Re: [CAD_CAM_EDM_DRO] Ball screws

on 2014-07-03 07:22:17 UTC

Ball screw is use because not back lash when adjusted corrected a regular screw or acme will always have back lash this is so the machine can go one way and then go n the opposite with out have to take up the back lash

On Sunday, June 1, 2014 1:21 AM, "'Andy Wander' ohawiseguyeh@... [CAD_CAM_EDM_DRO]" <CAD_CAM_EDM_DRO@yahoogroups.com> wrote:

"trapezoidal" threads? Do you mean Acme?

Andy Wander

From: CAD_CAM_EDM_DRO@yahoogroups.com [mailto:CAD_CAM_EDM_DRO@yahoogroups.com]
Sent: Saturday, May 31, 2014 4:10 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: RE: [CAD_CAM_EDM_DRO] Ball screws

I think that a trapezoidal thread form is being used in most “home brewed” CNC machines. A conventional 60 or 50 degree thread does not transfer enough torque to work. They also are not made accurately enough.

You can improve the fit and polish of a trapezoidal screw and nut. The thread form can be polished to a high luster finish, a plastic nut made, saw the nut in half and, after heating the screw, force the nut halfs into the the thread to reform the threads to a very well fitting nut. Two were used with a higher force spring between them to minimize the backlash. Someone published a ‘You Tube” video about this a while back.

Ball screws are best (generally) but trapezoidal screw are easier, cheaper and work well for a long time. Most Bridgeport mills have trapezoidal screws with bronze nuts for the table travels. Do they have backlash? Yes they do but a good bit of work gets accomplished on them.

R. Wink

From: CAD_CAM_EDM_DRO@yahoogroups.com [mailto:CAD_CAM_EDM_DRO@yahoogroups.com]
Sent: Sunday, May 18, 2014 11:04 AM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Ball screws

Hi,

I am a newbie to the world of CNCs so i apologise for any impertinent questions and mistakes.

I read online that a ball screw is a must if you want to build a CNC machine.The reasons being that the backlash or 'Play' that is always present in other screws is not tolerated.I also read that requirements are a little bit flexible for homemade CNC lathes.

My first question is,How are ball screws made?

I have not been able to to find much about their manufacturing process despite using a variety of methods.By profession I have a small workshop where I have a thread whirling attachment (Locally made,not sandvik) and can resonably grind a tool well enough to make threads of any profile.So please guide me about their making process

My second question is,Can I bypass ball screws and use simple lead screw and nuts to retrofit a steel turning lathe into CNC?

I am asking this question because i do not have the funds to make a small prototype CNC lathe and then implement to a larger lathe.And ball screws cost a bomb to acquire.So what are other options to having a ball screw for lathes.I am also assuming that funds are little bit tight always when you want to go on such projects.Please forgive me if I'm wrong.

All ideas are welcome and any help will be gratefully appreciated.

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