7mm Mickoo's Commercial Workbench

[mickoo]

Once the idea forms, I have found many and various means of assisting builds

Agreed, though to be fair, none of my previous ones have worked so well (as well as I wanted) or felt so self satisfyingly smug as this one

Like everyone else, I tend to view the 3D printer as a detail or model object replicator, not as a tool supplier, test pattern (Slaters SG motor pattern) or functional object (DCC chip holders) maker.

 

[simond]

The Ultimaker (hot string printer) at work generates a honeycomb fill for solid bodies.

I wonder if there is some way of applying this approach to resin prints.

 

[mickoo]

The Ultimaker (hot string printer) at work generates a honeycomb fill for solid bodies.

I wonder if there is some way of applying this approach to resin prints.

Yes there is

I've seen it used a fair few times to span large areas for support work and reduce resin wastage, it'd take a bit of lateral jump to make it a 3D (pun) concept for larger volume objects as opposed to slabs.

The most complex is a geodetic honey comb with 3D voids, the simplest is a pile or tubes top to bottom like a nuclear reactor. The only concern (real risk) of the enclosed geodetic voids is trapped resin, you've seen how it clings to the model once printed, that will occur inside every single void and cause problems later. It's a good concept for FDM printers, not good for SLA

It'll save resin but not print time.

 

[Arun Sharma]

Yes there is

I've seen it used a fair few times to span large areas for support work and reduce resin wastage, it'd take a bit of lateral jump to make it a 3D (pun) concept for larger volume objects as opposed to slabs.

The most complex is a geodetic honey comb with 3D voids, the simplest is a pile or tubes top to bottom like a nuclear reactor. The only concern (real risk) of the enclosed geodetic voids is trapped resin, you've seen how it clings to the model once printed, that will occur inside every single void and cause problems later. It's a good concept for FDM printers, not good for SLA

It'll save resin but not print time.

I agree. On another [7mm] forum last week we saw an example of home-made honeycombing as a way to strengthen a wall. The problem was that it became impossible to wash all of the uncured resin out and the ends/insides of these tubes were unable to be cured because they were perpetually in shadow. Over a very short period of time the whole structure distorted and collapsed.
That was a commercially produced item which suggests that there are some traders about whose products are better avoided.

 

[adrian]

No afraid not, I just build and ship, signatures are for artists and the like

My Dad used to have a set of small builders plates etched for his scratch built locos that we'd solder either inside the frame or loco body somewhere.

 

[mickoo]

My Dad used to have a set of small builders plates etched for his scratch built locos that we'd solder either inside the frame or loco body somewhere.

That's the traditional way of doing it, it has been suggested by a couple of clients I do the same but with a small 3D printed plaque, given my penchant for that medium

If people specifically want a plaque I'll add one, but it's not something I'd do as a rule.

 

[Big Train James]

I really do appreciate how you are always considering new ways to do things, always willing to experiment. We have very different goals, you as a commercial builder and me working for myself, but I too am often thinking about different ways to tackle various issues. Often times the things I come up with are dysfunctional on a certain level, but if only for myself than I'm the only one that suffers for it. I realize you don't often have that liberty.

I will say that I've used 3d printing to create wire bending fixtures for handrail wire, and I've designed a pair of parts to aid in folding radiator screens for the sw1500, essentially a punch and die set.

 

[Pencarrow]

That's the traditional way of doing it, it has been suggested by a couple of clients I do the same but with a small 3D printed plaque, given my penchant for that medium

If people specifically want a plaque I'll add one, but it's not something I'd do as a rule.

Now then Mick, you could add a signature item, a bit like the Cuneo mouse, somewhere on the locos. Probably on one of the 3d prints. Then, as entertainment, leave the owner to find it. Given your avatar, perhaps an imprint of a Minion?

 

[simond]

I agree. On another [7mm] forum last week we saw an example of home-made honeycombing as a way to strengthen a wall. The problem was that it became impossible to wash all of the uncured resin out and the ends/insides of these tubes were unable to be cured because they were perpetually in shadow. Over a very short period of time the whole structure distorted and collapsed.
That was a commercially produced item which suggests that there are some traders about whose products are better avoided.

I can imagine the challenge here. It’s clearly not right to treat one’s customers as guineau-pigs, but equally there is a limit to the experimentation a small business can do, to prove a concept or component. One would hope a full refund was provided (small comfort if the said object had been built-in and painted, possibly at some expense) and that “lessons were learned”.

Clearly washing is an issue, maybe the curing can be mitigated by long exposures, and the whole thing would need to be made with a suitable parting plane, a bit like an Easter Egg.

Despite the “can be done”, sounds like “but don’t bother…”.

cheers
Simon

 

[richard carr]

Mick

Would a different type of FDM printer offer a better solution for this, a lot faster and a lot cheaper. People are printing sleeper beds for turnouts using them which look pretty good.

A great idea idea though, I would certainly recommend them for decoder holders and speaker enclosures.

Richard

 

[mickoo]

Mick

Would a different type of FDM printer offer a better solution for this, a lot faster and a lot cheaper. People are printing sleeper beds for turnouts using them which look pretty good.

A great idea idea though, I would certainly recommend them for decoder holders and speaker enclosures.

Richard

A FDM printer would work, but you really need the surface to be smooth, any ridges or high points will almost certainly show as witness marks on the thin brass sheet, it's barely 10 thou thick, more like 8 thou being half etched with raised rivet detail.

The Pannier tank dolly will be quite long and thin so orientation will be important to avoid warping, probably print pure vertical which will take ten or more hours I suspect. I'll also bore two (maybe three) 10 mm holes down the core and stuff NS rod in there to make sure it stays straight over time.

The saddle tank had a wall thickness around 2.5/3 mm and if you grip it in the middle it will flex a little, but you do have to grip it quite firmly, I reckon a 5 mm wall thickness would be plenty strong enough to make a dolly with; especially if you add a couple of 3 mm thick bulkheads mid way and maybe one central longitudinal one.

 

[mickoo]

I agree. On another [7mm] forum last week we saw an example of home-made honeycombing as a way to strengthen a wall. The problem was that it became impossible to wash all of the uncured resin out and the ends/insides of these tubes were unable to be cured because they were perpetually in shadow. Over a very short period of time the whole structure distorted and collapsed.
That was a commercially produced item which suggests that there are some traders about whose products are better avoided.

One of the biggest issues is people printing for speed, they're running exposure times so close to barely hardened to gain a few hours of print time, consequently the parts are coming out green and need further curing, actually all parts really need further curing but less so if you run higher exposure times.

The other issue is getting unspent resin out of cavities, swishing it in a butter tub or one of these wash cubicles never really gets in all the cavities, the best way by far is an ultrasonic cleaner. I simply put some fresh IPA in a margarine tub and float it in the main tank, clean for five minutes and the difference is staggering. I'll swish the tub around a bit in the tank to agitate the IPA a little but you don't need to do it that much to get a clean surface.

I run my printer like a three course meal with some wine and a coffee to finish off, most run theirs like a fast food drive through; and then wonder why they have indigestion!

 

[Arun Sharma]

I've just finished designing masters for [yet another] London Transport underground car. The 'L' shaped sides and floor are printed by an SLA high definition process but the separate roof [being a piece of uniform cross section and no significant surface detail] was printed on an industrial FDM machine using ABS filament. If a part requires to be robust, or has no surface detail or can be sanded smooth then FDM is probably a good and very much cheaper way ahead.

In this model - a 7mm Q31/Q35 District Line trailer, the end and sides are printed on an SLA machine. Note that several temporary sacrificial supports have been built in. The roof is printed on an FDM machine at a significant cost saving. The seats [shown in part on the nearside] are printed via FDM as they can be sanded smooth. All of these parts will be used as masters for polyurethane resin casting via room temperature silicon moulds.
Essentially, you should choose the most appropriate form of additive manufacture for the task in hand.

 

[mickoo]

...... but equally there is a limit to the experimentation a small business can do......

Balderdash, sorry

It depends on how you value your customer and their continued support to sustain your business.

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

I'll concede 100% may well be impractical (time and cost, but that is dependent on the items complexity) but most customers are reasonably happy with a reliable 85-90% quality.

 

[Richard Gawler]

I can imagine the challenge here. It’s clearly not right to treat one’s customers as guineau-pigs, but equally there is a limit to the experimentation a small business can do, to prove a concept or component.

Balderdash, sorry

Surely the amount of experimentation depends on the industry where you work. A lone modelmaker works outside every formal regulation and standard I can think of.

 

[mickoo]

I really do appreciate how you are always considering new ways to do things, always willing to experiment. We have very different goals, you as a commercial builder and me working for myself, but I too am often thinking about different ways to tackle various issues. Often times the things I come up with are dysfunctional on a certain level, but if only for myself than I'm the only one that suffers for it. I realize you don't often have that liberty.

I will say that I've used 3d printing to create wire bending fixtures for handrail wire, and I've designed a pair of parts to aid in folding radiator screens for the sw1500, essentially a punch and die set.

I saw somewhere in the great wilderness of the internet where some one had made a nice little jig from metal to form grab irons, it was simplicity and elegance in it's own form and now I can't find it.

I've never even considered a 3D jig to achieve the same result or as a jig to bend hand rails etc, that's a light bulb moment and I can see a use for one to form the handrails over the front of smoke boxes uniformly.

I did consider a stamp and die set to try and form stamped louvres as seen on SD9/24's etc, FNG might cope with it if the material was thin enough, but probably only a one shot process, the die would survive I think but the stamp might not.

To be fair my drive is economics, if I can reduce the time to achieve a certain process and replicate that consistently, then it has to be a benefit to the build process. In some cases it's to cover a lack of skill set, I now people that can form metal with a broom handle, some cardboard and a piece of rubber mat and it'll look perfect; that comes from years of experience which I don't yet have.

 

[mickoo]

Surely the amount of experimentation depends on the industry where you work. A lone modelmaker works outside every formal regulation and standard I can think of.

Agreed, but we we're talking commercial businesses, money has exchanged hands so you have a duty to provide the best possible product and not use customers as your test bed.

Hobbyists are a totally different spectrum, you can do as you please as the only person affected is yourself; but the minute you sell items they you are (or should be) constrained by much more stringent ideals/morals.

 

[simond]

True, as I said, customers are not Guinea pigs.

But you can’t age your 3DP parts for ten years before you sell one. Practically there’s a limit and trying new products will find it. DAMHIK!

 

[Richard Gawler]

Surely the amount of experimentation depends on the industry where you work. A lone modelmaker works outside every formal regulation and standard I can think of.

Agreed, but we we're talking commercial businesses, money has exchanged hands so you have a duty to provide the best possible product and not use customers as your test bed.

Yes. What I am trying to say is, a professional modelmaker has few if any regulatory constraints on their work. They have far more scope to experiment than the person making (say) medical devices. The main thing, as in all business, is to not take the mickey out of customers. If customers are coming back for more, then you are surely doing the right thing.

Hobbyists are a totally different spectrum, you can do as you please as the only person affected is yourself; but the minute you sell items they you are (or should be) constrained by much more stringent ideals/morals.

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.

 

[Arun Sharma]

But you can’t age your 3DP parts for ten years before you sell one. Practically there’s a limit and trying new products will find it. DAMHIK!

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.