ACME question

[aslatte2]

What is the difference between "ACME 1/2-10 2 start" and "ACME 1/2-5 1 start"?

They both have the same TPI.

Thanks,

Alex

[Jesse B]

The way I look at it is that with "1 Start", the thread starts once. On "2 Start", the thread starts twice. This means that you have two separate threads running around the lead screw. Higher start screws have higher lead than single start screws, and are generally preferable. Stepper motors lose torque and their speed increases, so lower RPM's are preferable.

[steve323]

Originally Posted by aslatte2 What is the difference between "ACME 1/2-10 2 start" and "ACME 1/2-5 1 start"? They both have the same TPI. Thanks, Alex

Both will move 0.2" per revolution, but one will have 5 coarse threads per inch and the other will have 10 fine threads per inch. The nuts will be completely different.

Steve

[CarveOne]

Here is an example of the end of a 5 start 1/2x10 ACME screw.

CarveOne

[Aryantes]

Someone will have to verify this but...

Aren't the threads not as deep on a multi start screw?

I think speedwise they are the same but...

I think multi start screws might still be more efficient / stable due to how they are cut and the root diameter of the screw.

I thought I read that somewhere, but I could be wrong.

[CarveOne]

The thread depth and width visually appear to be the same on my one start versus my five start lead screws. My caliper jaws are not narrow enough to fit into the threads and the twist wouldn't allow it to anyway. My depth gauge won't fit either. The five start threads are a little more rounded on the top of the threads than the one start, which is almost flat topped.

Below is a photo comparing 1/2-13 all-thread, 1/2-10 one start Acme, and two short pieces of 1/2-10 five start.


CarveOne

[Aryantes]

Ahh I found it.

http://www.nookindustries.com/Acme/A...ailability.cfm

1/2 - 10 TPI ( single start ) has a root diameter of 0.359"
1/2 - 2 TPI ( 5 start ) has a root diameter of 0.406"

Of course, this isn't comparing 2 TPI single start vs 2 TPI multi start. I can't find data for a 2 TPI single start screw.

Not sure if that is significant hehe.