixed to a 3mm ply firewall with the front of the motor fixed, outrunner bit behind & the prop in front of the firewall whilst the ply mount in the video is 6mm (cos its easier to hold). I have to admit that the motor seemed quieter when fixed in the 6mm mount......could the 3mm ply be too thin & flexing?? Both ply mounts are made from decent birch ply not the rubbish "liteply" we find everywhere..... I think I will hold the thicker mount in me workmate & try it with a prop on....... Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted April 27, 2009 Share Posted April 27, 2009 Sounds like a plan, cos as i say, it dont sound too bad to me. The only bad noise I ever get from the turnigy motors ( and I have loads right up to 1500Watt jobs ) is when the timing is wrong or they are just overrevved due to excessive volts. These are budget motors after all. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted April 27, 2009 Author Share Posted April 27, 2009 Right...the results of this evenings testing........ I mounted the 3mm mount on my workmate & made everything secure & opened the throttle.......it span up fine....no noise, just the usual brushless motor sounds....so I swapped for the 6mm mount & again no drama just spooled up fine. So I mounted the motor back in the model using the 3mm mount & away it went...again sounding quite normal although there was some resonant vibration at the top end...not much but there non the less. So in went the 6mm & it was perfect...span up just fine...no vibration...completely smooth. I have video footage of all this but frankly its pretty boring so I haven't posted it up. Conclusions:- I have looked hard at the decisions I have made during convertion (this is a plan built IC model I'm converting to electric....a KK Mini-Super if anyones interested) & with hindsight the way I have mounted the motor doesn't offer sufficient "clamping area" for mounting the firewall & I think this along with the 3mm ply are allowing sufficient flexing of the mount to cause the vibrations & subsequent problems. Plus as Timbo says these are budget motors (albeit good 'uns in my opinion) so maybe we have to accept that it is a tiny bit out of balance as standard..... So what to do...? If I go for a 6mm mount this leaves the ply standing 3mm proud of the front of the aircraft which looks a bit naff so I'm going to try laminating a mount that will allow 6mm around where the motor mounts but only 3mm at the fixing points, hence the extra 3mm will be inside the cowl rather than outside...OR.....I might keep the 3mm plate & use the "reverse mounting" "X" but clamp it to the rear of the firewall thus spreading the load across the former a bit better. In addition I am going to ensure there is more "clamping area" to ensure the former is better based. After all was done I took the motor out of the model & ran it without the prop....it still screams!!!! One thing this has taught me is an increased respect for our leccy motors....we all tend to get a bit blase about safety don't we but there is no wake up call like a 9x6 prop flying across the garage & shattering against the wall to remind you just what we're dealing with here.....& all this at a measly 250watts or so......can't see me ever going for the really big stuff....IC is much safer!!!!!! Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted April 27, 2009 Share Posted April 27, 2009 Nice one Steve, glad you sorted it. And a good parting comment too, - I HAVE actually witnessed the results of a big ( 1000 watt ) motor throwing a prop across the garage - one piece of prop ( black glass filled nylon @ 15 X 8 ) dug a hole in to the linoleum covered floor, and severely scratched the concrete beneath. The other bit went AWOL, until several months later I was moving stuff around, and found it buried some 2 " deep into the side of a wooden chest of drawers. Scary. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted April 28, 2009 Author Share Posted April 28, 2009 Yeah, the really scary thing for me about electric motors is that they don't stop...stall an IC motor & it stops & stays stopped......stall an electric motor & it tries even harder to turn & as soon as the obstruction is released it starts up again!!!! Plus an IC motor will Plus they often seem so small & light......little M3 screws to mount them, 1.5mm ply mounting plates, an M4 shaft......it all seems so weedy after a chunky IC motor & this lulls us into a false sense of security about what is actually a pretty powerful piece of kit......!! Theres me in the video holding the motor in my hand while it runs up to speed....can't see me doing that with an equivalent IC motor..... Quote Link to comment Share on other sites More sharing options...
Terry Whiting Posted April 29, 2009 Share Posted April 29, 2009 Steve, I had a very simular problem with a 250w motor. It was in a test rig, at a certain throttle setting a strange sound was emmited, I could also feel through rig a high frequency vibration.I did not open the throttle any further as I was sure something nasty would happen. I removed the prop which I knew was truly balanced and ran the motor, I still had the same fault. The motor had a metalic lable which only spanned half the motors circumference. I removed the lable and lost my vibration. To-day any motor I purchase with such lables I remove. Edited By Terry Whiting on 29/04/2009 12:17:00 Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted April 30, 2009 Author Share Posted April 30, 2009 Thats interesting Terry......my motor also has a label as you describe so I shall peel that off & see if it helps.....at 1100 rpm/volt I think it's probably turning at around 10,000 rpm under load so even a very small imbalance would show up..... Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted May 3, 2009 Author Share Posted May 3, 2009 Final Installment......I laminated another 3mm thick piece of ply to the motor mount so the bit where the motor fixes is now 6mm thick & also improved the mounting to give more support........ Result.....totally smooth......spools up perfectly & runs just as you would expect. What have I learned? Well I think it shows that even though an electric motor is generally well balanced a good firm mounting cannot be overlooked. I look around my fleet & some have only 1.5mm ply motor mounts & these are fine but then the mounts are well supported by the surrounding structure & the one I had designed wasn't. Also this is actually a reasonably powerful motor...350-400 watt rated with all the mass that implies.....I'm only running around 250watts but even so it seems to me that the mass & size of the motor should dictate the security of the mounting rather than just the power you expect to extract from it.... Thanks to all who contributed.... Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted May 3, 2009 Share Posted May 3, 2009 Thats great news Steve - and agood lesson to all of us. Did you remove the label incidentally? Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted May 3, 2009 Author Share Posted May 3, 2009 I did but can't say I noticed any difference!!! Quote Link to comment Share on other sites More sharing options...
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