Ething brass with PPD.

[ednadolski]

For anyone who may be interested:

https://en.wikipedia.org/wiki/Accuracy_and_precision

It's an academic point anyways.  I've never had to do anything out to 8 decimal places, and PPD seems fine with the drawings I send even tho I don't use metric.   That said, discussions are of course always easier when everyone is using the same units.

Ed

[wcfn100]

Because a millimeter is 1/25th the measurement of an inch, which means an eight-decimal-position millimeter measurement is 25 times more accurate than an eight-decimal-position inch measurement — very handy when working in 3D modeling programs.

Okay, but does that matter for N scale?

Looking at the N scale conversions from the prototype to scale dimensions I get this:

100 inches = .625 in = 15.875 mm
25 inches = 0.15625 in = 3.96875 mm
1 inch   = .00625 in = 0.15875 mm
1/2 inch = 0.003125 in = 0.079375 mm
1/4 inch = 0.0015625 in = 0.0396875 mm
1/8 inch = 0.00078125 in = 0.01984375 mm
1/16 inch  = 0.000390625 in = 0.009921875 mm
1/32 inch = 0.0001953125 in = 0.0049609375 mm


In each case the decimal places are the same which makes them the same as far as accuracy goes, yes?


Jason

[bbussey]

Solidworks maxes out at eight decimal positions. I'd rather be working with millimeters. PPD and the Asian contractors use metric. Makes little sense to use Imperial in that regard, but you should use whatever you feel comfortable with.

[craigolio1]

I'm planning to switch my future drawings to metric, or at least convert them when I'm done. My problem is that I cant visualize  in metric. If you put a bunch of styrene scraps out, and tiod me to grab specific imperial sizes, I could no problen. Not so much in metric.

[svedblen]

I fully understand your problem. I have the same but the other way round. I can visualize a foot, an inch and even half an inch, but 1/4", 1/8" and so on...then I have to convert to millimeters. Not to mention square feet  That concept is impossible to grasp 

[peteski]

Not to mention square feet  That concept is impossible to grasp 

But you probably have no problem visualizing flat feet.   With square feet one needs some strange looking shoes. 

I was born and raised on metric, but 30 plus years in US has converted me into Imperial measurements. While for large dimensions (like home construciton) I use inch fractions, for small scale modeling I use decimal notation.

[Lemosteam]

I have to work in Metric all day long so I have become accustomed to relating Imperial to Metric especially in minute terms of fit and clearance.

[Chris333]

Everything I do at work is in Imperial. If I type in to move registration "20 up" that means I just moved it .020" up. Plus there is standard styrene sizes. When I draw I can just guess what size I need.

[craigolio1]

I'm looking at how to etch a ladder. I don't want a flat ladder that has rungs that just spill out into the beams.

The beams would have been about 2" wide flat, and the rungs were about a 1" thick bar.

My soldering skills are very good.  Is it realistic to etch the beams with .008" holes in the sides with the intent of sliding .008" phosphor bronze wire through and soldering it in place?

Using .2mm thick brass, is it possible to etch a piece say, .5mm wide, with a .2mm hole in it thread the wire through?

Would a piece that small survive the process?

I'd really like to avoid over sized ladders.

Thanks. Craig

[ednadolski]

Is it realistic to etch the beams with .008" holes in the sides with the intent of sliding .008" phosphor bronze wire through and soldering it in place?

Using .2mm thick brass, is it possible to etch a piece say, .5mm wide, with a .2mm hole in it thread the wire through?

The only sure way to know is to try.  Leaving less than the metal thickness on either side of the hole seems rather dicey.  In any case I think you'd likely end up with a very delicate part.

Regardless of skill, soldering that small would have to be done very precisely.   How would you keep everything aligned and square?   There would be little or no room for misalignment, excess solder, etc and after soldering you would have to flush trim the PB wire at each joint, without bending anything.   (FWIW, brass wire would be easier to work, so why PB if the rest is brass anyways?)

It may be worth considering alternates, such as a thinner stainless steel with the rungs as a half etch.   Still a delicate part, but sturdier than brass.

Ed

[craigolio1]

Thanks for the reply Ed.

PB because I have it. Haha. But I can get brass as well.

For this ladder the rungs protrude through the beam and are rounded off. They look like a rivet on the side of the beam. It's a very recognizable feature that I wouldn't get if I half etched.

I agree they would be crazy delicate. I'd preferred to etch them in brass as the rest of the etchings will be.

Craig

[Lemosteam]

Since the brass is so easy to drill, who cares. At minimum you will have a perfectly located dimple to use as a center.

I just did this but for stainless handrail stanchion, I did not get holes, and instead had perfectly sized holes for my .009" stainless handrail.  Only tip: drill the holes while the part is still in the fret.

Here is my result:
[ Guests cannot view attachments ]

[bbussey]

Use stainless steel instead for the etchings and the wire. The finished ladder will be incredibly strong, Well strong enough to survive handling.

[craigolio1]

Alright thank you. I'm sure as I go along I'll find other parts that will be better in stainless, making it worthwhile to do a fret.

What size of hole should I etch to pass a .008" / .2mm wire through?

Craig?

[Lemosteam]

My holes were 0.25mm and did not etch all the way through 0,25mm stainless.