Ething brass with PPD.

[craigolio1]

Makes sense. I'm pretty sure PPD says that for through hole etching in stainless you need to multiply by factor of 1.2 x the thickness for the smallest hole or something like that.

With holes in general, that you want to be able to slip a wire or a little tab through, is there a rule about making the hole slightly larger to ensure fit?

Craig

[Lemosteam]

Makes sense. I'm pretty sure PPD says that for through hole etching in stainless you need to multiply by factor of 1.2 x the thickness for the smallest hole or something like that.

With holes in general, that you want to be able to slip a wire or a little tab through, is there a rule about making the hole slightly larger to ensure fit?

Craig

My earlier point was why bother when they can be drilled to the EXACT size you want.  How many attempts will you have to try before your etch is perfect?  I think that is simply a waste of money, IMHO.  22.00 every drawing iteration plus the cost of a new etch.  I got lucky with this one- they already made the tool but did not etch the metal, so I was able to avoid another $80. 

[craigolio1]

Good point. However with a very small and delicate piece drilling, 10 holes in the sides invites a lot of opportunities to destroy it. I would like to get as close to the right size as possible.

That said it's way easier to expand a hole than to drill a new one.

Craig

[ednadolski]

How many attempts will you have to try before your etch is perfect?  I think that is simply a waste of money, IMHO.  22.00 every drawing iteration plus the cost of a new etch.

Unless you are producing in quantity, with small parts it's usually not much of an issue to make several size variations on a single etch.  Yes, you will throw some away, but if you keep track of the results, then you learn how the process works in practice and can apply that on future efforts.

(If you are producing in quantity, you would have to be pretty lucky to get everything right on the first attempt anyways )

Ed

[bbussey]

My earlier point was why bother when they can be drilled to the EXACT size you want... 

^ This.

As long as the dimple or undersized hole is there, you can drill out to the needed diameter without bit-drift.  You have to be more careful the thinner the metal, and it's easier with brass than stainless.  But it's far more economical than continuously resubmitted artwork plate charges.

I usually design to the thickness of whatever wire is being inserted regardless of the thickness of the metal, which protects me from over-etching, and then drill if necessary.

[bbussey]

Another observation regarding your ladders — you don't have to use the same metal for the entire structure.  If you are uncertain about etching the stainless posts, then etch them and brass and use stainless wire for the rungs.  That wouldn't be as strong as all-stainless, but they would be strong enough to withstand handling once secured to the model.

I've also done entire two-step etched ladders in .125mm stainless, posts and rungs.  The posts would be half-etched and the rungs full etched (or half-etched from behind).  Plenty strong and they look round after painting.  The Keyser Valley caboose kit had etched stainless steel ladders and grabs, and you've seen various photos of the model assembled over the past few years.

[wcfn100]

I had to chase down my mail man to sign for it, but I got my louvers today.



I haven't compared it to the drawing yet in terms of how the parts finally measure after under cut and everything else.  I may put that to a new thread.

I like what I see so far, but I can tell that some stuff didn't go as entirely hoped.


Jason

[Lemosteam]

Good point. However with a very small and delicate piece drilling, 10 holes in the sides invites a lot of opportunities to destroy it. I would like to get as close to the right size as possible.

That said it's way easier to expand a hole than to drill a new one.

Craig

You won't destroy it if you leave it in the fret.  I drilled those tiny, and I mean tiny, stanchions on this fret:

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