Lathe alignment question

[bowseruni]

I ended up getting a secondhand Hafco AL-340A, yes it's chinese but has coolant, brake and work light plus some tooling and under $2k. Plan to use it for a while then upgrade to something better when the finances are right, I don't think I will lose out.

anyway, i'm in the process of levelling and aligning it and wanted to check i'm on the right path.

So far I have levelled it with a digital protractor and across the bed it's spot on at 0 deg both tail and head ends, along the bed the headstock end is slightly higher but this allows the coolant to drain back.

anyway, I'm in the process of aligning the headstock using rollies dad's method (known lathe alignment technique) using a 400mm length of 38mm hydraulic cylinder rod which ran out even in v blocks.

horizontally I have adjusted the headstock adjuster bolts so the near end gives +2/-2 thou and sliding to the end of the bar gives +10/-10 thou. I'm thinking this is correct as it gives 0/0 to the bed.

Is this right?

anyone got a proper test bar they want to lend?

[cba_melbourne]

Congrats to the new lathe.

How do you level a lathe "with a digital protractor"? I only ever seen this done with a spirit level. You need something able to resolve close to about 0.1mm/m

Please do NOT touch the headstock bolts, before you are 100% sure what you are doing and what the consequences are. On some lathes, touching the headtock adjustment opens a can of worms.

[Stustoys]

Hi

Congrads on your new lathe.



using a 400mm length of 38mm hydraulic cylinder rod which ran out even in v blocks.


If you're adjusting the headstock its not RDM(though the list what "RDM"s is seems to be growing daily). Anyway*, RDM isn't for lathe alignment, its for accurate misalignment. RDM assumes certain things, If you've moved the headstock you no longer have one of those things. So you have to start over with a level bed. Level in the 0.1mm(or better) per meter sense. What your digital protractor? 0.1 degree? thats (I think) 1.7mm per meter

Though just how fussy you need to be depends on just what you are going to be making and how accurate that needs to be?


Stuart

*As I understand the what I believe to be the original purpose of RDM to be

[bowseruni]

thanks guys, it got the better of me, made some adjustable bolt down feet today and bolted it to the floor and got it perfectly level with the digital angle finder (across and along the ways).

Adjusted the head stock so the bar gets -4/+4 thou near end and -10/+10 thou at far end 10" out which from my understanding of RDM means it's true.

plan on ordering a 3MT test bar to fit in the tail stock and align it.

is not perfect but i'm not planning on turning bits for NASA just yet, will get the tail stock aligned then spend the money on a precision level and get it fully dialled in.

[simonl]

Congratulations on the new lathe. Since you are reasonably happy with your alignment job, Put a piece of 2" bar in the 3 jaw and take some very light cuts along about 100 - 150mm length. Then measure the diameter at each end. If it's parallel then you have done well.

Simon

[bowseruni]

using the tail stock Simoni?

i ordered a test bar last night and still have to align the tail stock as i'm guessing its now out with the headstock changes made

[cba_melbourne]

using the tail stock Simoni?

i ordered a test bar last night and still have to align the tail stock as i'm guessing its now out with the headstock changes made

That was not a good idea to undo the headstock alignment. The headstock only needs alignment if the lathe had some sort of accident, was dropped in transit or the like. Especially on a brand new lathe, there is absolutely no reason to undo the headstock alignment. I wolud go as far as to say, if the Headsock on a brand new bench lathe is off, return it to the seller for a warranty exchange.

Now that you have misaligned the headstock, you will need some tools to get it right again. The first thing that you need, is probably to read a good book like Georg Schlesinger's "testing machine tools". Then you need to borrow or buy a reasonably accurate "machinist's level" to level the lathe bed to at least better than 0.02mm/m, that is an absolute pre requisition to put the headstock alignment bach where it was when new. Next you need a test bar to fit directly into the spindle taper, do not use a sleeve. And a magnetic stand with a reasonably responsive (not gunked up) DTI.

The Rollie dad's method is NOT suitable for headstock alignment, it is only intended as a shortcut method to untwist the bed when no accurate level is available. The RDM method relies on the headstock being already properly aligned. It actually uses the headstock alignment as the reference to untwist the bed. Also forget your "digital protractor" - I assume its one of these alarm clock sized things with only half a degree resolution. You need something 50 times more accurate than that for lathe alignment.

[pipeclay]

Do you intend to look for the mentioned book or a machinists level?

I take it you have some type of dial indicator,do you also have a micrometer?

Seeing that you have already adjusted the Headstock it may need to be re adjusted.

With your piece of rod in the chuck was there any great variation when traversing in the horizontal with your indicator mounted on the top of your bar,if not you could say that the Headstock is sitting flat on the lathe bed.

If there was a significant amount over your test piece then there may be crap under the Headstock,if no crap you may need to shim it to get it running parallel to the bed.

If it is all good I would suggest putting a piece in your chuck as suggested and turn the OD for the suggested length and then measure and see if there is any taper.

If there is a taper then you will need to adjust the Headstock to remove it , by using the pushme/pullme screws.

If this is the case just crack the Headstock hold down screws and then adjust.

After you get the Headstock cutting reasonably well without to much taper or none at all,mount your bar between centres and do a test cut.

If there is a taper present then adjust your tail stock to reduce or eliminate it.

[simonl]

Do you intend to look for the mentioned book or a machinists level?

I take it you have some type of dial indicator,do you also have a micrometer?

Seeing that you have already adjusted the Headstock it may need to be re adjusted.

With your piece of rod in the chuck was there any great variation when traversing in the horizontal with your indicator mounted on the top of your bar,if not you could say that the Headstock is sitting flat on the lathe bed.

If there was a significant amount over your test piece then there may be crap under the Headstock,if no crap you may need to shim it to get it running parallel to the bed.

If it is all good I would suggest putting a piece in your chuck as suggested and turn the OD for the suggested length and then measure and see if there is any taper.

If there is a taper then you will need to adjust the Headstock to remove it , by using the pushme/pullme screws.

If this is the case just crack the Headstock hold down screws and then adjust.

After you get the Headstock cutting reasonably well without to much taper or none at all,mount your bar between centres and do a test cut.

If there is a taper present then adjust your tail stock to reduce or eliminate it.

Basically, what PC said. Don't worry about your tail stock, it's neither here or there, for now. Any adjustment on the head stock is a complete waste of time unless you have your bed levelled to a degree of precision achieved using a precision level.

I agree with CBA, you probably shouldn't have loosened your head stock, but it's done now so you need to align it anyway.

Cheers,

Simon

[bowseruni]

thanks guys, will get a machinist level and get it levelled before worrying about the tail stock. I was planning on doing this just not straight away.

also, it's not a new lathe, it's a secondhand 2002 (from memory) Hafco AL340A (no longer sold), I have no idea of its history. I'm not too worried about adjusting the headstock, yes i haven't done it before but with the right tools and information i'm more than competent at getting it sorted. For what I plan on using it for I'm not too worried if it's not the most precise lathe in history, i'd be happy to get it back to OEM spec or slightly better.

Yes i have a micrometer and a DTI. The bar I was using didn't change over the 10" in the vertical plane indicating the headstock is parallel to the ways in the vertical plane (not much bed wear).

I have also been stripping and cleaning it up as there was excessive backlash in the cross feed and very sticky in the cross feed and tailstock, these are heaps better now

[bowseruni]

I'll go into a little more detail of the process used so far.

bolted the lathe to the floor

levelled to 0.00 deg across and along the ways (yes it's not a machinist level but best I had in the shed at the time - plan on getting a machinist level and getting it spot on)

installed 38mm polished hydraulic cylinder rod in the 3 jaw chuck, tightened it evenly. measured diameter to be even using digital verniers (yes not the best but didn't have micrometer big enough yet), set the DTI to dead centre of rod at jaws. tested runout as close to jaws as i could, was 4 thou at two opposing spots (ref them zero spot 1 and 2) on the bar indicating it had a slight bend, adjusted it even +2/-2 at point 1 zero spot, traversed 10" up the bed taking note of variance to point 1 zero on the DTI, checked runout again taking note of +/-, added them together to get a reference for how many thou it varied from the chuck measurement.

repeated for the second zero point on the bar, averaged the two measurements. adjured the headstock adjustment bolts to give equal +/- at 10".

repeated many times. Now when I set the chuck DTI reading at 0, traverse along 10" at point 1 zero the DTI doesn't change, and for point 2 zero it also doesn't hang from 0 and both have equal +/- runout of 10 thou.

repeated the same for vertical and got the same runout at chuck and 10"

besides not using a machinist level to get it level, is there any problems with this process of headstock alignment?

The lathe only came with a 3MT dead centre and no 5MT-3MT collar for the head (3MT tail, 5MT head) and I currently don't have a 5MT dead centre so have no way of mounting the test bar between centres until I get one.

[pipeclay]

Not sure what you mean about checking at opposing jaws ( it is a 3 jaw ) or do you mean at opposing points.

How much runout is there in the 3 jaw chuck.

Are you able to use a 4 jaw chuck ?

May be with your aligning of the headstock you have centred your 3 jaw chuck.

Are you able to put another piece of round material in the chuck and re check it ( not the same piece you already used.)

You can place a piece of material in your 3 or 4 jaw chuck and turn a 60 degree point on that and use that as your Headstock centre and run the drive dog for your work piece off the chuck jaws.

Have you machined along the length of a piece of material yet to see if there is a taper.

[steran50]

I'll go into a little more detail of the process used so far.

bolted the lathe to the floor

levelled to 0.00 deg across and along the ways (yes it's not a machinist level but best I had in the shed at the time - plan on getting a machinist level and getting it spot on)

installed 38mm polished hydraulic cylinder rod in the 3 jaw chuck, tightened it evenly. measured diameter to be even using digital verniers (yes not the best but didn't have micrometer big enough yet), set the DTI to dead centre of rod at jaws. tested runout as close to jaws as i could, was 4 thou at two opposing spots (ref them zero spot 1 and 2) on the bar indicating it had a slight bend, adjusted it even +2/-2 at point 1 zero spot, traversed 10" up the bed taking note of variance to point 1 zero on the DTI, checked runout again taking note of +/-, added them together to get a reference for how many thou it varied from the chuck measurement.

repeated for the second zero point on the bar, averaged the two measurements. adjured the headstock adjustment bolts to give equal +/- at 10".

repeated many times. Now when I set the chuck DTI reading at 0, traverse along 10" at point 1 zero the DTI doesn't change, and for point 2 zero it also doesn't hang from 0 and both have equal +/- runout of 10 thou.

repeated the same for vertical and got the same runout at chuck and 10"

besides not using a machinist level to get it level, is there any problems with this process of headstock alignment?

The lathe only came with a 3MT dead centre and no 5MT-3MT collar for the head (3MT tail, 5MT head) and I currently don't have a 5MT dead centre so have no way of mounting the test bar between centres until I get one.

HI,
Just one thing when you say you are Levelling across the Ways of the Lathe Bed. Make sure that your Level is not touching the 'V' of the Bed. A good way to avoid this is to use two 1-2-3 blocks and sit them on the flats of the Lathe Bed and Level across them. Good luck with it.

[Stustoys]

The Rollie dad's method is NOT suitable for headstock alignment
No argument there.



it is only intended as a shortcut method to untwist the bed when no accurate level is available.
Not as I understood it. RDM method is for making a worn but level lathe cut parallel by twisting the bed. The name has since be applied(or misapplied) to just about every lathe alignment technique I have seen, including the "two collar method" which has been around since year dot.

Stuart

[bowseruni]

been in the car all day so haven't had a chance to cut a test piece yet and thanks for the tip on not being on the bed V when levelling, will keep that in mind when I source a precision level.

a couple of questions (may seem basic but i'm learning)

what is the best way to test chuck run out?
good source of online lathe accessories (chasing a 5MT dead centre and precision level amongst other things)?
and a loaded question, what is the best way to align a headstock assuming it is levelled?

[pipeclay]

If you have a piece of ground stock place it in the chuck and rotate it with an indicator touching it,you could use a drill without a damaged shank or end mill or slot drill.

But if you have already adjusted the headstock this reading May or not be correct for the chuck.

It would be better to turn a piece of material and see if there is a taper in it,if so then you may have to adjust the headstock left to right to correct.

No real need to chase a M/T 5 spindle taper as these machines use an M/T 5/3 sleeve.

Best source of online stuff would be eBay or similar or international tooling suppliers.

[cba_melbourne]

Not as I understood it. RDM method is for making a worn but level lathe cut parallel by twisting the bed. The name has since be applied(or misapplied) to just about every lathe alignment technique I have seen, including the "two collar method" which has been around since year dot.

Stuart

Hi Stu,

I think this is the original document on the "Rollie's Dad's Method of Lathe Alignment" from 2001. Before it was applied(or misapplied) to just about every lathe alignment..... The idea was to setup a lathe without owning a precision level and a test bar.

http://www.neme-s.org/Rollie's_Dad's_Method.pdf

[.RC.]

I feel like I am having deja-vu..

[Stustoys]

Hi Stu,

I think this is the original document on the "Rollie's Dad's Method of Lathe Alignment" from 2001. Before it was applied(or misapplied) to just about every lathe alignment..... The idea was to setup a lathe without owning a precision level and a test bar.

http://www.neme-s.org/Rollie's_Dad's_Method.pdf
I'm pretty sure the first mention of RDM I saw was from those guys. Though I recall a nice little story to go with the method. But as I cant find a link I guess its besides the point.


I feel like I am having deja-vu..

Now that you say that you may well be right. lol

Stuart

[PDW]

I feel like I am having deja-vu.. Unfortunately yes but this always happens on forums after a while.... PDW

[Jekyll and Hyde]

I feel like I am having deja-vu..

And I feel like a fortune teller - I could see where this thread was going to go right from the first post :doh:

[bowseruni]

And I feel like a fortune teller - I could see where this thread was going to go right from the first post :doh:

Armchair experts like yourself really get me, i'm sorry i'm not an expert on lathe alignment and thought this forum would be a a good place to learn, not receive smartarse comments like yours.
Don't bother posting if your not posting something constructive to help out and thanks to the guys who have actually posted useful information.

if this has been covered before why don't you summarise the previous threads and get the mods to make it a sticky, rather than throw comments from the peanut gallery.

[PDW]

if this has been covered before why don't you summarise the previous threads and get the mods to make it a sticky, rather than throw comments from the peanut gallery. Because you end up with a full page of stickies which is a big PITA. You might have lucked out and not screwed your HS alignment, it's hard to say. However RDM is a *kludge* and is widely recognised as a kludge, not the technique you should use first up. There are copies of Schlesinger and Connelly out there on the net, it'd be a really good idea to download *and read* them before altering anything else on your lathe. Level the lathe, then turn a bar (big diameter, aluminium is good) doing the 2 collar test, then use a good micrometer reading to 0.0001" or metric equiv to measure the collars. If they're the same size or very close to it, buy a lottery ticket and don't screw with anything. PDW

[janvanruth]

Forget about the precision level.
Unless you want to scrape the ways its a waste of money.
All you need is a ground testbar with the apropriate morsetaper and a, or several in different length, round, true bar centerdrilled at both ends.

The purpose of a lathe is to make round and true non-tapered objects.
Unless your headstock bearings are shot all objects turned will be round.

If your carriage moves in a straight way, horizontal and vertical, all objects turned will be true.

If your carriage moves true to the center of the spindle there will be no taper.

Wear in the ways will affect trueness and taper.
Levelling the ways lengthwise and crosswise will not give you better trueness or taper.
It will not compensate for wear as wear will not be consistent over the entire length of the bed.

If a taper is to be avoided turn between centers and adjust the tailstock.

Due to wear in the ways the object will not be true.
Twisting the bed might by lifting one of the four corners of the bed make things better or not.

In turning not between centers the taper might be adjusted by adjusting the headstock in the horizontal and vertical.
As the wear in the ways is not consistent it will only be effective for the distance where the wear is somewhat consistant and not for other distances.
Again lifting one corner of the bed may make things better or not.

You use the testbar to find the relation between spindle and wear of the bed for any given distance.
Realignment of the headstock would have to be done for every given distance away from the chuck.
It is not feasible to do so every time over again.
It is feasible to do for one distance where most turning is done, mostly near to the chuck.
It wil not likely completely take out the taper but will make it less.

You will use the other bar(s) for alignment of the tailstock and finding out where and how much wear the ways have.
Twisting the bed may lead to better results.
The bar will give an idication to what is happening while twisting.

The final proof will always be a testcut where trueness and taper will be checked.

All the above goes unless you are willing to scrape.
While scraping the ways you will need a level.

The tailstock is probably the most important part that has to be adjusted.
Wear of the contact area with the ways will primarily occur on the front side of the tailstock.
Center-hight will drop.
This will lead to problems in centerholding and drilling.
Adjusting the height to the centerheight of the spindle by shimming mainly the front end will be necessary.
Problem will be that for each given distance away form the spindle the ways on which the tailstock slides will have worn differently.
So an adjustement will only be perfect for one given distance. But given that the wear on the ways is relatively small to the wear on the tailstock itself, it will only have minor influence.

Cheers Jan

[bowseruni]

thanks for that, my test bar showed up today, it has a taper to fit my tailstock and measures spot on along the length. Will have a play with it tomorrow or over the weekend depending how much free time I find.

I did manage to take some light cuts on a 1" MS bar, it tapered 0.003" over 150mm (larger dis at tailstock end) so there is work to be done. Pretty sure I have found a mate who has a decent level that I can borrow

[.RC.]

Armchair experts like yourself really get me, i'm sorry i'm not an expert on lathe alignment and thought this forum would be a a good place to learn, not receive smartarse comments like yours.
Don't bother posting if your not posting something constructive to help out and thanks to the guys who have actually posted useful information.

if this has been covered before why don't you summarise the previous threads and get the mods to make it a sticky, rather than throw comments from the peanut gallery.

The problem is everyone has a different way that may work for them and most threads like this end up getting locked.. Everyone has different expectations and needs and wants so what works for one may not work for another...

I suggest you go searching older articles on model engineering type places..

And remember US styled lathes and UK styled lathes are usually quite different in a critical design and thus have different pitfalls to catch the unwary.... That being the headstock alignment on UK style is adjustable and US type not adjustable..

[Jekyll and Hyde]

Armchair experts like yourself really get me, i'm sorry i'm not an expert on lathe alignment and thought this forum would be a a good place to learn, not receive smartarse comments like yours.
Don't bother posting if your not posting something constructive to help out and thanks to the guys who have actually posted useful information.

if this has been covered before why don't you summarise the previous threads and get the mods to make it a sticky, rather than throw comments from the peanut gallery.

Don't own an armchair, and not a great fan of peanuts.

My comment was in reference to the fact you used the phrase 'Rollies dad's method', no more, no less. If you'd like to see where your thread will end up, just search that phrase on this forum, and you'll see the argument about its purpose and validity is just getting started...

[.RC.]

OK I will elaborate on my first post and get the ball rolling :D

How I would do it...

Since you said you have "realigned" the headstock it only leaves you with a few options to get it back right... Totally ignore any of these "two collar tests" and other like that... They are designed for US type lathes where the headstock sits on V ways and is unadjustable.. Like a Hercus for example..

In my opinion your only option now is to get a level and get any twist out of the bed through the levelling screws... Does not have to be perfect..

Since you most likely will not have a test bar for the headstock and no sleeving a test bar does not work good enough for me you are left with the cut and try method...

so a bright steel bar say 40mm diameter or more, 150mm or so poking out the chuck, make two collars on it and take very light test cuts using a sharp HSS tool ..keep adjusting until you get it within your satisfaction.... Do not try for perfection, the further most end from the chuck can be smaller then the chuck end. It will be frustrating as all hell to do...

Now align the tailstock in your usual fashion...

Job done, use the lathe..

[pipeclay]

After you have machined an undercut on the bar, set your depth of cut on the outer end, finish the cut and without moving the tool depth traverse to the end and cut that, then measure.

Make the undercut deep enough so you can do numerous passes

[janvanruth]

After you have machined an undercut on the bar, set your depth of cut on the outer end, finish the cut and without moving the tool depth traverse to the end and cut that, then measure.

Make the undercut deep enough so you can do numerous passes

Wouldnt that be like putting two collars on a piece of stock?:roll:

[pipeclay]

Yes,only reason I would think you would shrink collars on would be if your stock was small diameter.

[PDW]

Wouldnt that be like putting two collars on a piece of stock?:roll: Yes and if you had it, I'd loctite 2 bits of aluminium onto a steel bar and proceed. PDW

[Oldneweng]

Two sections 150mm apart to machine and compare. The relieved area between these two sections is only to minimise tool wear and so get as close to the same result as possible so that any variation can be attributed to lathe adjustment/accuracy.

Dean

[Ueee]

After doing the above in steel several times i would highly recommend using ally or even an engineering plastic. Trying to get good consistent cuts in steel is very hard especially that far from the chuck. All but (and sometimes even) the sharpest HSS tool will push the stock away.
Any searching for RDM or alignment will lead you to one repeated fact, and here it is again, do not touch your headstock alignment! 99% of the time it ends up that there was another error at play and then you have to chase you tail for ages to get the head back into alignment and probably only get it 80% as good as it was. Remember that head was aligned whilst the bed was brand new and there was no wear to contend with.

Ew

[steamingbill]

................. even an engineering plastic. ............................

Ew

Ew,

Wow. Thanks. Never even thought of that.

Bill