7mm Mickoo's Commercial Workbench

[mickoo]

MOK King Arthur tender pretty much all done now.

There's two extra fillet plates to scratch build that go behind the drag beam next to the brake cylinder plate work and once those are in then the tender sanding pipes can be added. I've also got 95% of the information I need to add the two pipes that run down the insides of the valance.

On the RHS is the steam pipe, on the LHS is the vacuum pipe which has the drain bowl attached (nice casting supplied in the kit). Both pipes terminate next to the brake cylinder plate work and there must be some sort of bracket, the shape and position of which currently eludes me

I changed the rear upper lamp iron bracket for one matching a photo I have or an early tender (the model is based in 1926 LSWR livery with SOUTHERN text) I also added little strips of etch to the footplate ones to thicken the area that simulates the pocket, as well as bending the upper tang with a dog leg in it that sits in the pocket. It's a nothing thing but does change the way the lamp irons look and makes them a little more 3D in appearance.

The biggest down side to adding the footplate lamp irons and vacuum pipe stand will be the painting of the rear LSWR panel, I may look into making the vacuum pipe stand removable, not an easy task as it relies on the tender rear bracket for a lot of it's support.

To complete I should really add the lower end of the tang sticking out of the bottom of the pocket, to that end some 5 thou strip will be cut and shaped and 'stuck' below the pockets.

The final task will be to blend the corner castings with the sheeting, despite being soldered and smoothed I know the solder between the two will sag and create shallow depressions that will smack you in the face once high gloss paint is applied. To that end I'll fill with car knifing filler and blend smooth with 1000 grit wet n dry to give a smoother finish.

 

[Pencarrow]

A thing of beauty.

 

[Lancastrian]

Eeeee, turned out nice again ! Lovely Mick

Ian

 

[mickoo]

MR Compound tender bogie test build, a quick and rough assembly, couple of FUBARS and own goals....normal on a first pass...for me

The biggest mistake was the slots in the centre box section to take the inner end of the diagonal braces. These are designed to hold the cross braces flat and securely, leaving you to just focus on getting the end into the transom beam correctly.

Sadly I placed the slots in the incorrect location, aligning with the lower flange, not the upper, you can clearly see the mistake in the end of view...show here to let folks know that C't'ain cock up visits us all With nothing to hold the inner end it's near impossible to get the braces nice and neat.
There was also a small sizing error in the fold up flanges that fit under the cross braces at the outer ends.

I'm not happy with the brake hanger inner angled brackets, they're designed to fit into a half etched recess in the transom beam, the fit is fine but the half etch area is easily distorted and leaves a witness mark on the outside of the transverse beam.

The final niggle is the axle bearings, once built you're never getting the wheels out again, not overly comfortable with that so some sort of slot and retention needs to be designed, and it has to go outside as there's naff all room inside....which means an internal slot in the cast axle box fitted later.

Still, if it were easy I'd not need test builds To be fair, the areas that have proved troublesome were already mentally flagged as potential areas of concern, the test build simply confirms the design concept isn't as good as it can be.










For the record, it appears PPD are now fully Roman, 0.375 material does not exist, it's now 0.4 mm, not a lot of difference but enough to throw off some compensations I had in place, plus they over egged the etch pretty much doubling any tolerances I had.....the wrong way, pahh.

 

[mickoo]

Midland Railway Compound bogie tender progress, pretty much all of the chassis bits are done and test fitted.

I left all the doors and windows open for C't'ain cock up and his crew to visit on a couple of pieces, sometimes you just sit back and think 'what were you thinking of at the time ' Still, they're easy to fix.

One or two parts have had a design revision, which should make fabrication and construction easier.

Just need to make up the front bogie and check clearances, then on to the brake gear and tank top.

 

[mickoo]

Brief update, front bogie plate work completed, changed the axle bearings from holes to slots, allows you to build the bogie easier, then drop the wheel sets in last before adding axle box cover castings.

Tank inner core complete, lower front end and tank top just requires tank filler hatches and fixing down to complete.

Need to revise the centre fixing points, not enough rigidity in the floor and it flexes when tightened. I'll simply add a U shaped beam across the core at that point with the nuts on the inside.

 

[Eastsidepilot]

View attachment 137327


View attachment 137328

Oi! steady on mate I can see solder

Col.

 

[Focalplane]

I have decided that visible solder means the structure is stronger than it otherwise would be. Of course it must be invisible after painting to be as good as the less strong models. Therein lies the rub.

 

[mickoo]

Oi! steady on mate I can see solder

Col.

I can't photoshop it all out........

 

[mickoo]

Last of the big bits all now fitted, couple of tweaks needed to make some joints easier to assemble.

The material is 0.40 mm which means you need some serious muscle to form the flares and even then the radius is not quite tight enough.
Several choices going forward, make the side sheets half etch thickness; I'm not a fan of large areas half etched, they have a habit of curling due to the etch process and rarely go back flat again.

Make the whole sheet 0.30 mm thickness; just need to tweak some bend lines and slots to suit.

Carve off the side and end sheets onto a new (third) 0.20 mm sheet. The flat doubling panels would need to move over as well and a few other bits would benefit for being easier to form in the thinner material.

The last option is of course the correct option, it also happens to be the one requiring the most work The space left by the removal of parts will need the rest of sheet 2 rejigging to make neat and not waste space.

The tank fillers are a suitable length of tube, around the base a riveted strip is added, around the top a simple flange strip, quite a faff so for the second one I'm going to trial a 3D printed trunk with details and then simply add the etched lid on top. The same applies to the front footplate (I presume) sand boxes, they're an awkward curved shape, easier to 3D print the canister and then add the etched lid.

 

[adrian]

Beautiful work.

The material is 0.40 mm which means you need some serious muscle to form the flares and even then the radius is not quite tight enough.
Several choices going forward,
....
The last option is of course the correct option

I'd beg to differ - I'd say the etches as is in 0.4mm is the correct option - you just need a bigger hammer! It just needs dressing with rawhide mallet to get the flares correct.

 

[Eastsidepilot]

Beautiful work.


I'd beg to differ - I'd say the etches as is in 0.4mm is the correct option - you just need a bigger hammer! It just needs dressing with rawhide mallet to get the flares correct.

Yes, can't beat a bigger 'ammer, I've tended to opt for 0.010" for flares but that's a choice you can have with scratch building, and I suppose with a kit your not going to etch sperate items on another sheet of different thickness to the main superstructure etches.

Col.

 

[mickoo]

Beautiful work.


I'd beg to differ - I'd say the etches as is in 0.4mm is the correct option - you just need a bigger hammer! It just needs dressing with rawhide mallet to get the flares correct.

Thank you.

Mmmm, your mileage is clearly greater than mine I'm of the opinion that if you have to beat things with a hammer, then someone further back up the design chain hasn't done their job right, and that works for etches as well as container crane rail brakes

There is a strong historical tendency to keep material thickness variations to a limit, a cost factor I'm sure....but only for the developer, not the consumer. Granted a new sheet for one or two small items is perhaps prohibitive, but, the tender has enough large parts (two sides, an end and corresponding strengthening overlays) to fill half a sheet, paired up you have a full sheet.

That does of course mean that if you were only making one model you'd have a spare set of tank sides......practice ones?...... In reality the time and effort saved by choosing the right gauge material often out weights the 'perceived' monetary wastage, especially if it turns a 60 minute job into a 5 minute job.

Time is the one factor rarely taken into account with kits, but it is our most valuable commodity, once it's gone you cannot get it back.

So, tank skins are now on their own bespoke sheet in 0.20 mm, which in NS is more than strong enough.

I admire those who can form delicate metal shapes with obscenely large tools, I'm not one of them

 

[SimonT]

tank skins are now on their own bespoke sheet in 0.20 mm,

Good man

 

[LarryG]

I had ideals back in 2008 when my initial 4mm scale Stanier coaches were etched. Coach sides were on 12thou brass, floors, ends and underframe were on 15thou and solebars were on 22thou. Unnecessarily expensive tooling and production when it was found that later coaches on one 15thou sheet were barely different in appearance.

 

[OzzyO]

Ordered

CousinsUK seem to be the cheapest from a quick web surf.

Mick,
I've seen a product called Horolene recommended. It's used by clock makers/restorers to clean brass and supposedly gets rid of tarnishing. The clock expert on the 'Repair Shop' uses it. Available on-line from various sources,I keep meaning to try some out so will order some this week.

all the best
Tim

Ordered

CousinsUK seem to be the cheapest from a quick web surf.

Mick,

have you had chance to use the Horolene yet? I'm only up to page 52 in your thread so I may not have seen you mention it again.

OzzyO.

 

[mickoo]

Mick,

have you had chance to use the Horolene yet? I'm only up to page 52 in your thread so I may not have seen you mention it again.

OzzyO.

Yes and it didn't work....might have been down to a number of factors but it seemed to make it worse. I've still got some left and might have another trial at some point.

 

[mickoo]

Nearly there, just a few more pieces to finish the MOK Ivatt 4MT tender, hopefully by end of play tomorrow.

There's a few gaps in the plate work to fill, they're just a touch too big for solder, or more as likely, if you tackled them with solder then something else would come undone near by, a dab of filler will be fine.












The revised MR tender artwork off this week as well so a short break from that until they come back for (hopefully) the final test build.

Hopefully pick some more of the Garratt off next week then back to the King Arthur engine.

 

[Dan Randall]

Hi Mick

Apologies for hijacking your thread (looking good, by the way!), but could you possibly run a Vernier across your wheel treads and measure their diameter please?

I'd be interested to know, as my wheels appear to be under sized, resulting in the bottom of the guard irons, barely clearing the rail head and misalignment of buffers, with adjacent vehicles....


I believe the prototype had 3' 6" diameter wheels, which is obviously, 24.5mm in 7mm scale, but check this out - what I expected....


What I got!....


I must have had a good reason for buying these particular Slater's wheels (via the S7 Stores, I think), but interestingly, Slater's seem to think they're actually 3' 9" diameter!....


Unfortunately, I can't aim these back to Slater's or the S7 Stores for exchange, as they have the enevitable coating of rust on them....

I'll have to flash out on another set of the correct diameter, so if anyone knows the reference number for the correct S7 wheels (regardless of whatever size Slater's think they are!), I'd be glad to hear please.

Also, can anyone suggest a suitable loco or tender application for the duff wheels please?


Regards

Dan

 

[daifly]

Hi Dan
The last two digits of the Slater’s product code are the wheel diameter in inches! Your wheels are 3’ 3” diameter as they should be. The product was mis-labelled by Slater’s as 3’9”. There is no 3’9” dia. wheel in the S7 Stores list. The ST part of the code gives a clue as to their intended use. They were added to the Stores list for the MOK Stanier 8F kit as pony wheels. Do you have 3 x 8F kits to build? There may be other options!
Dave