Analog read out

[Ned Ludd]

What mess?
Ned

 

[Lakc]

Each mark on the dial is .04mm. Took me a second to figure that out myself. If you force yourself to use the dials, you will probably get real good at counting by 4's rather quickly.

 

[steamnut2010]

One of the more confusing things I have had to learn as a newby is how to use the dials on the lathe and mill.

I started out with the eyeball method, and then used calipers to see how close I was every so often. This method definitely does not work well.

Then I started using the crossfeed dial, but that was way off for some reason. Then I figured out that on my lathe, 0.001" on the crossfeed dial will cut 0.001" off of both sides of a round piece, for a total cut of 0.002".
I have read machining books, but lathe types vary, and dial types vary, and until you get in there with some test (hopefully inexpensive) stock, it is hard to get a feel for your equipment.

Then I started looking at the lathe carriage dial, confident that it was just like the crossfeed dial (not!). It measures in 0.004" increments. Who makes these darn things and what were they thinking?

So here is what I do, and I am not sure if this is correct or the best way to do it, but a newby-made-up way, but I rough a piece out and get a size approaching what I need. Then I rotate the crossfeed handle to make a light cut, and set the crossfeed adjustable collar to zero when I do this.
I then measure the work with a micrometer or a good caliper.
Lets say I measure the diameter of the work at 2.35", and I want 2.25" for a final diameter, then I use (2.35-2.25) divided by 2 or turn the crossfeed dial in by 0.05, or 50 increments on the dial that has 0.001" increments.

 

[steamnut2010]

I actually turn the dial slightly less than 50 increments, since it is not easy to un-cut a piece once it is too small. Also, I noticed that once you polish a piece, the piece gets slightly smaller, and for a critical fit, this is no good.

For the carriage dial, I again make a fine face cut, and then set the carriage adjustable collar to zero.
I measure the thickness of the piece in the chuck, and assuming the same dimensions as the first example, say the piece measures 2.35" thick, and I want to face it off so that it is 2.25" thick, then I take 2.35"-2.25" = 0.1"
Divide 0.01" by 0.004" which equals 25 increments you have to turn the carriage dial. Since the carriage dial is making a face cut off of one side of the material only, unlike a rotating cut on a round piece, then you do not need to divide by 2.

One website suggests that if you need a fine final cut on the crossfeed, set bit where it touches the work (not while it is running), and then use a piece of shim stock between the carriage stop and the carriage, say 0.001".

I have to remember to remove the carriage stops, otherwise I jam the carriage shortly after the above step.

I highly recommend a newbie go through the steps to learn the dials using some test stock. It is a pain, but a very valuable learning step. Now, I can start with a rough piece of stock, make a few rough cuts, set the dials as described above, and bingo, I am spot-on. The time to make an accurate cut is reduced by a factor of at least 10, not to mention it is much more enjoyable to take the guesswork out of it, especially when using expensive stock like brass.

 

[mklotz]

Then I started looking at the lathe carriage dial, confident that it was just like the crossfeed dial (not!). It measures in 0.004" increments. Who makes these darn things and what were they thinking?

It may be that you have a metric screw and a dial marked off in (approximate) Imperial graduations.

A 1 mm pitch screw would advance 0.03937" in one revolution. Divide that by 100 marks on the dial and you have 0.003927" per mark. Now, round that off and you have 0.004" per division.

This means that the dial is in error by 0.04-0.03937 =~ 0.0006" per revolution or six thousandths in ten revolutions.

You can check the pitch of the screw with a pitch gage or, alternatively, put a DI on the carriage and see how far off it is in ten revolutions of the handle.

 

[steamnut2010]

So now, confident in my newbie method of using the dials on the lathe, I try to use the dials on the mill.
Surprise surprise, yet again another system for the mill dial, with a range of 0 to 12.5.

I always expect the dial to read 0-10 for some reason.
I have learned to ignore the total dial range, and pay attention to the increments, i.e. each mark on the dial equals either 0.001" or mm, or 0.004" or mm, and pay attention to whether you are cutting off of a diameter of a round piece, or making a face-type cut.

Then just use the procedures above, and dial in the correct increments.

Another thing I had to practice on (with inexpensive stock) is keeping track of my decimal places. At first I would calculate a dial rotation of say 20 increments, and would rotate only 2, or vice versa.

Anyone newbie can sit down and master the dials in an afternoon.
Make notes and hang it next the the machines until you have it memorized.

 

[steamnut2010]

The vetran guys have used the dials for so long that they don't even think about exactly what they are doing. It is just natural for them, but I can vouch for the fact that the first time you do it, it can be awkward.

 

[steamnut2010]

The mess in your photo is actually much cleaner than when I started out.
I did not even know you were suppose to be neat and organized until I saw photos of other people's lathes.
Neatness has been a learned thing for me, but it makes it easier for me to be neater.

 

[steamnut2010]

From a previos post:
It may be that you have a metric screw and a dial marked off in (approximate) Imperial graduations.
A 1 mm pitch screw would advance 0.03937" in one revolution. Divide that by 100 marks on the dial and you have 0.003927" per mark. Now, round that off and you have 0.004" per division.
This means that the dial is in error by 0.04-0.03937 =~ 0.0006" per revolution or six thousandths in ten revolutions.
You can check the pitch of the screw with a pitch gage or, alternatively, put a DI on the carriage and see how far off it is in ten revolutions of the handle.


Pardon my ignorance, but just a newbie trying to understand.
If he rotates the dial by 0.002mm, then he should get exactly a 0.002mm cut, right.
For metric threads, wouldn't that be accounted for in the gear ratios, not the dial?

 

[Deanofid]

Marv, did you notice the dial says:

Ø 0.04mm

This is a direct readout dial. Whatever you dial in will be how much comes off the diameter of the work piece in increments of 0.04mm.

That's confusing for people who are used to working with dials that normally tell the movement of the slide, which is probably how all the other measurements read out on the other dials of this machine, and on your mill, too.
Now I can see why you want some dial indicators to mount to your lathe! It makes things difficult when all the dials aren't calibrated the same way. Some of these importers should be thrashed!

Dean

 

[mklotz]

Dean,

Yes, I noticed. However, as the quote in my post shows, I was addressing steamnut's comment in post #22 about how he found it curious to have a dial marked in 0.004" divisions.

Some of the importers build their products to metric standards and then, for export to the USA, slap dials with imperial calibrations on them. As expected, the results are not pretty.

 

[student_Machinist]

Some of these importers should be thrashed!

Dean

I agree completely :bow: The only reason i got these was that i was i got a scholarship from school to get a lathe and mill and these were the only available tools at the time for the right cost

The mess in your photo is actually much cleaner than when I started out.
I did not even know you were suppose to be neat and organized until I saw photos of other people's lathes.
Neatness has been a learned thing for me, but it makes it easier for me to be neater.

thanks ;D i'ts been almost 4 years since i got them and i still havent worked out good storage or workbench.
I'm going to have to raise the lathe and mill about a foot as the stands they came on are way to short for me. does anyone know a good way to do this?

 

[Deanofid]

Marv, I didn't mean your previous post was incorrect. I just wondered if you had noticed the diameter
symbol on the dial.

If this dial had simply been marked with a radius cut, like many lathes, the divisions would read in 0.02mm, and could have been marked in easy to add slash marks in 10's.

I once owned a lathe that had a mix 'n match dial/leadscrew typical of some far east stuff. The dials read out in .0625" rotations. I think that lathe made me the ornery person I am today. Drove me mad, too.

 

[Deanofid]

The only reason i got these was that i was i got a scholarship from school to get a lathe and mill and these were the only available tools at the time for the right cost thanks

You don't need to make excuses for it. There's nothing wrong with the lathe. It just has a non-machinist friendly cross feed dial. You might be able to buy a dial for it that is graduated in 0.02mm. At least it would be easy to add up the ticks.

Dean

 

[steamnut2010]

Maybe this is a dumb question, but then again, no one has ever accused me of being smart.

But why do they not use the same dial increments on all dials, say 0.001 inches, or 0.001 mm, and have all dials read from 0 to 10?

I remember asking a question in grammar school about why they had the words "to", "too" and "two", and all sounded like "to".
Also "knot", "not", you get the idea.

There must be a locical reason such as the dial gets too big or something.

 

[Groomengineering]

Not a dumb question at all. Acme screws on imp. machines are fairly coarse so marking out .001" is fairly easy. Metric thread forms are usually quite a bit finer, .001mm marks would be extremely close together. Metric pitches are also based on a ratio to diameter of the screw instead of a 'real' number i.e. 1/2"dia-18tpi. That's why the dials don't end up 1-10.

Cheers

Jeff

 

[steamnut2010]

Groom-

I think I followed you up to the "That's why the dials don't end up 1-10" point, then I got lost.

I will try again:
My lathe has 0.001" increments on the top dial, and 0.004" increments on the lower carriage dial.
So are you saying they use 0.004" on the lower dial because otherwise, there would be too many increments for the dial.
Why not make the dial larger? Maybe they want to just build one dial for all parts?

When people start taking about screw pitch, I think in terms of gear ratios, and setting the knobs on the left side of the machine to drive the carriage at the correct speed for the desired thread pitch.
But I don't see the connection between the gears and the dials. I can dial any dial at any time independent of the gears, and indeed, some lathes have no gear cutting threads at all.
So how are threads per inch related to dials?

For an example, if I want to cut off 0.1" off of a piece, I just turn the dial the correct number of increments to get a 0.1" cut (that may be a hypothetically large cut). So why not, as with engineering scales, just have the scale run from 0-10?
What you must be getting at is the relationship between the thread on the dial shaft and the reading on the dial collar?
The dial collar readout, ie: 1-10, or 1-12.5, etc. is tied to the thread pitch used on the dial shaft, is that what you are saying?

It's all as clear as mud, but I think I am making progress.
Thanks for your help in understanding.
I guess it should be obvious, but it is not.

 

[steamnut2010]

Here is a photo of my upper dial (crossfeed dial?), not to be confused with the upper dial called I think the compound rest dial.
It appears to have a range of 1-10, increments of 0.001", and also has a separate dial for simultaneous metric measurement.

The photo of the lower dial has increments of 0.004", a range of 0 to 0.58?, and does not have the metric thread.

So if I am looking at it correctly, you can have a range of 1-10 on the upper dial, but not the lower?

Questions, questions.

 

[kvom]

The lathes I used in school don't have DROs. To measure along the Z (carriage axis) we use a DI attached to a "MightyMag" holder. For measuring travel greater than the 1' range of the DI, use a 123 block as a spacer.

As an example, suppose you want to turn down some stock for a length of 3.5". Position the carriage at the right end of the stock. Now, position the DI/magnet against the carriage with the tip slightly depressed and zero the DI dial. Move the carriage left .5" by watching the DI needle turn 5 times back to 0.

Then hold the 123 block with the 3" length against the side of the carriage and position the DI/magnet so that the tip is depressed less than 1 full turn (i.e., less than .1"). Zero the DI dial.

Now when you turning down the stock, you can use the DI needle as an indicator as to where to stop. As soon as the needle starts to move, slow down and gradually approach the 0 mark.

This use assumes that there is a spot on the lathe bed or headstock where you can place the DI and magnet parallel to the bed.

 

[Groomengineering]

Sorry to muddy it up! ;D

The dial collar readout, ie: 1-10, or 1-12.5, etc. is tied to the thread pitch used on the dial shaft, is that what you are saying?

Yes. The pitch on the feed screw sets the actual movement and the dial has to be marked to accommodate it. From your pics it looks like the "lower" dial is the carriage traverse dial? If so it probably runs a gear on a rack on the side of the bed. My SB doesn't have a dial on that handle, but the feed is fairly coarse so that .004" per mark sounds right. Again, the dial has to accommodate the actual movement so it's not always pretty.

Hope this makes some sense, explanations are not my strong suite. ???

Cheers

Jeff