[widgitmaster]

I think I have finally got it! :cheers:
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]

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 :cheers:

[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]

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]

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]

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

[teebee]

Just another possible solution...
http://www.kerkmotion.com/learn/kerk...h-overview.asp

[sanjiv]

cant we make these slides in home work shop?
these manufacturers are all commercial
what about hobbists?

[lerman]

that they assume a constant pitch screw. A system with compliance (a spring) between the two nuts can automatically adjust for pitch variations. A system with a rigid connection between the two nuts must have enough play to permit the nut (pair) to fit at both the maximum and minimum pitches. This translates directly into backlash at the loosest points.

If we are using ground screws, this shouldn't be a problem. For cheap threaded rod this will be a problem.

A cheap, but laborious, approach might be to mechanically lap a length of threaded rod against a long nut using appropriate abrasive. This would cause the threaded rod to have a constant pitch that matched the pitch of the nut. Then the nut could be cut into two lengths and ridgidly connected with little clearance.

Ken

[gmc6711]

Moved

[ZipSnipe]

Hey Widgit, I was studying what you have made. On the third picture from the left, does the little circle piece have a threaded hole? It seems like it should. On the fourth picture it looks like its inserted into the bigger piece and its threaded but I can,t really tell by the pics you have posted. Anyway if it is threaded nice job! If its not threaded , please explain how that would work?

[widgitmaster]

Actually, this was an experiment that proved to be too costly, not very efficient, and I just lost interest in it!

The design was to have the 2nd nut slide in a bore, and have two 10-32 SHCS put tension on the pitch to remove the backlash on the thread!

This design does remove the backlash, and would probably work really good under normal conditions; however, as someone pointed out already, the pressure on the SHCS is to much. And yes, had I threaded the OD of the 2nd nut, and the ID of the main nut the concept would be flawless!

I just have too many projects going on, and need to make money to fund my very expensive new shop! You are welcome to use the concept and improve upon it!

Eric

[handlewanker]

Hi all, The method using a fixed back-up nut is too inflexible and will still have backlash, even if it's only a thou or two at first it will progressively get worse. I used the method as already stated with the spring between two nuts, in a housing. The housing is attached to the machine body with one nut captive. The other nut is pushed apart, by the spring, and prevented from rotating, just keeps it against the opposite flank. The spring must be strong enough to hold the drive force when reversing under load. It works beautifully on a centre lathe cross feed nut, no lost motion when single point screw-cutting and backing out. Also helps when parting off to prevent pull ins.
Ian.

[sanikaclinton]

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

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