I'm under the impression that my tailstock is not precisely centered, I'm sure there can be a multitude of reasons on why my parts are slightly off but let's just assume my tailstock is off center and I need to center it, this is something I've never done so i'm looking for help. I asked a machinist from a contractor we sometimes work with how to do it and he told me, but since he isn't at the machine while I do it I'm unsure of how accurate I am and my boss doens't like me asking contractors for free help even though he told me to call him anytime for help since he feels bad for a 22 yr old machinist with no one to help him.
Anyway I've enclosed pictures of my set up, also I'm unsure of how to even adjust my tailstock, I have a Haas TL-1 and don't fully understand what makes it move up n down or left to right but that I can do some more research in, but if you know how to please advise me.
So you can see I've got a dial indicator, the horizontal kind I believe, mounted in my chuck. In my tailstock I've got my drill chuck holding a large dowel pin, the machinist I asked about this said indicating on a tapered part wouldn't be correct, ie indicating the inside of my tailstock. Should I indicate to a non tapered section of my drill chuck? So Anyway I rotate my chuck my hand and see the indicator value change, basically what are the do's n don't of this.
--We Ain't Building Pianos (TCNJ Baja 2008)
The way that you kind of look at Tail stocks is as a tunable accessory, not technically a constant precision accessory if it is used periodically to compensate taper on longer parts parallelism. As they say, sh#t happens, so expect the tailstock may need realignment periodically too.
First thing I would do is verify if the lathe will take a light cut(.002) to produce a matching parallel diameter in 2 locations on a 1-1/4 to 1-3/4" round bar at the same X axis position....oh, say near the chuck and 12-16" from the chuck. This tells me if the lathe is sitting level and I won't be making adjustments to the tail stock to compensate a twist in the bed ways. Reset level with the footing adjusters if required to make it cut parallel.
If this is an adjustable tail stock, you can see the sub-base under your tail stock. There are often screws on each side that can push the tail stock casting front or back, relative to the sub-base which rides on the inner bed ways. You loosen one and tighten the other to push it front to back. There is no up and down adjustment.
Take note on whether the lever operated mechanism that locks the unit to the ways does not also lock the tailstock to its base, preventing the adjustment to register. In other words, the tailstock will be locked while indicating alignment, but may need unlocked to make any adjustments.
Using the spindle chuck to indicate the tailstock just like your pictures. Indicate the quill bore or dowel up close and backed way(using that bar you turned the two parallel diameters on earlier) from the chuck and take an average, split the difference or decide which matters to you more. You can also verify it with the quill all in or all extended and see if locking the quill shifts it when applying the locking clamp.
Keep in mind that indicating on a dowel in a drill chuck that sits on jacobs taper on a morse taper adapter in tailstock bore; can have its own set of accumulated variables. To prove its integrity, remove it from the bore, rotate it 180deg and indicate on the dowel pin again. Any deviation might not be worth fighting.
You can see here variables won't get it set for perfection in all cases, but when the application requires tuning, you will know how to compensate for it by tweaking the tail stock and how to return it when that need arises too. It is tuneable for that reason. Most of the time, I just want it reliable.
Last edited by One of Many; 05-14-2009 at 10:57 AM.
Learn cause and effect through experience. Mastering those relationships is the "Common Sense" ability within the art of any trade.