7mm Mickoo's Commercial Workbench

[mickoo]

Accepting that many folk choose not to believe that uv cured 3D printed parts are effectively lifed, the alternative [if they are for sale] to ageing them for ten years, is to use them as masters for polyurethane resin casting. Yes, it's more expensive than just printing them but you do have a responsibility to your customers.

I think people do believe it has a life expectancy but they simple choose to ignore it, a spin off from the I want it now culture that prevails in most walks of life these days.

The demographics for and against 3D are interesting (from my interactions) younger people accept it in a more carefree attitude, even when you explain the life expectancy is unknown (that caveat is made very clear to anyone I send stuff to), the elderly want the detail now and view it'll last longer than them, after that it's someone else's problem.

The middle ground, well those are the most resistant/hesitant/cautious.

At the end of the day, most materials are lifed, especially plastics, be it injection moulded, printed or otherwise and you can't be away from it, the difficult part is peoples expectations.

O gauge is a strong hold for metal models and longevity, it's the old guard for want of a phrase, other scales appear more loosely minded and accept other materials more readily.

For one off models or clients who are prepared to accept the risks then 3D is an alternative, for commercial kits then I feel an alternative should be sought, be it metal castings or polyurethane resin. However I do feel that 3DP for certain 'small' blocky objects is an option for kits, domes, sand boxes, tool boxes etc, but that's highly subjective and personal.

 

[mickoo]

I wasn't thinking of hobbyists at all. I think those who contribute to public forums ought to at least try their best in what they write and present to the world. Sorry for misleading anyone here.

Not sure I'm following, what's been written that was misleading or not presented in the best form?

 

[Dan Randall]

Accepting that many folk choose not to believe that uv cured 3D printed parts are effectively lifed, the alternative [if they are for sale] to ageing them for ten years, is to use them as masters for polyurethane resin casting. Yes, it's more expensive than just printing them but you do have a responsibility to your customers.

Hi Arun

As someone who enjoys designing and 3D printing stuff, but mindful of any potential long-term cons (such as warping and/or brittleness), I’d be interested in knowing more about the polyurethane resin casting process.

For example, do the items being cast need to be sprued in any way (with subsequent clean-up), or are they just cast, as one would wish the final product to appear? Also, what about things like window apertures and the like?

If you have the time and inclination, a thread on the basics of the process, with a few examples of patterns and finished castings would be very interesting please.

(With apologies to Mickoo for the hijack).


Regards

Dan

 

[Ian@StEnochs]

Not all of us have the equipment, skills or inclination for 3d printing however the idea of using a print as a former for an etching is interesting. However one can usually rig up something similar from stock materials.
I don’t build many kits but sometimes need to shape a few similar parts. This steel former, mostly shaped with saw and a big file, was made to make shaping the cab fronts and roof for Benjamin Conner designed engines easy and repeatable. The annealed brass blank was beaten over the former with a hide mallet and trimmed to size before soldering the sides and pre curved roof on. Time taken to make the former about 1/2 hour and 5 cab fronts about the same. More time spent waiting for the brass to cool than actually beating it!

Ian.

 

[Dan Randall]

More time spent waiting for the brass to cool than actually beating it!

 

[Arun Sharma]

I think people do believe it has a life expectancy but they simple choose to ignore it, a spin off from the I want it now culture that prevails in most walks of life these days.

The demographics for and against 3D are interesting (from my interactions) younger people accept it in a more carefree attitude, even when you explain the life expectancy is unknown (that caveat is made very clear to anyone I send stuff to), the elderly want the detail now and view it'll last longer than them, after that it's someone else's problem.

The middle ground, well those are the most resistant/hesitant/cautious.

At the end of the day, most materials are lifed, especially plastics, be it injection moulded, printed or otherwise and you can't be away from it, the difficult part is peoples expectations.

O gauge is a strong hold for metal models and longevity, it's the old guard for want of a phrase, other scales appear more loosely minded and accept other materials more readily.

For one off models or clients who are prepared to accept the risks then 3D is an alternative, for commercial kits then I feel an alternative should be sought, be it metal castings or polyurethane resin. However I do feel that 3DP for certain 'small' blocky objects is an option for kits, domes, sand boxes, tool boxes etc, but that's highly subjective and personal.

I agree pretty much with everything you've said. On Monday, the 3D printed Q35 trailer will go off to Birmingham to be cast in polyurethane resin and duplicated in a form that should be around when these original SLA masters have long turned to dust.

 

[Arun Sharma]

Hi Arun

As someone who enjoys designing and 3D printing stuff, but mindful of any potential long-term cons (such as warping and/or brittleness), I’d be interested in knowing more about the polyurethane resin casting process.

For example, do the items being cast need to be sprued in any way (with subsequent clean-up), or are they just cast, as one would wish the final product to appear? Also, what about things like window apertures and the like?

If you have the time and inclination, a thread on the basics of the process, with a few examples of patterns and finished castings would be very interesting please.

(With apologies to Mickoo for the hijack).


Regards

Dan

OK - I'll start a thread somewhere.

 

[michael mott]

Frankly there is only one limitation to experimentation, until it's right. Anything else is just shoddy and lazy.

As one time commercial model builder building any and any type of model with up to12 staff. I couldn’t agree more. One’s integrity as a builder is far more important than a quick buck in my humble opinion. My company did international architectural models and long before 3D printing and so we had many challenges with surface details depending upon the design of the building. I did many experiments with materials and techniques to replicate the surface of various designs. This would happen prior to construction and presented to the client as part of the cost proposal. Once in a while things went haywire and I had to change tacks. It might cost the client a bit of time but I ate the cost. My screwups were mine and mine alone.
Michael

 

[mickoo]

Hi Arun

As someone who enjoys designing and 3D printing stuff, but mindful of any potential long-term cons (such as warping and/or brittleness), I’d be interested in knowing more about the polyurethane resin casting process.

For example, do the items being cast need to be sprued in any way (with subsequent clean-up), or are they just cast, as one would wish the final product to appear? Also, what about things like window apertures and the like?

If you have the time and inclination, a thread on the basics of the process, with a few examples of patterns and finished castings would be very interesting please.

(With apologies to Mickoo for the hijack).


Regards

Dan

Not at all, it's a process I'm thinking of doing in the future.

There's quite a few videos on Youtube that explain the basics but basically it's a silicone or RTV mould, you do half at a time with the part in the middle, usually help in place by the tubes you're going to pour resin in later. You need to make register points in the two halves so they are accurately aligned for the pour stage.

Then you just pour your resin mix in and let it set, break open the mould and there's your part.

Another way is to place the part in the middle of your mould and then pour the RTV in as one hit, let it solidify and then cut around the part with a very sharp knife to split it apart, the knife cuts act as registration marks to align later.

Ideally you need a degassing station, one to get the bubbles out of the RTV mould as it cures, second to get the bubbles out of your resin as it cures.

The other option is to just give your pattern to someone who knows what they're doing and pay them to do it professionally.

Windows need to be blanked off, usually 5 or 10 thou plasticard, that'll create a thin membrane in the final part which you break out and trim up the opening.

If you're doing large lumps like coach sides or roofs then getting a commercial company to do it is probably best, if you're doing domes, sand boxes and small items then doing it at home is probably more economical, and fun.

 

[mickoo]

Not all of us have the equipment, skills or inclination for 3d printing however the idea of using a print as a former for an etching is interesting. However one can usually rig up something similar from stock materials.
I don’t build many kits but sometimes need to shape a few similar parts. This steel former, mostly shaped with saw and a big file, was made to make shaping the cab fronts and roof for Benjamin Conner designed engines easy and repeatable. The annealed brass blank was beaten over the former with a hide mallet and trimmed to size before soldering the sides and pre curved roof on. Time taken to make the former about 1/2 hour and 5 cab fronts about the same. More time spent waiting for the brass to cool than actually beating it!

Ian.

View attachment 208770

View attachment 208768

That's where skill bases differ, I wouldn't even begin to make a metal dolly, I don't have the experience to achieve what I want, I have/had the skill set to do it but neither the tools or patience to make it how I want it any more.

I'd argue (robustly ) there's more skill in producing a metal dolly by hand than there is doing it by CAD.

Neither is right or wrong, neither should be held as the only way at the expense of the other, they're just different ways to achieve the same result and wholly dependent on your preferences and skill sets.

 

[mickoo]

I agree pretty much with everything you've said. On Monday, the 3D printed Q35 trailer will go off to Birmingham to be cast in polyurethane resin and duplicated in a form that should be around when these original SLA masters have long turned to dust.

Look forward to seeing the assembled model, Kettering maybe

 

[Paul Cheffings]

Hi

Home resin casting for small items is quite easy. Most of mine have been single sided moulds

The bogie side frames on this wagon were cast at home as were the barrel ends

Cheers

Paul

 

[76043]

As one time commercial model builder building any and any type of model with up to12 staff. I couldn’t agree more. One’s integrity as a builder is far more important than a quick buck in my humble opinion. My company did international architectural models and long before 3D printing and so we had many challenges with surface details depending upon the design of the building. I did many experiments with materials and techniques to replicate the surface of various designs. This would happen prior to construction and presented to the client as part of the cost proposal. Once in a while things went haywire and I had to change tacks. It might cost the client a bit of time but I ate the cost. My screwups were mine and mine alone.
Michael

Hello Michael, I was an architectural modelmaker for ten or so years freelancing in London. Did you work in London? If so what company?

I also worked for a toy prototyping company, we spent plenty of time casting PU resin with vacuum chambers etc, I wouldn't fancy doing any of that at home. I only touch hobby type chemicals these days, not worth the whole messy smelly operation in my view.

I recall the time a colleague spent weeks making a toy wrestling ring prototype, but had forgotten when it came to tooling on a Friday afternoon in rubber the ring is hollow. It imploded like a certain submarine in the vacuum chamber and he spent all weekend starting again for a Monday AM deadline.

I since work in the art world where inkjet prints are passed off as giclee prints to make them sound fancy. Giclee is French for inkjet apparently. The early inkjet prints are dye based and are basically watercolours, so not light fast... There's going to be some disappointed art collectors out there that will be seeing their pride and joy disappear slowly in front of their eyes.

Tony

 

[Brian McKenzie]

. . . . I wouldn't even begin to make a metal dolly. . .

'Bog', as per pic, is useful for a quick former - as it is cures rapidly (used for a diesel loco cab). Also, laminations of MDF or lumps of wood.

 

[mickoo]

Calling the tender done, or so I thought until I took the photos Forgot to fit the vac and steam pipes and the coal gate needs it's handle.

There's a little niggle in the right hand side cab roof joint which needs a little low temp flooded in and dressed smooth, my mistake as I pushed a little hard with the iron tip in the paper thin sheet; such a shame as the former worked really well only to be cocked it up by clumsy clutz, the universal smart/dumb balance was restored

I've cleaned it with an aggressive cleaner which turns solder dark grey and left it so people can see where all the joints are, 95% are on the inside but four (two each side) had to be done outside, the tank side base and the folded top where it meets the coal raves.

Even though the surface is smooth and polished the solder forms a faint stain which shows up with the cleaner.

The reservoir cover is still loose at the moment as I need to give the area in and under the tanks a waft of black; it's near impossible to get in there later, and near impossible to solder the cover on without bubbling the paint later. I'll also tend to the radius relieving grooves with filler to smooth them out before final fitting.

Leaving the sides off worked well, it helped me in my build process, but it may not be for everyone, just a different way to do it.

 

[Pencarrow]

So shiny! Love it.

 

[mickoo]

Stage one of the Jubilee rebuild after paint. Generally getting the model back up on it's feet, cleaning out all the bearings and making sure you have a free rolling chassis, I also cleaned out the buffer shanks and made sure the heads moved freely.

As a rule of thumb I paint the wheels here so there's less chance of them getting mixed around and being as this engine is going to be weathered I've blown a very light thin coat of etched primer black on the motion. I still need to do the return crank and rear crank pin nut (which will be steel on the final rendition).

The thin coat gives the weathering paint a good base so that it won't rub off when handled. Yes, the painter could do this but I'm overly possessive about my wheels and motion The buffer heads and bogie axles will also be blackend in due course.

The next step is to wire up the pickups and motor and get it running and oiled up, then I'll start to add back the missing pieces, glazing, cab windows, cinder screens, reach rod, cab doors, hooks, tender draw bar and finally coal.

Normally I'd have built the backhead by now, but I've been busy with other projects so that'll get done shortly, I don't mind as I find the break nice and therapeutic, fitting all the details and painting.

With a good breeze it'll all be done by Kettering and will be on Warren Haywoods stand as he'll then take it away for weathering.

For the next few days it'll be the LNWR 2-4-2T and hopefully an update on that next week, then back to the Bulleid as that also has to go for paint at Kettering.

 

[Clarence3815]

Very nice too.

What is the source of the wheels?

 

[mickoo]

Very nice too.

What is the source of the wheels?

Just standard Slaters out of the box.

 

[mickoo]

So shiny! Love it.

Precious likes?