Boring to depth on an HLV-h (clone)

[jccaclimber]

I have Sharp HLV-H clone. I understand how to thread to a stop, but want to bore to a stop using the carriage power feed. Currently I get it close on the power feed and then walk it in by hand on the DRO, which results in either telling me how much I overshot, or getting to the right place but with a very different feed rate than the rest of the bore.

On a Colchester I used to use there was a clutch on the carriage drive rod and a bolt on micrometer carriage stop. However, it was explained to me that the clutch was there for emergencies only, and using it would eventually result in breaking the shear pin on a good day or a gear tooth in a bad one.
On an HLV-H there are clutches on the power feeds. Are these designed so that I can mount a rigid stop and disengage after running into it, or is that inadvisable?
If it is inadvisable I can always wire a relay into the feed motor so that it stops the feed motor when I hit a switch.

 

[modelmakerblue]

From my 50 years of machining experience I would suggest it is a bad idea to hit a rigid stop under power and rely on the clutch to knock off, best to power feed close to the stop and feed by hand up to the rigid stop. I'm sure others will have different thoughts.
Tony

 

[rons]

I never use those stops. A indicator is more accurate.

 

[rklopp]

Currently I get it close on the power feed and then walk it in by hand on the DRO, which results in either telling me how much I overshot, or getting to the right place but with a very different feed rate than the rest of the bore.

That's how I do it, and try really hard not to overshoot. I just get as close as I can under power feed and live with the final hand feed portion having different feed rate. I usually stop a few thousandths short of depth on roughing passes and then take those remaining few thou off with a facing finish pass.

 

[Billtodd]

The Hardinge power feed clutch is designed to slip under high load , so running into a dead stop is ok even ,as previously suggested, if not all that accurate.

 

[jccaclimber]

I’d have to build a dead stop first, but how accurate it “not that accurate” in this context? For me hitting +/- 0.0006” or so would be close enough that’s what I’ve seen for the auto thread disengagement, though admittedly n<10. That’s a mile for some things, but my gut is telling me that it would be ok to bump the bottom of a bore that hard and not damage anything. I would still need to clean the bottom with a finish pass if it needed to be clean.

Until using this lathe I was always super stressed, or slow, when boring or threading to a shoulder on a manual, and now threading is as comfortable and dead easy as anything else. Thinking about it, I guess I’m more looking for that comfort and convenience for boring operations, and curious how close I can get it to the threading experience.

 

[rons]

The stop collars are on the rod that moves right and left. That rod is connected to the upper lever on the head stock.
Grab onto the rod and move it right and left. Quite a bit of slop in that rod. That is not useful for accurate work.
Even Harry Home Shop guy would not like it.

 

[car2]

I also use the power-feed, then either either the DRO or a micrometer stop. I use one of the hardinge indicator stops (the casting that fits over the bed, without the dial-indicator) for a fixed stop , and a micrometer on the carriage. I found that the dial-indicator stop was difficult to get tight enough with the one rear tightening screw, so I tapped and drilled a hole in the top near the dovetail, and added a brass-tipped t-bolt to force the dovetail vertically against the way--that's repeatable to a couple of thousandths.

 

[Mark Rand]

The Hardinge removable bed/carriage stop has a micrometer calibrated in 0.001" increments. It works for me when I need to bore or turn to a depth. I usually leave a few thou extra so I can fake a final cleaning cut to remove any steps caused by the insert not having a 90° angle.

 

[jackary2003]

On my old Chipmaster lathe there is provision to run up to a pre-positioned bed stop under power feed and this will disengage the power feed with accuracy. It is a very useful function.
Alan