Re: Linkage repair on a brass locomotive
Daniel A. Mitchell
Due to the tiny size of the rivets used in HO valve-gear, the tools needed to set them are mostly available only from the suppliers of such rivets. That’s Bowser (ex Kemtron), maybe PSC, and someone mentioned some european (German?) supplier. Others?toggle quoted messageShow quoted text
Similar tools (not necessarily rivet-sets) are also available from commercial jeweler’s suppliers. Some of these are useful as a PART of the rivet-heading process. Ideally, using a proper rivet-set, the entire rolling operation can be done in one application. Note that my personal experience is the the heads form better with repeated light impacts rather than one big smash. However, the result can be achieved using several different tools applied in the proper order, such as …
1) a tapered tool like a center punch used to start the flare of the rivet, to perhaps 45 degrees
2) a ball-shaped tool to continure the flare out to perhaps 90 degrees. A small bearing-ball works well here. A Jeweler's “dapping” punch works well here if you can find a really small one.
3) a punch with a cup-shaped hollow tip to continue the roll well past 90 degrees. Jewelers use such “bezel-stone setting punches" for setting jewels. Watchmaker’s use such punches for setting small bearings … I have several varieties. Often these come with a small frame to hold the punches in alignment with a setting anvil.
The simple hand-tool set is not very expensive. The watchmaker’s set with alignment frame, etc., is quite expensive. How much of such work do you expect to do? Simple, cheaper tools will usually work even if they louse-up sometimes. How many blank rivets can you buy for the cost of the watchmaker’s setting device? Hundreds at least.
This is careful, fussy work for sure. It takes proper technique, experience, a good rivet blank, and some luck. Ideally the rivet can be flared and rolled without cracking it. That’s not always possible. Sometimes the rivets are too hard and brittle making a proper roll impossible. Such rivets are made of brass, copper, and steel. The softer the better. If the new head cracks examine it under strong magnification … you’ll have to decide if it looks good enough. If it’s mostly rolled over it’ll work … these little things are NOT highly stressed. If it’s rather squashed flat with several cracks, it’ll likely fail. Often it’ll take more than one try to get it acceptable.
If one has a small lathe the job becomes easier since you can make your own rivets and the tools to set them. They are not complicated.