NEW DESIGN For Anti-Backlash Acme Nuts!

[widgitmaster]

I think I have finally got it!
It took a little work, but this nut will eliminate all Backlash from a Rolled Acme 1/2-10 threaded rod!

This is my first attempt, its big and bulky, and weighs over a pound!
I made is out of solid bearing bronze! In the future I plan on streamlining it to reduce the weight, and the diameter of the flange!

Has 4x 1/4" Dia. Holes on 1.875 Dia. Bolt Circle
OD=2.375" (Reduced to 1.375" Diameter)
Flange Thickness= 3/8"
Length= 1.875"
Weight=1lb 7oz

By turning the two #10-32 SHCS, this nut can be manually adjusted to remove backlash as the nut & screw wear from daily use!

Not sure if a grease nipple is necessary, but there is pleanty of room inside to hold a small quantity of grase!

I thought about using springs, but it didn't appear to need them!

Will make another nut with a 15/16-16 OD thread, like the ones on a Thompson ball nut, but not every DIY mechanic has a tap that size!

I have made a total of four nuts, using different materials such as: Delrin, Brass, Bronze, and Cast Iron. All are identical in size, but have different strengths and weights!

Here is the eBay listing!
Eric

[fkaCarel]

I miss the tightening after adjusting. The parts are now sort of floating, so the adjusting nut can (and will) rotate a little, and due to the looseness it is able to unadjust itself. Murphy is always looking over your shoulder

Carel

[sdantonio]

Wow, beautiful work. When mine wear out I just may order a set (that is if your thread can be taken as an offer to sell a few, or is it just informatiive).

Steven

[CrazyRonny]

Originally Posted by fkaCarel I miss the tightening after adjusting. The parts are now sort of floating, so the adjusting nut can (and will) rotate a little, and due to the looseness it is able to unadjust itself. Murphy is always looking over your shoulder Carel

If the conterbore of the two part are the same diameter of the socket head cap screw, the screw will act as a keyway and it will prevent any possible small rotation.

Great job widgitmaster!

CrazyRonny

[standles]

How much and in what sizes???

Steven

[Geof]

With this design when the nut is being driven in one direction the force is acting directly through the body of the nut but in the opposite direction the force is being transmitted through the #10-32 SHCS. Only half of each screw head is in contact with the inner adjustable nut so there is only a very small area of contact. This is the location where deformation of the soft nut material will occur allowing the inner piece to move and introduce backlash. The deformation is almost certain to be accentuated with stepper drive because each step will produce a hammering effect on this small area.

[Climatepro]

Eric, very nice machining work!

Cheers from another Erik

[widgitmaster]

Originally Posted by Geof With this design when the nut is being driven in one direction the force is acting directly through the body of the nut but in the opposite direction the force is being transmitted through the #10-32 SHCS. Only half of each screw head is in contact with the inner adjustable nut so there is only a very small area of contact. This is the location where deformation of the soft nut material will occur allowing the inner piece to move and introduce backlash. The deformation is almost certain to be accentuated with stepper drive because each step will produce a hammering effect on this small area.

If I make the nut out of Titanium, and use Inconel screws, then you will be able to put the enormas force on the 1/2-10 Acme thread you are refferring to! But because this desaign is for the DIY home built router which according to my polls, is being used for light cuts in aluminum, plastics, foam, and wood, I do not think the bronze will wear as excessivily as you described!

Also, because 50% of the nut is solid, the most it could move is the total sum of the origonal backlash! Usually .003-.007" This entire problem could be resolved by including a threaded ring which would screw into the body of the nut, giving 360 deg. of contact, But I still do not see the necessity!

Eric

[Geof]

Originally Posted by widgitmaster If I make the nut out of Titanium, and use Inconel screws, then you will be able to put the enormas force on the 1/2-10 Acme thread you are refferring to! But because this desaign is for the DIY home built router which according to my polls, is being used for light cuts in aluminum, plastics, foam, and wood, I do not think the bronze will wear as excessivily as you described! Also, because 50% of the nut is solid, the most it could move is the total sum of the origonal backlash! Usually .003-.007" This entire problem could be resolved by including a threaded ring which would screw into the body of the nut, giving 360 deg. of contact, But I still do not see the necessity! Eric

You miss my point; it is not wear that I predict it is plastic deformation and it is not the thread that is going to deform it is the material directly under the head of the 10-32 SHCS. The area in contact under the head of this screw is a very tiny fraction of the area of contact in the acme screw. Also it is not the average cutting load that is important it is the maximum load that occurs when the stepper steps; this will be much higher than the average load.

You are quite correct that a threaded ring would solve the problem; actually it does not need to be a ring just thread the adjustable part of the acme nut into the body of the other part and have a locking screw.

[rhino]

i have made a anti backlash nut pretty similar to yours but mine uses a spring and a plate on the end of the bush, i have also added a couple of indicators when i should replace the bronze bush on the inside. will post a couple of pics when i get the digital camera thing working.

[joecnc2006]

Originally Posted by rhino i have made a anti backlash nut pretty similar to yours but mine uses a spring and a plate on the end of the bush, i have also added a couple of indicators when i should replace the bronze bush on the inside. will post a couple of pics when i get the digital camera thing working.

Any Pictures and picture of assembly?

[ironDigit]

what is it exactly that makes this design more efficient and in what ways would it do so in contrast to a double nut set-up with a spring in between??

just trying to collect some info on how to make an anti-backlash screw and what would be the diffrences in just buying an extra nut and a spring??

all this back-lash sometimes gives me headlash 4 real

thx for sharing looking very pro m8