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USS Constitution - Model Shipway’s Kit No.: MS2040

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Baggywrinkle

Sun Nov 08 2020, 10:10pm

Registered Member #5759

Joined: Sat Sep 19 2020, 03:36pm
Posts: 172

Nice work on the pumps Jonathon, the technique is very sound and you should end up with some very nice rocker arms. Are you centre-puinchinga dimple in the centre of the solder mass to help guide the drill bit?

cheers

Pat

Jonathan G

Mon Nov 09 2020, 02:13am

Registered Member #4155

Joined: Thu Mar 14 2013, 09:01pm
Posts: 1017

Baggywinkie - I did, but the drill has a very small but persistent side drift when a little downward pressure is applied. Getting the hole precisely dead center is also compounded by the fact I can't see the drill touch the metal very well. I wear tri-focal glasses so my focal distances are fixed. I keep banging my head against the stand trying to get closer to see. Magnifying glasses are too bulky to get close as well. Like I said in the post, there is something to be desired with this old Dremel drill stand.

Charles

Mon Nov 09 2020, 01:21pm

Registered Member #1923

Joined: Mon Nov 28 2011, 06:07pm
Posts: 980

I think you do a good job on those hole
For one that do not see 3D I know how hard drilling center can be

jacknastyface2

Mon Nov 09 2020, 03:28pm

Registered Member #5239

Joined: Sat Apr 21 2018, 05:29pm
Posts: 612

I know how hard it is when our eyesight fails us as we get older and I have had the same problems Jonathon. I think if you have any similar problems for future ships, instead of a blob of solder, it would be better to insert a triangular piece of brass (same thickness as the legs) at the crux of the two legs and make that the junction point for soldering. The centre punching could be done before soldering. I know,--- it still comes down to ---eyesight and possibly --jigs.

Keith.

Jonathan G

Mon Nov 09 2020, 03:48pm

Registered Member #4155

Joined: Thu Mar 14 2013, 09:01pm
Posts: 1017

I did consider using a piece of brass between the legs but the 1/32" thick triangular piece required would have been base-height 3/32" - 1/16". It was just easier to drop a blob of solder in the apex than try cut a piece of brass I could barely hold, let alone precisely shape. The apex web has two jobs, hold the legs together and provide a place to drill a hole. Neither of these functions demand much structural strength.

Thanks for your thoughts guys.

Jonathan G

Mon Nov 16 2020, 08:30pm

Registered Member #4155

Joined: Thu Mar 14 2013, 09:01pm
Posts: 1017

The bilge pump rocker arms have arm extensions so that the ship’s crew can consolidate the pumps for more working space when not in use. The photos of the actual ship show the bilge pumps in their stowed configuration with the rocker arms extensions removed and lashed to the pumps.

I plan to have the arms fully extended so the typical viewer can understand their function better. There are two kinds of rocker arm handles. The double pump has a “Y” branch to a double brackets for the handle while the quad pumps have a single bracket and a long handle connecting two pumps. To top it all off, the rocker arms are tapered to the handles from the extension joint. These details required me to further refine my bilge pump plan.

Jonathan G

Mon Nov 16 2020, 08:37pm

Registered Member #4155

Joined: Thu Mar 14 2013, 09:01pm
Posts: 1017

First, I tapered the rocker arms, then I created the handle brackets out of 1/16” brass tube. The problem that presented itself and which drove me crazy was that there was extraordinarily little surface area to bond the bracket to the arm. I threw away my two-part epoxy and bought fresh. The bond failed again. Once more the cured epoxy was more like a hard rubber. I could peel the epoxy off the brass with a dull knife. So, it was back to solder. Before every attempt, I cleaned all the surfaces with mild acid. It took nearly three tries per bracket till I finally got a solid bond.

Almost as frustrating, was the Y-branch bracket – how to make it and keep it strong? How do I create a 3-part joint and then connect it to the rocker arm? I came up with a solution but there is probable a better solution out there. I just didn’t think of it. My solution was to double twist two brass wires and create a kind of brass rope. I could then open up the braided strands to insert the rocker arm and handle. Once I had that, I lathered the brass rope with solder flux and solder paste and fired up the torch. The idea was the solder would fill in the voids in the rope making a solid piece. This too took numerous attempts. The excess solder was then filed off. I had to be careful here because I didn’t want to remove too much solder and weaken the bond…again.

I almost forgot, the handle material is music wire, very stiff. Wood would have broken, burned, and it doesn’t solder very well.

Jonathan G

Mon Nov 16 2020, 08:43pm

Registered Member #4155

Joined: Thu Mar 14 2013, 09:01pm
Posts: 1017

The last bit to complete the rocker arms were the extension joints. This is where the extension arm slides into a short pocket to create the extension. I though about gluing 1/16” piece of wood to simulate the “box” bracket, but in the end. I just wrapped some thread around the arm with a dab of CA glue to create the illusion of a boxy bump on the arms. Most of imperfections will disappear under black paint and low light viewing conditions.