On 27/04/2018 19:11, T i m wrote:
On Fri, 27 Apr 2018 16:50:23 +0100, Nightjar
wrote:

snip

However, if you are printing 'appropriately sized' things and that
actually suit the *actual* finish needs of the job, many of even the
cheaper printers (these days) will do a perfectly good job....

My application would be making one off sizes of products that I rarely
get asked for and that I don't now sell, because they would not justify
the cost either of tooling or of holding a quantity in stock.

Ok, that's the sort of 'non production' use that may be appropriate.

Nobody is
going to be happy paying £100 or more for something that looks tatty,

Is this an assembly as I'm not sure you would get though even 15 quids
worth of filament in one print job on a 'std' sized printer?

Materials are rarely a significant part of the cost of any manufactured
item. IME, around 10-15% would be typical.

so
surface finish is important.

Is it though? So we aren't talking utility' here then?

They have to look as good as anything else I am selling, which means
that, ideally, they should look like injection mouldings. In some cases,
they would be used with injection moulded items.

One option I have considered is an
Ultimaker 3, which has dual nozzles. I don't yet know if it would work
that way, but I was thinking of using one fine nozzle for the outer
surfaces and a coarser nozzle to bulk fill between the outer layers.

No, I don't think it would because each print layer is one layer and
of a uniform thickness (irrespective of the nozzle diameter).

Plus I think you are more likely to suffer registration and changeover
errors with a dual extruder (possibly sorted with a post cleanup etc).

Much as I expected, which would mean very long print times to get a good
quality product. Another option I might consider is using the printer to
make a master for lost wax investment casting of the items.

Like I mentioned, no one has ever commented on the finish of any of my
print jobs ... because they weren't *expecting* any specific finish
and whatever they say must have been considered acceptable? shrug

I can't think of anything I could print to be (realistically) worth
much over the cost of the materials and electricity ... because it's
not that sort of thing (ignoring the design time etc).

As I am running a business, I can't ignore design time, the capital cost
and depreciation of the equipment, general business overheads or the like.


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Colin Bignell