7mm Mickoo's Commercial Workbench

F

Fitzroy

Western Thunderer
mickoo said:
The first tranche of B17 casting masters has been completed. These are not be the actual parts that go for casting as this stage is simply about maximizing surface quality, deformation and orientation for printing the production ones.

However they are ideal to stick on the test build etches to make sure everything fits and aligns.

The red oxide paint is Tamiya fine filler primer, it's an excellent coating for casting and an important stage in the process. It gives a lovely smooth finish but most of all shows up the tiniest artifact or blemish; most can be worked out with small files, scrapers and fine grit foams but the worst really need reprinting with a better orientation or support structure.

Sharp of eye will note that the keep plates are all a little bowed, it's not by design but the optimum angle to print and get all the spring detail in puts extra pressure on those two arms and bows them.

You can spend further time exploring different orientations and supports but sometimes you need to be a little pragmatic and look down stream. In the end they will be in brass and it takes a mere few seconds to straighten with pliers before they go in the box.

It's much easier to push the (almost) inevitable bad part of a print into the easiest place to post rectify.

View attachment 256573
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They look great Mickoo, but I'm curious, what do you allow for for contraction between master, wax mould, and finished casting?
Pieter
 
mickoo

mickoo

Western Thunderer
Fitzroy said:
They look great Mickoo, but I'm curious, what do you allow for for contraction between master, wax mould, and finished casting?
Pieter
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Cheers, the shrinkage is dependent on the casters, their process and the material they use, it's hard to give an accurate figure as they all vary.

The best option is to talk to your caster and ask them what shrinkage rate they have and then compensate on the master.

The resin I use also has a shrinkage factor but it's spread over months, so if you're casting something with a critical tolerance like valve gear or motion parts then it's printed, prepped and hopefully with the caster in a week or so for master moulds to be made; for less critical stuff that's stand alone (sand boxes, tool boxes etc) then that's not really an issue.
 
G

Genghis

Western Thunderer
Very nice too.

The Scottish B1's seemed to get reinforcements to the footplate front and rear angles. DJH (Piercy) catered for this by having a sacrificial part of the whitemetal footplate. The Gladiator (ex Meteor) kit ignores the possibility. Are you catering for this?

Cheers,

Dave
 
Pencarrow

Pencarrow

Western Thunderer
mickoo said:
Some more DA N class work this week, nothing overly untoward so far on the upper works.

It did take a bit of the ole Geoff Capes to form the firebox, but it got there in the end and produced a nice square clean unit, just need to add all the details now.

View attachment 257543

View attachment 257544

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Coming along nicely Mick. To me they always look slightly naked without the smoke deflectors, but even at this stage it's obviously an N.
 
mickoo

mickoo

Western Thunderer
Pencarrow said:
Coming along nicely Mick. To me they always look slightly naked without the smoke deflectors, but even at this stage it's obviously an N.
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It should have been done by now (real life and other stuff/crap getting in the way) and missed the paint delivery run last week, so the next target point is Kettering for hand over.
 
RichardG

RichardG

Western Thunderer
mickoo said:
Connoisseur B12/3.
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In these photographs, the two sets of side rods seem to have been swapped. The articulated part goes between the second and third coupled axles.

Having written this, I guess their ability to fit the wrong way round is quite a testament to the standards of the kit and of the build :thumbs:
 
PaulRhB

PaulRhB

Active Member
RichardG said:
In these photographs, the two sets of side rods seem to have been swapped. The articulated part goes between the second and third coupled axles.

Having written this, I guess their ability to fit the wrong way round is quite a testament to the standards of the kit and of the build :thumbs:
Click to expand...

Seem to be several photos online with them the other way round.

mikemorant.smugmug.com

GER locomotives - MikeMorant

No. 61524 was one of the Scottish contingent of original Holden B12 4-6-0's that had been t5ransferred from the GE section to the GNSR in the 1930's and is depicted here at KittyBrewster (Aberdeen) on 17/6/49. 61524 had moved to Scotland in 1933 and had its BR branding applied in July 1948...
mikemorant.smugmug.com mikemorant.smugmug.com

mikemorant.smugmug.com

GER locomotives - MikeMorant

Holden B12 4-6-0 no. 61507 in BR apple green livery at Aberdeen's Kittybrewster shed on 25/4/52. 61507 was a visitor from Keith mpd and would be withdrawn at that depot in April 1953. [H. C. Casserley / Mike Morant collection]
mikemorant.smugmug.com mikemorant.smugmug.com
 
mickoo

mickoo

Western Thunderer
Knuckle leading or trailing makes no odds as the axle spacing is identical so just swap to suit.

Typically knuckles lead on older period engines with square bosses trailing & intermediate), those seem to have swapped out around late LNER early BR for round boss rods and trailing knuckle; but, as always, check you references as there are exceptions to that.
 
-missy-

-missy-

Western Thunderer
Apologies if I have missed it in this thread mickoo but who do you use for casting? Im very interested in finding out.

Thank you.

Julia :)
 
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