Single vs double beam couplings

[hobgobbln]

I need to replace the motor couplings on my benchtop mill. The existing ones are the 3 piece spider type Lovejoys. The ones that have a hard neoprene/urethane type center section.

I was never very happy with them but they worked well enough for what I was doing at the time. Since they are shot and I need to replace them anyway, I was planning to change them over to helical beam couplers. My other smaller mill has the helical ones and they have been great.

Before I order them I was wondering what the difference between the single and dual beam helical couplers are and why to pick one over the other.

Thanks,
Griz

[warmstrong1955]

Double beam will handle a higher degree of misalignment than the singles. They are generally longer, and handle less torque, although that's not always the case. Varies by design style & manufacturer.
There are also multi beam or multi start helical couplings. Even better at handling misalignment, but again, more starts, generally means less torque capability.
Some of the multi start couplings can handle 5 degrees mis alignment, which is a lot.

As far as jaw couplings, the regular old straight jaw Lovejoys are cheap, easy to get, and work OK, but not the best in my experience. I have replaced many with curved jaw style which is far superior life wise and torque wise. Urethane is far better choice for a spider too. I think the standard Lovejoy straight jaw uses a nitrile spider.

Bill

[hobgobbln]

That's kind of what I figured but I wanted to make sure before I threw more money at the machine.

Thanks Bill,
Griz