Anyone here try doing an electronic lead screw retrofit? How did it go?

greenbuggy · Apr 1, 2014

Wasn't sure if this should go in the CNC forum, since those guys have no need for an ELS, whereas some of us with old American iron would really like to cut metric threads and have some other features that were never offered or parts are unavailable to get. I'm curious if anyone here has done it and if so, how it went, would you do it again, how much (ultimately) did you spend in terms of time and dollars to complete the project?

I'd feel a lot more comfortable plunking down the money for one of their kits if their website had a page showing off some pics or videos of successful conversions!

Electronic Lead Screw Main Page for those curious.

TGTool · Apr 1, 2014

They've got a photo page. Dunno if you have to register to see it, but that shouldn't be any pain. The page of installations is at https://groups.yahoo.com/neo/groups/E-LeadScrew/photos/albums

Larry on Lake Superior · Apr 2, 2014

ELS-kits
Someone in the UK is marketing/bought the rights for the controller. Check out medw.co.uk. I'm thinking about buying one but it's far down the list.
Thanks,
Larry

JRIowa · Apr 2, 2014

If you want a CNC, buy a CNC. Conversions are just that.
JR

WILLEO6709 · Apr 2, 2014

most oem electric lead screws were not for threading. I have a monarch EE tracer lathe carcass that had an oem electric feed rod. No lead screw. I don't know how the HLV-H works, never ran one but I believe they had an electric feed rod with a some other mechanism for accurate threading...

It would seem there would have to be some tie in between the actual spindle rpm, the qc gearbox setting, and cairrage movement. Sounds like an easy thing to screw up to me.

matt_isserstedt · Apr 2, 2014

I don't know how it works but theoretically you'd want spindle encoder, leadscrew detached from the thread gearbox and end gearing, and a servo motor on the leadscrew.

Controller sets servo position to "cog" or time with the spindle for any gear ratio you can think of, ideally you'd input TPI or mm pitch or whatever, and then goto town.

dazz · Apr 3, 2014

Hi
When I last looked at ELS, it used one pulse per spindle revolution. This isn't enough to maintain proper control, specifically at the start of a cut where the load (and motor speed) change. The expected result is thread pitch variation for the first few threads.

Ideally you want a spindle encoder and a DRO connected to a control system like LinuxCNC.
Such a system would allow the half nuts to be disengaged and still be able to pick up the workpiece thread for cutting either metric or imperial.

Fulmen · Apr 3, 2014

With the proper software you won't need to disengage the half nuts, you just stop the feed and reverse with the ELS, it would keep track of everything. Next cut would be another push of a button.

Miguels244 · Apr 3, 2014

Look into MachMotion.
CNC Controls & CNC Kits - MachMotion.com Home

dazz · Apr 3, 2014

Fulmen said:
With the proper software you won't need to disengage the half nuts, you just stop the feed and reverse with the ELS, it would keep track of everything. Next cut would be another push of a button.

You're right, but the point I was trying to make is that with a spindle encoder and DRO you have the option of disengaging the half nuts.

Fulmen · Apr 3, 2014

True. Anyhow I don't see how a single pulse per revolution would be accurate enough to maintain an accurate pitch. Should be good enough for turning, but for threading you'd need something more. Don't think you need any absolute references unless you'd want the option of disengaging the half nuts, but you'd definitely need more pulses per rev.

Doozer · Apr 3, 2014

I bought and used for a project, a servo motor and controller that
Automation Direct sells. It an take an encoder input. There is a
set up option screen to allow the input of a ratio between the encoder
and the servo motor. It is in the form of one number divided by another
number. This would work great for an ELS. Only issue is you needed
a laptop (or whatever) set up running their software to change the
ratio value. As to say a better stand alone front end interface would
be needed to make it less clunky. But I agree, having a single pulse
per rev input is hokey in my mind.

-Doozer

dazz · Apr 4, 2014

Fulmen said:
True. Anyhow I don't see how a single pulse per revolution would be accurate enough to maintain an accurate pitch. Should be good enough for turning, but for threading you'd need something more. Don't think you need any absolute references unless you'd want the option of disengaging the half nuts, but you'd definitely need more pulses per rev.

A ELS is a dead end road with no option to expand.

With a DRO, spindle encoder and servo driven lead screw, you get the option to go the next step and add a servo to the cross feed.

A standard DRO isn't smart enough but Newall make transducers that can be interfaced to a budget laptop/PC. The PC can run the free LinuxCNC controller software.

You would then have a reasonable CNC machine at a reasonable price.

matt_isserstedt · Apr 4, 2014

dazz said:
You would then have a reasonable CNC machine at a reasonable price.

I would disagree about the reasonable CNC machine unless you went thru the trouble to fit ballscrews or some other degree of backlash reduction.

TGTool · Apr 4, 2014

dazz said:
A ELS is a dead end road with no option to expand.

With a DRO, spindle encoder and servo driven lead screw, you get the option to go the next step and add a servo to the cross feed.

A standard DRO isn't smart enough but Newall make transducers that can be interfaced to a budget laptop/PC. The PC can run the free LinuxCNC controller software.

You would then have a reasonable CNC machine at a reasonable price.

I don't have an ELS but I've been following their discussion. With their current design it is possible to also power the crossfeed lead screw and cut tapers. I don't think they really compare it to a CNC, but it can be a solution in some instances for more threads than the lathe's native design or to do occasional tapers without a taper attachment. They're aware of the limitations, but there are actually some expansion options with newer crops of small single board computers like the Beagle Bone and others.

The single pulse per rev also limits some things that could be done, though it seems to work just well enough. Newer chips with faster processing might resolve this limitation too. It's a niche market but it works there.

Fulmen · Apr 4, 2014

dazz said:
A ELS is a dead end road with no option to expand

Don't confuse concept with execution. The concept of an electronic lead screw is sound even if the current or most common approach isn't perfect. Steppers will get the job done if you don't push them too far, and there are other solutions than single pulse per rev or a full encoder. Simply increasing the number of pulses would go a long way, a 4" disc should easily provide 100 ppr.

David Utidjian · Apr 4, 2014

There is at least one commercial maker of ELS systems for lathes. I have seen their product demonstrated at EASTEC a couple of years ago. Babin Machine Tool (They call it Servo Electronic Digital Threading) which is a pretty slick system. Probably ideal for a prototype shop that needs the capability and a LOT cheaper than buying and tooling up a new machine. For the home/hobby shop the open source system linked to above seems like it would be an easy and inexpensive way to add metric threading and precision tapering to a manual lathe. It is NOT pretending to be CNC or a CNC substitute.

As far as I can tell from reading the literature of the ELS project they use a single "notch" on the spindle for "indexing" and multiple "notches" for speed encoding. I think they provide for up to three separate spindle sensors.

I have never used it and I don't know anyone who has. They do have an active user group so it is not "dead." If anyone thinks it is a CNC retrofit or a CNC substitute then yes, it is not only a "dead end road" but also not even foot path.

-DU-

Fulmen · Apr 4, 2014

David Utidjian said:
they use a single "notch" on the spindle for "indexing" and multiple "notches" for speed encoding.

This seems like a sensible approach. If properly executed I have no doubt you could get a fairly decent result without any costly servos or encoders. But CNC it's not, and shouldn't be judged as that. It's simply what the name implies, an electronically controlled lead screw for a precise, yet infinitely adjustable feeds.

David Utidjian · Apr 4, 2014

I should add that, unlike the commercial version, the 'hobby' ELS system will also do tapers because it can control two leadscrews at once (Z and X.) With the crossfeed leadscrew set up it can also do variable rate feed for facing and parting off. I don't know if it can also vary the spindle speed.

Similarly there is also the DivisionMaster rotary table controller DivisionMaster - Model Engineers Digital Workshop though it was designed for the hobby market I have heard it was very useful in professional shops also.

-DU-

CalG · Apr 4, 2014

I've given the idea some thought. And see an ELS similar to a Hardinge TFB. Good for a very large assortment of typical turning applications, but may or may not include thread cutting.

Having used the Parker stepper drives for other automation, I have been pulled toward the use of the SX -6 or SX-8 series programmable drives (Or some contemporary equal.)

These drives have built in axis tracking that accepts external pulses. I put up a chopper disc with a Si photo detector, and the drive did all it was asked.

A simple Dos/Windoze program instructs the drive that is loaded via any terminal application. The Parker program edit software even has a terminal function that works fine. Connection is via rs232 serial.

One could easily generate a table of ratios to match any mechanical gearing associated with any lathe.

The drives have all the usual features such as hard and soft limits, velocity profiles etc etc.

Simple old hardware technology with the PC part only to modify and load a program.

It would be my path if I crashed the gear box on one of the screw cutting lathes in the shop.

' Just throwing out fodder for the canons

Cheers

PS Parker offers an interface in the RP240 that would allow modification of the ELS parameters without PC connection.
Emerson does as well for their FX servo drives. I have both. Having both get's confusing at times, as there is syntax and "jargon" associated with each.

Anyone here try doing an electronic lead screw retrofit? How did it go?

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