Etching Limits

[JimG]

I'm drawing up some artwork for the hardware for my S scale Caledonian coaches and I think I might have come up against a problem - i.e. how narrow can an item be? I'm doing grab irons and have been taking measurements off the St. Rollox drawings and some parts of the grab irons will be down to eight thou wide in S scale (half an inch full size). I would be looking to etch the grab handles in six thou brass. Is the eight thou width pushing my luck? The widest part of the grab handle will be sixteen thou.

Jim.

 

[28ten]

General rule is supposed to be minimum width = the thickness of the sheet. there is not going to be much undercut in 6 thou so you might be ok. I would have thought they would be very fragile though and 10thou would be safer on both counts.
Have you thought of flattening a suitable gauge of brass wire? its a trick I have used in the past and it is fairly robust

 

[JimG]

General rule is supposed to be minimum width = the thickness of the sheet. there is not going to be much undercut in 6 thou so you might be ok. I would have thought they would be very fragile though and 10thou would be safer on both counts.
Have you thought of flattening a suitable gauge of brass wire? its a trick I have used in the past and it is fairly robust

Cynric,

Thanks for the general rule. I have something to work to.

My main reason for looking at etching rather than forming brass wire is the number that I will need. The ten four wheeler coaches I am building will require eighty grab handles and I'm just about to start doing some 45ft stock which will require a lot more. So I am looking for a quicker way to make them.

I take the point about the 6thou stock. I will up the gauge to 10thou to make them a bit stronger. I had actually thought about using nickel silver instead of brass for a bit more strength, but would them lose the brass look.

Jim.

 

[3 LINK]

Hi Jim,

Could you have some castings done especially as you need so many of them, I have no knowledge of the casting process or methods used but the grab handles I have used which are supplied in the jltrt coach kits are very sturdy.
I know I am talking 7mm scale here but surely they will still retain enough strength in S scale ?

All the best,

Martyn.

 

[JimG]

Martyn,

Hi Jim,

Could you have some castings done especially as you need so many of them, I have no knowledge of the casting process or methods used but the grab handles I have used which are supplied in the jltrt coach kits are very sturdy.
I know I am talking 7mm scale here but surely they will still retain enough strength in S scale ?

I've been thinking about etching since it is comparatively easy for me to do - i.e. I draw the parts up in CAD and PPD does all the hard work. I don't know how strong a lost wax brass casting would be in S. If I stick to scale sizes, the grab handle would be about eight thou by five thou at its thinnest point, although the five thou dimension would be increased to eight or ten thou with etched parts for strength, so could also be done with a casting. And I'm not sure if such a part would be easy to cast with such small cross sections. I also have no experience of metal casting so don't know if there are real problems there. A fellow member of the S Scale Society had been doing his own metal casting for the past two or three years with a Tiranti spin caster and he has had a very steep hill to climb in gaining his experience.

Jim.