Spindle Speed

[Henryrifle]

My lathe uses a 220v single phase motor. I've seen lathes with 2 phase motors and VFDs turn very slow. Now that I've been drilling and boring to direct read concentricity using a DTI, it would be awesome to turn the lathe under power super slowly--maybe around 5 RPM or possibly slower. Is there any way to do that?

Thank you,
Hank

 

[B Nettesheim]

Put a crank from a ford 9n tractor on the outboard spindle
All joking aside a vfd would help but im unsure how good they work on that small of a single phase motor

 

[LVLAaron]

VFD conversion isn't a small task. You need a 3 phase motor.

for dialing barrels... just put it in neutral and spin it by hand.

 

[SKWERLZ]

For a turndown ratio like that you’ll need a fairly specialized motor thermally capable of it and it probably will be three phase or DC

 

[V35]

Change some pulleys possibly?

 

[Road_Clam]

My lathe uses a 220v single phase motor. I've seen lathes with 2 phase motors and VFDs turn very slow. Now that I've been drilling and boring to direct read concentricity using a DTI, it would be awesome to turn the lathe under power super slowly--maybe around 5 RPM or possibly slower. Is there any way to do that?

Thank you,
Hank

So what size lathe do you have and what's the current motor rpm ? Any thoughts on a brushless VFD conversion ? I bought a "universal" 2hp 1500W kit for my Grizzly 11x29 and the total conversion was not difficult, just took a lot of time. Not sure what your lathe drive gear ratios are but you can run a minumum of 300 rpm's on these brushless motor kits. Check them out maybe you can make one kit work.

https://www.servomotorkit.com/

 

[BuffaloBill]

What hp motor is on your lathe currently?

 

[skeeljc]

I cannot imagine needing anything slower than 60 rpm.

 

[linebaugh]

A DC motor with a variable drive would do what you want. probably not practical due to cost, then again amazon and ebay have some deals.

 

[Road_Clam]

With my Grizz lathe set on the slowest belt / pulley configuration and the min 300 rpm's I have a spindle speed of 48 rpm's . Very threading "friendly" when you don't have a lot of runoff undercut , or up against a shoulder threading metric having to keep the half-nuts engaged. The biggest advantage of brushless is the substantially better low rpm torque vs a AC induction motor. My motor can also be programmed for varied stop braking behavior, ie a slower deceleration or an almost instant "stop" again REAL handy for threading metric. Here's a link to how I did the complete conversion :

G9972Z DRO and Brushless VFD mods

So been very busy the past 4 weeks with my 11x29 lathe. Lots of cool upgrades going on ! First is the Little Machine Shop magnetic DRO kit. After much research I opted to buy the LMS "universal" kit so I could custom configure the whole system. You get a 40" long scale and you cut it to...

www.hobby-machinist.com

 

[BuffaloBill]

I just checked out surplus center to see what they had for low cost 3P motors. The shaft looks non-typical on this one but the price is sure attractive:

WEG | Brands | www.surpluscenter.com

WEG,Brands, 3 HP SPL 3480 RPM 208/230 VAC COMPRESSOR DUTY MOTOR Brand new, WEG model# Z00336OS1C022416 capacitor-start, capacitor-run electric motor.

www.surpluscenter.com

I see some 1 HP VFDs out there for under $200, although it’s a brand I have not used. And I didn’t dig up a spec to see what HP rating it offers when powered from single phase 240v. Am guessing a 2HP VFD might be rated for 1HP powered by single phase, etc. The reason for this derating is the extra stress placed on the VFD’s aluminum electrolytic capacitor bank, from the larger ripple currents when powered from single phase.

I have a Hitachi VFD on my RML-1440 wired with a jog button. It will operate down to 0.5Hz in SLV mode (sensorless vector control), generating more than sufficient torque to position the chuck/cat head. A few Hz, depending on the spindle gear selected at the time, I find a handy speed to watch indicator needles like you mentioned.

Never once have I regretted equipping my lathe, mill, or drill press with a VFD (actually the drill press came with one, I didn’t install that one). The adjuastable acceleration/deceleration rate is very nice, makes a smooth operation. Nothing really needed. But a nice-to-have.

edit to correct sensorless vector acronym and add this note:
I checked the rating on this VFD and see it IS rated 1HP when powered by single phase:

1 HP TECO VFD Motor Controller 230 Volt AC 1Phase Input 3 Phase Output Variable Frequency Drive L510-201-H1-U | Variable Frequency Drives | AC 3 Phase Motors | Electric Motors | www.surpluscenter.com

1 HP TECO VFD Motor Controller 230 Volt AC 1Phase Input 3 Phase Output Variable Frequency Drive L510-201-H1-U, Variable Frequency Drives, 1PHTECO-Westinghouse,L510-201-H1-U ,

www.surpluscenter.com

 

[LVLAaron]

For those with the smaller lathes, check out Clough42 on youtube. He has a whole series on converting his grizzly 11" to a 3 phase with VFD. He's also created an electronic lead screw... which I wish I could fit to my lathe... it's REALLY cool.

 

[USMCDOC]

For those with the smaller lathes, check out Clough42 on youtube. He has a whole series on converting his grizzly 11" to a 3 phase with VFD. He's also created an electronic lead screw... which I wish I could fit to my lathe... it's REALLY cool.

ELS 4 Pro - Electronic lead screw control for lathes

Lead screw control and cycle control for lathes. Allows free feed selection, fully automatic thread turning, taper, radius and more.

www.rocketronics.de

 

[DRK]

A DC motor with a variable drive would do what you want. probably not practical due to cost, then again amazon and ebay have some deals.

A very wise man indeed.

OP, you should be able to set the Jog parameter of a VFD to do what you want. Call Precision Electric, they will point you in the right direction, good people.

Precision Electric, Inc. - Buy Drives, Motors, Phase Converters & More

Buy industrial AC/DC drives, electric motors, phase converters & more from Precision Electric. Trusted since 1983 for fast shipping, expert support, zero-downtime solutions.

www.precision-elec.com

 

[LVLAaron]

ELS 4 Pro - Electronic lead screw control for lathes

Lead screw control and cycle control for lathes. Allows free feed selection, fully automatic thread turning, taper, radius and more.

www.rocketronics.de

Metric only.

CLOUGH42 Electronic Leadscrew (ELS) Combo Interface and Control Panel Kit | eBay

For more information on this project, search "Clough42 Electronic Leadscrew" on YouTube, or "clough42/electronic-leadscrew" on GitHub. Clough42 v1.6 LED&Key display and button PC board. ELS Boost v2.1 PC board assembly.

www.ebay.com

 

[Road_Clam]

Metric only.

CLOUGH42 Electronic Leadscrew (ELS) Combo Interface and Control Panel Kit | eBay

For more information on this project, search "Clough42 Electronic Leadscrew" on YouTube, or "clough42/electronic-leadscrew" on GitHub. Clough42 v1.6 LED&Key display and button PC board. ELS Boost v2.1 PC board assembly.

www.ebay.com

CLOUGH42's lathe is basically the same lathe as mine that's some cool stuff with the digitally encoder driven lead screw. Absolutely agree, the change gear(s) swaps per TPI requirements is a royal PIA .

 

[USMCDOC]

Metric only.

CLOUGH42 Electronic Leadscrew (ELS) Combo Interface and Control Panel Kit | eBay

For more information on this project, search "Clough42 Electronic Leadscrew" on YouTube, or "clough42/electronic-leadscrew" on GitHub. Clough42 v1.6 LED&Key display and button PC board. ELS Boost v2.1 PC board assembly.

www.ebay.com

nothing that a calculator can't fix.. just sayin

 

[LVLAaron]

My calculator doesn't have a servo attached to it.

 

[PatMiles]

I installed a Hitachi WJ200 VFD along with a Baldor EFM3558T 3 phase 2 horse motor on my Jet GHB-1340A lathe a couple of years ago. a bit pricey and a somewhat involved project but what a difference. Instant braking at lower speeds, instant speed changes without having to stop the lathe to switch gears. The tach shows 5.3 RPM which is sloooooooooooooooooooooow. A twist of the rheostat will increase the speed up to 80 RPM in an instant. Moved all of the electrical connections from the ill thought out location on the back of the gearbox to the gray box to the left of the VFD. I'm in the process of tooling up to chamber barrels. Pray for me!

 

[PatMiles]

He's also created an electronic lead screw... which I wish I could fit to my lathe... it's REALLY cool.

That series looks like a weeks worth of YouTube videos! I'll be up til all hours watching them though.