Reply with QuoteHow are you going to accurately attach the nut to the pulley?Originally Posted by homer93
rotating lead nut design
right im designing a machine out of MDF.
instead of having a rotating lead screw, im wanting to have a rotating lead nut
ive made a design, but im not sure if it will work. or if its too much.
any ideas on what to improve my design?
would it be better to have the bearing in one piece of mdf? so just one nut as well.
ive also missed a collar off, which mounts to the nut, so the thrust bearing is in between the collar and the MDF.
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How are you going to accurately attach the nut to the pulley?
i started to think of that just before. tbh i dont really know.
another design i had was a round nut and a pully fit over it, with a cap head or grub screw to tighten it onto the screw. with thrust beariings between the nut and MDF.
You could get one of these timing gears: and set screw it to the nut (if the hole was big enough for the nut to fit in). I've seen bigger pulleys on this site, just needed to find a similar one for picture.
A machine is only as accurate as the tools used to build it. "CNC = Computer Numeric Control - or on some days - CNC = Can Not Control" Imagineering
yeh that was my other design. i can get a pulley and machine the diameter bigger.
but with the size of nut i have found i cant get a bearing onto the nut and be in the MDF.
is it possible to get a really long nut?
Maybe something like this?
"http://www.amazon.com/SteelWorks-Corporation-11846-Threaded-Coupler/dp/B000H5WZB0/ref=sr_1_5?s=industrial&ie=UTF8&qid=1304035341&sr=1-5"]Amazon.com: SteelWorks Corporation 11846/70106 Threaded Rod Coupler Nuts NC: Home Improvement
A machine is only as accurate as the tools used to build it. "CNC = Computer Numeric Control - or on some days - CNC = Can Not Control" Imagineering
I am currently working on a rotating lead nut design. The design has been tested successfully and I am currently working on the patent. Except for one custom milled part, everything else can be user built. Extremely simple. I am looking for a machinist able to work in aluminum or steel. I'm just currently out of money and time to pursue this project on my own. There are a lot of people looking for a product like this, but without help it will be a long time before I can make this available. You will need to sign a non-disclosure agreement. Anyone interested?
You will need AXIAL bearings for that, and you can find cheap ones used in car front wheels, although i wound not suggest using that method since it is quite complicated to make it work with no backlash and no play and for that you would need some type of adjustment to have some preload on the bearings. To date i have seen only one industrial machine use that type of movement and it was on a GEISS 5 axis 2.5x2x1.5 meter work envelope ( to bad the owner doesn't want to sell it since it is rusting outside and it is missing the control board and the spindle, i offered 1500 euros for it but no go).
Also i have seen one DIY here on the forum that uses that but it doesn't mention anything about how he went about building it.
Regards,
Tom
http://www.hossmachine.info/images/z...%20%282%29.jpg
http://www.hossmachine.info/images/c...ed_800x461.jpg
Hoss uses this design for the z axis of his machine. It's pretty simple.
i decided not to bother with my first idea.
used the other easier idea.
i made a 3D model of it. but in still having problems finding a long lead nut.
with what the parts ive been able to find i can buy there is like 1 or 2 mm being held by the bearing in the MDF.
if i could find a pulley that i could screw onto nut which had a flange it would be easier. i would have more area for the bearing to dit on then.
there is two thrust bearings in the design. one uses some washers, which is the smaller one. the other one is just between the pulley and a metal plate. do i need the washers here or not?
thanks
You realize that my 1970's Bridgeport boss uses this design. Good luck with that patent...
does that include the one i just did?
Before you go and patent yoru idea, there are TWO THK 20-04 rotating nuts on eBay now... I believe they use an ISO bolt pattern for the pulley.
It's really not a complicated thing to make, just complicated to make WELL with DIY tools (unless you have a mill or lathe or both.) You would just take a piece of bar stock, turn the ID to fit the leadnut (or ballnut), then turn the OD for a flange and two AC bearings; then thread the end for a locknut. The flange would be drilled and tapped to accept a pulley. The bearings would be mounted to a plate, like a fixed end bearing, and the motor as well, with a pulley to turn the nut. Adding too many parts means more potential areas of backlash.
Very well explained, thank you very much.
B.Th.W. i missed the part about patenting it, and i can chime in, good luck with that since there are so many similar designs already patented and in use. I mentioned somewhere I, again 'I' have seen only one LIVE that i could touch and play with ( also walk on the table since it is over 3.5 meters tall), but i have seen many on the net that use that same principle.
It was one the first ideas that came to mind when i started a bigger cnc a year ago, but i found out that having 40mm lead screws has a nice side effect: you can use two bearings on one side and leave the other end free. To explain it easier here are some pics of what i made using all thread and some NSK industrial assemblies i found at a junk yard.
On the first pic you can see a piece of wood that has chamfered places for bearings on both sides so there are two bearings one on each side folowed by two nuts on each side so i can preload the bearings and fix them in place, but you can not see the other side on the second picture. The third pic shows what is normally a ball nut ( in my case two more nuts adjusted for minimum backlash and the forth pic shows the other end of the all thread. I have this setup working for nearly a year and i have it tuned to about 0.02mm backlash. Luckily i use it rarely and i am aware that is not an 'be all end all' solution but it will take me about 20 minutes to change everything when the backlash goes bigger since inevitably it will when using all thread.
The last picture shows the 40mm NSK ( yes 1.5" ) ball screw and nut as they were fitted on a huge mill ( the X table weighted over a ton ) and i can do 250 rpm with no whip, i did not try anything faster since i don't need it.
Regards,
Tom.
If I saw 1-1/2" leadscrew whipping, I'd probably run!Very well explained, thank you very much.
B.Th.W. i missed the part about patenting it, and i can chime in, good luck with that since there are so many similar designs already patented and in use. I mentioned somewhere I, again 'I' have seen only one LIVE that i could touch and play with ( also walk on the table since it is over 3.5 meters tall
It was one the first ideas that came to mind when i started a bigger cnc a year ago, but i found out that having 40mm lead screws has a nice side effect: you can use two bearings on one side and leave the other end free. To explain it easier here are some pics of what i made using all thread and some NSK industrial assemblies i found at a junk yard.
On the first pic you can see a piece of wood that has chamfered places for bearings on both sides so there are two bearings one on each side folowed by two nuts on each side so i can preload the bearings and fix them in place, but you can not see the other side on the second picture. The third pic shows what is normally a ball nut ( in my case two more nuts adjusted for minimum backlash and the forth pic shows the other end of the all thread. I have this setup working for nearly a year and i have it tuned to about 0.02mm backlash. Luckily i use it rarely and i am aware that is not an 'be all end all' solution but it will take me about 20 minutes to change everything when the backlash goes bigger since inevitably it will when using all thread.
The last picture shows the 40mm NSK ( yes 1.5" ) ball screw and nut as they were fitted on a huge mill ( the X table weighted over a ton ) and i can do 250 rpm with no whip, i did not try anything faster since i don't need it.
Regards,
Tom.
Check out blurrycustoms, their tables feature hollow-shaft servo motors, pretty cool (and probably expensive) design... and I believe they can be ordered as well...
Going from their G540 Ironman router to the hollow shaft servo setup looks to be about a $20,000 upgrade. It's not really the same machine, though, as the PCX version is made of a composite stone material, and looks to have a 3HP spindle as standard equipment. But $26,000 for a 20"x30" machine?
I've never seen anyone with one of their $5000 machines. I doubt I'll ever see the $26,000 one.
Gerry
UCCNC 2017 Screenset
[URL]http://www.thecncwoodworker.com/2017.html[/URL]
Mach3 2010 Screenset
[URL]http://www.thecncwoodworker.com/2010.html[/URL]
JointCAM - CNC Dovetails & Box Joints
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(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
They have an ultraman on ebay now I believe, with a 5hp columbo spindle, for 33k... I think their bench mill is 26k! I could get a used Haas mini mill for that price...Going from their G540 Ironman router to the hollow shaft servo setup looks to be about a $20,000 upgrade. It's not really the same machine, though, as the PCX version is made of a composite stone material, and looks to have a 3HP spindle as standard equipment. But $26,000 for a 20"x30" machine?
I've never seen anyone with one of their $5000 machines. I doubt I'll ever see the $26,000 one.
8020 rotating lead nut
here is a rotating nut design that is easy to mount
Re: 8020 rotating lead nut
i cannot open your pdf file.
Re: rotating lead nut design
I have rotating nut on my designed and built CNC machine.
Here's the build thread: https://www.cnczone.com/forums/cnc-w...gineering.html
Since converting from R&P I'm really happy with the rotating nut setup. The main bits including the nut was purchased from Hiwin.
It works very well but is more expensive that other methods. Conversion on my machine was a $3k upgrade over R&P costs for 2 8 foot screws and 1 3 foot screw with nuts. Nuts were much more expensive than the shafts due to their complexity. You also need to come up with pulleys and an attachment method for the nut and servo/stepper with timing belts. Mine runs on 1hp servos and I'm dual driving my gantry x-axis.
Also the motors are traveling on the gantry vs standard ball screw with rotating screw so you have more gantry mass to deal with. Not an issue I'm worried about with my design but some designs might suffer.
Difference is night an day in accuracy over R&P. I was getting best case +/-0.004" with R&P with lots of fiddling and compromised feed rates. With Rotating nut I'm getting typically +/-0.0005" when cutting harder materials like Corian, and aluminum plate with no fiddling needed.
Andrew
