Model Boat Mayhem
Mess Deck: General Section => Beginners start here...! => Topic started by: tight-lines on June 20, 2009, 10:53:53 am
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hi,i got 2 graupner speed 500e 2 days ago and spent 2 days trying to get them to stop making vibration noise when conected to the propshaft,,,
i have done everything,ive took them out and set them up new again with the propshaft,,9 times,no kidding,,
ive alighned them with solid couplins,rubber couplins,the red hinged type,,,
it can be two things,,,the two new propshafts,which are 10" long,,,,
or the motors,,
the motors do vibrate a realy small amount,when not conected to anything or the shaft ,just a small amount to the softest touch,
but this is realy small,,but this gets enhanced by anything that is conected,,,
and like i said ive set them up at least 9 times,,,
not being use to motors,,my first time working with them,i dont have anything to compare them to,
so this very small amount of vibration,might be more than normal,
they are set on two mfa metal mounts,,,
ive set them glued to the hull,
siliconed to the hull,
foamed to the hull,
i found that when siliconed to hull ,this worked for stoping vibration to the hull,but as soon as the perfectly alighned shaft was conected,
where noisey again,,
is it normal,to always have some small vibration from a motor,,,realy small amount,,,,,
or are there motors that dont move or make noise,,
could it be my propshafts that are causing it,
should i hit it with a hammer,36 times hard,,,
please help,bcos im ready to go out and buy new props and motors,,,
or use the hammer and take up golf,,,
ps do you guys manage to get silent running gear,,apart from natural noise from motor running,,
12v makes it worse,,obviously,bcos of extra rpm,,
but i need it on 12v, 6v is too slow,
again please help,dont just read,,bcos ive spent two days solid,,,,,many many thanks
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Could be the shafts. Have you taken them out and checked them for straightness on a pane of glass or something? Do they both vibrate or is one worse than the other?
If the tubes and shafts stick out the back of the boat does putting pressure on the tube as if to bend it make any difference?
Are the inboard ends of the tubes properly supported close to their ends?
Does it make any difference if you take the props off?
Colin
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Could be the shafts. Have you taken them out and checked them for straightness on a pane of glass or something? Do they both vibrate or is one worse than the other?
If the tubes and shafts stick out the back of the boat does putting pressure on the tube as if to bend it make any difference?
Are the inboard ends of the tubes properly supported close to their ends?
Does it make any difference if you take the props off?
Colin
they seem straight,
i dont have any grease in my shaft bcos i cleaned it out,,,could no grease be causing it?
yes moving the shaft does change the noise but only for a second,no matter where i move it it comes back in seconds and never goes away much,just gets a bit better for a few seconds
yes they was suported perfect now ive ripped them out again,,suported or not they make noise
when you say take the props of,,do you mean the blade or shaft ever way,,,it makes the noise from the shaft,,,when running only motor no shaft its a bit better,as soon as shaft goes on,gets worse,
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Pack the shafts with grease, I use Dow Corning Number 7 Silicon Release Agent.
I'm currently doing up an old boat with an old Taycol motor in it, before I greased it you could hear it for miles, now it purrs like a kitten.
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This may sound strange,
I had a tug that was very noisy on the bench then when I put the thing into the swimming pool just to test for water ingress I also ballasted down then for no other reason tried the drives and other than the ESC whine there was very little noise or vibration.
R,
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the couplings may be the wrong size there are metric and imperial ones and some are very close try running the motor with the brass part on and the red bit removed, there have been a few post on hear that have turned out that way also roll the shafts on some glass or flat plate and see if they roll ok .
Proteus
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I had terrible trouble with one of my shafts vibrating like blazes.....It turned out to be the centre section of the coupling being very loose,changed the coupling and that solved the problem.....
Maybe worth a check.
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What is the hull made of?
Have you supported the inner end of the shafts?
What couplings are you using?
Which motor mounts are you using?
All these do have a relevance to vibration.
Bob
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hi guys thanks for helping,had a feeling that you would be bored with helping people with the dreaded vibration questions,but no,you still helped,so a genuine thanks :-),,,,,
i have greased the shafts,one with vaseline,and one with silicone grease for plumbing,
this has defo helped :-)),,,but :((,,,,there are a few tweeks now bcos it is still fairly bad,,but a lot better,,
i think the grease helps bcos the shafts are probably not 100% true,,but as near as i think where gona get as far as new shafts go,
bcos when turning the innershaft in outer shaft by hand, i could here a slight scraping noise,,,grease has helped this,,,
with being new to the boat building,this noise might just be nit picking,,but i thaught that the tiny bit that its out in the shaft sections must get alot worse when running,
also the spindle coming out the motor,seems to help abit when its pushed back into the motor a bit while running,,
eg,,, all set up and running with no blade on the end of the propshaft,,,while running push back on shaft,this makes noise go down to,,
also,,,,the red coupling with the hinge in the middle,,,seems to make noise when ever it wants too,,,if you move the shaft the pitch changes,,,two seconds later its changing again,,and it does this all the time and there both new,,, i think these red ones suck!
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Why not post a few .....jpgs of your motors...+ couplings ...+ outboard prop supports etc........ ok2 ...this may help our more experienced members to offer a comment....... O0 ....Derek
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hI THERE
Tightlines, I think Mr Bluebird did warn you that 'SOME' Graupner motors were a tad noisy and a bit prone to vibration did he not! ?????????????
Should have gone to FLJ
please yourself.
aye
john
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hi i would do,but ive took everything out the boat now,so there isnt to much to see realy,,,,but i have made some progress,,,i took out my red couplig and installed mu rubber one,,,,peice of rubber tube,,,same brass thread fittings as red coupling,,and this matched with the grease in the shaft has helped alot,,nearly there,,,,,,,, :-)),while pushing back against the motor,,,
dont know how to keep it pushed back against the motor yet?
but this is out of the boat,,so god knows what will happen when its back in the boat,,,
blue bird you are right,,ive been thinking some one said that for 2 days,thinking i should of listend,,and belive me graupner 500 scream like a banchee,,,but they do rev at 12000 rpm,,,,so maybe bcos of these revs as opose to springer type motors? which are around 4-5000 rpm,
at a guess
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Shouldn't worry to much till you've tried it in the water.
I have a Graupner motor in my coaster which on dry land makes heads turn,in the water lovely and quiet.
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Just like mine DickyD, and when the boat is in the water the thrust from the prop will push against the motor armature so therefor acting as you when your pushing on the shaft,
R,
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I have been looking in with interest on this one. Everyone's experience of the Speed 500e appears to vary somewhat. My own experience is that I have been installing them in boats for ten years now as most of them used this motor. In that time, I have fitted hundreds and never had a dud yet. I find they are well built and take an immense amount of punishment long before they give up. The carbon brush sets are actually built on pivoted arms which are tensioned by seperate springs, something not found on cheap motors. I have alwasys found them to be well ballanced and the off load current at 12 volts is 4oomA on every motor I fitted. I rate these motors very highly indeed.
Now I don't just say this because want someone to buy motors from me, thats not what i do, I only fit them into kits, but I wouldn't fit them if they were no good and I certainly don't want customers subs breaking down in the middle of the pond.
As for the vibration problem on a model, if you have aligned everything correctly and the shaft is straight, it may simply be a coupling problem, I havent found many of these nylon couplings to be sufficiently accurate for the high rpm figures generated at 12 volts and they will cause quite a bit of vibration at high speed.
The best way to get around the problem is to fit a pair of them in line. You join them with a short piece of shaft as in the picture or buy a splined coupler which fits in place of the standard brass fitting and simply joins both couplings together without the need of an interconnecting shaft. This will help immensly since A: you can fit a shorter prop shaft (better for high speeds) and B: it eliminates the alignement problem completely. With this setup, you can mount your motor completely out of line with the propshaft without worrying about any binding or stiffness in the setup.
With the best will in the world, you will struggle to completely align a motor with just a single coupling at these high sppeds.
Give it a try, it really is worth thee ffort and it works!
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check the shaft, may seem straight BUT it doesn't take much of a bend to make a hell of a noise
grease shafts
try silicone couplings
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Oh, and i should add that Cat and Dicky's points are also valid and you may find that with everything set up correctly and under load, your 'out of the water' problem may simply dissappear. Running stuff up up the bench, off load at high speeds, will cause all sort of noises and bad vibes.
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also, check the propellers, a damaged blade may also thow them out of ballance.
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Got a 550e and a 600e no problems.
I run them on the bench before installing them to check everything is o.k. not too high revs, both ways
In the boat. check out the engine mountings are secure and don't wobble about I also like to support the rear of the motor as well. The type of mounting used can cause viberation to the hull. The coupling doesn't have play in is centre axis and if it has splined end parts check these are not worn. Coupled up to the shaft make sure you have backlash on the motor / shaft. Also check that the coupling end is not rubbing up against the motor body where the driveshaft comes out. Everything is in line, propeller blades are o.k. no nicks or little bends or parts missing. I had a squeal on mine sometime ago and it was the grub screw slipping on the prop inner shaft. Removed it and drilled a little hole in the shaft to accommodate the grub screw. sorted.
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Hi Guys
I also had problem with speed 700's vibrating.
Rolling the shafts on glass showed a very slight bend. I tried Graupner and JP shafts
and all of them were out of true by some degree.
The thread is also a variable, some are a little on the loose side of accurate.
Putting the threaded brass ferrule of a red coupling on the worst shaft showed 0.3mm out of true,
i.e. running eccentrically.
I ended up with over long shafts, chopping the ends off to form a plain shaft,
truing on a sheet of glass and using a graupner double coupling.
I was quite surprised at the variable quality of stuff were are supplied with and I am now the
proud owner of 10 shafts to get three good ones.
Cheers
Mark
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so much good info,dont know where to start,,but start i did and had 1 more bash for today,,bedded motors down on silicone,,with a home made straight solid coupin for alighnment,made the hole bigger where the propshafts exit boat,,siliconed the shaft in place,with probably to much silicone,,,and when set (2moz), im gona take of solid coupling and replace with rubber pipe,,,home made couplin,,,,,,pretty much what i did at the start but instead of just wd40 in the shaft i know have a mix of silicone grease and vasaline,,
which out of the boat helped,,when pressing against the motor,,
fingers crossed,,oh and thanks again
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Are the shafts held in with silicone?
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this time yes,just silicone,,,,last time they was fixed solid along 7 inches of it with expanding foam,,,and just siliconed where they exit,for a seal,and under motor base,,the alighnment ,realy was 100% spot on bcos i could see clear as day,when pushing inner rod up througth tube to motor spindle
this time everything is set in silicone,,so maybe vibrate with out touching the hull,or move to much,,
i think probably the way i did it the first time was spot on ,but with out the grease made it realy bad ,but didnt reliseat the time it could be down to that,,,think the shafts are a little out and thats not helping,only a tiny amount,so i think the grease is letting the bent shaft spin against the grease and let it slide instead of knock and vibrate as much,
i think its not one thing causing it,,but a few little ones,
strange how pressing against the motors help,,
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Dont think I've heard of anyone fixing propshafts with silicone, you'll have to let us know how long it holds the seal. :-))
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only did it bcos im a plumber and had some to hand,,i have used alot,,
will let you know
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The silicone is flexable so will allow the whole propshaft to move causing slight misalignment and yes vibration!!
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think your right,,ive put a bit more expanding foam in aswell,,just for luck,,,problem is it took me 3 hours getting the foam out of one hull,and it wasnt all out then,now ive done it again in both,,,
and they say god loves a try'r ,,well hope he loves me this time bcos ,god knows ive try'd
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Is it the stuff we use around the sinks n baths and never goes solid ?
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yes the sink and bath ,sealent is called silicone,and thats what i have used,,in large amounts,shouldnt leak i hope
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personally i'd have used silicone grease or axle grease not bath silicone
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I think he meant fixing the tubes in place Ghost, not lubricating them!
Colin
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yeah fixing them in place,,,,,,i did use a silicone grease in the shafts,,,,,but a normal silicone sealent to seal,,,,,,
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does rolling prop shafts down glass,,,show more problems with straightness,,,,,,,,instead of rolling down my kitchen worktop,,,
also do you check,roll,, the inner and outer shaft,on the glass,,,
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Your silicone will allow some movement of the prop shafts as it does not set solid.
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Hadn't noticed it in the above, but does the vibration reach a peak at certain revs. I.e. does it resonate? If this is the case, then having a double coupling or shortening the outer tube and refitting the bush can change the frequency out of the rev range.
Just a thought.
Tony
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I think he meant fixing the tubes in place Ghost, not lubricating them!
Colin
oh, !!
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just tryed them again b4 i get some sleep,and i think the propshafts must be not straight enuff, ive got them sounding better,but they keep getting hot which must be where the slight kick in the steel rod must be rubbing on the oter shaft,,and no matter what i try,,when i get it good again it goes bad again,,,,think i might pay one of you lads,,,,to fix it if i cant get it to work soon >>:-( {:-{,,
is it normal to feel heat in the shaft?,,,
word of warning never get a plumber to make a boat
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If the shafts are lubricated they can get a little warm as the bearings bed in, but anything over a little warm does indicate a problem.
Bob
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... i think the propshafts must be not straight enuff, ive got them sounding better,but they keep getting hot which must be where the slight kick in the steel rod must be rubbing on the oter shaft...
as Adam savage (off Mythbusters) would say "There's your problem!!"
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Plumbers job: .. Keeping water in!
Boaters job:.....Keeping water out!
Shafts hould not get hot, definately something out of line or bent by the sound of things. Make sure the shaft bearings are not sloppy and the shaft can't wiggle sideways in the bearing. At high speed the shaft will wobble and oscillate like a good un and will not only make a hell of a noise but will soon deisplace the grease you put in
HHMMMM.... food for though... Keep at it mate, you're definately a try'er. ;)
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my propshafts,i dont think they have bearings in,,,they have a 4ml oil seal ,then on the main shaft ,they have a smaller bore pipe insert,,,on each end,,which is the 4ml size,
so when people say bearing,do they mean the type that have the little roller bearings in,bcos mine just have the little pipe reducers to centre the inner shaft,
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Do your prop shafts have lock nuts on each end and are they too tight to the outer shaft. This can cause over heating.
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they have a lock nut on one end,other end is held by the couplin conector,,but both of these are,,couplin about 10ml away from shaft,and blade nut not on,just the shaft sticking out,,,,
think im ready to admit defeat,,,but ive spent 400quid in bits,,,,im not a happy camper now,,,
could be the shafts are a bit out,,
im getting ready to see if theres anyone near preston i can pay to get them done of here,,,think ive made one of my motors change its noise pitch,so might of buggerd the bushes a bit too,all i need
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ripped it all out again,,,not a happy chappy now,no way
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There are several known causes of the vibration you describe.
Starting from the aft end.
At 20000 are the props balanced to take those revs, you are getting in the realm of Fast Electrics.
Is the shaft straight and a good sliding fit in the bearings?
Is the shaft supported at the inner end?
Is the shaft held firm within the hull?
Is the inner coupling end close to the outer proptube, you only need a tiny bit of clearance.
Are the coupling ends bored central, there has been several instances of the ends being drilled off centre.
Is the coupling central?
If the shaft is firm you can use silicone but you have to line up the motor well and ensure that the shaft will not transmit any thrust to the motor.
Bob
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tight-lines........I think we all understand your out of balance frustration >>:-( >>:-(
Whilst there are 40 odd suggestions here.......my recommendation is to take your vessel to a model boat club meeting......explain your vibration issue to 'a listing ear'.........I am sure constructive comment :-)) will follow......Derek
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At 20000 are the props balanced to take those revs, you are getting in the realm of Fast Electrics.
,,,running 12000 rpm,,about 10 at a guess in water,,
Is the shaft straight and a good sliding fit in the bearings?
,,,little bit of sideways movement,,,rolled inner on a mirror,,,showed about 1ml out of its 10" length,,,,,so i would say at the 12000 rpm will be a problem,what would be nothing in terms of sound to a boat or springer at 4000rpm,,,bcos at 6v it doesnt vibrate half asmuch
Is the shaft supported at the inner end?
well it was solid,,but i thaught bcos it was solid that i was getting the noise,so did it in silicone for a bit of movment,,to dampen the vibration,,.,,,but looking back now i was trying to solve a problem,that wasnt right,if you get me,,
Is the shaft supported at the inner end? tried both
Is the shaft held firm within the hull? tried both
Is the inner coupling end close to the outer proptube, you only need a tiny bit of clearance.
had it from tight to a inch away
Are the coupling ends bored central, there has been several instances of the ends being drilled off centre.
yes
Is the coupling central?
yes
If the shaft is firm you can use silicone but you have to line up the motor well and ensure that the shaft will not transmit any thrust to the motor
,, right by your process of elimination,,,i think that the propshafts are out ,,,
i have had it in my hands set up ,out of the hull and running with no noise,,but it seems that the grease moves in the shaft after 2 mins of running,,which lets the metal vibrate again,,
think im going to buy two big motors and new shafts and run them at lower rpm,with big props,,if i cant fix it
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one thing i did with nord icelandia, was replace a double dog UJ with a piece of propshaft with two bits of silicone tubing on the ends. went from growl and hum to a whisper
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Shouldn't worry to much till you've tried it in the water.
I have a Graupner motor in my coaster which on dry land makes heads turn,in the water lovely and quiet.
Hi tight-lines, have you tried the hull in the bath/water?
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Shouldn't worry to much till you've tried it in the water.
I have a Graupner motor in my coaster which on dry land makes heads turn,in the water lovely and quiet.
Hi tight-lines, have you tried the hull in the bath/water?
no ive not been able to yet,bcos ive been to put off by the noise,,knowing even if it helped in water,,it would have to be holy water to total remove the problem noise :-),,,
i think i know what it is,,are you ready bcos i dont think you will belive me,,and i promise this has took alot of messing to get to this conclusion?
its the motors,yep thats what i think,,its the speed 500e,
i think i might have a bad batch,seriously,,
i done all kinds of experiments,,
but if a hinged couplin cant spin on a flat work top,conected only with the grub screw at one end,,which is the motor end,,,and the other end is left to spin around the inner shaft im holding,,tight and level,,,
it must be the motor,,i also conected just the brass couplin insert on to the motor ,,tight to the motor,,and turned it by hand ,and it was tight ,then loose ,then tight etc etc,,
as if the spindle is a millionth out of line,,,
so when running the motor on its own,you cant tell,so at that stage you would think all is good
but as soon as anything is conected,,its vibration hell !,,
at time of conecting things it can sometimes be made to go away ,moving angle of prop etc,but it could not be posible to fit it to such extremes,,bcos where ever it is held,,it soon finds its vibration in the body of the motor again and amplifies it,,
also it could be that i dont have the natural skills to pull this off,,,,but i am usually good at making things
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or in other words,the motors might be ok,but bcos there rated at 12000 rpm,,,it takes serious skill to fit,,,or at there rated 12000 rpm they just suck,for vibration,,
i would not be surprised if one of you quality boat building guys could get these to purr like a kitten,,,,but i would not be surprised if you couldnt,what ever skill level,,,,
the only last option i can see is ,,that rubber couplings,,,and single red hinged couplins just wont do at that rpm,,,
i think there desighned for small speed boats,on 12v,,and as such not to botherd about the un avoidable noise on standerd setups,,
two red joints on each motor might help,but its more bloomin money
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Have you any other motors to try?
Bob
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no,just started looking for more options,,feeling a bit lost with this right now,,think im gona leave the boat alone for to night,and take a break,,,and start reading about new motors