Model Boat Mayhem
Mess Deck: General Section => Model Boating => Topic started by: Mike M on January 06, 2021, 12:54:04 am
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Hi, need some help on mounting my Raboesch motors #109-73 in my Fairmount Alpine.I purchased Vibr. absorbers #104-03 and tried to make a motor mount by attaching these parts to a wooden plate.I am getting a lot of noise and vibration.Looks like everything is aligned.
What could be the issue?
There are only 2 threaded holes on this motor, doesn't seem like enough?? Any help would be appreciated.
Regards Mike :-))
(https://modelshipworld.com/uploads/monthly_2017_04/58f25a9787896_FairmountAlpineBox.thumb.jpg.0f5604bd8db5bdc679cc80cce86dfc83.jpg)
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Shafts may be very noisy if:
1. How long are the shafts?
2. At high speed, out of water / not under load.....
3. Usually modellers don't use those types of rubber mounts in-line with a motor,
4. Usually the motor is screwed hard to a mount and soft mount the mount to hull if required.
(https://i.ibb.co/0V961Gv/Mount-1.jpg) (https://ibb.co/rfpzqwN)
(https://i.ibb.co/rxJqj0h/Mount-2.jpg) (https://ibb.co/Vg8b19G)
(https://i.ibb.co/vd1GtCt/Motor-Mount-Holder-Seat-Bracket-For-380-390.jpg) (https://imgbb.com/)
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Thank for your prompt response.Shafts are from Raboesch . Would you recommend the motor mounts pictured and not use the rubber mounts ?? Could you provide a link for the motor mounts? I think the problem is the rubber mounts do not give enough solid support to my homemade mount.
Regards Mike
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Can you post a photo of your current setup?
( https://www.modelboatmayhem.co.uk/forum/index.php/topic,61103.0.html )
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Tried uploading not working for me
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OK, email me any photos, I'll post for you, martin@modelboatmayhem.co.uk
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Hi Mike
Have a look at UKMike's Fairey Huntsman Becomes a Sports Fisherman in Pleasure Boats etc. as he has used them. But he has used 4 and a metal cross mount.
Most of us don't use those though and use the brackets as shown which are perfectly fine. Use a decent coupling though - the alloy ones with the rubber piece in the middle are good.
Chris
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Hi Mike
Have a look at UKMike's Fairey Huntsman Becomes a Sports Fisherman in Pleasure Boats etc. as he has used them. But he has used 4 and a metal cross mount.
Most of us don't use those though and use the brackets as shown which are perfectly fine. Use a decent coupling though - the alloy ones with the rubber piece in the middle are good.
Chris
Link: https://www.modelboatmayhem.co.uk/forum/index.php/topic,64836.msg689684.html#msg689684
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Hi, This is something I had in mind, my motor can only has 2 mounting holes. BTW sent you a pic
Again thank you for your help Mike
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From Mike....
Hi Martin, Here is the pic of my set-up As you can see the rubber motor mounts are screwed into the can.I have since taken them off so I can figure out a different solution.My couplings seem OK,would they have to be perfectly aligned,or is there some self alignment? I have since contemplated buying some proper motor mounts.Beyond me why Raeboesch doesn’t have the motor mounts available.Probably some of the noise is because the props are not under load.
(https://i.ibb.co/wRqgb52/Mounter-mount-a.jpg) (https://ibb.co/t46KNV1)
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I make motor mounts from a piece of L-shaped aluminum from the hardware store. It comes in 3 ft. lengths, so just saw off a piece a bit wider than the footprint of your motor. No vibration isolators between motor and motor mount. But I do use a piece of ⅛" thick black rubber sheet between the motor foot and the hull, or whatever the motor sits on. On this boat I made a sub-base for the motor from ⅛" plywood.
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I make motor mounts from a piece of L-shaped aluminum from the hardware store. It comes in 3 ft. lengths, so just saw off a piece a bit wider than the footprint of your motor. No vibration isolators between motor and motor mount. But I do use a piece of ⅛" thick black rubber sheet between the motor foot and the hull, or whatever the motor sits on. On this boat I made a sub-base for the motor from ⅛" plywood.
Excellent How thick is the aluminum?When you run your motor on land is it noisier then when in the water under load??
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Have since taken off the mounts waiting for a solution.
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From the photo, the rubber should be between the wood bulkhead and the motor..... but the shaft then won't be long enough.
... plus there are only two rubbers, you'll get side to cushioning but not up and down.... {:-{
This is a way I did it: https://www.modelboatmayhem.co.uk/forum/index.php/topic,63982.msg686051.html#msg686051
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Hi Mike m
Are these style of mounts in the link available to you in canada
https://howesmodels.co.uk/product-category/radio-control/motors/motor-mounts/ (https://howesmodels.co.uk/product-category/radio-control/motors/motor-mounts/)
Jason
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Mike
A picture of mounts i make my self 3mm aluminium angle
[/size]Jason [/font]
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Thank you everyone for your helpful advice Much appreciated :-))
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Excellent How thick is the aluminum?When you run your motor on land is it noisier then when in the water under load??
The aluminium section will be whatever thickness the hardware shop sells. Usually sold in 1 metre lengths of extruded section.
As pictured, the mount is just using the treaded section at one end, the rubber section appears to be just hanging there, doing nothing. Motors are mostly intended to be rigidly mounted to a bracket using the two screw holes provided, then the bracket is used to spread the fixing load. Usually a screw in each corner. If the rubber decouplers are used, they go under the bracket feet.
As suggested earlier, a layer of rubber sheet between the underside of the bracket and whatever it is fived to will do the job.
Model boat hulls do tend to act like musical string instrument bodies - any sound inside them gets amplified.
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Thanks :-))
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Hi Mike m
Are these style of mounts in the link available to you in canada
https://howesmodels.co.uk/product-category/radio-control/motors/motor-mounts/ (https://howesmodels.co.uk/product-category/radio-control/motors/motor-mounts/)
They do not ship to Canada
Jason
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He was asking if that style of mount is available in Canada rather than ordering from Howes.
Just done a search on Ebay Canada for Model Motor Boat Mounts and plenty come up including some I wish we had over here!
Note that water cooled mounts are fine as well even if you don't use the water cooling.
Chris
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I have made my own mounts and have the motor lined up with the shaft.When testing the alignment I am noticing the shaft at the point where it connects to the coupling gets quite warm.Is this normal?? I am using the Raboesch self lubricating shafts with the compatible Raboesch nylon couplings.Second question.when testing the motors on high speed on a work bench, will it be more noisy than when the props are under load?
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The shaft will get warm as it is transmitting the heat from the motor. Be careful of how long you are running the motors as the lower bearing in the prop shaft is Delrin and is water lubricated.
Noise will be less when the boat is on the water as some of the noise will be deadened by the water and the motors won't be able to rev as high.
How are you testing the alignment? Using a solid connector to set up is a good idea and then replace with the flexible coupling. Some folks prefer to use a wattmeter.
Chris
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Excuse my ignorance How is a wattmeter used to align the shaft to the motor?? Right now I have things set up with clamps and run the motor and shaft and shift until sound is minimal.At that point the part that goes through the hull gets quite warm.Interesting you say the part of the shaft gets lubricated by water.I thought they where sealed with lubrication.I try to align by using straight edge and a mini level.Maybe I am expecting it to be too silent while out of the water.
BTW thank you for your advice so far. One more thing, I have 2 versions of mounts I'm trying.One is a flat piece of ply mounted to the rib with motor attached second two 45 degree blocks which cradle the motor and then put in place with silicon.Maybe better to source a proper mount???
Regards Mike
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Hi Mike
It's not a method I've used but basically you get the lowest reading on the wattmeter when the resistance to turning is lowest i.e. when the alignment is correct. Even when using a UJ or other flexible coupling the alignment needs to be as accurate as possible. As it's that side of the coupling that's getting warm it does suggest an alignment issue. The ballrace housing isn't turning is it causing the heat? This should be epoxied to the prop shaft though I'm going to tape some of mine in place, initially at least.
I use the Raboesch maintenance free prop shafts as well. The top bearing is a greased ballrace and the lower one is Delrin as stated. There is no other lubrication in the prop shaft. Given the ballrace bearing and accurate location of the shaft accurate alignment is very important and so yes source some proper mounts. The only boat I've got without one is my Club 500 race boat where the motor is held in a cradle with rubber bands, but that is a cheap and cheerful boat and gets some abuse unlike my Fairey scratchbuilds!
Photos of one of my installations; with solid alignment coupling and then with UJ.
Chris
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Watemeter / ammeter / noise. The lower the watts, or amps the better the alignment. I use a 1.5v dry cell (or two depending on voltage of motor) and listen for the quietest position before bonding the motor mount down. Sometimes a layer of masking tape or paper underneath etc to adjust height. Many more than one way to do it.
Can't comment on your shafts. Tried one once years ago and it was way tight to turn so got a refund and always use regular shafts. They must work, but I didn't like them.
Noise will often be louder when the motors turn and the hull isn't floating. I've seen beginners tripped up with this many times.
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Thanks Everyone :-)) :-))
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I've put some extra info. in my post - particularly see the bearing housing comment as a source of heat.
I've got one 5/10mm prop shaft and that is a bit tight. The other one and my 4/8mm prop shafts turn easily. I don't use anything else in my builds.
Chris
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Thanks Chris Where do you buy your motor mounts? Thought I could source them from Krick,don't think they ship to Canada.Lot's on e-bay but comes from China shipping takes forever. >:-o
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I've put some extra info. in my post - particularly see the bearing housing comment as a source of heat.
I've got one 5/10mm prop shaft and that is a bit tight. The other one and my 4/8mm prop shafts turn easily. I don't use anything else in my builds.
Chris
Some of the Raboesch shafts have a green rubber seal on the inboard end which drags against the shaft - it doesn't seem to be in place in your pictures, but I would bet it's the cause of the heating here.
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No Green seal on these shafts .I'm pretty sure it's caused by an alignment problem
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Hi Mike
I bought my alloy mounts from Cornwall Model Boats and Anglia Model Centre (via Ebay) and it looks as though they were produced by the latter as the marks on them where they were bent were the same. Unfortunately Anglia Model Centre ceased trading - wish I'd bought more now! I can get them in black nylon but I like the alloy ones especially after a bit of fettling and polishing!
Chris
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Evening Chris
Steve at modelboatbits sell the alloy mounts
https://www.modelboatbits.com/MOTORS-MOUNTS/MOTOR-MOUNTS/ (https://www.modelboatbits.com/MOTORS-MOUNTS/MOTOR-MOUNTS/)
Jason
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Thanks Jason
Yes, I was having a search through the suppliers I've used in the past and found those but they are too big - I use the 500 - 600 mounts.
Chris
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Hi Chris
No problem :-)) [size=78%] may be next time you need mounts make your own as i like to [/size]
Jason
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I may well have to, you've made a nice job of yours.
Cheers, Chris
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Mike did you get anywhere with that pointer to the Canadian shop over on rcgroups? Your kind of getting the same advice in parallel on both forums.
I can't remember your motor size, but there's also a company called mfa over here who do motors and mounts, component shop also sell mounts. Considering most motors we use are "standard" can sizes there's usually a mount somewhere, or with a little imagination the mounting holes can be filed or reamed to size, or make an adapter plate to suit. You may not find an off the shelf mount for every motor simply because of demand, and easy enough to make "DIY" so they're raylored for about 3-5 commonly used motor sizes. As a living room table top modeller I try to modify something close as no workshop to use. Have to say though there's many many ways to mount motors and each to their own as long as it works though my pet hate is seeing jubilee clips wrapped round them, or gluing motors down!
The rcgroups thread recommendation was to use the dog bone joints common in the US. My one and only experience of them was they wear out, even when aligned. It's perfectly normal to use double huco joints, but still align as best you can in first place!
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Yes I went to see the fellow in Victoria.He gave me some good advice also.The advice I got on this forum and RC groups has also been good.I have ordered 2 mounts, so that's the route I have decided to take. We'll see what happens ok2