Small files

[DaveyH]

I have recently started building brass and white metal locomotive and rolling stock kits in both 7mm and 4mm and have found the whole process really satisfying.

 

I have hit a snag though and I now have the need to file the hole in a 4mm nickel silver coupling rod in order to slightly enlarge it in one direction only. If it was simply to be enlarged all round I would use a broach.

 

I have found the existing files I have are either too large or too soft and I wondered if fellow RMWeb members could advise what files they use for such work and where they may be bought?

 

Thanks

 

Dave

[smokebox]

How big/small is the hole?

[DaveyH]

The existing hole is 2mm internal diameter and I want to add approximately 0.5 mm to slacken off the motion.

[Izzy]

 Will sound extremely crude I know, but I would just use a rat tail needle file, whether you want to produce a 2mm slot, or a 2.5mm hole with the centre offset from where it is now ( not sure which it is you want to do). With most the end dia will/can be under 1mm and some will have a more gentle increase in size than others. An ordinary fine grade will cut n/s quite easily, no need for diamond ones, indeed just use slow and easy strokes.

 

I won't ask why you want to enlarge/offset the crankpin hole in a coupling rod.... just to say that if it's because they don't match up to the chassis .... don't. The loco will never run well. Axle and rod centres must always match, however sloppy the fit between them. If I have this all wrong I apologize.

 

Izzy

[Argos]

Hi Cornerman,

 

What you need is a cutting broach set rather than a file.

 

You'll find these in most of the specialist tools stores,

 

https://eileensemporium.com/index.php?option=com_hikashop&ctrl=category&task=listing&cid=1135&name=transfers-fixing-masking&Itemid=189

 

I've linked to Eileen's Emporium but you'll also find them elsewhere.

Edited November 18, 2017 by Argos

[DCB]

Poor quality needle files used to be available from Poundland but the pound sliding seems to have priced them out of Poundland's reach, however they are widely available from markets and trade stands where the same old tat can be bought for 10 times the price. Even the cheap and nasty needle files should be ok for elongating holes in N/S as long as you don't want to do too many, but I do wonder why they need doing offset as the axle holes should normally be bored using the coupling rods as a guide.

[Grasshopper John]

You could try a chainsaw blade sharpening file, they come in various sizes and are round.

[Kylestrome]

The answer to this is to use very small files called escapement files:

 

https://www.cousinsuk.com/product/round-3021-vallorbe-swiss

 

They come in all shapes and sizes, including round. Genuine Swiss Vallorbe files may seem expensive, but you will only need a couple and good tools are always preferable to ceap ones that wear out or break.

 

HTH.

 

David

 

PS. I have no connection to Cousins. Mine came from Shesto Tools.