Hardinge HVL lathe question, How do the carriage stops work when chasing threads?

[Lowell K]

Long title but it says it all.

Back story. I bought a HVL lathe. It is an old machine. According to Hardinge based on the serial number it was built in 1957. I was built in 1953 so it is a bit younger than I am. I have an operators manual for a HVL-H that was published in 1978. My machine is not much different than the one the manual was written for.

The section dealing with thread cutting, page 10 if you have a book, reads in part as follows:

"CAUTION: Lock carriage stops securely before starting to cut threads. Do not release carriage nut ( half nut ) until threading operation is completed.
With carriage at rest and quick acting handle in the forward cutting position feed the number of thousandths for each threading pass using cross slide handwheel.
Move lever H (carriage control lever) to the left and carriage will travel until it contacts the carriage stop at the headstock end of the machine. The spindle will continue to run. Carriage stops only cause only the gear box, lead screw and carriage to stop.
After every pass, withdraw the threading tool from the work with quick acting handle and return carriage to starting position by moving control lever to the right."


SO... I understand the procedure but I am left with a question, how does the carriage stop stop the carriage? I don't like not knowing how things work. Any help will be appreciated, a long winded explanation would be most welcome.

Lowell

 

[george wilson]

I don't have an HLV,I have an HLVH,but they might be the same in many respects,except for the narrower bed on your machine,and the manual way you have of regulating speed.

My HLVH has rods with collars that you adjust so that when your lathe reaches the desired end of its travel,the carriage has pushed on a collar that you pre set against the side of the carriage. The carriage pushes the collar,which is mounted on a steel rod. As the carriage advances to the left,the rod is pushed further and further into the QC gearbox until it disengages the gear and the carriage stops.

Once you have this collar set exactly right,the carriage will stop within .001" accuracy every time. I hope this is correct as I haven't used the carriage stop in years. However,when threading the lid of shallow pill boxes,the stop reliably worked for me just before the threading tool kissed the inside of the lid. It is a very valuable feature when doing a job like that,where the lid is very shallow,and every useful thread counts in making a lid securely screw on.

To get the collar set exactly right would be nearly impossible just by using the collar. What you must do is set the collar as close as you can manage. Then,use the compound at its 29 1/2º angle,to set the final exact depth on your job. There is plenty of "sideways" motion in it to accomplish the job in conjunction with the collar. Once you get the depth set,bring the compound up to the surface of the metal with the cross slide,and zero your dials.

Don't forget to swivel your compound the other way for cutting INTERNAL threads. Or,you can also use the stop collars for outside diameter work as well (I was used to using mine for those lids). At the speeds that the carriage can move when threading on a Hardinge,the stop collars ae very reassuring that you don't crash.

I hope this makes sense!!

 

[Lowell K]

I don't have an HLV,I have an HLVH,but they might be the same in many respects,except for the narrower bed on your machine,and the manual way you have of regulating speed.

My HLVH has rods with collars that you adjust so that when your lathe reaches the desired end of its travel,the carriage has pushed on a collar that you pre set against the side of the carriage. The carriage pushes the collar,which is mounted on a steel rod. As the carriage advances to the left,the rod is pushed further and further into the QC gearbox until it disengages the gear and the carriage stops.

Thanks for the reply.

My HLV has a rod and collar set up as well but the rod does not seem to move. It may never have been used as the under side of the rod covered in swarf to the point that the collars cant be moved without removing the build up. There is a nut and washer at the headstock end of the rod that might serve as a hard travel limit at the tail stock end and none at the tail stock end. Does the nut might serve to limit the amount of travel?

I wonder whether the rod and collar system is the same on the HLV and the HLVH are the same, all the photos I have looked at seem to be the same. Speaking of photos, both models have a 7/16"-20 set screw that takes a 7/32" Allen wrench what is the purpose of that?

Sorry to have been slow to reply, I got busy for a while and had to put this on hold for a while.

 

[f350ca]

I have a HLV the insides of the headstock are the same as the H, the H might have a threaded adjustment on the stop collar. The stop rod should move back and forth with the carriage control lever. It controls a dog clutch that is geared 2:1 to the spindle, hence it indexes the tread every time it engages.
Not sure which set screw your referring to.
Haven't tracked down the age of mine, its serial number 300 the first machine that you could remove the spindle from to change belts without sending it back to the factory.

Greg

 

[Lowell K]

@f350ca,

It may not be a set screw but it is a tapped hole, lower most on the head stock, actually the assembly below the headstock but on that side to the left of the Q/C gear box, to the right of the low/stop/high speed lever. Looking in to the hole I see a female hex socket that accepts a 7/32" Allen key, this leads me to think set screw.

Thank you for your observation that the head stocks are the same on the HLV and early HLV-H machines. I located a 1956 HLV-H maintenance manual that deals with that part of the machine about an hour ago but have not read in to it as it is late. I agree that from what I saw initially that they are the same. From GW's comments along with yours.

I am beginning to think that the machine was never, in the last couple of decades, used for chasing threads using this mechanism. It is prolly gummed up and stuck from years of unuse/neglect. I welcome any and all ideas as to how to free it up as well insight in to how the thread stop mechanism works.

My main concern is that I not blindly follow procedure and break the mechanism because of the factor detailed above.

Lowell

edit, I am wrong about the manual date but it is a 50's manual.

 

[f350ca]

Lowell if the hole you are referring to is in line with the carriage stop rod, it has a ball and spring behind it that drops into detents in the rod. Might be worth removing it if the lever won't move the rod.

Greg

 

[Lowell K]

Hi Greg and all,

Yes, the hole is in line with the stop rod. It seems that the stop rod clutch is frozen in place due to lack of use. Any thought on how to free it up? Cleaning is a good start but I am open to ideas as to how to get it working.

Lowell

 

[f350ca]

Lowell, where do you think its frozen? Is there any movement in the stop rod or is the mechanism from it up to the dog clutch seized. The dog clutch is a two eared mechanism, it may not engage if the spindle is in the wrong static position, its meant to engage when the spindle is turning to allow it to line up.

Greg

 

[Lowell K]

The matter of the frozen stop rod has been resolved. YAY! To be precise it was the stop rod extension (SRE) that was frozen but I digress...

After being assured that the internal workings of the threading mechanism were the same and armed with a maintenance manual for a HLV-H which confirmed said assurances ( trust but verify ), I removed the stop rod plunger assembly (SRPA). The SRPA is housed in the lower head stock in the tapped hole that has been mentioned in previous posts on this thread. The SRPA is supposed to consist of four elements two set screws (7/16"-14), a spring and a ball bearing. I had two of the four on the bench after taking it apart, one of the set screws and the spring. I had a ball bearing and a set screw in my collection of stuff so that part of the fix was under control.

The stop rod extension, the part that the stop rod threads in to and is housed in the lower head stock, was indeed frozen so, I flooded the SRPA hole with WD40, waited a bit, set the shaft collar that is the adjustable left hand stop and used the carriage to apply pressure to the stop. It moved. It took some force to move it but not so much I was afraid I would break something.

To move it the other way I applied pressure to the right hand "positive" stop. The positive stop is pinned at the tail stock end of the machine, to prevent the carriage from crashing in to the feed control box I suppose, it is not adjustable. A bit less force moved it the other way. More WD40 and a few more moves and it moved freely. I reassembled the SRPA: ball bearing first, the spring and a set screw followed and tightened pressure on the spring until the ball was firmly engaging the detent grooves on the SRE and locked it in position with the second set screw.


Thanks to all who commented. What a great resource this site is!

Lowell

 

[f350ca]

Glad to hear you got it working. They're incredible to thread with, have fun.
Greg