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>> Home > Boat Building Blogs > The Vosper 46” RAF Crash Tender Kit By Vintage Model Works
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mdlbt.com/37275
The Vosper 46” RAF Crash Tender Kit By Vintage Model Works Print Booklet
Author: mturpin013   Posts: 13   Photos: 77   Subscribers: 5   Views: 1549   Responses: 25   |   Most recent posts shown first   (Show oldest first)

Showing page 1 of 2   |   Jump to page: 1   2  

mdlbt.com/38778
Propshaft and oiler fitting - Posted: 16th Feb 2018
Propshaft and oiler fitting
Now for the fitting of the propshaft, fortunately I have a long series drill that will go through the keel and through the bulkhead B4 into the motor compartment; this went well and came out in the expected place. Next a trial fit of the tube in the keel and into the skeg, again this lined up perfectly and all that needed to be done was to epoxy it into place. First I nearly forgot to fit the oiler system to the prop tube, careful drilling and deburring and making sure no swarf is left in the tube. Finally wrapping a piece of plumber’s PTFE gas tape around the tube to ensure a gas tight fit (oil tight) we are ready to commit the tube to final fixing. Epoxy mixed and applied I put a couple of small wedges in the skeg to stop it moving and a wedge under the oiler to make sure it was horizontal.

Attached Photos - Click To View Large


mdlbt.com/38776
Prop shaft bearing - Posted: 16th Feb 2018
Prop shaft bearing
I purchased a standard propshaft with Phosphor bronze bearings again from a well-known supplier, however I had also fancied a Raboesch type with a bearing at the motor end however at £30 plus think again. So I researched the bearing type and found at £2.50 each it was worth a go at making my own so quick sketch and an order placed from Modelfixings.com. A simple piece of machining and the part was made. A simple enough job to remove the existing bearing and slide on the new housing and it made a significant difference to the “feel” of the shaft when rotated. I also made a simple collar to retain the shaft in the hosing.

Attached Photos - Click To View Large

Response by Dave M on the 17th Feb 2018
Useful info on how to fit a bearing. Do yo intend to provide any protection from water ingress or are you relying on the oiler alone? It would be useful to know the specs (max revs) for the bearing, especially if you intend to fit a brushless motor.
Response by mturpin013 on the 17th Feb 2018
Sorry I can't find the one I bought from Model Fixings but here is an equivalent tech data

Bearing details bore 5mm OD 10mm Width 4mm 2 shields MB-032 Max rpm
Metal Shielded Deep Groove Ball Bearings: One of the most commonly used bearings, these types are manufactured with metal shields inserted into the outer raceway, these fit in closely to the inner race providing protection against light mechanical damage, some protection against the ingress of moisture, dust and other foreign matter and serve to retain the pre-filled grease in the bearing.
Shields can be easily removed for applications that only require 1 shield
Benefits: Provides light mechanical protection, limits moisture and dirt ingress, lubricated for life,
Branded MR1052Z Metal Shielded Deep Groove Ball Bearing 5x10x4mm
£2.80 ex VAT
Dynamic load C =0.4116 kN
Static load Co=0.1568 kN
Max speed=60000 rpm
Response by Dave M on the 18th Feb 2018
The specs suggest this is suitable and I doubt if you will be exceeding the max speed!
I have used small bearings in the past on projects, mainly for model steam, and have had problems with small bearings.
Looking forward to seeing the build progress

mdlbt.com/38774
Skeg - Posted: 16th Feb 2018
Skeg
Having seen the trouble others have found with the suggested method of production I decided to go straight for the robust version. I did a number of measurements to determine the size and shape of the arm and went for 2mm brass sheet. The tube was machined from 12mm dia brass with tapered ends to 8.5mm and an 8mm bore to suit the tube. Next I machined a 2mm slot the length of the tube to locate the brass arm in. Keeping the pieces spotlessly clean (not forgetting to clean the solder rod as well) the items were fluxed and wired together to keep then in a true vertical position whilst they are silvered soldered. A keen eye on temperature and a light touch and clean flow with the solder is recommended to keep final dressing to a minimum.

Attached Photos - Click To View Large

Response by robbob on the 17th Feb 2018
Excellent work Michael👍.
My second attempt a making a skeg for my boat was passable (eventually). I overdid the silver solder and spent ages filing the surplus away.....less is more, as they say.
I finally mastered silver soldering with some of the later brass fittings I made, fortunately you also have a lathe and clearly a great deal more experience than me.
Robbob.

mdlbt.com/38772
Rudder, water pickup and skeg - Posted: 16th Feb 2018
At this point I decided to fit the rudder tube, water pick up and skeg. I was able to mount the boat in the machine vice by gripping the keel; this ensured that the holes are drilled absolutely true and square, 2 x 8mm holes are needed to take both the rudder tube and water scoop. I purchased the rudder assembly from a well-known supplier but I didn’t like any of the proprietary water scoop tubes on offer so decided to make my own. Whilst the boat is in the vice I also decided to machine the slot for the skeg to fit in. This required drilling a series of 2mm holes and then opening them up into a slot using a long series slot drill again giving an accurate slot which the skeg can locate into.

Water scoop
Having dealt with the woodwork, I turned my attention to metalwork. To bend the ¼” brass tube successfully it has to be annealed, (cherry red and quenched in water), then inserting a tight fitting spring inside the tube to stop any kinking I gently pressed it round a former to the correct shape. Springs removed I filed the end to the correct angle which gives an oval opening, but the end didn’t look finished, so I machined a thin spacer and then squashed it to suit the oval end and silver soldered it to the end of the tube, this gives a much better visual appearance.

Attached Photos - Click To View Large

Response by RNinMunich on the 16th Feb 2018
An excellent tutorial, splendid stuff 👍👍👍
Several years ago I forgot the annealing stage, while making davits for my destroyer, and jammed the spring into the tube 😡 The tube didn't kink but it looked like an earthworm 🤔

mdlbt.com/38769
Chine stringers - Posted: 16th Feb 2018
Chine stringers
Again first job is to trim all the bulkhead corners so the stringers sit flat against each bulkhead. We can then start to trial fit each side to see what sort of curvature we need. This time I needed a tighter curve (2.5 litre paint tin) so again using a scrap piece chip board I made another jig. The stringers are fitted in the same sequence as the gunwhale stringers that is the first pair are trial pinned, then epoxied and fully pinned. When fully set the second pair can be fitted but this time using clamps only, no pins, to allow for trimming at a later stage. Then allow some time for it to set and check that all this tension in both sets of stringers hasn't caused any twisting or misalignment.

Attached Photos - Click To View Large

Response by RNinMunich on the 16th Feb 2018
Great work, LOVE the jigs 👍👍
When I built my destroyer (many many moons ago🤔) I just used loads of panel pins hammered into a chunk of pine board. You way is much more elegant. 😉
Response by mturpin013 on the 17th Feb 2018
Its all material I had lying around in my workshop, I never throw anything away so you can imagine the amount of "stuff" I have in my basement. The Yellow angle brackets are made of old neighbourhood watch signs they are made of 1/4" plasticard

mdlbt.com/38457
2nd Gunwhale stringers - Posted: 9th Feb 2018
Now for the more difficult stringer, this one has already been steamed and set in the jig. The outer stringer has to be put on using glue only and clamps, so no nails at all since it has to shaped to the profile of the bulkheads over its entire length hopefully using a jack plane (which don’t like nails). Clamps at the ready and glue in hand and away we go,

Attached Photos - Click To View Large

Response by Ron on the 17th Feb 2018
Is this a kit, using kit wood? The parts look like they will add too much weight. Am I correct?
Response by Dave M on the 17th Feb 2018
Ron
It'a a 46" model so the wood is the correct size. You have asked about clamps in your post and there are plenty of examples in this blog, you should subscribe to follow progress.
The kits by Vintage Models have been around fore a few years and make into a nice model if built carefully as in this model.
Response by mturpin013 on the 17th Feb 2018
Thanks Dave you beat me to it

mdlbt.com/38243
1st Gunwhale stringers - Posted: 4th Feb 2018
First job is to trim all the bulkhead corners so the stringers sit flat against each bulkhead. We can then start to trial fit each side to see what sort of curvature will be needed to steam the stringers prior to final fitting. I decide to make a jig for the stringers to “set” after steaming, I made this jig to accommodate all 4 stringers creating the same curvature, as the minor differences in curve will be flattened out during the clamping process. I used a domestic wallpaper steamer/striper and a piece of 4” plastic drain pipe blocked at both ends with a piece of cloth and steamed for about 20 minutes. The 4 stringers were then placed in the jig and locked into place with wedges and clamps. These were then left for a couple of days to thoroughly dry out
After steaming and setting, the stringers were dry pinned to the breast hook on both sides with brass pins, then followed back to the stern drilling and pinning to each stringer to the bulkheads as I went back. Being satisfied with the fit I now removed all the pins and started again from the front and epoxied and pinned each bulkhead on both sides.

Attached Photos - Click To View Large

Response by robbob on the 4th Feb 2018
Hi Michael.
Good idea with the jigs, it certainly minimises the possibility of snapping the stringers while they 'set'.
Rob.
Response by Ron on the 17th Feb 2018
This boat looks like it will be very heavy using those plywood bulkheads.

mdlbt.com/38026
Cabin sides and deck supports - Posted: 28th Jan 2018
Before we continue I must mention some fine detail that should have been mentioned in the previous build update and that is the preparation of the cabin sides. Because the bow end of the cabin sides narrow there is a need to score/cut through partially in the places indicated in the build instructions, this is around the cabin side window and enables the side to bend without cracking the external faces, and this also applies to the rear of the cabin sides where it joins B5. The cabin side extensions can also be glued into position as well

To continue, having secured all the bulkheads to the keel I can now epoxy the cabin sides to the bulkheads ensuring that the height is maintained side to side and bends smoothly round to the bow and stern. Allowing this to set for a couple of hours I can fit the deck stringers from ¼ x ⅛. These are cut to length to suite the gaps between the bulkheads and glued in place using aliphatic resin glue. I also added some extra support where the cabin side extensions are since its only a butt joint.

Attached Photos - Click To View Large

Response by Dave M on the 28th Jan 2018
Good building practice. Nice solid baseboard and lots of vertical jigs and clamps holding everything square whilst the glue dries.
I look forward to following your build
Response by jarvo on the 2nd Feb 2018
Just a thought mate, when you have completed the bulkheads etc, before fitting the skins, seal the wood with something like Zpoxy, this will make it easier when sealing the rest of the hull.

Mark

mdlbt.com/37716
More Bulkheads - Posted: 21st Jan 2018
All the bulkhead parts are made ready for assembly. I decided at this point modify CF2 and B2. B2 to enable easy access for further detailing of the cabin at a later stage and CF2 I cut out what will be the door opening into the cockpit. Each of the bulkheads had 2 x 12 mm holes drilled just below deck level for future wiring runs; they also needed support to secure them at 90 degrees so I made a number of right angle squares to support them squarely and at equal height at each side, these were secured with a temporary brass pin. The spacing at the keel was pre-determined when building the keel components, however the tops need correct spacing by dry fitting the cabin sides and just checking that each side measures the same height, finally the back end of the keel needs supporting to keep everything square. Each of the cabin sides and bulkheads can now be dismantled and reassembled with epoxy resin. NOTE at this stage only the bulkheads are epoxied to the keel, the cabin sides and CF2 are only there to ensure the bulkheads are square and correctly spaced at this stage.

Attached Photos - Click To View Large

Response by robbob on the 21st Jan 2018
Hi Michael.
You might want to consider enlarging the cut out in CF2 to allow you to get your hand easily into the interior of the cockpit. I think the small 'door' cut out will restrict access if you intend to detail this area with a wheel, throttles and instruments etc. And getting your hand inside is really helpful when it comes to glazing the windows.
Apart from that it looks like a 'proper job' 👍
Robbob.
Response by mturpin013 on the 22nd Jan 2018
Robbob hopefully the cabin roof will be detachable/hinged and the bulkhead at the back of the cabin will be solid apart from the door, so the bulkhead needs extending down to the floor when fitted, this why the cutout is in B2, its at floor level
That's the though at the moment.
Response by robbob on the 22nd Jan 2018
Ah...I see what you are trying to achieve now, I've never seen that done but that's not to say it isn't possible so if you think you can engineer it...why not 😜👍.
Rob.

mdlbt.com/37652
Bulkhead - Posted: 20th Jan 2018
Bulkhead
Time to fit the B1 bulkhead, at this point I was advised (by a well-known crash tender builder, more about him later) that I should dry fit the entire front end and to chamfer the appropriate parts prior to final assembly leaving only final trimming when fitting the skins (a good call). Again keeping all components square, vertical and level by using height gauges squares etc. they are pre-drilled and temporally pinned to ensure that they fit correctly. Its then all taken apart before final assembly with epoxy and pushing the brass pins fully home and clamped where required.

Attached Photos - Click To View Large


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