CI or GM Eccentric straps

[davejpc]

I have a choice for the 5" PANSY of cast iron or gunmetal eccentric strap castings. I would like to know if there is any major disadvatage in using cast iron and if I need to do anything different if using CI compared to GM. The eccentics are MS.

[Shawki Shlemon]

I have always used GM ,because they came with casting sets . There is no problem with cast iron at all . When they are finished soak them in oil overnight . The only advantage of GM for me at least is that I can silver solder the rod on the strap .

[ausdan]

I made some gun metal straps for my Hunslet, a year later they have worn about 1mm, so making a set of cast iron ones now...hopefully will get some longer running from them

[Myford Matt]

I'll be using GM on my Pansy - I've seen quite a few and they all seem to use GM, but as Shawki says it shouldn't much difference.

MM

[davejpc]

Good point about not being able to silver solder the rod, but I guess riveting should be OK.

[Myford Matt]

Rivetting thin CI sounds tricky – wouldn't it just crack?

MM

[mackintosh]

Don't know if this helps but my Minnie uses CI eccentrics and mild steel straps
Bob

[jgb7573]

A common way of fixing steel eccentric rods to cast iron eccentric straps is by studs and nuts. The eccentric rod has a palm at the eccentric strap end which is perpendicular to the rod. The palm has two holes in it. Two studs in the eccentric strap pass through these holes and are nutted up tight.

[Shawki Shlemon]

There is more than one way to skin a cat . When making parts that are not visible , use the most suitable method for you as long as it works and is reliable .To reduce wear I assemble all moving parts using graphite grease and regular lubrication . It works for me .

[spurley]

The good thing about John's suggestion also is that shims can be included between the rod and strap or material filed off to allow fine adjustment.

Cheers

brian

[davejpc]

Thanks for all the advice.
On Pansy, the four eccentrics which are 1/4" wide run against each other, also the rods are offset opposite in pairs. So I am not sure if there is enough room to put a palm as you suggest, although I like the idea.
If I rivet them I will have 1/8" thickness of CI to rivet against 1/8" MS strap. I think I may try an experiment on some scrap first before committing to making the whole strap, or go for GM.