Some lathe questions...

[barrydc1]

To me, the origional questions can one use a boring bar has been answered in summary: Yes, as long as the bar is rigid and the angle of the cutter is correct. A 3/4" boring bar with indexable cutter in an BXA tool holder would be just as good as a 5/8" tool holder with a same/similar cutter. That seems right doesn't it?

The next question how does one center a tool to the part for facing or turning? The pics here show what I use. The first picture shows it in the chuck while centering the tool cutter. At anyrate no one has mentioned this option yet. I made this device, but they are also available on e-bay, etc. for very reasonable prices. I bought a $5.00 howitzer (literally) level to use in mine and it is extremely sensitive and the device works 100% of the time.


A link for such a tool is here: http://www.ebay.com/itm/LATHE-BIT-C...223?pt=LH_DefaultDomain_0&hash=item5630cc3eb7

I have no affiliation with this seller.

 

[Hawkeye]

The switch was thrown and this train is heading down a side track. If you read the OP, he mentioned pre-drilling large-diameter stock for centres. The 10mm x 1000mm stock was just an example given to help clarify - didn't work too well.

I would hesitate to try to centre drill a piece 1 1/2" in diameter by 8" long (again, an example) without some kind of support. If it was smooth enough to work in a steady rest (or use my cat-head steady), it could be accurately centre-drilled using the tailstaock. Failing that, I would use the drill press or even a hand drill, after carefully centre-punching the end. Bernie has it right - punch marks can be moved when necessary.

 

[barrydc1]

So I'm using a mini lathe and had some questions I'm hoping you could answer.

- I have a QCTP with a boring bar holder. Is there any reason I can't use a boring bar for facing jobs? It seems like the boring bar is already configured for essentially that job. Plus it would save me extra tool holder for my QCTP.

- Currently to center a tool bit I'll take repeated facing cuts until it doesn't leave a nub. Is there an easier and faster way to do this?

- Does anyone have a good way to fasten a digital caliper or scale to the crossfeed? I'm having a hard time figuring out a way to do it while still allowing the compound to rotate freely when needed.

- If I'm working on a large diameter piece it would be really helpful to center drill it's end for the center before I put it on the lathe. Is there a way to do this accurately?

Sorry, I did address the first two questions, but didn't address the second two. Not a switched track for the train, just a train only traveling on one rail:yikes:. The two other questions would definitely require more info on the specific lathe, but a 1cm=10mm diameter stock is about 1/2 " in diameter which isn't very large, although 1M long or 3.28 feet is way too long, I would suspect, for a mini lathe without some rigged support. Even a very tall drill press would be difficult, but a horizontal attachment on a mill would work very nicely especially with a co-axial indicator to center the horizontal spindle to the stock, but I wonder if that is available in this case.

As for the caliper question, I can't comment on that for a mini-lathe in that application, but I did install a caliper on my tailstock as a poor-man's DRO and it works very well for tailstock drilling to accurate within .001" depth. Sorry for the de-railling if I was the cause!