Lathe set up

M

Matt P

New member
Hi
This may have been covered before, I searched but couldn't find anything. I have just bought a new lathe, so far I have unpacked it, read the instructions and put a piece of
1" stainless rod between centres and made a cut of 0.010" and measured the bar at the head stock and then at the tail stock (about 8" apart), the tail stock end measures 0.001" bigger.
What do I do to rectify this ???
Is this to do with tailstrock alignment ??
Thanks and sorry if this is a stupid question.
Matt P
 
Matt P said:
Hi...........
Thanks and sorry if this is a stupid question.
Matt P
Click to expand...

PUhlLEEEEEZE!!!!

THERE IS ONLY ONE STUPID QUESTION!!!!!

The one you neglected to ask :)

What brand of lathe? What does the setup manual suggest? Does it have a stand or is it benchtop? Do you have a machinists level?

Does the lathe have an adjustable tailstock? (If you look outboard or on the "back" it may have a little kindofa' scribed ruler. This is too gross to be much good but it indicates adjustability....)

The thing is...... a lathe can be trued up a number of ways. (liddle punnage there) Once you fiddle with it enough you'll learn how to make it cut straight but in the mean time it's daunting. An experienced machinist can set one up twisted on a slope in Alaskan permafrost, where a new guy will chase his tail in a heated concrete slab. In my opinion there's no quick and easy 'fix' here. You'll have to go through an elimination process, an experimentation process.

My first suggestion is to check the base for solid footing and for adjustability. Your ways are probably slightly twisted. It's quite unlikely that your floor is perfectly level. One really quick check is just to rock the lathe corner to corner, are all the feet down?

Next is to check for tailstock adjustability.

More description... size? Brand? will help.

Once you've established your main areas of adjustability there are guys here who can walk you through a setup, establish a method, much better than I can. I'm just answering you because it's late. :)

I'll hazard that within a couple days you'll get your answers and be cutting straight............... until the lathe settles in and you have to do it again!

Fun stuff :)

al
 
alinwa said:
PUhlLEEEEEZE!!!!

THERE IS ONLY ONE STUPID QUESTION!!!!!

The one you neglected to ask :)

What brand of lathe? What does the setup manual suggest? Does it have a stand or is it benchtop? Do you have a machinists level?

Does the lathe have an adjustable tailstock? (If you look outboard or on the "back" it may have a little kindofa' scribed ruler. This is too gross to be much good but it indicates adjustability....)

The thing is...... a lathe can be trued up a number of ways. (liddle punnage there) Once you fiddle with it enough you'll learn how to make it cut straight but in the mean time it's daunting. An experienced machinist can set one up twisted on a slope in Alaskan permafrost, where a new guy will chase his tail in a heated concrete slab. In my opinion there's no quick and easy 'fix' here. You'll have to go through an elimination process, an experimentation process.

My first suggestion is to check the base for solid footing and for adjustability. Your ways are probably slightly twisted. It's quite unlikely that your floor is perfectly level. One really quick check is just to rock the lathe corner to corner, are all the feet down?

Next is to check for tailstock adjustability.

More description... size? Brand? will help.

Once you've established your main areas of adjustability there are guys here who can walk you through a setup, establish a method, much better than I can. I'm just answering you because it's late. :)

I'll hazard that within a couple days you'll get your answers and be cutting straight............... until the lathe settles in and you have to do it again!

Fun stuff :)

al
Click to expand...
Al
It's a Tawainese tool room lathe sold by HAFCO in Australia 40" between centres, it has it's own stand and I leveled it but not with a machinist level,it doesn't rock. The tail stock does have adjustments for left and right, there is a scale at the back of the tailstock that is "centred" on the scale. I haven't bolted it to floor as I didn't think with it's weight it would be required.
Thanks
Matt
 
Matt P said:
Hi
This may have been covered before, I searched but couldn't find anything. I have just bought a new lathe, so far I have unpacked it, read the instructions and put a piece of
1" stainless rod between centres and made a cut of 0.010" and measured the bar at the head stock and then at the tail stock (about 8" apart), the tail stock end measures 0.001" bigger.
What do I do .........
Matt P
Click to expand...

Get on your knees and give thanks to our maker.

Seriously, as long as there is no twist in the ways from the headstock to the tailstock, leveling is not that important to accuracy. That said, if you have an on board coolant system, leveling is a consideration in getting the coolant in the pan back to the reservoir.

Whatever surface you are going to set a lathe in home-shop applications, the foundation is going to move, just an issue of when!!!
 
No one said anything about the tail-stock height, most are a bit high when first received and will wear in after awhile. You could take the tail-stock base halves apart and clean the mating surfaces, while your at it make sure the morse taper is clean also. Some of that preservative they use is is pretty solid stuff and can leave you chasing your tail.
 
As Jerry says, being level doesn't matter a whole lot, what does matter is having the entire bed, ways, in the same plane. So how does one determine if the bed is in one plane? The easiest way is to use a precision level and make sure it is level front to back on both ends. Said another way, the level is just a precise way of estabilshing a plane and adjusting the lathe leveling screws so that the entire bed is in one plane. For the same reason as Jerry suggested, I'd recommend getting it roughly level along the bed so that coolent flow works satisfactorily first, then ignore that and get the two ends level front to back.

So, before you adjust anything, either buy, beg, or borrow a precision level, or use some other method (not sure what that would be), to get the lathe ways all in the same plane. Once that's done, you can do some serious measuring to see how the lathe is aligned.

Fitch
 
Matt P said:
Al
It's a Tawainese tool room lathe sold by HAFCO in Australia 40" between centres, it has it's own stand and I leveled it but not with a machinist level,it doesn't rock. The tail stock does have adjustments for left and right, there is a scale at the back of the tailstock that is "centred" on the scale. I haven't bolted it to floor as I didn't think with it's weight it would be required.
Thanks
Matt
Click to expand...

Matt, Which model lathe is it? All the Hafco lathes I have seen have had adjustable tailstocks.........Ian
 
Ian
It's a AL960B and yes it has a adjustable tail stock, big question is which way do you adjust ???
Spoke to mate who works in a machine shop and he suggested doing the same test without the tailstock to try a see if it's the bed twisted or the tailstock out of alignment.
Matt P
 
Matt, If you can get a precision level the first thing to do would be make sure the bed is not twisted by placing the level across the ways at the headstock then move it to the tail stock end and make sure both measure the same......if they don't shim or adjust as required to get both measurements the same. Once you have done this redo the test you did before..........if the diameter at the headstock is larger than at the tailstock move the tailstock away from you, if the measurements are the other way around move the tailstock toward you......Ian
 
Matt, far be it for me to impersonate a machinist, because I am not, but you might try this KISS method.

I measured the round area of my live center, and pulled out a pin gage that matched its diameter (.384). Then I mounted the pin gage in my chuck and zeroed it. Then I ran down to the live center and checked for zero. If not zero, I adjust as necessary.

You could do the same thing with a trusted drill chuck, and a piece of drill rod, you would just have to remove the rod from the chuck and move it to the tailstock drill chuck.

TailstockAlignment.jpg
 
Matt P said:
Ian
It's a AL960B and yes it has a adjustable tail stock, big question is which way do you adjust ???
Spoke to mate who works in a machine shop and he suggested doing the same test without the tailstock to try a see if it's the bed twisted or the tailstock out of alignment.
Matt P
Click to expand...

Matt, you have a very nice lathe, I nearly bought its bigger brother, the AL1000.

You really need to borrow a precision machinists level, and check for twisting of the bed. When you level the machine and ensure there is no twist in the bed, just use it for a couple of months and check it again! Let the lathe(and floor!) settle for awhile, 'cause they can move around a little........

The Hafco Taiwanese machines are pretty good value, I bought one of their mills last year during a sale, and am really pleased with it!

Regards,

Darren
 
Butch Lambert said:
Ron,
You need to check with the ram all the way retracted and after it is extended.
Butch
Click to expand...
Butch,
You are right, the zero will change some. But it seems to change with every method I have tried. I found that this method gets you so close, so quickly, with so little effort.

The turning of a long shaft, as recommended in the books I have read, also suffers from the same errors. But if you extend the quill about the same length every time, the adjustment errors of the quill can be minimized or eliminated. It will change a little bit anyway no matter how you do it, because these machines are not perfect. I have not seen an easier or quicker way. But I am ready to learn.

It can also get you started running down where your problems are.
Ron
 
1" stainless rod between centers and made a cut of 0.010" and measured the bar at the head stock and then at the tail stock (about 8" apart), the tail stock end measures 0.001" bigger.
Click to expand...

That means that theres a .0005 difference in 8". Depending on what that stainless rod was made of, tool pressure could have pushed it more than that.

Thats way beyond any reason for concern. The tailstock center will have that much runout, and misalignment from taking it in and out of the spindle.

Turn your lathe on and run it for a while and it will probably be out the other way. Move the tailstock and it will read something different.

Your carriage has more run out than that.

Ask your self this, what are you going to turn in your lathe that has to be that accurate?

If you need that close of accuracy using your tailstock, you should be prepared to indicate it on every setup and with each operation.

I have programmable tailstocks on my CNC's and relying on them to repeat within tenths, will make a lot of scrap. Anytime you move that tailstock you will not get it back exactly where it was, it just ain't possible.

I know that turning a test bar is the accepted method for truing up a lathe, but keep in mind that in the day when that standard was applied lathes were only expected to turn within about .002-.005

The reality is, if you want to cut that close, under .001 in 8" your gonna have to indicate and fudge it everytime.

As for moving the tailstock over, put an indicator on the center and move the tailstock, 1/2 the measured dia, in what ever direction that you need to. There "usually" are set screws in the front and back of the tailstock, to adjust it over.

Just when you think you have it all figured out, take and cut your test bar, measure, then turn it around and cut it backwards and see if your measurements are the same.
 
Rollie's Dad's Method of Lathe Alignment
http://www.John-Wasser.com/NEMES/RDMLatheAlignment.html
Copyright 1997 by New England Model Engineering Society
What you need
A round bar
The bar length should be about 1/3 to 2/3 the bed length.
The bar should be of one diameter along most or all of its length. If it is not you will need a
micrometer to accurately measure its diameters.
The bar does not have to be completely straight.
Since Rollie has a car repair shop, he uses the shafts from junked shocks and struts.
A dial indicator
The end of the measuring rod should be flat.
A means of mounting the indicator on the cross-slide at lathe center height.
To do a vertical alignment: A means to mount the indicator on the cross slide so it is directly
above (or below) the lathe axis.
A chuck of any type to hold the bar.
Runout in the chuck is not a problem (for the same reason that a slight bend in the bar is not a
problem).
What you DON'T need
A tailstock, perfectly straight bar, a collet or precision chuck or any tool bits.
Applying the method (Horizontal Alignment)
1. Put the bar in the chuck.
2. Mount the dial indicator on the cross-slide at the center height of the lathe.
3. Pull the indicator's measuring rod back by hand (to avoid damage to the indicator) and move the
carrige so the indicator is near the chuck end.
4. Release the indicator rod and, turning the lathe by hand, note the highest and lowest measurements on
the indicator.
5. Average the high an low readings (add together and divide by two) to get the "near end average
distance". If you suspect the bar of not being a single diameter along its length, measure the diameter
and subtract half the diameter from the average to get a corrected "near end average distance"
6. Pull the indicator's measuring rod back by hand to clear any irregularities and move the carrige to the
end of the bar away from the chuck.
7. Release the indicator rod and again, turning the lathe by hand, note the highest and lowest
measurements on the indicator.
8. Average the new high an low readings (add together and divide by two) to get the "far end average
distance". If you suspect the bar of not being a single diameter along its length, measure the diameter
and subtract half the diameter from the average to get a corrected "far end average distance".
9. The difference between the "near end average distance" and "far end average distance" is a
measure of the misalignment of the spindle axis with the ways.
10. To correct the problem, put a piece of paper under the near-side foot at the headstock end of the lathe
(the feet at the tailstock end are sometimes pivoted to act as a single foot). Re-do the measurements
starting at step 3. If the alignment gets better, add more sheets of paper until the alignment is perfect. If
the alignment gets worse, put the paper under the far-side foot at the head end until alignment is
achieved.
Applying the method (Vertical Alignment)
1. Put the bar in the chuck.
2. Mount the dial indicator on the carridge so that it is directly above the center line of the spindle.
3. Pull the indicator's measuring rod back by hand (to avoid damage to the indicator) and move the
carrige so the indicator is near the chuck end.
4. Release the indicator rod and, turning the lathe by hand, note the highest and lowest measurements on
the indicator.
5. Average the high an low readings (add together and divide by two) to get the "near end average
distance". If you suspect the bar of not being a single diameter along its length, measure the diameter
and subtract half the diameter from the average to get a corrected "near end average distance".
6. Pull the indicator's measuring rod back by hand to clear any irregularities and move the carrige to the
end of the bar away from the chuck.
7. Release the indicator rod and again, turning the lathe by hand, note the highest and lowest
measurements on the indicator.
8. Average the new high an low readings (add together and divide by two) to get the "far end average
distance". If you suspect the bar of not being a single diameter along its length, measure the diameter
and subtract half the diameter from the average to get a corrected "far end average distance".
9. The difference between the "near end average distance" and "far end average distance" is a
measure of the misalignment of the spindle axis with the ways.
10. To correct the problem, put a piece of paper under both feet at the tailstock end of the lathe. Re-do the
measurements starting at step 3. If the alignment gets better, add more sheets of paper until the
alignment is perfect. If the alignment gets worse, put the paper under both feet at the headstock end until
alignment is achieved.
Why This Method Works
The bar acts as a circular cam. With a perfectly straight bar in a perfect chuck the bar is concentric with the
spindle axis. Since we don't live in a perfect world there is almost always a slight offset between the center
of the bar and the spindle axis. This offset varies from place to place along the bar due to slight bends
and/or imperfect mounting.
At any place you pick along the bar the center of the "cam" is some unknown distance from the spindle axis.
We'll call this unknown distance 'X'. As you turn the spindle axis the high measurement will be "Bar_radius
+ X" and the low measurement will be "Bar_radius - X". Their average will be:
((Bar_radius + X) + (Bar_radius - X)) / 2 =
((Bar_radius + Bar_radius) + (X - X)) / 2 =
(2 * Bar_radius) / 2 =
Bar_radius
As you can see, the value and direction of the deviation have no influence on the final result. That is why it
doesn't mater if the chuck is accurate or the bar has one or more slight bends.
If the bar is not the same diameter at both places we need to measure the diameters and adjust the readings.
Averaging the high and low readings gives us a reading for the local bar radius. We convert that to a reading
for the bar center by measuring the bar diameter and subtracting half the diameter (a.k.a. The Radius).
Common Error
Some people will find the near-end average distance, turn the lathe till it reads that distance and then move
the carridge down the ways with that mistaken assumption that the reading shouldn't change. That method
will only work if your bar is known to be perfectly straight and the chuck is known to hold the bar in
perfect alignment with the spindle axis. Do not confuse that method with this one.
I learned all this from a fellow member of the New England Model Engineering Society. Join us the first
Thursday of every month at the Charles River Museum of Industry in Waltham, Mass.
 
Align hs first

before checking tail stock to front of chuck alignment--you should check headstock spindle alignment with ways

Chuck up a piece of 3 inch diam aluminum about 12 inches long with 10 inches hanging out of chuck. using sharp toll take light cuts on the 10 inches until it cuts even all teh way around-then mic both ends--if different-the spindle is NOT aligned with ways and to do barrels in the spindle-the spindle needs to be aligned with ways
 
hi all
jim we are talking checom chuck what make's any one think that the jaws are ground true.??
2 cats heads front and rear of head stock,
long ground bar 1/10 tho dial ind and run the length on centers and adjust it true .
then bring up the tail stock with dial ind running on on the chuck or the face of the lathe
and run around the best dead center that you can buy beg steal or borrow adjust left and right
till reading zero .
if it is on left and right but not up and down try the tension wrench method to pull down to the right height
or shim if to low.???
and yes i do have the same lathe and it has been set up like this and there is a slight movement
of the needle on my 1/10 thou dial ind that is hard to see about 10 to 20 mil of a inch hor and vert
lathe is leveled with 2 machinist levels 0.02in1000

regards tasy_ted
ps: i also clocked up my quil on the tail stock it can be done time and a room at the same temp helps
 
Last edited by a moderator:
Chuck does not matter

Tasy

if you are checking for rotational alignment of the spindle with the ways-you would only need a truly ground in chuck if you are using a test bar. That is why I suggested a slug of 3 inch diameter aluminum and turn it with light cuts to keep deformation to a minimum and to establish the axis of the spindle versus the ways!!!! If the piece turns even, then the headstock is aligned with the ways. If out board end is larger, then the axis of the spindle is pointing to rear of lathe. If the turned section is bigger at chuck, then the axis is pointing to the front of the lathe.

Jim
 
The first thing you better do is get the twist out of the bedways!!! Then start checking for skew, etc.

None of this stuff is really critical for barrel fitting. The tenon is only 1"-1.3" long, and you better have a good float for the reamer and that is basically it.

Where some of the crappy looking finishes come in is the cheap ChiCom headstock and its components like bearings.
 
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