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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: 28   Photos: 220   Subscribers: 10   Views: 4670   Responses: 71   |   Most recent posts shown first   (Show oldest first)

Showing page 2 of 3   |   Jump to page: 1   2   3  

mdlbt.com/39275
Foam tank grating Pt 2 - Posted: 28th Feb 2018
Now I have the cut blank material it needs to be cut into 3mm strips, this can be quite tricky as I found. As the fence was set to 3mm and the first cut was made the slice started to catch the back of the blade and knock some of the pieces off. So I needed to make sure that it was guided past the back of the blade. So as you can see I set another piece of Perspex behind the blade 3mm wide to hold the piece clear as the cut was finished.
Next a trial fit of the pieces and it works just fine. Now I need to cut pieces to the length of the foam tanks ready for assembly. I need to cut some mahogany edging and a blank panel to complete the whole assembly. I then made a small jig to hold all the pieces together as they are assembled then each joint was “set” with a tiny drop of cyno and left to fully cure. When fully set I could then sand the surface to complete the tank tops, they will be varnished at a later date.

Attached Photos - Click To View Large

Response by robbob on the 28th Feb 2018
Hi Michael.
Excellent work on the foam tank gratings 👍

I assume you tried to source from Modellingtimbers initially?
http://www.modellingtimbers.co.uk/7.html

For those that don't have the kind of tooling that you have the gratings are also available from this alternative supplier:
http://www.rbmodel.com/index.php?action=products&group=016

Their product range and prices are very good, and delivery is remarkably cheap and very quick too considering they are based in Poland.

I have sourced various bits from them for my fireboat and I can thoroughly recommend them (although they seem to be presently out of stock of the 3mm gratings 🤔)
Rob.
Response by BOATSHED on the 28th Feb 2018
I like the gratings and was thinking, I wish I could make them. It's great to see that they are available from a source already made to cut to size required. Thanks robbob.

mdlbt.com/39274
A rest from skinning (foam tank grating) - Posted: 28th Feb 2018
I wanted to recreate the foam tanks as another blogger has (Rob) so I tried to order some grating from one of the model suppliers only to find he was no longer producing the size I wanted (3mm) and that he was unfortunately running his business down. So what to do, how about make my own. First decision was what material to use; I wanted a close grain, quite hard, stable wood and after some searching I came across an item in IKEA of all places - a bamboo chopping board. So the first issue is reduce the board to 6mm thickness, fortunately I have a milling machine which using a large dia cutter blade cutter and clamping direct to the table I first machined to 8mm to see how much the material had bent having relieved surface stress, to my amasement it was perfectly flat, so I continued to size the material to 6mm. The best method of producing the pieces is use a method which advances the cut each time by using the previous cut as a gauge. This has to very accurate, so first set the fence at 50mm and plunge the table saw through a piece of flat board (I used a spare wooden floor tile) this gives the slot for the blade (3mm) at this point secure the board to the table with panel pins. Next move the fence a further 3mm (be as accurate as possible) and lift the board from the table and again plunge through making another slot next to the first, this slot has to be filled with a 3mm strip that protrudes above the surface by 3mm (this is the guide) I used some 3mm Perspex. Next re-attach the board in the original position and secure the board again. Now raise the blade to 3mm and make the first cut, followed by a second and check the advance is 3mm if all is well continue across the board for as many cuts as you need.
TBC.

Attached Photos - Click To View Large


mdlbt.com/39273
Side skins - Posted: 28th Feb 2018
To enable ease of application of the side skins I decided to raise the building board up to 45 degrees, this allows a better view of the proposed joints
Before fitting the bottom skins the side skins have to be trimmed back to the stringers and deck line again using a red pencil to show how much material is being removed as I approach the stringers with the plane. Having done that little job it’s time to shape the skin. I followed the same procedure as I did with the side skins. Again after some time I got a fit I was happy with from the stern to the start of the bow curve. At this point I pinned the skin at the B2,3,4,5 leaving enough material to trim to the bow curve and also trim the cut-out where the skin joins with a butt joint as opposed to the overlap from bow to stern, this is all done prior to bending. Notice the steel shim protecting the chine from being cut as the bottom skin is trimmed for the overlap of the side skin. The bending was done simply by soaking in hot water for 5 - 7 mins and then forming around a suitable size paint tin and left overnight to dry. I first pinned the stern end dry and then epoxied the bow area then followed by more epoxy and progressive pinning towards the stern using brass pins into the bulkheads and smaller pins along the overlap which will be removed when the joint is dry. I made a tempory clamping arrangement at th bow by pinning some scrap ply to the top beck atea to enable clamps to be used, notice the use of a mirror to be able to make sure the joint had come together

Attached Photos - Click To View Large


mdlbt.com/38974
Skinning the hull (bottom) - Posted: 21st Feb 2018
The boat has to be placed upside down so first thing to do is to modify the base board so the hull is firm to be able to do any final trimming. Before the skins are fitted the bow areas have to be sealed being careful not to seal the parts which are to be glued The instructions say that the lower skins are fitted first and as they are 6mm oversize this allows for trimming to achieve a good fit. After some time I got a fit I was happy with from the stern to the start of the bow curve so at this point I pinned the skin at the B2,3,4,5 leaving enough material to trim to the bow curve prior to bending . The bending was done simply by soaking in hot water for 5 - 7 mins and then forming around a suitable paint tin and left overnight to dry. Before fitting I decided to trim the skin at the front bow area where it has a butt joint with the side skins, easier than trying to cut it out after it had been glued. Point to note was that while the bending was being carried out, I also bent he side skins as well. Having pre drilled all the holes for the pins and ensured the fit is as good as I can get I can now epoxy the first skin on.

Attached Photos - Click To View Large

Response by BigAlio on the 25th Feb 2018
nice too see a good quality job keep up the good work

mdlbt.com/38972
Trimming the stringers - Posted: 21st Feb 2018
Before fitting the skins the chine and gunwhale stringers have to be trimmed to the profile of the bulkheads, this is a time consuming job but is essential to get correct to ensure a good fit of the skins. Also final trimming of the bow k1,2,3 needs to be done now that they are fitted and “a virtual line can be drawn” to show where the skin will eventually sit flush. Using a red pencil to show how close to each bulkhead you have trimmed is a good guide’

Attached Photos - Click To View Large


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

Response by jaffy012 on the 10th Mar 2018
hi i am building this kit where can i purchase the prop tube bracket, i have looked every where i live in oz, many thanks colin👍
Response by jaffy012 on the 10th Mar 2018
sorry i did not scroll down and saw you had made it, colin
Response by robbob on the 10th Mar 2018
Hi Colin.
The propshaft, oiler and support are available from this UK supplier.

hxttp://www.modelboatbits.com/MAXIDRIVE-P-FRAME-4MM-1

Good luck with the build.
Robbob.

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

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