7mm Mickoo's Commercial Workbench

[mickoo]

I note that the holes in the boiler for the chimney and dome are more of a marker than full diameter holes for the castings. My thinking would be that this is good practice by the designer to minimise distortion when rolling the boiler. How will you cut the larger diameter holes required for the castings to fit without distorting the shape? Slowly ease them out by hand with tapered reamers? I'm pleased to see the firebox wrapper is a better fit than the A2!
Lovely build once again.

Richard,

You're right, it does limit distortion when rolled; the only problem with DA kits is the material gauge which makes rolling a right battle. I get why it's done like that as the wrappers are on sheets with other parts that benefit the thicker gauge but it's still a muscular exercise when compared to more modern kits. In support of the thicker gauge though, it limits distortion when we get to the next stage below, less chance of the drill bit snagging and stronger edge once the hole is complete.

I place the chimney centred over the small holes and scribe a line on the wrapper around the inside of the blast pipe holes, then I'll use a 1 mm drill and drill around that line with a row of closely spaced holes. To cut through the remaining fingers I just use the drill as a milling bit, pressure against the metal and drill up and down, crude but effective.

The jagged hole is then cleaned up with a drum sanding bit 2.27￡ 5% OFF|30pcs 1/4" sandpaper drum sanding disc sand paper sleeves polishing wheel for woodworking Nail dremel drill rotary tools DIY 6mm|polishing wheel|sanding discsdrum sanding - AliExpress so long as the hole is larger than the chimney bore you'll never see the edge.

I'll post some photos up later of the stages it goes through to open out the holes.

 

[mickoo]

As promised above.

I'm sure there are several ways to do this, but this is the way that suits me best, I've tired reamers and larger and larger drills. Reamers tend to leave a hard burr that needs removing as you go along, larger and larger drills run the risk of snatching and ripping the wrapper, more so if it's thin gauge material.

The photos should be self explanatory but a few notes never go amiss.

Step one, align chimney and mark the bores on the wrapper skin, top two pictures.

Step two, I use a 1 mm drill to make a circle of holes as close as practical, I centre the drill just inside the scribed line, then I use the drill bit as a mill and with a little side pressure whilst drilling up and down open out the little fingers between the holes. Take it easy and you won't snap the drill, even if you do, keep using the stub. It's the side that's doing the cutting, not the tip and it'll go in the bin afterward if you've snapped it anyway. At this point it'll be quite jagged.

Step three, using a mini drum sanding bit in a mini drill I round the edges off and slowly open out the hole, keep going so that the wrapper is no longer visible in the bore of the chimney. The holes don't have to be perfectly circular, just fractionally larger than the chimney bore

 

[mickoo]

Some more glacial progress on the Peppercorn A1.

I suspected the firebox front corner castings might be a problem and pulled out my biggest swear box before hand, it turned out not to be big enough.

I'd love to take the blame for building it all wrong but the sad fact is the corner castings are undersized by a significant amount, 3 mm at the base where they meet the boiler. They're also too short and do not sit on the footplate.....more filling later.

The close up of the RH firebox also shows the gap between the boiler wrapper and the firebox wrapper that needs to be filled as well. Logic dictates that you either move the boiler up or firebox down to close the gap, however, that then means the two wrappers are not lined up at the crown. I backed the hole with low melt and worked in some filler, it'll need a witness coat of paint to see if it's smooth enough and I suspect it won't be so more filler and primer required.

The gaps on the castings were backed with tape and the holes literally flooded with 70° solder, the resulting blob carved and hacked back to make good.

The reversing reach rod cover on the LH side is a little short (2 mm) and needs the rear end blending in with more filler, in hindsight I should have fitted a 3D print in there, it may still come to that in which case I'll blow torch the old one off and start again.

 

[Tim Humphreys ex Mudhen]

Hi Mick,
Is there also an issue with the fit of the right side firebox seating on the footplate?

Tim

 

[mickoo]

Hi Mick,
Is there also an issue with the fit of the right side firebox seating on the footplate?

Tim

Yes, I couldn't be bothered, didn't have the enthusiasm, to take a photo.

I know where your going...well maybe, take a bit out of the base of the firebox so it sits lower on the rear footplate, problem there is the firebox crown then sits too low with respect to the cab front and the boiler shorts out on the wheel rims.

The other option is to change the swept up foot plate so that it goes higher over the drivers, problem there is that the splasher tops then hacking to clear the boiler and you'll end up with a sloping footplate over the drivers due to the fixed height mini step by the motion bracket.

Changing the rear up sweep also has the effect of changing the length and you'll find the splashers no longer line up with the axle centers.

 

[7mmMick]

What a knife and fork job this is pal, I hate working on stuff like this. Even when I get to
the point where other folk or a customer is happy I never can be. I end up feeling disappointed that it never really went together properly. Maybe just me but it somehow sucks the joy out of the build. It’s all part of the journey though I suppose

For what it’s worth, outside looking in, it looks great

 

[Lancastrian]

What a knife and fork job this is pal, I hate working on stuff like this. Even when I get to
the point where other folk or a customer is happy I never can be. I end up feeling disappointed that it never really went together properly. Maybe just me but it somehow sucks the joy out of the build. It’s all part of the journey though I suppose

For what it’s worth, outside looking in, it looks great

I agree. I had similar issues/puzzles with the two DA Schools, and now I'm working on the thrid.....but at least I now where where there are any things to look out for. I'll be starting a D1 from the same stable as well soon.

Ian

 

[mickoo]

What a knife and fork job this is pal................

For what it’s worth, outside looking in, it looks great

Typical meat and two veg meal really, hard work to get it to champers, roe and canopies

I have a DA Royal Scot right after this one too so I'm hoping for an easier ride though I'm not expecting it after the (admittedly small but niggling) woes of the A1, A2 and 7F.

The problem is you have to be very careful what you adjust or else it all just unravels and you end up replacing nearly everything. So long as the level of comprise is consistent then the whole can look rather pleasing and DA kits tend to get to around 90-95%.

To get to 100% you either have to expend a lot of time, energy, new parts to get there which can be time/cost prohibitive, or, you start from the ground up, that iron is well and truly being warmed up.

On the plus side, most of the DA castings are rather good and this model came with a nice package of upgraded castings from Ragstone which add an extra level of fidelity for little extra work.

It'll look stunning on a big layout belting along with 10-12 on the back.

 

[mickoo]

Some more progress on the DA Peppercorn A1.

I wasn't happy with the kit reversing reach rod cover on the side of the firebox so it had to come off, it'll be replaced by a 3D print once the edges of the bolted flange have been (carefully) thinned down to 0.2 mm.

There's a few more nick nacks to finish up on the body then it's back down below to complete.

The brass is getting tarnished now, this close to the end there is no need to clean/polish it unless you need to add something, you're just wasting time; so long as the joints are all clean, neat and tidy and the surface is smooth, then the jobs a good un.

 

[mickoo]

New commission for some etched work to aid scratch building. Test build over the weekend and hopefully sign off for production runs next week

 

[simond]

Never saw them in the iron, but looking forward to the model.

 

[OzzyO]

Never saw them in the iron, but looking forward to the model.

I saw all but 8 of the 76s but I've only seen one of the 77s. 1981 around Guide Bridge and Reddish depo happy hunting grounds.

OzzyO.

 

[mickoo]

Pretty happy with the EM2 body core, it's almost good to go off the bat.

I've changed a couple of design features in hindsight from the test build as well as tweaking the cab front bend points to get a better alignment.

Next up is all the detail etch overlays and working up the 3D components.

 

[richard carr]

Mick

That looks really good. What are you going to do for the roof, because that was always the difficult part of an MMP diesel kit.

Richard

 

[mickoo]

Mick

That looks really good. What are you going to do for the roof, because that was always the difficult part of an MMP diesel kit.

Richard

The roof is a similar design concept but rather than have the fold under edges that MMP had it'll just be flat edges that overlap the sides a fraction.

The beauty of the EM2 is it's battleship plated and strap construction, there's a nice strap running along the cant rail to hide the joint.

It is a concern and is probably the hardest part to fabricate but hopefully being in three smaller sections they'll be easier to manage, that's why there's a test build, to see if the concepts are workable.

MD

 

[mickoo]

Just a quickie repair, client dropped this off as a non runner, a Finney7 A4, nicely built too by the look of things and fitted with Alan Harris wheels.

It's been looked at previously (persons unknown) with suspected quartering issues due wheels (singular/plural?) moved on axles, not uncommon and I've had a couple do this already on previous builds; such that I'm starting to wonder if the adhesive is beginning to loose grip over the years on the insulated bushes?

Anyway, whomever reassembled it flipped one side by 180° before fitting the split axle pin back in, it did bring a smile to my face.

Hopefully it'll be a case of pulling the tapered pin, re orientating the offending wheel and testing, hopefully it hasn't twisted it too far out of alignment, if they have then the whole axle and wheels will have to come out and the offending joint re-affixed once the quartering (authentic 120°) has been resolved.

 

[Brian Daniels]

Front lights on that EM2 need to be a bit more oval don't they

 

[mickoo]

As a quick update on the A4, all repaired and running, the LH rear driver had slipped on the axle by the amount in the photo, about 160° out of alignment. How it managed to do that I've no idea but the tapered pin was tight in the axle and paint still on the body shell screws so it had never been apart.

I can only assume it must have been going flat out and slipped, it's amazing none of the remaining rods or quartering went out.

It was a simple case of rotating the wheel on the axle until it was aligned correctly, marking the axle end and hub carefully and splitting the wheel from the axle. Both faces were cleaned and Loctite 603 applied and the wheel pressed back on and refitted.

Ran a treat on the first run and now needs reassembly first thing tomorrow. All in all a right good result and could have been so much worse.

 

[mickoo]

Finally completed the David Andrews A1, well almost, as is my want I do the back head as a mini (sanity break) project whilst the main engine is away for paint. The coupling and connecting rod oil pots also get added once all the motion is stripped back down.

Constant cleaning with soaps/cleaners and has tarnished the brass quicker than normal such that it's pointless trying to keep it bright past a certain point. The nickel silver chassis on the other hand is still as bright as the day it was completed many weeks ago.

Next stop is a complete strip down followed by the US cleaner then bagged up for the ride up north to the painter.

 

[mickoo]

A little more EM2 progress and some FUBARs, mostly alignments between holes in the core with the overlays, headlights and a couple of hand rail holes. The biggest one is the panel for the boiler access, it's in the bottom of the etchers tank somewhere, a simple case of forgetting to flood fill one of the panels.

On the plus side, the cab overlays all fitted perfectly, I've only added one door frame and rounded one front corner but the brass bits are just fine.

The sides are just held on with tape and that's as far as they'll go; the roof cant rail joint is too low, not sure how or why as all the math works out as does the CAD drawing. But it's too low by 0.8 so the core needs adjusting and the roof panels shortening accordingly.

I'll do the raised roof section to check it's height at the cant rail joint, then there's a few riveted straps to check and V2.0 will be off to the etchers.