Lathe calibration tool question

[SE18]

I'm going to HD tonight and am going to purchase several things for my lathe rebuild (see photos)

The specific question I have is for the lathe dial indicator needed to check play in a couple of the rebuild steps outlined in the rebuild book by Illion

I was thinking that the 6" stainless steel dial caliper is cheaper and has more functions than the pricier ones shown, and I'm not going to be using it much. Its tolerance is down to .001, which is what I need.

Does that look about right?

Also, I need a 1/2" spanner bit, unfortunately the bits at HD are listed by number and not inches so I guess I just measure the end across

 

[Tony Wells]

I wouldn't pay $39 for 1.00" dial indicator from HF. Cath them on sale (all the time, somewhere) for ten bucks. Probably would make up for the difference in any other items. Try Enco, Travers, Wholesale Tool, MSC...or a host of others.

 

[Hawkeye]

I have a handful of digital calipers, but the one I use most is a 6" SST dial caliper that I got last. It is easy to read and doesn't drift like the digitals (unless you spend an extremity or two for a top-name unit). If I really need more precision than 0.001", I reach for the micrometers with the vernier scale added.

 

[jocat54]

You can make the spanner really easy out of a washer (or old screwdiver as has stated). I couldn't find an old screwdriver that was wide enough so used a washer, works well.

 

[SE18]

thanks all! I was running late and didn't make it last night so this will be a big money saver, your tips, that is. You're all very resourceful. Washer turned into spanner, pretty nifty!. That just leaves the 1/8" pin spanner wrench as a purchase to make.

Regarding these products, what will the 2nd one listed below do that the first one won't. The first digital calipers has a depth gauge at the bottom. Isn't it what the dial indicator does as well?

Forgo the trip to Home Despot and order online from Shars or Harbor Freight. You can get all the same items there for half the price and digital at the same time. Like digital calipers for $17 (when on sale) http://www.harborfreight.com/6-inch-...per-47257.html

A digital (or dial) indicator for $30 http://www.harborfreight.com/1-inch-...tor-93295.html

 

[SE18]

thanks!!!!!!!!!!!!!!

So I probably need one with a stand like the Youtube shows.

I see now how it is much more useful than for just rebuilding the machine! I wonder how he decided where to measure the bar. e.g. if he would have measured it further out, it might have had a different reading if there was a slight bend to the stock. So I guess measure as close to chuck as possible.

I don't have a 4-jaw-chuck yet so I assume my 3 jaw chuck will always keep things centered perfectly

So now it's back online to hunt for a dial indicator with a stand

Edit: looks like this one comes with the base, actually looks like sold separately

http://www.harborfreight.com/1-inch-travel-machinists-dial-indicator-623.html

 

[SE18]

placed my order; by next week, I'll most likely start a thread in the lathe section on rebuilding the 9A. I'll document the entire thing

BTW, I found it interesting that the 9A is also called:

Bench lathe
hobby lathe
horizontal motor driven lathe
screw cutting lathe
back-geared lathe
workshop lathe

and a few others.

Did find my serial # 131187 and will look it up shortly

Thanks for all your help; I'm overwhelmed by the friendliness and assistance I'm finding here and hope to share my experiences with others, once I have experiences to share!

 

[Hawkeye]

SE18,

When you get your dial indicator, check your 3-jaw. They aren't perfectly accurate and, especially if used, may have different amounts of runout for different diameters of stock. you could easily find 0.003" of runout in a 3-jaw. There is usually one key location which will give better results than the other two, when you are tightening the chuck.

For jobs that really need to be accurate, a 4-jaw chuck and a dial indicator or test indicator are preferred.

 

[SE18]

thanks, Mike. a 4-jaw is the next item on my to-buy list

if the 3 jaw chuck is off, say, .003 or so, can it be recalibrated or can it still find some sort of usage that would make it worthwhile to keep? Seems 4-jaw ought to come standard with lathes and even drill presses for that matter if they can do everything a 3 jaw can and more

 

[Tony Wells]

3 jaw chucks can often be refurbished, but there are many variables that determine the methodology and practicality, and even the possibility of some. I see no overriding reasons to attempt a rebuild for 99% of common uses. 0.003 TIR is not that much for most things, and if you can simply chuck the raw material and complete the part in one chucking, there is no appreciable runout to be concerned with. It is only when you need to machine a new feature on a piece that is already machined that must run true, a repair that is done that must be chucked on existing surfaces, or the "other end" of some part that must run true. Honestly, for turned surfaces that are for clearances, 0.003 is of little concern.

If you consistently do work that requires low ruout, you probably should consider switching to a collet system anyway. In many years of commercial machine work, the default TIR on the drawings was 0.005 UOS. The specifics of certain critical surfaces were called out on details of those features, and typically were 0.002/0.003. Those features more often than not, were machined at the same time, so hitting the requirement was almost automatic. On features on opposite ends of course posed a bit more of a challenge, but usually it was no problem using bored soft jaws to hit the requirement.

In my shop, one of my lathes (the "new one" I call it) has a chuck that hits 0.001/0.0015 consistently. I rarely even check it any more, unless there is a specific requirement. In planning the jobs I do, I habitually run all turnings that need to be close in the same chucking, so there is very, very little runout. On the other hand, another lathe has a little rougher 3 jaw chuck, and I have to knock the job around a little, but can get it within 0.005 with little effort. I have never had a rejected part due to TIR made in my shop. I have 4 jaw chucks sitting on the floor in case I need them, but I don't do much work that I can't do in a 3 jaw. The day will come, but not since I set up this shop in '97. Well, maybe I retract that. I did a job around '99 in another lathe I kept a 4 jaw on. Don't have that lathe any more, so forgot about it.