I have been asked to add a metalic ring in place of a fore grip to a build.
I am very reluctant.
My limited experience with them so far has been horrible. I fitted one last year like i would a rubber/vinyl one, using rod bond as lube for the last 1 inch or so. Fitted in mid summer(100 plus temps) and in mid winter(at least 80 degrees colder). Rod broke right at trim ring.
I suspected it was the differing rates of expansion of metal(plated brass?) vs graphite.
The broken rod issue from rodmaker added some confirmation to that.
So what is the experience on this, are they 100% safe in a climate that swings 100 degrees or must you fit them loosely? Like go up one size so they can spin freely in place before gluing up?Or freeze them prior to fitting or what?

I would always make sure there is some "slop" in the fit of such a ring. I'm not sure there is going to be much expansion or contraction of the ring in a mere 100F, but a rod blank needs to be able to change shape when it flexes. Prohibiting that can certain cause a failure. I realize this is down near the handle, but under a heavy load rods do flex a bit in that area.

.................

I'd suggest going with a slightly larger ID and install it over a thread base.

Lou,

I agree with Tom and Bill. Go a bit bigger than you need and it should be fine. With a heavy fighting load the blank will ovalize I always try to do a matching under wrap for both cushion and slop.

Tight lines,

John Hernandez

Assuming you fit the parts up when it was 70 degrees F°, you are talking a differential of + 0.0003” to -0.0007” in the brass and move the decimal point one place to the left for graphite.

To cause problems you would have been using press fits when you assembled the rod. I would side with Tom and his elongation theory. An under warp would help

AND........... cold would make the ID LARGER, not smaller.......... A common misconception about expansion and contraction of rings...............
I used to use "cryo couplings" on satellites for propulsion systems refitting after sensitive equipment was installed that could be damaged by welding.
Cut fuel line was spliced by a fitting stored in liquid nitrogen to keep the ID large enough to fit over the fuel line. As it came to room temp, the ID DECREASED.
This was a specialized fitting that contained materials that were sensitive to temp changes so that they would expand more dramatically. However, the basic concept still applies.
The break was caused by the blank being constricted from changing shape when bent. (as stated above)