Rotating lead nuts

[ice]

The first coming,i know little about cnc machine,I think the forum will be helpful to myself.I am very pleased to be here.^-^

[project5k]

well actually in that drawing, the bolts that go through the delrin nut also go through the pullie, and then are threaded into the aluminum that the bearings are on... so that would stop the wobblie pullie and keep if from freewheeling..... maby tonight i can redraw it with the bearings sepperated......

[Kipper]

Originally Posted by derekj308 Hi Guys Picture of concept rotating nut design as promised. The design is generic enough to be adaptable to whatever nut/screw combination you want. It is half finished but with a little imagination you can see what I am trying to achieve. The parts I haven't added yet are the two deep groove bearings at each end, the separation springs, the nyloc nuts and bolts to hold it all together and the drive nuts. The basic idea is the separation springs push the nuts against each extreme of the thread and the bolt and nyloc nuts allow you to tune that separation so that it just gives a teensie weensie bit of clearance which would be taken up by grease. I was planning to machine it from acetal and press fit brass nuts (probably trapezoidal thread) into the nut housings which are also the pulley halves. The sleeves are to keep the two 'halves' aligned. Being machined from acetal would make the unit very light to rotate. The nut housing/pulley and the bearing adaptor is used twice in the assembly. There are 36 teeth on the pulley. Cheers

Now that looks like a solution for my "Z" axis! Thanks for posting the image

[handlewanker]

Hi Carel, we love the Dutch.Wouldn't dream of banning anybody. If you've got a point of view, let's hear it. An idea no matter how ridiculous may trigger off another idea and solve somone's problem, and we don't mind if you put a bit of Dutch magic in as we like a laugh too.
I reckon if everyone contributes their experiance and thoughts we'll all get along. Moral:- think twice cut once.
Common problem is how to make your nuts spin and not get backlash. If backlash can be compensated for to be almost neglible then we'd like to hear how it is catered for in the X Y profiling where the table is required to go back and forward, and not cause a problem. How much backlash are we experiancing?
I know that I get .5mm on my Bridgeport, but that is normal milling not CNC, and as there are compensating nuts on the X and Y axis leadscrews, then it's easy to adjust. My lathe is not so lucky, a 1/4 turn of the crossfeed screw is about normal (no compensating nut), and this is about .025". One day I'll make a new nut with a back up nut.
Ian.

[handlewanker]

Hi Project 5, re post #58, that goldwing must be worth a bob or two. I saw a whole lot of Bridgeports being auctioned on the USA Ebay site for around US$3k -US$4k. Have you tried any of these? Even if they're a "bit used" they're still good.
I bought my 'port from the firm I worked for when they downsized the toolroom in '97, and that was 20 years old then. After I bought it, all the guys in the toolroom said what a fool I was as they only got rid of the ones that were worn out.
Well I paid A$3K for it, and 4 weeks later when all the stuff was gone I started to get offers from the other guys, above the price I'd paid, for the "worn out" junk I'd bought. We were all into backyard sub-contract work, and I guess the others just missed the boat.
That was '97, and I still have the mill, and all it took was a clean up and adjustment of the gibs and nuts. At the time in our toolroom, if a mill didn't have a DRO or auto feed, then nobody used it.
Ian. (have mill use to travel.)

[fkaCarel]

Here you see my corcern on this forum, and probably the internet in general:
http://www.cnczone.com/forums/showth...t=24669&page=3
If I help with a maybe sound design, it will be burned down, just for the sake of burning down. No motivation, just SWAG in reverse.

My satisfaction was today's newspaper, mentioning the university of Amsterdam had let a cartoon drawn by one of our famous cartoonists. It was heavily protested by a Canadian guest teacher. She lost. Comment of the cartoonist agent: "Canadians don't have a sense of humor".

Nevertheless, I've had it.

[project5k]

um... ok you lost me dood, if you have a suggestion on how to make the rotating lead nuts work, then i'm interested in hearing it, and if it seems sound, and is within my abilities, i just might try it... but i have no idea what stalling in a toolpath and something about a cartoon had to do with anything....

[Pxsi]

Was I in an alternate universe for a second there?

I would like to see your new improved nut design. I would also like to hear how it goes when you get around to making it, I have an upcoming project that will most likely require a spinning nut. Any input of what does and doesn’t work in the real world could save me a lot of time.

Pxsi

[derekj308]

Hi Kipper

I hope you do build your Z-axis based on my design. I would love to see it in action. I'm too busy at work and too busy raising 3 monkeys and then combined with too lazy I'll probably never build it lol. I may even finish off the design and repost now that I know someone is interested.

Cheers and go the swannies!!! (its AFL grand final weekend here in Oz)

[project5k]

i will definately post my findings if and when i build a spinning nut system...