Why don’t pullers use acme thread screws?

[Hakeem]

Acme threads are stronger and tolerate debris better than V-threads. They’re used in vises, clamps, and jacks to great effect. Given the immense forces that a gear puller forcing screw sees, it seems like an acme thread would be ideal. And yet, all the ball joint presses and pullers I’ve seen use a standard 60deg V thread.

Is there a reason why these tools don’t use an acme thread?

 

[larry_g]

Cost.

lg
no neat sig line

 

[LopezBart]

Likely because ACME threads are too coarse. Most pullers use fine threads, providing far more force.

 

[whateg01]

Acme threads are stronger and tolerate debris better than V-threads. They’re used in vises, clamps, and jacks to great effect. Given the immense forces that a gear puller forcing screw sees, it seems like an acme thread would be ideal. And yet, all the ball joint presses and pullers I’ve seen use a standard 60deg V thread.

Is there a reason why these tools don’t use an acme thread?

I've wondered that in the past too. I could see cost being a factor in low cost models.

Likely because ACME threads are too coarse. Most pullers use fine threads, providing far more force.

There are some pretty fine pitch acme threads and iirc, the efficiency of the thread is much higher.

 

[RTM]

Ability to walk into your local hardware store and get a replacement almost immediately, depending on how small town your hardware store is?

 

[Debcrow]

Perhaps you can contact Wile E. Coyote and see if the Pullers in his catalog have ACME threads.

 

[whateg01]

Ability to walk into your local hardware store and get a replacement almost immediately, depending on how small town your hardware store is?

Maybe sometimes. My balancer puller has a 7/8"-20 screw.

 

[The Cobbler]

acme is probably too course and they also have a lower mechanical advantage than standard threads , 2 reasons why they're not suited

 

[u3b3rg33k]

my fancy puller doesn't seem to have acme threads:

 

[whateg01]

my fancy puller doesn't seem to have acme threads:

That's kinda the point of OP

 

[Hakeem]

acme is probably too course and they also have a lower mechanical advantage than standard threads , 2 reasons why they're not suited

Can you tell me more about the lower mechanical advantage? Does this mean that an acme forcing screw subjected to 100ftlbs of torque applies a lower amount of linear force than a V-thread screw torqued to the same value?

 

[The Cobbler]

Acme threads deliver lower mechanical efficiency than standard V-threads due to higher friction from their trapezoidal geometry, but they excel at handling heavy axial loads and power transmission. [1, 2, 3]

Mechanical Advantage and Efficiency

• • Standard V-threads (60-degree angle): Provide higher linear force per unit of torque and better mechanical efficiency in standard fasteners because of a steeper helix angle and tighter fit. However, they are prone to stripping under heavy dynamic loads. [1, 2]
  • Acme threads (29-degree trapezoidal angle): Feature increased friction caused by the wedging action of their sloped flank sides. This reduces their mechanical efficiency (typically around 40–50% even when lubricated) compared to ideal square or standard tightening threads

 

[amgent57]

The clowns/butchers who use impact wrenches on them wouldn't know the difference...

 

[whateg01]

Acme threads deliver lower mechanical efficiency than standard V-threads due to higher friction from their trapezoidal geometry, but they excel at handling heavy axial loads and power transmission. [1, 2, 3]

Mechanical Advantage and Efficiency

• • Standard V-threads (60-degree angle): Provide higher linear force per unit of torque and better mechanical efficiency in standard fasteners because of a steeper helix angle and tighter fit. However, they are prone to stripping under heavy dynamic loads. [1, 2]
  • Acme threads (29-degree trapezoidal angle): Feature increased friction caused by the wedging action of their sloped flank sides. This reduces their mechanical efficiency (typically around 40–50% even when lubricated) compared to ideal square or standard tightening threads

I'm pretty sure that's wrong.

 

[The Cobbler]

I'm pretty sure that's wrong.

well I searched what has easier torque, and got this
Standard V-threads are easier to turn and require less torque than Acme threads under the same load because they have less sliding friction

 

[whateg01]

 

[amgent57]

A copy and paste post.

yawn...

 

[whateg01]

well I searched what has easier torque, and got this
Standard V-threads are easier to turn and require less torque than Acme threads under the same load because they have less sliding friction

60 degree threads form a bit of a wedge. This is what centers a bolt in a nut radially. That force inward or outward, depending on which perspective, is wasted as friction as it pertains to motion.

 

[Rusted Nut]

ACME threads don’t come in UNF (fine) thread, which are stronger than course thread and give better leverage.

 

[gimpyrobb]

It was explained to me with an axle analogy. The finer the splines(thread) the stronger the axle. like a 35 spline vs 8 spline.

 

[u3b3rg33k]

The clowns/butchers who use impact wrenches on them wouldn't know the difference...

if the chrome ain't chippin', you ain't hittin'

 

[MacMcMacmac]

Fun Fact:

Toothpaste tubes use a buttress thread for the cap.

Why that is, I have no clue.

 

[finn]

acme is probably too course and they also have a lower mechanical advantage than standard threads , 2 reasons why they're not suited

This. The coarser the pitch, the more torque that has to be applied to twist the shaft to move a given load

 

[David99]

Perhaps you can contact Wile E. Coyote and see if the Pullers in his catalog has ACME threads.

All ACME products have Acme threads.

 

[u3b3rg33k]

All ACME products have Acme threads.

 

[whateg01]

All ACME products have Acme threads.

That reminds me... The movie comes out tomorrow, right?

 

[dynode]

My proto puller has acme threads, from my notes

• Proto 5/8”-12 Acme thread
• OTC Is all 5/8-18
• Snap-On is 5/8-18

I kind of wish I was in the 5/8-18 system so I could use snap on accessories. I've been scheming to make an adapter for a while now.

 

[KnurledNut]

Acme threads are stronger and tolerate debris better than V-threads. They’re used in vises, clamps, and jacks to great effect. Given the immense forces that a gear puller forcing screw sees, it seems like an acme thread would be ideal. And yet, all the ball joint presses and pullers I’ve seen use a standard 60deg V thread.

Is there a reason why these tools don’t use an acme thread?

Some of my newest pullers have acme threads and they have worked well.

 

[NHtoolguy]

I have some Taiwan-made three jaw pullers that use acme threads. Most of mine, however, use standard 60 degree vee threads.

 

[Steve_P]

Because of the thread geometry they require very coarse pitches which take more torque for given axial force. They also have significantly smaller minor diameters vs UNF which makes buckling under compressive forces a major issue. The coarse thread pitches also make them want to backdrive, especially when lubricated, (which is what you want for long life) tighten up, remove wrench and it self loosens.