Thread: Lathe headstock adjustment

I just faced off the drill press table, and the result is that it is now cupped in the centre by 0.2mm.

First question is, do I try to get it better?

Second question, if the DIAMETER of the table is 285mm, and the cupping is 0.2mm, do I bump the headstock by 0.1mm at the 285mm point? (or 0.2mm?)

My take is that moving the headstock is the absolute last resort unless you know something bad has happened. What alignment mechanism does your lathe have?

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How do you know its the headstock?

Does it turn parallel?

Unless you are saying "I don't care I want the table flat and I will move the headstock back later"?

Originally Posted by caskwarrior

My take is that moving the headstock is the absolute last resort unless you know something bad has happened. What alignment mechanism does your lathe have?

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The headstock is bolted to the bed, (4 bolts) and it has been removed & replaced, and it was never aligned perfectly at the time.

Originally Posted by Stustoys

How do you know its the headstock?

Does it turn parallel?

Unless you are saying "I don't care I want the table flat and I will move the headstock back later"?

I am out of my depth here, so would appreciate an explanation as to what else it might be?
I have never turned a test bar, so I do not know for certain that it does turn parallel.
The lathe is sitting on a steel framed purpose built table, but when I brought it home it was just put on the concrete floor as it was. I guess it might be time to set it up correctly.

If you know it's been messed with then align away but you won't get it right with an active project in the chuck. Also you need some form of test bar to do this easily.

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Lathes are typically set up so that they face slightly concave, there are specs for the expected amount of concavity. The idea is that faced cylinder will stand square on its end rather than rock.

To me a 0.2mm dip across the table of an average drill press (wonky spindle, dodgy chuck, lots of runout) is not a problem.

Trying to realign a bolt down headstock depending on the lathe can be an Alice down the rabbit hole exercise. BTDT. PM me if you are going ahead with a realign.

Originally Posted by ptrott

The headstock is bolted to the bed, (4 bolts) and it has been removed & replaced, and it was never aligned perfectly at the time.

Well have at it then! You can get it turning parallel when you need that.(though there are ways you do not want to try and get it cutting parallel if you are going to tweak the head to cut flat)
Do you have two dial indicators?
Do you really care about 0.2mm?(by all means feel free to say yes, its your table and time)

Originally Posted by ptrott

I am out of my depth here, so would appreciate an explanation as to what else it might be?
I have never turned a test bar, so I do not know for certain that it does turn parallel.
The lathe is sitting on a steel framed purpose built table, but when I brought it home it was just put on the concrete floor as it was. I guess it might be time to set it up correctly.

In a perfect world lathes are setup to cut "cupped". How much? lets not go there.
But its done with the carriage, not the headstock.*

Originally Posted by bob ward

Lathes are typically set up so that they face slightly concave, there are specs for the expected amount of concavity. The idea is that faced cylinder will stand square on its end rather than rock.

To me a 0.2mm dip across the table of an average drill press (wonky spindle, dodgy chuck, lots of runout) is not a problem.

Trying to realign a bolt down headstock depending on the lathe can be an Alice down the rabbit hole exercise. BTDT. PM me if you are going ahead with a realign.

I would like to try to set it up as accurately as possible at some point, so I will PM you at that time, thanks Bob.

Originally Posted by Stustoys

..............
Do you have two dial indicators?
Do you really care about 0.2mm?(by all means feel free to say yes, its your table and time)


In a perfect world lathes are setup to cut "cupped". How much? lets not go there.
But its done with the carriage, not the headstock.*

Two dial indicators, but only one stand, but I can buy another one.

0.2mm on the drill press table didn't overly concern me, just thought it would be an ideal time to tweak the lathe, but it seems not.

I am interested to hear what I can do with two dial indicators though.

I would like to determine how much twist there is in the bed and address that, because there is bugger all chance that it is dead on.

Originally Posted by ptrott

Two dial indicators, but only one stand, but I can buy another one.

Maybe no need.

Originally Posted by ptrott

0.2mm on the drill press table didn't overly concern me, just thought it would be an ideal time to tweak the lathe, but it seems not.

Not not really, but you can get your table flat and then worry about it.
Are you facing from the center out or the outside in?

Originally Posted by ptrott

I am interested to hear what I can do with two dial indicators though.

Well the thought was to mount one in the tailstock and one at the outside Dia, then knock the head around until you had 0.2mm difference between them*.(of course you need to be sure you are 0.2mm better and not 0.2mm worse )
You could do the same thing with a dial indicator on the cross-slide but I'm guessing you will be winding it in and out a lot unless you get lucky.

*I'm liking that idea less now and would likely check it with a single indicator anyway.

Originally Posted by ptrott

I would like to determine how much twist there is in the bed and address that, because there is bugger all chance that it is dead on.

Well the don't be doing the two collar method, or any of the rollie's dad until you get the bed sorted.

The cupping of 0.2mm isn't ideal to me and there has to be something causing it. Before you even consider aligning the headstock you need to make sure that the lathe bed isn't twisted. It doesn't matter if the lathe is not level in the sense that the headstock is uphill or downhill of the tailstock, but the 'BED MUST BE FLAT WITH NO TWISTING'. A level like this https://www.ebay.com.au/itm/Electron...oAAOSwJUdedcja or a machinist level is an ideal if not essential tool to do this with. Here's two links to some video's on levelling a lathe https://www.youtube.com/watch?v=FER3aNLtcPs and https://www.youtube.com/watch?v=yufFBg_NgOA . What make & model of Lathe do you have ?.

Originally Posted by steran50

It doesn't matter if the lathe is not level in the sense that the headstock is uphill or downhill of the tailstock

Yes in theory, but surely you'd use level as a datum, as it's easier to check and there's no advantage to do otherwise.
Only exception I can think of is if it's to be installed on a boat, where a spirit level is useless.

Originally Posted by steran50

The cupping of 0.2mm isn't ideal to me and there has to be something causing it. Before you even consider aligning the headstock you need to make sure that the lathe bed isn't twisted.

Well normally yes. But this case isn't normal, the headstock has been removed. Currently the OP wants to remove the 0.2mm. We(or at least I) am not talking about aligning the headstock, we/I are talking about making the lathe face flat. If you align the headstock there is a good chance it wont face flat. How close it will be is anyone's guess.

Originally Posted by nadroj

Yes in theory, but surely you'd use level as a datum, as it's easier to check and there's no advantage to do otherwise.

Not really, sure your level has to be level*, but that doesn't mean the lathe is.

*assuming you are using a bubble level. with an electronic level you can use any number you like. Though I haven't done the maths on just how good that level is.

I should have worded that better Nadroj. The Lathe bed does have to be flat though ie with no dip or rise along the bed. I am aware Stustoys that the headstock had been removed and then it was refitted.