Sunday, 17 February 2019

Mast(erblaster) part 5

After another period of frustration, I feel like I'm making progress again.  The mast is on and the lifting mechanism working (for now...see below).

I've remade the hinges from brass (with the help of my friendly milling machine owner).  They were machined down from brass square to a rectangular profile, turned on the lathe to make locating pins and then shaped with a files.

The hydraulic cylinder brackets are also brass and the hydraulic cylinders made from aluminium tube.

The mechanism is a mini servo with a borden cable attached which runs out of the wheelhouse and then through the 'dummy' hydraulic cylinder.  I had to modify the servo mounting as it was too low and left too much unsupported bowden cable.  I'm also not convinced this mechanism is robust enough...   Even with an Action Servomorph, there's not quite enough travel to lower the mast fully so it's supported by the dummy hydraulic cylinders - the while weight is on the bowden cable.  So on a drive to the lake with the mast lowered (as it's too tall to fit in the car, the bowden cable kinked and so was then useless.  I've since tried brass rod but it's too stiff for the servo to drive.  I've since found that With the mast lowered slightly it will fit in the car so for the time being, I've reverted to a replacement bowden cable.  I'm hoping that with the mast lowered only a little, most of the cable will be supported and so is less likely to kink; time will tell.  Otherwise, the only idea I have left is to make a linear servo as the bowden call will then run on a straighter line rather than the arc of the servo arm.

Anyway, here's a video of it in action...


Saturday, 22 September 2018

Close the Door


I have been making progress and after too many years, I've nearly finished my Tamar.  One of the biggest tasks recently has been getting the transom door opening mechanism working, and also the mast lifting mechanism.

The transom door was first and now works.  It's operated by a sailing arm servo, attached to a square brass tube to which the 'hydraulic' rams attach.  The rams rum through the square tube and are adjustable at that end.  I had initially considered trying to also fit dummy hydraulic cylinders to but that would have been very complicated and they're inboard anyway so barely visible.

This is the mechanism



...and this is the door in operation.

The deck hatches are also on.  I used miniature hinges rather than the kit parts.  The hatches were heated and shaped to the deck curvature before cutting into the four parts.  the next job here is to make hinges to attach the moving 'bridge' piece that spans the gap between the boat and open transom door.

Saturday, 18 August 2018

A long time coming

I'd forgotten just how long it's been since I posted!  After a long time getting frustrated about just how inconsistent my spray painting must be, I've finally got a decent finish on the wheelhouse.  So that's meant I've spent the autumn and winter attaching the fittings.

This is where I've got to;



There's still a lot to do.  I need to remake the mast hinges because the plastic ones I made aren't up to the job.  The replacement brass tube one I made also failed.  So, these will be made from brass square milled down to the correct section and then pinned in place.

Next on the agenda is the fendering...

Wednesday, 11 April 2018

Radar Love

[I wrote this post ages ago but for some reason didn't post it!!!]

I've now finished the radar.  I had several suggestions from others who have built a Tamar but decided to stick with my original plan!  It's a little overcall and not 100% accurate but it'll do me.

It tool a few attempts to get right.  My first go ended up being too small for the motor,  the second too big and the final one is a little tight but does the job.  It will come apart to get the motor out but hopefully that won't ever be necessary as I'm not sure the box would stay in one piece...

It's all made with plasticard though I used filler for the front and rear faces of the bottom half.  As I needed to use thin plasticard, I hoped that using filler would let me round the edges and it worked though the filler may not survive taking it apart in future.  The arm is square plastic tube with half round styrene rod.

So here's the line up of the base parts:


And the finished item.


Tuesday, 2 May 2017

Mis-Shapes

Next up was the mast supports.  I was really keen to use to use the kit parts as they are nice white metal castings complete with brackets for the rail to the windscreen.  My plan was dashed though when I test fitted it to the boat.  As I've modified the mast so that the arches slope forward and are wider at the base than the top, the 'vertical' part of the support had to follow that and I concluded I couldn't do that with the kit part.

So I set to make a pair of new ones with 2.4 and 3.2 mm brass tube and square section brass tube cut down for the bracket on the wheelhouse.  I used small strips of brass to then make the smaller brackets.  Sounds simple but I had to resolder the main parts several times to get the correct angles to follow the mast.  Still all done now.

Saturday, 11 March 2017

Pump up the Volume

So this post shows a lesson in checking references properly!  I've been working on the pump box and the hand/guard rail.

The hand rail was fairly straight forward especially once I'd found something of the right diameter to use as a former.  The harder part for me was the uprights.  First because my soldering could still do with improving and secondly to get the lengths right given the deck camber.  So, I cut them over long, solder onto the rail and removed to engine hatches so that I could use the deck to mark the right length for each.  (Only the base plates for the uprights to make.)

The pump box should have been easy; make lid and attach to drum.  Unfortunately for me, I used my RNLI drawings and not my photos.  The plans show the pump box square to the vertical rather than just sitting on the deck.  So, I made and fitted an angled fillet for the pump box.  Then I looked at my photos and realised my mistake.  Off with the fillet and feeling a little daft for wasting time on it!

The last part to make were the securing straps from the etched brass parts.  I pinned into a piece of balsa and then soldered on centre disc.


Job done.

Tuesday, 7 February 2017

Y Don't You - part 2

As promised last time, some more on the transom door and deck hatches.

So, here's the transom door all finished.  There's a few small bits and pieces to finish of like painting the bolt heads and filling the end of the fendering.


I've also finished the deck hatches save for painting.  I had to cut out a new set of hatches though.  In order to get the deck camber into the hatches I heated them in the oven but got it too hot so the kit part ended up as this!


But now all finished, with hinges for dolls houses and the strengthening beams underneath.  The hinges are slightly over scale but not too bad I hope once painted.


That's it for now.