RUNABOUT SLIPPING SILICONE COUPLING SOLUTION ?

Started by jbkiwi
7 replies 30 likes Last activity: 5 years ago
#8

RUNABOUT SLIPPING SILICONE COUPLING SOLUTION ?

Hi Gary, - the first name's the same as his, - haven't started mouldering yet though😁. Most of the fittings were made by making male masters and making impressions in modelling clay, baking that, coating the inside with f/glass mould parting wax, the filling them with polyester resin. taken out of the moulds, cleaned up and painted with chrome paint, (there is a section on my runabout building blog showing how it was done). very simple and cheap to do.

The bow T cleat was just brass strip and rod, and flag pole base was brass strip and tube. Spotlight was a modified hardware item (plastic screw cover). I don't have a lathe unfortunately, although I'm looking at some small modelling lathes at present, but don't like the price. There are a few nice Myfords for sale, but they still command a high price.

I do have a large bench drill/mill which gets used for everything, Mill, router, sander, (sometimes 'vertical lathe' for light stuff) press for brushless motor shafts etc. One of the handiest tools is an Austrian EMCOSTAR multi machine, (bench saw, band saw, disc sander, belt sander, jigsaw etc) which I was given,- a perfect tool for modelling. Other than that, everything is just made by hand with ordinary tools.

Regards, JB
Liked by dave976 and stevedownunder and
#7

RUNABOUT SLIPPING SILICONE COUPLING SOLUTION ?

Hi JB, every time I see your initials for some strange reason I always think John Brown, but don't ask why because I don't know. Out of curiosity do you have a lathe tucked away in your workshop, as you make as per your latest creation fine detailed fitting and fixings? Plus, it's the fine detail that really makes the difference between good and exceptional. Regards, Gary.
Gary Steam Marine, the only way to go.
Liked by stevedownunder and Martin555 and
#6

RUNABOUT SLIPPING SILICONE COUPLING SOLUTION ?

Hi Gary, no chastising necessary 😂 all suggestions welcome😊 Your tube solution would have been good if I had been able to line the shafts up perfectly (actually purchased some of your suggested devices off Ali Expr, (nice looking expensive brass ones) but the tolerances of the holes were so bad, I couldn't use them). I had thought as you did, a solid connection would be good, but I couldn't buy anything from China which wasn't drilled to stupid sizes and almost rattled the motors out of the boat😐

I now have a good collection of almost every connection they sell for boats and cars, and all are useless. Good for slow revving boats or rock crawlers only. High revving shafts need precision fittings, and with Chinese stuff , it's all different, and mixtures of metric and imperial ( I mean, what sort of size is 3.25mm for a shaft,- why not just 3mm,4mm etc, and ream a hole for clearance in the fittings) I think they make stuff to be easy for hobbyists to assemble, and don't worry about precision. Too many companies making too many things to their own tolerances.

The one good thing about silicone I've found, is that even if the shafts are a little bit out, they still flex and run smoothly. Re pond weed,- My HSL ran into a patch last year, and both the shafts twisted the silicone off, which saved the expensive in-runners. Had to launch a rescue mission with my faithful old Vic Smeed MTB (only has 25mm 3 blade props which don't seem to attract weed so much.) Not a lot of weed where I run the boats, but long strands seem to pop up from the bottom occasionally and snag things.

JB
Liked by stevedownunder and GaryLC and
#5

RUNABOUT SLIPPING SILICONE COUPLING SOLUTION ?

Hi JB, could I kindly with your permission cancel my last comment, I should have known that you would have a very good reason for going down that particular road, consider be to be suitably chastised. I wasn't aware you had to deal with pondweed, my local boating lake on the seafront is seawater with nothing in there except the odd shopping trolley. Regards, Gary.
Gary Steam Marine, the only way to go.
Liked by stevedownunder and Martin555 and
#4

RUNABOUT SLIPPING SILICONE COUPLING SOLUTION ?

Hi JB
I have used silicon tubing and agree it gives a very quiet link. I use home turned brass ferrules on each shaft fastened with grub screws. For the more powerful setups I use a pin thro the ferrule and silicon. You seem to be using fuel pipe and I find silicon IC exhaust tube much more resilient, but it really depends on how much power you are transferring, and for small scale models not a problem. Seen the video and enjoyed watching.
Dave
Liked by stevedownunder and Martin555 and
#3

RUNABOUT SLIPPING SILICONE COUPLING SOLUTION ?

Hi Gary, there are collars fitted on the shafts to stop them moving back. I use the silicone tube, as its much quieter and doesn't transmit so much noise to the hull. Also takes up any slight misalignment in the shafts, and can step up/down different motor/shaft sizes. Another reason is to protect against stalling from being caught in weed etc. The motor will rip the silicone, or break the grip and spin, rather than let the smoke out.

I've used this method for years on all my electric boats, and apart from having to replace the silicone if it gets oil on it or it rips, it's usually trouble free,- and cheap. The secret is to find good quality silicone. Just not the best for high torque loadings, but fine for scale. The only real problem is the migration towards the motors, (too much torque turns it into a screw and winds it up towards the smaller shaft,- least resistance)- hopefully the stops will fix this. Have fitted them now, so the next run will show if it has.

There is a vid in the media section, (they don't show in the main RH listing for some reason) Not brilliant clarity,- need a better camera.
Regards

JB
Liked by stevedownunder and Martin555 and
#2

RUNABOUT SLIPPING SILICONE COUPLING SOLUTION ?

JB, Looking at photo one I was surprised to see no thread nut and washer on the end of the prop shaft, to stop the shaft from migrating down the tube. As the alinement of prop and motor looks spot on,
why not a metal tube type coupling with enough thickness to take the thread of a couple of grub screws on at each end. That does seem to me to be a sensible solution to your problem, but maybe there is a good reason for not going down that road. Mind, a great-looking boat and am looking forward to an all-action video. Regards, Gary.
Gary Steam Marine, the only way to go.
Liked by stevedownunder and dave976 and
#1

RUNABOUT SLIPPING SILICONE COUPLING SOLUTION ?

During the first running of my runabout, the usual problem with silicone couplings (silicone tube inside a plastic outer) occurred. If too much torque is applied, they tend to migrate towards the motor and bind on the bearing casing, causing erratic slow running and starting. I have come up with a simple idea which may stop this. I've made small shaft stand-offs to hopefully keep the tubing away from the motor face. The stand-offs are just a brass washer with a brass tube (which matches the bearing center) soldered in, with a few mm proud on the bearing side (to sit on the bearing without touching the casing) and flat on the tubing side. Hopefully this will stop the tube creeping and binding.

Pics show the result of the forward movement (having been pulled back away from the motors) and the stand-off.
Liked by stevedownunder and Colin H and

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