# PM 1236 VFD Conversion



## Ray C (Feb 4, 2013)

All,

Now that the lathe has a new bench, it's getting converted to 3 phase VFD before final positioning and leveling. The VFD is the ever-popular Huanyang 1.5kW VFD shown here: http://www.ebay.com/itm/BRAND-NEW-2...272?pt=LH_DefaultDomain_0&hash=item2c69b9a1c0

Here's the correct motor for the lathe matched to the power of the VFD: http://www.globalindustrial.com/p/m...ors/iec-metric-motor-90l-ip55-3ph-c90t17fz2cc EDIT: BTW, the motor is wireable for 2 speed but that's ignored for our purposes.

Last night, I programmed the VFD and tested an external pot and signal lines on a bench setup. As soon as I double check registers and test thoroughly, I'll post the settings here.

Also, here's how I'll probably rewire the control aspect of the unit. 
	

		
			
		

		
	

View attachment 1236 VFD Control Wiring.pdf

I might tweak this a little so, hang-on until I'm done being the guinea pig. I'm not sure if the native switches are normally open or close and I'll try to reuse as many as possible. The FWD and REV switches on the lathe are mechanically mutually exclusive. The JOG button is not so I'll need to see how the VFD reacts if JOG is asserted while either FWD or REV is active. ... thus, I may need to tweak things a tiny bit. Here's a quick sketch -about as simple as it gets...


Ray

Edited to correct a broken sentence.


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## GaryK (Feb 4, 2013)

Looking good Ray!

I'm kind of curious about how you plan on using it. Will you leave the gearbox speed settings at one speed and set the speed from the VFD.
If so do you have any idea what setting you'll use?

Or will you just use it to get the speeds between the standard speeds?

Or bypass the gearbox entirely?

What are your reasons for the VFD?

Yea, I know, a lot of questions!

Gary


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## Ray C (Feb 4, 2013)

Some folks leave their lathe on the same gear and just clock the VFD up/down but that's got to be putting the gears through hell.  That's the same reason crankshafts break when you go too slow in a high gear and why trans gears get shredded when you go too fast in low gear.  My plan is to leave the VFD normally set for 60 HZ and use the lathe and gearbox the way it was intended.  I may tweak the frequency down a tiny bit once in a while to avoid a weird vibration if one happens to pop-up.  That kind of adjustment is usually just 3-10 Hz at most.

Other than that, the real reason is that I want "slow-start" capability with a 2-4 second (or so) ramp time.  That goes a LONG way to making your gears last longer.  And also near-and-dear to my desires is the smoothness of a 3 phase motor.   You can feel the 60 Hz pulsing in a single-phase motor -you cannot feel it in a 3 phase motor.  -This is more of a personal satisfacton thing for me...  I happen to love 3 phase stuff and the mathematics behind it.


Ray




GaryK said:


> Looking good Ray!
> 
> I'm kind of curious about how you plan on using it. Will you leave the gearbox speed settings at one speed and set the speed from the VFD.
> If so do you have any idea what setting you'll use?
> ...


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## darkzero (Feb 4, 2013)

Awesome Ray! The slow start has got to make a big difference in wear. Sometimes I hate the sound the gears make when starting the spindle. With a VFD, is dynamic braking a feature? I always wondered about lathes that have dynamic braking & I would love to have that. I figured it's only possible with 3-phase motors?


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## Ray C (Feb 4, 2013)

Hi Will...


Yes, these VFDs support dynamic braking.  I've never used it on any VFD because the need hasn't arisen.  BTW, I just got this unit a while ago.  My other VFD's are from Automation Direct.   These are half the cost.  Both have poor documentation.  These unit itself can do some degree of magnetic braking with a controlled/expedited ramp-down but, true dynamic braking requires additional an additional external resistor that can handle a good bit of heat.  ... Keep in mind though that letting things coast to a stop is the easiest on the gears, bearings and even the wound wires in the motor.  Also, yes, it's pretty much a 3 phase-only capability.  Theoretically, a single phase could do it but, nobody really supports that kind feature... -Too much complexity switching capacitors, centrifugal switches etc...  It would be a nitemare.  I only know of 1 manufacturer that makes a true single phase output VFD -and it only works with very specific types of single phase motors.  -Don't bother with it.

Ray





darkzero said:


> Awesome Ray! The slow start has got to make a big difference in wear. Sometimes I hate the sound the gears make when starting the spindle. With a VFD, is dynamic braking a feature? I always wondered about lathes that have dynamic braking & I would love to have that. I figured it's only possible with 3-phase motors?


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## darkzero (Feb 5, 2013)

Thanks Ray. I know very little about VFDs, never looked into them but maybe one day. 

For the dynamic braking I was just thinking it might be good for threading metric. I remember seeing a video where a guy was threading without using the half nut. When he turned off the spindle to reverse it stopped pretty quick & I thought that was pretty nice. It was old American iron.

Many times I thread close to a shoulder or with no relief at all. When I turn the spindle off it coasts too much & is not consistent when i'm threading metric. I use the spindle brake in these cases but it seems like a lot of wear but luckily I don't thsingle point metric too often. Is there a better way?



Ray C said:


> Hi Will...
> 
> 
> Yes, these VFDs support dynamic braking.  I've never used it on any VFD because the need hasn't arisen.  BTW, I just got this unit a while ago.  My other VFD's are from Automation Direct.   These are half the cost.  Both have poor documentation.  These unit itself can do some degree of magnetic braking with a controlled/expedited ramp-down but, true dynamic braking requires additional an additional external resistor that can handle a good bit of heat.  ... Keep in mind though that letting things coast to a stop is the easiest on the gears, bearings and even the wound wires in the motor.  Also, yes, it's pretty much a 3 phase-only capability.  Theoretically, a single phase could do it but, nobody really supports that kind feature... -Too much complexity switching capacitors, centrifugal switches etc...  It would be a nitemare.  I only know of 1 manufacturer that makes a true single phase output VFD -and it only works with very specific types of single phase motors.  -Don't bother with it.
> ...


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## Ray C (Feb 5, 2013)

Metric threading certainly seems like a good use for dynamic braking.  Still though, adding VFDs to manual lathes is (in certain respects) still in it's infancy.  By my accounting, it wasn't that long ago that VFDs were becoming common-place and when they first came out, there was a wave of poeple burning up their old motors because they weren't designed for running at speeds other than 50 or 60 Hz.  Now, let's extend that logic just a bit more and ask ourselves if our 1950's design lathes (yes, our modern lathes are pattern variations of mid-1950's technology) were really made to take the pounding of dynamic braking.  Don't get me wrong...  I don't have all the answers and am figuring this out as I go but, my intuition tells me to do some thinking before proceeding.

When big gears turn small gears and vise-versa, the torque applied and stress on the teeth must be considered.  That's just one of the reasons why transmissions have stepped gears in the first place... -So you don't knock the teeth off all the small gears.  If you were going down the road in your 6 speed manual transmission at 65 MPH, pressed-in the clutch, shifted to 1st gear and dumped the clutch...  Good Bye Car!  So what's the difference between that and dynamic braking?  -Nothing.

Somone out there probably knows the answers to these things but, often times, people come back and say "I've been doing it that way for years so, it's OK"...  -Sorry, that kind of answer doesn't cut it for me.  It's a valuable data point but not a good answer.

Ray






darkzero said:


> Thanks Ray. I know very little about VFDs, never looked into them but maybe one day.
> 
> For the dynamic braking I was just thinking it might be good for threading metric. I remember seeing a video where a guy was threading without using the half nut. When he turned off the spindle to reverse it stopped pretty quick & I thought that was pretty nice. It was old American iron.
> 
> Many times I thread close to a shoulder or with no relief at all. When I turn the spindle off it coasts too much & is not consistent when i'm threading metric. I use the spindle brake in these cases but it seems like a lot of wear but luckily I don't thsingle point metric too often. Is there a better way?


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## Pacer (Feb 5, 2013)

> people come back and say "I've been doing it that way for years so, it's OK"...



Yep, thats me --- Got a SB lathe and a Bridgy clone both on VFD's for some 5-6 years and it just might be considered abusing the crap out of them? I run the lathe in every gear and from 0hhz to 75hz and all ranges between. When threading I select a lower gear and control the cut strictly off the pot, bringing the cut to a gradual stop at the end, back the tool out and can either run the lathe back under power for metric, or just use the carriage. I dont think in my home shop I could ever do enough wear to be a factor, even though I am a pretty active user of my machines.

On the mill I use the VFD and power tap on almost all threading, being able to advance the tap as slow as I want, even down to 3-5rpm. Now I do keep the mill in the mid range of belt settings for 95% of the time, using the VFD to control the speeds, here again from 0hz to max.

I have my units set to utilize the stop/start parameters in the unit and set both at 2 seconds, I find this to be a wonderful feature.
I have always used Hitachi VFD's, but recently on a rebuild of an old Sheldon lathe I was a bit short of funds and went with the Huangyang like you (they are MUCH cheaper!) Seems all the mfgs manuals are rather poor, but I had become familiar with the Hitachi and could program one quickly - the Huangyang gave me some probs, with parameter settings just enough different to give me some trouble. The Sheldon is already has variable speed drive, and I find I use the lathes drive and the VFD about equally.

Love my VFDS!!!!


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## darkzero (Feb 5, 2013)

Ray C said:


> When big gears turn small gears and vise-versa, the torque applied and stress on the teeth must be considered. That's just one of the reasons why transmissions have stepped gears in the first place... -So you don't knock the teeth off all the small gears. If you were going down the road in your 6 speed manual transmission at 65 MPH, pressed-in the clutch, shifted to 1st gear and dumped the clutch... Good Bye Car! So what's the difference between that and dynamic braking? -Nothing.



Hey Ray,

Not quite the same at all but I see your point. Of course our lathes aren't designed for dynamic braking but I don't see much damage that can be done if set up properly. It could not be worse than using the spindle brake.

I was curious so I briefly searched on it. Many people do use dynamic braking & set up different delays for e-stop, regular stop, etc. In the case I was referring too, dynamic braking would be used at lower spindle speeds & the braking would not be instantaneous as with the lathes I have seen with dynamic braking. Higher speeds & large rotational mass (depending on what you're turning) would definitely not be good if you tried to stop the spindle quickly.

Just with some of the details I found while searching on VFDs, this thread, & Pacer's post above, I want VFDs too now!

Thanks Ray for adding more things to my long list of things to buy!


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## Ray C (Feb 5, 2013)

Truth be known, I'm trying to be cautious about the "recommendations and modifications" that are being described because, it could cause someone grief.  I could absolutely see someone ruining their lathe by hitting the dynamic brake at 2000 RPM.  I think bad things would happen for the reasons I mentioned -and the analogies I use are an attempt to explain what's going on using examples  people can relate to.  -That's the real thinking in my mind.  Yes, dynamic braking would be tolerated by our machines if used judiciously...

Stand by, I've got a little update on the switches on the machine.  Just checked everything out and did some preliminary wiring and tests... Need a few moments to organize the pictures.






darkzero said:


> Hey Ray,
> 
> Not quite the same at all but I see your point. Of course our lathes aren't designed for dynamic braking but I don't see much damage that can be done if set up properly. It could not be worse than using the spindle brake.
> 
> ...


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## Ray C (Feb 5, 2013)

Quick update.  Pulled the panel off to see how things were wired and also checked to see if the switches on the operating rod were normally open or normally closed.  Turns out, everything works perfectly in our favor.

Just so folks know, I'm setting this thing up so the coolant pump, indicator lamp and work lamp all still run off the original wiring.  The input power for the VFD will simply be tapped off the power cord coming into the electrical panel box.

So... Here's a pic of the unadulterated font panel switches.  Nothing complicated going on.  -Don't panic but  I've already rewired it to bypass the stop switch and jog switch.  Everything else is left alone.   I will later give step-by-step instructions on which wires get jumpered and where. The pictures were taken as I went along -just don't have time today to write it all up.  -Takes a while to proofread so nobody gets steered wrong.





It really is a simple job to do the wiring so I went ahead and did it.  For now, I'm just sneaking the two new circuits along some of the outside wiring that leads to the panel box.  Later on, I'll find a better way to hide those wires so the front panel can be screwed on tightly again.




There are two switches underneath the gearbox connected to the operating rod.  Four wires run from the switches to the panel block which I marked on the right side as B(lack), R(ed), G(ray) and Br(own).   In forward mode, Black and Red are closed.  In Reverse Black and Gray are closed.  In Neutral, Black and Brown are closed.  The catch here is that the circuitry expects to see a closed signal when the unit is in neutral so, a jumper is needed on the terminal block between Black and Gray (second picture of the next two).  After that, the other wires are used as the FWD and REV signals into the VFD.  And for your edification, the left side wires marked B & R are the foot-brake switch.  They are normally open and closed when the foot brake is pressed.  The cover switch is in plain view (but not photographed yet) so that's an easy wiring job.  The 1st pic just shows the wiring block, the second pic shows the jumper to fool everything into thinking it's still connected to the operating rod.






Wanted to do a quick test run to see if the emergency stop still worked along with testing Fwd and Rev.  I set things in place (the VFD is on the floor underneath the table and the motor was nearby). Everything worked just fine.  The pump and panel light work, E-stop and Fwd/Rev does what it's supposed to.  Wires for the jog switch were run but not connected to the VFD.  I'm still deciding on how I want it to work although I did figure-out how to program the multi-speed inputs on the VFD.




Again, I will write-up better instructions later on -just want you to know that this wiring job was analyzed and roughed into place in under an hour.  This is not a difficult re-work.

More to come but, it's going to take a couple days.  -I'm still battling some tough issues at the office these days...


Ray


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## Ray C (Feb 6, 2013)

Here's the final control schematic. -Finally decided to keep jog simple and preserve original functionality. Was thinking of supporting a Fwd and Rev jog but that would mean getting a different Jog switch and using two multi-speed inputs instead of one. -Just not a priority right now.

Enjoy...

Ray


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## Ray C (Feb 6, 2013)

FWIW...  I just capped-off the wiring project and gave it a test spin.  It's not the same lathe anymore.  It's the Rolls Royce I was searching for and reminds me of the stability of the old LeBlond 16x54 I grew up on.  Still have work to do.  I suspect the default programming for the power curve is not correct.  It's only showing a draw of 1 Amp.  I could be wrong though and maybe was looking at the wrong read-out.

I test ran it with new bench and old single phase motor and the heavy bench made a big improvement.  The overall smoothness of the 3 Phase blew me away!  The bench is not in final position and since the garage floor is unlevel, one of the legs is 1/8" off the floor.  Even still, I can't really feel any vibration in the machine at any speed.

-Success!


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## Ray C (Feb 8, 2013)

... Just to let y'all know, this is coming along nicely but, I'm not happy about the power curve from the default settings on the VFD.  I'm going to fiddle with that later today and this weekend.  All the ramp times are working fine but at some gear settings (higher speed gears) the motor has trouble turning things over and takes too long.  Definitely an issue with VFD programming...  Gimme some time to noodle this over.  Hang in there...


Ray


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## Ray C (Feb 8, 2013)

Duuhhhh!  Boy do I feel stupid.  Was up till 1AM yesterday wondering why the motor was having troubles coming-up to speed with the lathe in high gear.  The manual for the Huanyang VFD is very poorly written so, I read it about 10 more times trying to interpret it and learn all the functions.  Checked, double-checked and triple-checked all the register settings and also experimented with making small changes.  -Could not find a problem.  Laying in bed, thinking about it (2AM now and 6AM wake-up time is all too near).  Light bulb goes on!  The motor was still wired for 460V and I was feeding it 230.

Taking the motor off in cramped quarters is not fun so, since the wiring was 600V insulation class, I was just going to change the VFD output to 460.  Nope, the VFD doesn't support it.  Take off the motor, rewire it.  That did the trick.

I still haven't programmed the Jog function because the manual is so poorly written but, I think I understand what needs to be done.  I have all the registers written down and will post them soon.

Really too bad the instructions are so bad because it seems like this VFD has pretty good functionality -getting to it is next to impossible.

One other thing...  The PM 45 belts are hard/tedious to switch between high and low ratio.  I think I'll make new sheaves for a flat automobile belt and incorporate a quick release tensioner.  -Yet another project on the list.

Anyhow, with the new VFD at 60Hz, the actual chuck RPM are all very close to the stated values.  They're running about 8% high (checked with an LED tachometer) but this is expected since the old motor had a lower base RPM.  I also discovered that belt slippage varies depending on the gear settings and belt slippage accounts for quite a bit of RPM loss at the chuck -like 5-7%.  Mine are properly tightened now and slippage is minimal.  -And BTW, sometimes a loose belt is not a bad thing.

Ray


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## pdentrem (Feb 8, 2013)

This is one of my near future projects for my lathe. I have too much until Easter, but after that, yes. I may not be using the same control but the process will be about the same.
Pierre


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## Ray C (Feb 8, 2013)

If I may suggest...  The VFDs from Automation Direct are quite good.  The user manual is slightly better than the Huangyang, their website gives better examples, their phone support is very good and they have built-in rheostats for frequency control.  My other two are from A-D and they serve me well.  They are about 50% more costly though...

Ray





pdentrem said:


> This is one of my near future projects for my lathe. I have too much until Easter, but after that, yes. I may not be using the same control but the process will be about the same.
> Pierre


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## pdentrem (Feb 8, 2013)

At the shop, I have setup a few for the work machines, but there it is a larger budget than what I have for myself. I have not made any decision on the unit but I have been to Automations website before. I will keep them in mind.
Pierre


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## GaryK (Feb 10, 2013)

Ray C said:


> View attachment 46839



Just thought that I'd mention that the 3 switches in series on your diagram (panel, brake & cover SW) need to be pictured as normally closed and rather than normally open.

Gary


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## Ray C (Feb 10, 2013)

Yes, for running operation, the panel, brake and cover switch should be closed but showing as all open is a valid configuration. There is a minor error that I was hoping no one would pick-up on...  The operating rod guarantees mutual exclusivity for the Fwd, Rev and Neut positions so by definition, one of them should be shown as closed.  The idea here was to show the wiring connections which was accomplished but, I copy/pasted the switch figures and made a boo-boo... The wiring is correct so no worries there.

BTW:  I tested the VFD to see what happens when you assert conflicting signals. It accepts and operates with the first applied signal and ignores anything after.  Any time the control circuit is opened, it comes to a stop unless you have braking or tracking enabled in which case, it finishes it's cycle first.  This could be over-ridden by employing the stop signal, taking the E-Stop switch out of the series chain and wiring through an inverting switch.  -More trouble than it's worth in my opinion.   The tracking feature is just not warranted for this kind of application and the braking feature will do it's job and slow down the machine faster than if it came to a coasting stop.

Ray




GaryK said:


> Just thought that I'd mention that the 3 switches in series on your diagram (panel, brake & cover SW) need to be pictured as normally closed and rather than normally open.
> 
> Gary


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## mrbreezeet1 (Mar 24, 2013)

Do you guys think that "the pounding of dynamic braking" hurts a non gear driven lathe. 
When you say "dynamic braking" are you talking about a deceleration stop of say 3 seconds, or are you talking about one with a breaking resistor added to the system?
Take for example, My Oliver 159 wood lathe, I just put a VFD on. It uses a reeves drive. 
And I may put one on my Logan 10" lathe, it is just v belt to the flat wheel on the jack shaft, and flat belt from the jack shaft to the spindle. It does have back gears. 
Thanks,
Tony



Ray C said:


> Metric threading certainly seems like a good use for dynamic braking.  Still though, adding VFDs to manual lathes is (in certain respects) still in it's infancy.  By my accounting, it wasn't that long ago that VFDs were becoming common-place and when they first came out, there was a wave of poeple burning up their old motors because they weren't designed for running at speeds other than 50 or 60 Hz.  Now, let's extend that logic just a bit more and ask ourselves if our 1950's design lathes (yes, our modern lathes are pattern variations of mid-1950's technology) were really made to take the pounding of dynamic braking.  Don't get me wrong...  I don't have all the answers and am figuring this out as I go but, my intuition tells me to do some thinking before proceeding.
> 
> When big gears turn small gears and vise-versa, the torque applied and stress on the teeth must be considered.  That's just one of the reasons why transmissions have stepped gears in the first place... -So you don't knock the teeth off all the small gears.  If you were going down the road in your 6 speed manual transmission at 65 MPH, pressed-in the clutch, shifted to 1st gear and dumped the clutch...  Good Bye Car!  So what's the difference between that and dynamic braking?  -Nothing.
> 
> ...


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## Ray C (Mar 24, 2013)

Tony,

My understanding (and I could be misguided) is that dynamic braking involves a resistor AND the VFD supplies a reverse voltage causing the motor to stop within fractions of a second.  Anyhow, I don't think a belt will suffer the possible consequences that a gear would although it certainly would place more stress on it -how much, I don't know but, belts are more forgiving when it comes to transmitting torque.

Ray



mrbreezeet1 said:


> Do you guys think that "the pounding of dynamic braking" hurts a non gear driven lathe.
> When you say "dynamic braking" are you talking about a deceleration stop of say 3 seconds, or are you talking about one with a breaking resistor added to the system?
> Take for example, My Oliver 159 wood lathe, I just put a VFD on. It uses a reeves drive.
> And I may put one on my Logan 10" lathe, it is just v belt to the flat wheel on the jack shaft, and flat belt from the jack shaft to the spindle. It does have back gears.
> ...


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## mrbreezeet1 (Mar 24, 2013)

I see, Ok Thanks,



Ray C said:


> Tony,
> 
> My understanding (and I could be misguided) is that dynamic braking involves a resistor AND the VFD supplies a reverse voltage causing the motor to stop within fractions of a second.  Anyhow, I don't think a belt will suffer the possible consequences that a gear would although it certainly would place more stress on it -how much, I don't know but, belts are more forgiving when it comes to transmitting torque.
> 
> Ray


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## Ray C (Mar 28, 2013)

I've got a little project going on (actually, 5 of the same thing) that is finally putting the VFD to good use.  VFD's are certainly optional equipment but, it's paying off on this 2.5" piece of 316 SS.  This piece is ornamental and must be perfect.  It was very nice to set a base speed with the gearbox and tweak the R's down to make a perfect cut.  Don't know if this picture shows it well but, the face cut on that piece was done with auto-crossfeed and the VFD was used to gradually increase the R's as the diameter decreased.  The finish is perfect, no rings, no ripples, no gear ghosts...

In addition to 3 PH motors showing less vibration artifacts, fine speed control is why VFD's kick-butt!





Ray


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## darkzero (Mar 29, 2013)

Very nice finish Ray!


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## Ray C (Mar 29, 2013)

darkzero said:


> Very nice finish Ray!



Thanks, Will.  And I maintained the finish on the 1st pass all the way to the last one.  With VFD, you set the lathe to the diameter instead of cutting until you find the sweet-spot diameter given the closest RPM as per table look-up.  Did the bulk removal in several cuts, saving the last 15 thou pass for the finish.  I want everything on this project within 0.0001 of spec.  I took the temperature at the end, made the expansion calculations, dialed-in and took the cut.  2 hours after it cooled, it was dead-on.  Immediately after making the cut, while still hot, it was 0.0006 over.

Ray


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## Ray C (Mar 30, 2013)

... And the VFD really helps with threading too.  This was cut with HSS and I was able to tweak the RPMs fast enough to cut a nice thread and still have good control of the halfnut lever.  The finish inside the threads came out very smooth.  I do a fair amount of work on SS shafts and prior to having the VFD, there was a always a sacrifice in thread quality leaning toward slow RPMs to not crash the bit.  I have 9 more of these to make and I'll try some carbide cutters later on.


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