Loading Antibacklash Nuts

[sdantonio]

There appears to be two popular ways to make antibacklash nuts and I want to get your opinions on both:

(a) Two opposing threaded pieces are snugged together against the thread of the leadscrew threads using set screws.
(b) Two opposing threaded pieces are held apart against the leadscrew threads with a compression spring.

Which of the two methods do you use? Which is best in your opinion and why is it best? If you use the compression spring method, what is the approximate spring constant you have on your system.

[7ofclubs]

Hi SD,

I am by no means an expert and I am just starting out but I can tell you why and how I created my anti-backlash nut.

I chose the compression spring method because it seemed fairly easy and cheap to setup. And it is cheap too. The parts are readily available. The only drawback to using the compression method is that the nuts and lead screw need to be replaced on a regular basis because the compression causes the nuts and lead screw to wear faster. No problem because the system is cheap and easy to replace.

I use 1/4-20 threaded rods for my lead screw. Lowes has inch long 1/4-20 nuts that are 3/8". A 3/8" socket fits them perfectly. I attach two wooden blocks about 2" a part on the bottom of the table. Mounted into each wooden block are the two 3/8" sockets. Both of the sockets are glued into the wooden blocks. One one of the nuts I place tape around it and press it into the socket to eliminate play, the other nut is left to free in the socket. I then thread the lead screw on with a spring between the two nuts.

As for how much compression I use? I figured that there is a relationship between nut/lead screw wear and spring compression: the higher the compression the greater the wear. I use justed enough compression to eliminate backlash.

Hope this helps but like I said, I'm not an expert and a nube.

7ofclubs

[chich2]

I use a method not mentioned in the poll. On my X axis I have a second nut that is bolted to a flat plate. The bolt holes in the plate are slotted around the axis of the lead screw. By loosening the bolts and turning the nut and re-tightening the bolts the back lash is eliminated from the nuts.
Hafco Metal Master HM-52 CNC Conversion

Chich

[Willbird]

I had figuired on putting a .100" thick plate between the two mounting flabges for the ball nuts, and grinding the .100 plate to remove backlash. The knee of my knee mill is too heavy to rely on springs I figuired.

Bill

[hondahak]

make a .75 thick nut, slit down the center length wise about 75% thru, instal nut on screw, take screw driver , insert in slit and spread the "nut', been doing this for years.
hondahak

[Willbird]

Honda ?? this works on ballscrews ???



Bill

[hondahak]

no, home made screws