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Author Topic: Hamina Class Missile Boat 1:28 Scale  (Read 53538 times)

Harrison

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #150 on: January 12, 2010, 08:44:24 AM »

My local engineering firm are pretty good for turning, I expect they can do the cuts without too much trouble.

I've gone for the 'all in one' type coupling which you would think will go the distance, getting them made does also mean that both ends can be the right bore.

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HS93 (RIP)

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #151 on: January 12, 2010, 08:53:34 AM »

My local engineering firm are pretty good for turning, I expect they can do the cuts without too much trouble.

I've gone for the 'all in one' type coupling which you would think will go the distance, getting them made does also mean that both ends can be the right bore.



getting the correct material is going to be the problem a lot of research goes in to them I have read as just 1deg will cause bending and metal fatigue  , its the same as bending a bit of metal back and forth but 30000 times a min ..
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Harrison

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #152 on: January 12, 2010, 09:23:53 AM »

I was going to use stainless, I was hoping for an M5 set screw. I suppose I could bore them out.

I've made a start on the parts of the bulkheads which the longerons fit in to, the hull is the only part which will see 'non serviceable' assembly methods (welding).

I plan to tac each one in place then fit the panels to the outside and weld them from the inside using Technoweld rods.
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Harrison

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #153 on: January 12, 2010, 10:24:34 AM »

I've finished all the longeron slots in the bulkheads, I think I have an A50 in my spitfire in the shed. I can't remember if it's an A50 or an A60, I do know that it's very cold out there!

Perhaps a coffee and some warm clothes are required.
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derekwarner

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #154 on: January 12, 2010, 11:07:16 AM »

Military  [naval applications] use flexible drive couplings with thin mechanical wafer shims that flex.......so....... the resultant TIR [total indicator run out] between mating shafts  is ZERO. ZERO..... {-) 0.00 .....surprisingly these are also used in our Collins Class "noiseless' submarines......... <*< ......Derek
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Derek Warner

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Harrison

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #155 on: January 12, 2010, 12:16:09 PM »

Thanks for the gen, I'll see what else is about before getting anything made... Silent would be nice.

I've just finished modelling the Hacker A50-10S, my poor spitfire..

Now on to the mounts.
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Harrison

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #156 on: January 12, 2010, 12:37:29 PM »

It's starting to look like a boat.
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Harrison

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #157 on: January 30, 2010, 01:40:42 PM »

Been super busy lately with work so I've not had much chance to get a great deal done on the boat.

I've just finished doing the notchy things which secure the longerons to the bulkheads (feel free to point out any terminology that I may have missed along the way), I'm not sure what to do next as there are so many things to do... Perhaps the servo trays for the jet drives...

Thinking that the more control the better.. I'm going to a servo per side to steer and a servo per side to control the bucket for forward/reverse, the idea here is that with independent motor control an element of sideways maneuvering is possible (at least thats the thinking behind it).
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Harrison

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #158 on: January 30, 2010, 01:42:12 PM »

Ah.. Yes, engine mounts may be a good place to start as the servo trays are going to be somehere nearby..
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tonyH

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #159 on: January 30, 2010, 09:19:27 PM »

Just on the subject of couplings, Kehrer seem to use Robbe or VERY similar which are available up to 6mm. The advantage is that there' plenty of meat for the grub screw to hook into.

Just a thought.

Tony
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Harrison

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #160 on: January 31, 2010, 09:31:43 AM »

Hi Tony,

Thanks for the info, I will check them out.

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Harrison

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #161 on: February 06, 2010, 11:58:38 AM »

I'm making a bit more progress on the design today, I've pretty much got the motor mounts finished which only uses 2 x unique parts (well three if you count the aluminium servo mounts that I have a box of).

I have made them adjustable just in case I am a few tenths of a millimeter out, they want to be perfectly in-line with the drive shaft on the jet drive units.

Servos and linkages next for the drive, any ideas for getting servo arms outside without letting any water in???  Think 5 meters underwater, so I guess whatever submarines use.. Any suggestions would be great.
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andyn

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #162 on: February 06, 2010, 12:13:36 PM »

Looking fantastic :-))

GA7A should be what you're after:

http://www.prestwich.ndirect.co.uk/hdwraccs.htm
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Harrison

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #163 on: February 06, 2010, 12:18:51 PM »

Thanks, I don't suppose you have one of these do you? I could do with the measurements.
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Harrison

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #164 on: February 06, 2010, 12:44:31 PM »

I called PMB, it's a 10mm hole and the rod end is 1.5mm.
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Harrison

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #165 on: February 06, 2010, 12:53:02 PM »

Thanks for the feedback, it's great to see that people are interested and following progress.

I'm hoping to get the design of the main hull and superstructure ready for sea trials this summer, I'll have to design plenty of mounting holes inside for all the other stuff yet to be developed.
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Harrison

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #166 on: February 06, 2010, 01:14:46 PM »

I've traced the photo on the PMB website site and scaled it to the 10mm neck (10mm hole according to PMB) then modelled the bellow, It's looking a little tight on space.
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derekwarner

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #167 on: February 06, 2010, 02:02:44 PM »

Harrison........certainly your CAD or Inventor skills are great :-))....but I am still unsure if you have resolved & decided on a 'commercially available' motor + drive coupling

Electronic design is fine  :}....but some where you must nominate actual components as a building block to enable a real mathematical & physical understanding or scenario of your build to be established ........ O0 Derek
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Derek Warner

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Harrison

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #168 on: February 06, 2010, 02:22:53 PM »

I have modelled a commercially available coupling, the motors are Hacker A50 10S and the mount I am making from 2.5mm sheet aluminium.

I'm never really too concerned about parts being 'commercially available', if there is something which does not already exist.. I will design and develop it.. Like almost every part of everything that I have designed and made for consumer applications including injection moulded parts, I have a CNC machine which can machine insert mould tools and a small hand injection moulding machine. I try to avoid using it as its quicker to mill plastics or aliminium.

I have modelled the MG995 servo and floated it in to the assembly
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colin-stevens

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #169 on: February 06, 2010, 04:15:43 PM »

love youre adjustable  motor mounts, however, adjustmets on the side, up against hull! defeats the object.you might think about rotating the mounts 90Deg so you can adjust from above. youre motors are going to be spinning at quite a few revs so alignment will be important. best to make it as easy as possible. i have used the Kehrer shaft/motor connectors on a fast reving motor and work fine.
all the best, have fun with lofting
colin
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Harrison

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #170 on: February 06, 2010, 06:18:50 PM »

Hi Colin,

The mounts need to be at this angle, as this is the rotational alignment which could require adjustment due to minor tolerances in the jet drive model. There isn't much access to adjust them so it will be ring spanners on both bolt head and nut (which will be in the inner side near the coupling).

The mounts will be bolted to the bulkhead with couplings screwed to the jet drive shafts, the motors then slid on the couplings and pushed up until the moving part of the motor mounts sit flush against the motor face which has the fixing holes. Once in place the screws Will fix the motor to the mount and (with the boat in a vertical position) the mounts fixed using the bolt/locknuts, the motors will then be perfectly aligned to the driveshafts and fixed in place.

Development and testing comes after the design phase, like with the Bofors Mini MK111
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hollowhornbear

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #171 on: February 07, 2010, 10:29:06 AM »

could you not use a rivetnut or hankbush on the outside of your mount and then a socket cap setscrew from the inside, as a sheetmetal worker it makes more sense to me than trying to use to ring spanners in a confined space, you'd only need an allen key.
Unless i've missed something could you also explain why 3 linkages per side through the transom? do you not only need to control the reversing bucket? steering being achieved by independent motor control.
This is such cool project i wish you well with it.
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Harrison

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #172 on: February 07, 2010, 11:00:42 AM »

Thanks for the advice, that sounds like a pretty good idea.. Perhaps I could some how captivate a nut on the outside and use the Allen key bolt from the inside..

I think the difference in maneuverability between just using motors and turning the drive units will be quite significant, also I plan to control them independently as well as move the nozzles to get some sideways movement.

We shall however see on testing.
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hollowhornbear

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #173 on: February 07, 2010, 01:54:38 PM »

this may help you, you drill the correct size hole then pein the spigot down, viola one captiv fixed nut. used them for the last 30 years, no problems.
http://www.rivetwise.co.uk/productrange/hankbushhex.htm
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tonyH

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Re: Hamina Class Missile Boat 1:28 Scale
« Reply #174 on: February 07, 2010, 09:19:56 PM »

Don't know if it's relevant to this hull form, but there was some photo evidence on other vessels with twin jet drives that there were shallow fixed fins on either side of the drives to reduce the crabbing effect that could occur. I know they are present on both USCG and Finnish 45 ft boats with the Rolls Royce KaMeWa units, but I'm not sure that is applies to Hamilton or other units.

You've probably got this covered anyway.

Tony
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