magnesium vs. aluminum risers
09-19-2005, 03:14 PM
#2
Giant Nontypical
Join Date: Feb 2003
Posts: 9,175
RE: magnesium vs. aluminum risers
The good thing about magnesium risers - forged magnesium, like your MagnaTec - is the riser is heavier and stronger. Good mass weight for stability. Excellent strength to avoid flex and bending, also creating additional stability. It will withstand pressures that would bend a more expensive riser machined out of aluminum billet.
The structure of the forged metal itself has a vibration damping quality, unlike machined billet risers. Take a bare riser of each type and drop them on a concrete floor. Machined aluminum risers vibrate and ring like a bell without external damping doodads. They go CLANG-G-G-ng-g... where a forged riser just goes Clank. So, the forged riser makes for a quieter bow with less shock and vibration. Start out with a quieter riser with less vibration and then add the extra damping doodads, and what do you have....
That bit about strength most definitely DOES NOT apply to straight cast risers though. the riser has to be forged to get that benefit.
The bad thing about the magnesium risers is, they are heavier. After a long day, you feel like you're toting a chunk of lead.
Overall, I strongly prefer a forged magnesium riser over the machined aluminum. But they've done a whale of a job at marketing the machined riser, and it's hard to find anything but machined any more.
The structure of the forged metal itself has a vibration damping quality, unlike machined billet risers. Take a bare riser of each type and drop them on a concrete floor. Machined aluminum risers vibrate and ring like a bell without external damping doodads. They go CLANG-G-G-ng-g... where a forged riser just goes Clank. So, the forged riser makes for a quieter bow with less shock and vibration. Start out with a quieter riser with less vibration and then add the extra damping doodads, and what do you have....
That bit about strength most definitely DOES NOT apply to straight cast risers though. the riser has to be forged to get that benefit.
The bad thing about the magnesium risers is, they are heavier. After a long day, you feel like you're toting a chunk of lead.
Overall, I strongly prefer a forged magnesium riser over the machined aluminum. But they've done a whale of a job at marketing the machined riser, and it's hard to find anything but machined any more.
09-20-2005, 05:19 PM
#4
Join Date: Feb 2005
Location: MN
Posts: 28
RE: magnesium vs. aluminum risers
Comparing just the materials, magnesium and aluminum alloys, magnesium is not as stiff as aluminum and it is also softer (because of this, the mag risers are often thicker).Magnesium is lighter than aluminum though. Aurthur Pis right on about the magnesium naturally dampening vibrations better.....aluminum really is about the worst material for deadening vibrations. The processing and fabrication of the risers bring with them a whole new set of considerations.
09-20-2005, 06:15 PM
#5
Giant Nontypical
Join Date: Feb 2003
Posts: 9,175
RE: magnesium vs. aluminum risers
The points you make about magnesium vs aluminum are correct, MDE86, but that is why I very carefully made the distinction between FORGED magnesium risers and plain cast magnesium risers.
The forging process is done under high pressure, which compresses more magnesium into the same volume. It also forces the grain structure of the magnesium to follow the contour of the riser throughout the whole part. It winds up being much stronger than the same design that is simply machined out of aluminum billet stock.
I spent 20 years working extensively with magnesium forgings as an aerospace machinist and learned a thing or three about the stuff.
The forging process is done under high pressure, which compresses more magnesium into the same volume. It also forces the grain structure of the magnesium to follow the contour of the riser throughout the whole part. It winds up being much stronger than the same design that is simply machined out of aluminum billet stock.
I spent 20 years working extensively with magnesium forgings as an aerospace machinist and learned a thing or three about the stuff.
