Warco Major mill drill convert to ball screw

[Derek cottissParticipant @derekcottiss41883]

Warco Major mill drill   convert to ball screw but stay as manual

is this possible and what are the plus and minus points

anyone done it

any advice given will be appreciated

[VicParticipant @vic]

Interesting question. Given that small CNC machines use them I’ve often wondered why they’re not used on manual machines? Here’s hoping you get some helpful answers.

Edit: Actually I think I saw an article or web page somewhere years ago about fitting ballscews to a VMC mill so it could be used for CNC work. Maybe do a Google on that one.

[Speedy Builder5Participant @speedybuilder5]

I looked at replacements for my Warco Economy – similar to the Major, but from what I could see was that the pitch of the ball screw is so coarse (compared with the original lead screw), that it would be difficult to move the table by 0.001″ accurately by hand.

You could move the table using electric pulses, controlled by software. I have done this with the original lead screw using Nema 23 stepper motor, and Arduinos, but suffer backlash problems.

Nice idea though.

Have you seen the article on Mycncuk.com

[Michael GilliganParticipant @michaelgilligan61133]

The typically coarse pitch of ball-screws also tends to make them NOT self-locking … and therefore there is a fairly high risk of table creep in a machining operation.

MichaelG.

[Michael Gilligan]

On Michael Gilligan Said:

… coarse pitch of ball-screws also tends to make them NOT self-locking …

Which is why they are pointless on manual machines.

Andrew

[JasonBModerator @jasonb]

Not knowing your setup but if the reason for changing is backlash you would do better spending the money on a half decent DRO than fitting ball screws.

You will also likely have to modify the machine in some way, do you have the equipment to do this while the mill is stripped down and out of action.

I’m not sure how the general advice to lock all the non moving axis when making a cut and the potential to creap go together but could see it happening if you did not lock every time after putting on a cut.

Y

[Alistair Robertson 1Participant @alistairrobertson1]

I would definitely advise against using a ball-screw on a manual machine.

A friend of mine decided that he would use a ball-screw from a redundant Bridgeport CNC in his manual machine. I cautioned him that there would be no resistance to unintended movement (no stiction? )

Well first job involved a 50mm dia. milling cutter to face a edge.  The cutter grabbed the job and pulled the table all the way along!  He thought he hadn’t held on to the handle tightly enough! and he tried again gripping harder! This time he broke a finger and a thumb!  End of experiment!!!

[SillyOldDufferModerator @sillyoldduffer]

Wot speedy. Alastair and Michael said.   Although a ball-screw can out-perform a lead-screw, they’re not a straight swap.   Getting the benefit out of a ball-screw also requires the machine to be upgraded with CNC style motors and drivers,  in which case one might as well go the whole hog and go CNC fully.    I for one don’t want that.

Ball-screws are an example of a technology that’s gone from incredibly expensive to dirt cheap over a few decades.  Used to be found only in the incredibly expensive early high-end CNC machines, if you have to ask the cost you can’t afford it!   But as is often the way with mechanical engineering, once someone has refined a production method and developed a machine to implement it, items like ball-screws can be churned out very cheaply.   Thus we find ball-screws in 3D-printers galore, and everyone can own one.   That I’ve not come up with an application yet could just be my lack of imagination!

Dave

 

[DC31kParticipant @dc31k]

There is information available if you search to tell you when a ball screw will back drive and when it will not (example: https://www.linearmotiontips.com/how-to-determine-if-a-screw-will-back-drive/).

You would need to find a candidate ballscrew that meets the non-backdrive requirement while also having other necessary characteristics, such as being small enough to fit in the space available.

One challenge is that a typical ball nut is larger than its Acme or trapezoidal equivalent cut into a piece of bronze. That can make fitting it into the space available a little difficult.

Hence, I would say do your research on the issue before deciding one way or the other.

[JasonB]

On JasonB Said:

 

You will also likely have to modify the machine in some way, do you have the equipment to do this while the mill is stripped down and out of action.

I looked at ball-screw conversion some years ago and this is a gotcha.

In addition, finding room to accommodate the ball-screw nut looked like being problematic. I didn’t proceed.

 

[Martin ConnellyParticipant @martinconnelly55370]

This a a similar (Rong Fu) mill with ball screws but CNC controlled.

https://youtube.com/watch?v=fQqP8HFljpk

You can fit ball screws if you don’t mind stripping and rebuilding a few times as you need to adapt parts or measure them to make new pieces. Only do it if you are planning to go CNC otherwise as has been said already fitting a DRO is the best option.

Martin C

[SillyOldDuffer]

On SillyOldDuffer Said:

…….  That I’ve not come up with an application yet could just be my lack of imagination!

Dave

 

Making use of the “back drive” characteristic, have a big weight on a ball nut on a vertical screw, driving a clock?  I think this was one of the options looked at for the “Clock of the Long Now“.

[NealebParticipant @nealeb]

 

Making use of the “back drive” characteristic, have a big weight on a ball nut on a vertical screw, driving a clock?  I think this was one of the options looked at for the “Clock of the Long Now“.

… leading to another fascinating thread on how to measure ball screw rotation in a jitter- free manner!-

But coming back to the original topic,  I have a Wabeco mill set up for CNC with both profile rails and ball screws.  It also has calibrated handwheels and a switch on the control panel for manual operation which disables the servos. However, it is virtually unusable for the reasons given – especially not having any lock for unused axes. Slides move too easily and calibrations are too coarse. I do “manual” milling by leaving it in CNC mode and typing in manual commands. You need to develop a feel for cutting speeds in mm/min rather than literal “feel” but it is a workable technique. But most machining is CNC anyway. Manual milling is so 20th century…

[DC31k]

On DC31k Said:

One challenge is that a typical ball nut is larger than its Acme or trapezoidal equivalent cut into a piece of bronze. That can make fitting it into the space available a little difficult.

 

This was an issue on the build log I saw online some years ago converting a VMC.

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