Re: Looking for Lead Screws
 

Attached is a picture of our calculations. We are trying to optimize the Rpm, as to not draw to much power and have a good mix of speeed and torque.

Re: Looking for Lead Screws
 

Igus(FIRST sponsor) has some.

http://www.igus.eu/wpck/2371/drylin_trapezgewindemutter

Re: Looking for Lead Screws
 

Do you guys have any recommendations for attaching a manipulator and slides to the lead screw from past experiences?

Re: Looking for Lead Screws
 

What kind mounting features are on the nut that you are using? Can you post a link or photo?

Re: Looking for Lead Screws
 

You are running the leadscrews far too fast. They literally cannot tolerate those kinds of rpms without failing.
There is another thread that I saw a few days ago that had a link to a chart of safe rpms for leacscrews.

Re: Looking for Lead Screws
 

Not sure if it was the same chart, but here is a chart with some guidance on ballscrew/leadscrew design.

http://www.thomsonbsa.com/pdf/bsa_en...og_section.pdf

Re: Looking for Lead Screws
 

That's the one. It does depend on what diameter leadscrew you use, but running so fast with a 3/4" will not work. You are exceeding the absolute maximum with a fixed-fixed configuration even at the maximum speed of 2000rpm.

Re: Looking for Lead Screws
 

This is the info from the other thread: http://www.chiefdelphi.com/forums/sh...69&postcount=7

Depending upon design, you might have to consider buckling issues too. The first pdf has a graph to help with that calculation.

Re: Looking for Lead Screws
 

We ordered yesterday from www.Roton.com We used them because I wanted to make sure all parts "mated" the first time rather than having to modify/send it back/wait for right part. We prototype d with smaller lead screws from Igus that we had hoarded from past years. We used Igus' sleeve nut and flange to test. It worked great! We're having a build off between a cable/Modulox modified transmission/CIM lift system and the screw next week. I'll post a video of the build off unless it really sucks badly for both.

Here's what we ordered:

59284 Acme Lead Screw, 1/2 - 10, RH, Steel

89403 Acme Sleeve Nut, 1/2 - 10, RH, Bronze

89838 Flange, Steel

19660 Acme Anti-Backlash Flange Nut, 1/2 - 10, RH, Plastic

Re: Looking for Lead Screws
 

I'll second what other people are saying, this is not going to yield good results. My team used a large lead screw attached directly to a CIM last year to lift our ball holder into the air, and it performed very poorly. If you absolutely have to do this I recommend using more motors geared down some, and making absolutely sure that you leadscrew is fully supported on either end. There is limit for the length of unsupported rod you can have in a system that is based on the size of the rod itself.

I don't think that a leadscrew powered elevator (or whatever you are planning) is a bad idea, just that there are a lot of concerns when using leadscrews that are easy to overlook.

Re: Looking for Lead Screws
 

I second Roton.com as a lead screw source. I've used them for years and had good results. We're using the 3/8" x 1.000 torquesplines this year.

Re: Looking for Lead Screws
 

Whew...I feel better now. I pretty much just fished for the screw system that we needed. It truly stinks that I'm just a teacher and not a seasoned mechanical engineer. We're a bit short on mechanical engineer mentors this season. That forces me to expand my scope...well as much as I can...LOL

Re: Looking for Lead Screws
 

Hello,

I too looked at lead screws for 70", but the critical speed for a long unsupported shaft I calculated to be under 400 RPM which with 1/2" lead which makes it under 3ips. We felt it was not fast enough. Lots for force, but not enough speed.

This is a good reference for calculating force, and critical speed
http://pic-designcatalog.com/images/.../section_3.pdf