HLV-H : maximum pitch screw cut?
I've been asked, in the past, to cut some course pitch acme threads on my HLV-H but have had to refuse the work, because I did not believe it was possible to cut greater than 10tpi on the machine.
Today, I re-read Peter Haas's excellent metric threading thread and realised he had included all pitches upto 6mm.
So, can a HLV-H cut this pitch safely ? (I'm worrying about the gearbox and dog-clutch parts)
Would I be correct in thinking that if the Hardinge gearbox can withstand the forces produces by cutting 10TPI @ 1000rpm (which is a loose interpretation of the manual ) then cutting say 5-6mm @ <<500rpm should be OK?
Has anyone here cut course threads on an HLV?
I've cut threads as coarse as 8 tpi (@ about 400 rpm) on my TL which is the forerunner to the HLV-H and has the same gearbox and dog clutch design. I would have been rather nervous going any faster or coarser. The shock to the dog clutch upon engagement and the pressures on the gear train were near what I considered acceptable.
It is possible that the HLV-H is beefed up in the change gear train but I don't think that is the case because many of the HLV-H parts in this area bear TL part numbers.
I was playing with the lathe at 11tpi this morning; It's definitely the shock or inertia load that would be the problem if the lead-screw is geared up - TILT!
I just wondering if I can re-configure my VFD wiring so that the spindle powers down at the end of a thread (e.g. a micro switch on the threading lever) so that I can use the VFD to soft start the spindle and threading gears to cushion the blow (so to speak).
I suppose the ultimate way to go is a servo motor driving the lead-screw and some electronics to sync the whole thing together (like this Electronic Lead Screw Main Page).
 just been looking at Babinmachine.com's ELS conversion - looks very good (but outside my price range I suspect)
Electronic leadscrew retrofit
It seems you have discovered our new retrofit kit for the HLV-H lathe.
You can check it out on You Tube by searching for "hlv leadscrew" or under our name.
The "shock" of a 4 pitch or 6mm thread on our servo system is softened somewhat with the electronics and the fact that our control will keep you from having the spindle speed too fast for the pitch.
Advantages are many such as rapid retract, touch screen programming,actual RPM display, and multi-start threads.
We successfully cut a 4 pitch thread, triple start, into a 3" dia cast iron sleeve .
Low spindle speed of 150 rpm I believe.
If one had to mechanically convert a HLV for metric threading, you would need the external gears, banjos, cast covers and oversized cover door. This would get you a few mm pitches.
Setting up for English threads that are not on the threading legend plate, you would need to do about the same.
Our retrofit needs only 2 holes to be drilled and tapped plus the original gears are always there in case they are ever needed. You could contact me for pricing. Hopefully you will be pleasantly surprised.
I hoped you'd reply
I really like your system I think you've got that system perfectly targeted for HLV users; I've spent the last few hours hunting down electronic lead screw systems and all seem to have gone down the 2 axis cnc route (i.e. too complicated). Your electronic gearbox is, I think, exactly what the manual lathe user will want.
Is your system suitable for the EU's bureaucrats? (RoHS CE marked etc. etc. )
Paul, what is your targeted price for a DIY install of your kit?
To answer Bill's question first, as of now it would be difficult to sell to the European mkt.
I would like to establish the US market first.
We are still beta testing but plan to show a rebuilt HLV-H lathe with electronic servo leadscrew at May's Eastec machine Show.
As you know Hardinge had come out with their own version of a servo leadscrew for the last year or so of production.
It seemed too complicated trying to include the DRO for position stopping and starting.
The Taiwan version that has been offered for a while now works well but it was not a retrofit package, only new.
To answer Jim's question about target price, I will first say this: we tried to use USA made items where we could and to get the best value, not necessarily the lowest price.
Given that, we use a California made Animatics Smart motor with built-in drive and PLC. Also USA made gear reduction gearhead. Also needed is a color touch screen with it's own power supply. Power supply needed for the servo motor. Custom cables and connectors. Limit switches and encoder for spindle orientation. You'll love how we figured an easy way for the spindle encoder to mount.
Power supply enclosure, E-stop switch, circuit breaker protection, brackets and fabricated cover components.
The software development is obviously crucial but my guy Bryce is a genius.
So, our introductory price will be just under $3K.
Probably take less than 45 min to an hour to install. We also will offer, if needed, replacement HLV leadscrews at about half the factory price.
Given what a factory mechanical external gearing setup would cost for specific threads, this should be a good value. 4 - 250 TPI and equivalent mm
Touch enter Eng. or metric, enter the pitch, answer rapid retract or not, if yes to rapid retract you can touch slide to adjust the speed, defaults to single lead but double and triple leads there to touch enter. You can alternate between the threads in the multiple lead or finish a single thread before proceeding to the next. RPM is displayed and turns to red if over speed for that particular pitch. Simulated lamps for microswitch on/off. This helps with adjusting the left and right position stops.
So if anyone has need and has been looking for a HLV-H-EM to come along at a good price, now you can consider an English only gearbox lathe and perhaps get more for less.
I am open to ideas or insight or feedback regarding this. Thank you all.
I guess you're using the o/p spindle of the 3 change , since it's there in the gearbox
You'll love how we figured an easy way for the spindle encoder to mount.
Are you sensing direction with a quardrature encoder? or picking it up from the dog-clutch shaft with the end-stop micro switches?
We extend the shaft that has shifting fork and add trips for 2 microswitches, one for each direction of commanded motion. When the set factory thread stop block on the apron rod moves the the rod during threading, the microswitch for that direction trips out.
Moving the threading lever to the right will initiate the rapid retract and end at the right hand stop. Now ready for next pass by adjusting compound and initiating threading lever to left.
Did you view the video?
Basically, everything is essentially the same as original factory other than the way you set the pitch. Operating and cutting a thread is the same. The bonus is the rapid retract to save time, especially with fine threads.
Would you be giving away too much to tell me how big (watts) is the servo motor ?
Contact me with a private message if you would like.
I don't want to give away the store just yet but I will try to be helpful.
You could also contact me from our web site as well.
I reguarly used to machine worms on my HLV with a pitch of .156" ie about 6.3 tpi, I worked with the retracting topslide and the cross slide jibs pretty tight and ran at bottom speed. The gear train was calculated using the method described by Ivan Law in his book 'Gears and Gearcutting'
Originally Posted by Billtodd
I had no trouble with the clutch etc but it got pretty exciting as things got deeper and the tool could dig in.
Thanks for that. At least it confirms my original idea was possible
However, I have just looked back at the drawings of the parts I was asked to make and the thread is not 4mm, as my failing memory recalled, but a double start 4 i.e. 8mm pitch, which is beyond even Paul's magic electronic gearbox.
Our electronic threading retrofit can do the 4mm pitch.
We also offer single, double, triple and quad leads.
The 4mm double start thread, I believe, translates to 2 mm pitch when measured point to point or peak to peak. The second start fills in the area between the 4mm pitch.
I do not pretend to know too much about threading, so correct me if i am wrong.
With our system, one can choose to continue with the first threading lead before starting the second thread lead or you can alternate between the leads.
You could also program a fractional 6.25 TPI pitch or 24.75 TPI as we can input to two places after the decimal.
Before Hardinge recently stopped making the HLV-H lathe with their version of a servo driven leadscrew, we basically tried to at least offer the threading range that they did.
We are currently performing a partial rebuild of a HLV-H in our shop and we will be installing the electronic leadscrew retrofit on this lathe. I will make another video of a specific thread for you if interested in such.
I noticed above that you are also supplying replacement lead-screws; Have you considered replacing the lead-screw with a ball screw?
The larger pitch and lower friction of the ball screw would enable the machine to cut an even greater range pitches, albeit at the loss (temporarily) of the use of the standard gearbox.
BTW that thread was a dual-start 8mm pitch trapezoidal, incorrectly described as 4mm on the drawing.
Regarding an 8mm lead, we probably could include such metric pitch in our software but mechanically, the Hardinge probably would not have enough power to do it given only 1/2HP in low speed range and probably not enough speed out of our servo setup. Depends on spindle speed I guess.
Replacing the leadscrew with a ball screw is feasible on a CNC conversion, but does not seem appropriate on a manual precision lathe. The existing halfnuts are able to dis-engage whereas a ball screw cannot.
We have done many CNC retrofits on a HLV-H and yes we do fit ball screws. The CNC can essentially program any pitch and with a higher HP spindle motor, more threads are possible.
All in all, the Hardinge HLV is one of the nicest lathes for precision toolroom threading. Our retrofit just makes the existing mechanical threading operation that much easier and somewhat faster given it's rapid retract feature and it's wide range of English and metric threads without the use of external gear train. Easy multi-start threads are a bonus as well.
I just read this lead, and wonder how much the electronic screw-cutting attachment costs?
what does it take to install?
We quote $2,750.
Two holes to drill and tap for installation.
Original gearbox remains intact with only the cover door being removed.
The servo comes with coupling and brkt to mount in-line with leadscrew.
Microswitches for left-right stopping
Color touch screen to enter threading data and such.
Power supplies for screen and servo/plc
Pre-wired and 115V input supply.
Should take about 1 hr to install.
See it at Eastec next month or on You Tube.
Shelled 30 tooth gear
I am new to this forum but not to the PM board. I have been using HLV-H tool room lathes since the very first one built in 1961 and I can tell you to be really careful with 10 pitch and bigger threads. I have cut a number of 10 pitch right and left hand acme threads on my 1989 home shop Hardinge and I have shelled the teeth off of the 30 tooth change gear three times now. Not sure its the thread or if the gear was just heat treated to hard and was brittle but non the less it let go. I have four more Hardinge lathe in my business and I have told the guys if you need to cut a 10 pitch or bigger to use one of the engine lathes. Oh and by the way this little gear is or was the last time I purchased one $80 bucks.
I've admired your work over on the SB forum for some time
I am new to this forum but not to the PM board.
Thanks for the warning. Another Plus point for Paul's servo system I think
 Dennis, I assume you meant the 30T external change gear not an internal one. Is that right?
Peter, are you using Hardinge or Myford gears? (Myford gears are 20dp(?) and a lower cost alternative over here in the UK)