thoughts on rotating nut design (acme)

[johngalt47]

here is a conceptual drawing for a rotating nut design that can easily add to a 8020 build. I hope to get some input to improve this design and come up with a useable design that is not too expensive to implement

[lgalla]

Good idea.good luck

[prcdslnc13]

I was looking at a similar design, Id love to see how yours turns out!

[Pplug]

If you are going to spend this type of money and resources on a leadscrew, why not go a step up and get a ballscrew? they are more efficient and will probably last longer.

[jsheerin]

I'd suggest putting a feature in to radially locate the washer for the thrust bearing. I'd also suggest making the mounting plate thicker (or allowing room for it to be thicker).

If you're just looking for something for yourself, I'd buy a rotating nut ball screw on ebay for $200 (~8' long). I understand if you're trying to design something everyone can use though. I designed one a few years ago and it was really cool (similar to yours), but I decided it wasn't worth building it. I'd personally go with rack and pinion instead. I think acme screws with plastic nuts hit a good price point / simplicity level for 4' and under machines that don't go super fast but are fast enough to do some good work with (I have one). If you want faster and longer axes for maybe slightly more money, go rack and pinion. It can go way faster than the plastic nut will be able to before it starts to have problems with surface velocity between the screw and nut.

[Phife]

Originally Posted by jsheerin If you're just looking for something for yourself, I'd buy a rotating nut ball screw on ebay for $200 (~8' long).

where are you finding rotating nut ball screws on ebay? i havent seen a single one.

Care to share a link?

[lgalla]

Listing ended and the guy is not relisting.They were brutes,32mm dia 32 lead,100" long.
The crate was 120"long,100lbs.Shipping is so high they were not worth selling.
Larry

[jsheerin]

Somebody needs to find out where he is and go pick some up. They were nice - Hiwin. The ad said he had 40 of them.

[JohnZ]

Originally Posted by jsheerin Somebody needs to find out where he is and go pick some up. They were nice - Hiwin. The ad said he had 40 of them.

Using the completed listing option, I found that ad at ...

Hiwin Rotating Nut w/ Ball Screw - eBay (item 190515560758 end time Mar-26-11 05:40:05 PDT)

It says that the seller is in Guernee IL. That is a sweet deal if you need a ball screw longer than 8' long. - John Z

[johngalt47]

I have a cnc plasma cutter to cut out parts so it is easy for me to design the plate out of 10 guage steel the thickness should be fine as it is as stiff as 1/4" aluminum. I am working on redesigning to make reduce the amount of machining. rack and pinion is a great option.

[johngalt47]

I have been reading about ball screws and rotating nuts. the issue is the centrifical force on the circulating balls will cause them not to circulate as designed. they are speed critical to prevent this from happening.

[mactec54]

johngalt47

Your design looks good, the mounting plate wants to be at least .500 thick & you can use Aluminum timing pulleys