my new AL960 cutting a taper

[eskimo]

I have leveled the bed across the ways (and best I can length ways... does it really matter if the bed slopes left to right by say a few thou?)

It cuts a 0.001" taper from the tailstock (smallest dia) to headstock (largest dia) over 2 inches. (without use of tail stock....on mild steel bar 1.5" inch dia, 4" long...with just enough material outside of jaws of of chuck to get 2.5 inch of turning)

On the back of the lathe above the motor mounts but on the headstock are 3 cap screws. Are these for aligning the headstock to bed?

the pulley end one is loose. The centre one seems to fixed and the far end one (chuck end) also seems to loose ( i cant get to it as I need to drop the motor out of the way)

[pipeclay]

They will be Pushme Pullme,generally they would come with Lock Nuts to secure them from coming loose.

If you have trouble getting to them without droping the motor you may want to consider changing to Hex head set screws,maybe easier to get an Open ender and Ringy on.

The well also be the Bolts securing the Headstock to the Bed that will need to be cracked so you can do your alignment.

[eskimo]

They will be Pushme Pullme,generally they would come with Lock Nuts to secure them from coming loose.

If you have trouble getting to them without droping the motor you may want to consider changing to Hex head set screws,maybe easier to get an Open ender and Ringy on.

The well also be the Bolts securing the Headstock to the Bed that will need to be cracked so you can do your alignment.

Whats the centre one for?...to pull/push the head but that could be done with just the two outer ones

I am going to get a long series hex drive and replace the short hex in 1/4 socket drive

I might just have to lower the motor rather than take it out..I might even get away with out doing that..I'll see?

[pipeclay]

The Centre screw is probably just there for good measure,from what I can see it serves no other purpose.

[Dave J]

I have leveled the bed across the ways (and best I can length ways... does it really matter if the bed slopes left to right by say a few thou?)

It cuts a 0.001" taper from the tailstock (smallest dia) to headstock (largest dia) over 2 inches. (without use of tail stock....on mild steel bar 1.5" inch dia, 4" long...with just enough material outside of jaws of of chuck to get 2.5 inch of turning)

On the back of the lathe above the motor mounts but on the headstock are 3 cap screws. Are these for aligning the headstock to bed?

the pulley end one is loose. The centre one seems to fixed and the far end one (chuck end) also seems to loose ( i cant get to it as I need to drop the motor out of the way)


Three words "Send it back" or have there tech guy come out and fix it right. This is supposed to be a "Taiwanese quality lathe" and even my Chinese lathe came turning true.
There should have been a spec sheet with the lathe and this will be way out of spec.

If you touch it yourself you void the warranty and will spend many many hours trying to align it. It's just not worth your time to have to do it.

Dave

[.RC.]

could be deflection of the workpiece making the taper.

[simonl]

In my limited experience I find it's best to do as many measurement testing as your skills and equipment will allow before loosening any bolts.

After you take the measurements and the findings agree with your turning results, walk away, have a think of another way to do the test and re-test.

It's amazing what you will think up once you walk away. AND at this stage you haven't needlessly adjusted, voided a warranty or (in my case) stuffed something up!

The old saying of "only fools jump in" is equally relevant with me and engineering!

Have you tried a headstock alignment test such as Rolle's Dad's method? Very quick and easy to set up and test.

Just a few thoughts based on my limited experience/knowledge.

Simon

[krisfarm]

Eskimo
I agree with Dave, ring the agent up and have them come out and align it.
That set up on your lathe is similar but different to my AL1000D. Mine has four allen screws set up in pairs comprising one long one and one short one right next to it,each pair are at the ends of the mounting.In each pair one screw is threaded into the outer part of the mounting and the other screw into the inner part, this enables you to push/pull to adjust and then tighten all four to lock in place. Not the best system but it works in the limited space. There are other screws and nuts that lock the headstock down securly once you have adjusted it.It looks like they have done a similar set up with your lathe but have only one screw the centre one to lock it all up.No screws should be loose,could have come loose in transit.
The amount of taper you have is way too much. I tested my lathe's headstock with a ground bar mounted in a collet with a dial indicator.
Bob

[Dave J]

I looked back at your first post and noticed you never said what tool you where using for the cut, so RC brings up a good point.
Are you using sharp HSS or high rake carbide tips? When doing stuff like this I prefer sharp HSS.

Dave

[lather]

The bolts on my al 960b were tight, but did not place much force on them when checking

isn't the center bolt used as a type of pivot and locking bolt to keep some force on the long adjusting bolts against the surface they push on, to reduce the chance of any movement of the headstock when tightening the headstock bolts.
the center bolt moves the headstock in the opposite direction of the 2 outer adjusting bolts.

One curio noted from your second pic, and is the same on my lathe is that there is no headstock lock bolt near the way, even though there is a threaded hole in the bed.
the manual shows the 4 lock bolt points on the bed.
you can notice the hole at the rear with no bolt.

[eskimo]

could be deflection of the workpiece making the taper.

taking 2-3 thou cuts..I wouldnt have thought that would be a problem on that size bar?

and too late..i have started to adjust

but what is that hole at the rear?

will have a look tomorrow night

[Dave J]

Try to keep it in line with the tailstock when the tailstock is aligned by the marks on it.

Dave

[GDD]

and too late..i have started to adjust



That's a pity. My AL960B cut a worse taper than yours and 100% of the problem was bed twist. Using a variation of "Rollie's dad's method", I got the twist out of the bed and the lathe cut parrallel. I think the problem now will be getting the headstock back to where it was after precision alignment at the factory. I'm sure there is a way to do this but I dont know what it is.

Graham

[steran50]

HI:),
I just had a look at My AL-960 in Reference to the hole in the second Pic, Mine is the same. Eskimo did You try a Lathe Test Bar RDGTOOLS 5MT LATHE PARALLEL TEST BAR | eBay (http://www.ebay.com.au/itm/RDGTOOLS-5MT-LATHE-PARALLEL-TEST-BAR-/290614565947?pt=UK_Home_Garden_PowerTools_SM&hash=item43a9fa5c3b) directly into the Headstock to check the Headstock Alignment Directly from the Spindle ?. I just recently Bought one of the Test Bars in the Link (only took 4 days to arrive) to check My Lathe. I also just Bought one of these 0.001 Dial Indicators Yesterday New Digital Dial 0.001mm Dial Indicator Range 25.4mm Guage Caliper | eBay (http://www.ebay.com.au/itm/New-Digital-Dial-0-001mm-Dial-Indicator-Range-25-4mm-Guage-Caliper-/160685752226?pt=LH_DefaultDomain_15&hash=item25699dffa2) so as I can check My Headstock Alignment.

I will be interested in Hearing how you Go as I am sure will other AL-960 Owners. Good Luck with it Eskimo.

[pipeclay]

That's a pity. My AL960B cut a worse taper than yours and 100% of the problem was bed twist. Using a variation of "Rollie's dad's method", I got the twist out of the bed and the lathe cut parrallel. I think the problem now will be getting the headstock back to where it was after precision alignment at the factory. I'm sure there is a way to do this but I dont know what it is.

Graham
It would appear if the lathe had been precision aligned that they must of forgot to precision tighten the screws.
Its not a big drama setting the head it just takes a little time,.001" taper is not much over that short distance to chase.

[pipeclay]

When you come to check the alignment you may be better off try to cut a longer piece of material un supported.
I would try for a bit at least 300 long.
Will be easier to see how much your moving the head with the indicator,at 300mm it should give you around .006" taper.

[Woodlee]

That's a pity. My AL960B cut a worse taper than yours and 100% of the problem was bed twist. Using a variation of "Rollie's dad's method", I got the twist out of the bed and the lathe cut parrallel. I think the problem now will be getting the headstock back to where it was after precision alignment at the factory. I'm sure there is a way to do this but I don't know what it is.

Graham

I agree with Graham .
Sounds to me like your problem is bed twist .
Rollies Dads method is a good procedure.
I wouldn't gin about with head stock alignment until it's the last resort.
I would accept .001" over 8"-10", not over the distance you turned the bar

Kev.

[Stustoys]

Hi eskimo,
I think I've asked you this before but I've forgotten.
What sort of level do you have?
Just be sure you have any twist out of the bed before you start resetting the headstock.

Stuart

[simonl]

How is the finish on the piece that you turned? Is it good quality? Have you tested to see how much the spindle or chuck will move when you apply upward or downward force?

Perhaps the preload on the spindle bearings were not set properly from factory?

Simon

[Bryan]

could be deflection of the workpiece making the taper.

Wouldn't deflection make the tailstock end bigger? Because it would push away from the tool and reduce DOC?



It cuts a 0.001" taper from the tailstock (smallest dia) to headstock (largest dia) over 2 inches.

[Dave J]

I am pretty sure he has 2 or 3 high precision levels, so he is on the level as far as that goes,:D

Dave




Hi eskimo,
I think I've asked you this before but I've forgotten.
What sort of level do you have?
Just be sure you have any twist out of the bed before you start resetting the headstock.

Stuart

[GDD]

It would appear if the lathe had been precision aligned that they must of forgot to precision tighten the screws.

These screws dont have to be tight. They don't hold anything. Also I would be surprised if they are used in the alignment process at the factory (for reasons below).

Its not a big drama setting the head it just takes a little time,.001" taper is not much over that short distance to chase.

I can't say as I haven't done it, but the maths suggest to me that it might not be easy. I just checked my lathe and the three adjustment screws are about 90 mm apart. ie 180 mm between front and back with the middle one in the middle. Let's assume the headstock will pivot on the middle screw. Its about 300 mm from the centre screw to the front of the 4 jaw, so any movement of the front adjustment screw will give about three times that movement at the front of the chuck. If the taper is .02 mm, (about a thou) adjustment required is half that or .01mm. This is at the job, so movement at the front adjusting screw will be one third that or .003 mm. Those screws look to me to be M8 which means pitch of 1.25 mm, so the turn on the front adjustment screw required to get the adjustment needed is 1.25 divided by .003 which is 1 over 416 of a turn or 0.8 of a degree.

It might be easy for you, but I don't think I'll try it.

Graham

[Stustoys]

Hi Graham ,
I think you forgot that both ends of the job will move. You need to move the far end .01mm further than the near end. So if my math is correct and the job is 50 long if the far end moves 0.01mm the near end will move 0.01/7*6=0.0086mm. So you'll need to move the far end 0.071mm........

Who wants to check my math?

Stuart

[GDD]

Hi Graham ,

Who wants to check my math?

Stuart

Mmmmm.... too hard for me. I realise my "analysis" is grossly simplified but I just wanted to make the point that we are talking about very fine adjustments and a very coarse adjustment mechanism.

If there is a photo attached, it is my bed alignment tooling.

Graham

[pipeclay]

One of the reason why you would use the longest piece of material you can to get the greatest taper you can for ease of checking.
Not sure of any calcs involved,just using an indicator and time.

[.RC.]

Wouldn't deflection make the tailstock end bigger? Because it would push away from the tool and reduce DOC?

That would be true in the northern hemisphere not the southern hemisphere :wink:

[eskimo]

I am pretty sure he has 2 or 3 high precision levels, so he is on the level as far as that goes,:D

Dave

I've only got TWO Dave!...the cdco and CTC ones

and I used the same one for both ends....

is it just me or is this WWF server experiencing some problems just of late..yesterday and now?

[Bryan]

That would be true in the northern hemisphere not the southern hemisphere :wink:

Of course. Silly me.

[eskimo]

now I know why I won it in a raffle...its a dud:~

[simonl]

How is the finish on the piece that you turned? Is it good quality? Have you tested to see how much the spindle or chuck will move when you apply upward or downward force?

Perhaps the preload on the spindle bearings were not set properly from factory?

Simon

Oops. If the diameter of the taper is larger at the headstock end then I guess it can't be bearings or preload huh?

Simon

[.RC.]

Just one thing I would like to point out...

For the most part US designed lathes, the headstock sits on the V-ways... As such the headstock on them is not adjustable... This includes the South Bend and clones like the Hercus.

So with the likes of the two collar test, then you twist the bed to suit, bare in mind that this works because you know the headstock is square with the ways..

Also I think the two collar test is really only applicable on light short bed lathes like a Hercus... Not a lathe that is metre between centres..

That is why I would precision level it to remove twist...... Then adjust the headstock to suit..I have adjusted the headstock on two lathes now... it is not hard, just time consuming..

[Stustoys]

Hi RC,
Well said.


Stuart

[Dave J]

now I know why I won it in a raffle...its a dud:~


I can just see it now, your in the shed working hard on the lathe getting it into alignment, you wife walks out and you start swearing about the free lathe and why they gave it away. Your story will be fully believed for good.LOL

Dave

[eskimo]

Just one thing I would like to point out...

... it is not hard, just time consuming..

Good ...come and do mine then

[eskimo]

I can just see it now, your in the shed working hard on the lathe getting it into alignment, you wife walks out and you start swearing about the free lathe and why they gave it away. Your story will be fully believed for good.LOL

Dave
its all a cleverly disguised cunning plan....:rolleyes::D:D:D

[simonl]

OK. So there's actually nothing wrong with the lathe is there? :U

Simon

[Dave J]

Just to let you in on it all Simon, Eskimo hid his last small lathe under the bench still new in the box for a few a while. Then when he got it out, he wasn't lying if he said to his wife, I have had it for ages. LOL

This one he won in a raffle. $5 ticket, but he never told her he bought 900 odd tickets, LOL

Dave

[simonl]

Just to let you in on it all Simon, Eskimo hid his last small lathe under the bench still new in the box for a few a while. Then when he got it out, he wasn't lying if he said to his wife, I have had it for ages. LOL

This one he won in a raffle. $5 ticket, but he never told her he bought 900 odd tickets, LOL

Dave

Ah! Karma....

When it come to the wife, I know I'm dealing with forces I couldn't possibly comprehend!

She's like the Oracle. She knows all!

[eskimo]

OK. So there's actually nothing wrong with the lathe is there? :U

Simon

Unfortunately there is Simon

[eskimo]

Just to let you in on it all Simon, Eskimo hid his last small lathe under the bench still new in the box for a few a while. Then when he got it out, he wasn't lying if he said to his wife, I have had it for ages. LOL

This one he won in a raffle. $5 ticket, but he never told her he bought 900 odd tickets, LOL

Dave

big mouth.....
Dont believe him Simon...it was in storage

[Dave J]

Lol

[eskimo]

I am pretty sure he has 2 or 3 high precision levels, so he is on the level as far as that goes,:D

Dave

couldnt help myself...3

Amazon.com: Starrett 98-6 6-Inch Precision Machinists Level: Industrial & Scientific

only AU$92.26 delivered:D:p:U:)

god help me:roll:

[Dave J]

I have never bought from them, but from what I read in the shipping page they said they don't ship tools overseas.

Dave

[eskimo]

I have never bought from them, but from what I read in the shipping page they said they don't ship tools overseas.

Dave

Hi Dave

when I have tried to order from them in the past (for goods they wont send overseas eg telescope stuff) they wont let you finalise the order...this order went thru so I'll wait and see

should know by tomorrow morning I reckon

[simonl]

If really keen and they don't deliver outside us then go through one of those on forwarding companies that have a us postal address. There's a hubby/wife team in bendigo that provide such a service. Think they charge 5% of the value+ shipping.

Simon

[Stustoys]

Hi Dave,
Where?
I found this
Amazon.com Help: International Shipping (http://www.amazon.com/gp/help/customer/display.html/ref=hp_nodeid_596184_restrict?nodeId=596184&#restrict)
"Additionally, some products in the following categories:

automotive, baby, clothing, consumer electronics, health and personal care, home and garden, industrial and scientific, jewelry, pet supplies, shoes, software, sporting goods, tools, toys, video games, and watches
can be shipped to the following countries:

Australia"
Stuart........ who really doesnt need another level................ or does he?

[eskimo]

If really keen and they don't deliver outside us then go through one of those on forwarding companies that have a us postal address. There's a hubby/wife team in bendigo that provide such a service. Think they charge 5% of the value+ shipping.

Simon

I have a US forwarding address...If i need to use it

[eskimo]

Hi Dave,
Where?
I found this
Amazon.com Help: International Shipping (http://www.amazon.com/gp/help/customer/display.html/ref=hp_nodeid_596184_restrict?nodeId=596184&#restrict)
"Additionally, some products in the following categories:

automotive, baby, clothing, consumer electronics, health and personal care, home and garden, industrial and scientific, jewelry, pet supplies, shoes, software, sporting goods, tools, toys, video games, and watches

can be shipped to the following countries:

Australia"

Stuart........ who really doesnt need another level................ or does he?

course you do!:D

[Dave J]

I will go and have another look. I have 2 different levels so I don't need one, but I have been chasing something else for a long time and it's always on there the cheapest.

We can tell Eskimo is not level headed,:D or is he,now with 3 levels :D

Dave

[Dave J]

They must have changed it because it used to be a different page set up, do they take paypal?

Dave

[Stustoys]

Amazon.com accepts American Express, Diners Club, Discover, JCB, MasterCard, Eurocard, Visa, Visa Check Cards, payment from your checking account, Amazon.com gift cards, Amazon.com Gift Card claim codes, Amazon Payments Stored Balance, and the Amazon Store Card.
We do not currently accept international wire transfers, PayPal, or Smart Cards. For grocery purchases, we are unable to apply manufacturer's coupons or food stamps.

[Dave J]

Your quick Stuart, I couldn't find it,:doh:
I logged in and found I am a member there already, must have signed up a few years back but never bought anything, I an going shopping.:D

Dave

[eskimo]

can I put the belt cover back on..its 0.0001 over 2 inch?

now watch the temp of a hot day change it....I can an aircon coming up

[GDD]

can I put the belt cover back on..its 0.0001 over 2 inch?



So tell us how you did it. After all the discussion I'd love to hear the details.

Graham

[steran50]

can I put the belt cover back on..its 0.0001 over 2 inch?

now watch the temp of a hot day change it....I can an aircon coming up

HI:),
Yep You can put the Cover back on and then You can come and do Mine LOL. Seriously Well Done:2tsup: thats Good. So not to Time consuming then ?. Yes the day Temperature will certainly change it. I have two Fibreglass Corrugated Sheets in My Shed on Sunday the one above the Lathe and Mill got covered it Chrome Paint the other will get done this Weekend when I get some more Chrome Paint. have You considered Whirly Vents on Your Shed Roof ?, I put two on My Shed Roof and it has certainly made the Shed a lot Cooler on Hot Days.

Out of Interest what Chuck were You using to do this 3 or 4 jaw ?. In Regards to Mail Forwarding Greg Q pointed this one out to Me fairly recently USA Address & Mail Forwarding (http://www.shipito.com/) I haven't used them as Yet. I gonna Buy another Level Myself, I have two already a Digipas Electronic one it works well. The other I got from Shars it will equalise (isn't their another word ? for that I can't think of it though.) to the Temp in the House but I haven't yet been able to get it to equalise to the temp in the Shed, perhaps it needs more Time than what I have given it.

Did You see these Levels eskimo ?Amazon.com: TTC Precision Machinist Spirit Level - Model: SL-279 SENSITIVITY PER 10": 0.0005" (10 seconds): Industrial & Scientific ,they come from France according to the Travers Website they also have a 20 second to the foot one. I am Tempted, but the Starret levels look to be better made.

P.S. I meant to Say if Your Shed is getting quite Hot on Hot days perhaps the Whirly Vents might be a cheaper option than an Air Conditioner. Although than Air Con will give You a much stabler Temperature. My Shed was getting to far to Hot on Hot Days. Thats why I went to the Whirly Vents which made a big improvement. Now I am in the Process of Painting out the Skylights until I get a chance to change them to Corrugated Iron.

[pipeclay]

Out of Interest what Chuck were You using to do this 3 or 4 jaw ?.

Due to lack of knowledge,would it be of any importance if a 3 or 4 jaw chuck was used for alignment?

[steran50]

Out of Interest what Chuck were You using to do this 3 or 4 jaw ?.

Due to lack of knowledge,would it be of any importance if a 3 or 4 jaw chuck was used for alignment?

HI:),
In My Opinion Yes and No. A Cylindrical Workpiece in a 4 Jaw Chuck can be set to Zero TIR. With a 3 Jaw Chuck the Work Piece generally can't be set to Zero TIR. The reason being is that 3 Jaw Chucks aren't as accurate a 4 Jaw, because a 4 Jaw allows you to Adjust each of the Jaws independently it is a far more accurate Chuck.

In answer to Your Question You could use either after all both Chucks are going to be used on the Lathe over time. Using the 4 Jaw though should enable You to set the Alignment up more accurately though than the 3 Jaw providing the Workpiece is the 4 jaw is set to Zero to begin with. Perhaps someone else can explain it better than Me.

I was asking the Question about which Chuck He used just out of interest. All eskimo can do is Align his Headstock as close as possible. Once He has done that He just has to put up with Temperature changes the small variation in TIR when changing Chucks just like the rest of us.

I am glad He didn't have to much Trouble going about the Process.

[Bryan]

Once he's taken a cut it doesn't matter how it's held. I think that's what PC is driving at.

[eskimo]

So not to Time consuming then ?.

I have two Fibreglass Corrugated Sheets in My Shed

You considered Whirly Vents on Your Shed Roof ?,

Out of Interest what Chuck were You using to do this 3 or 4 jaw ?.

In Regards to Mail Forwarding Greg Q pointed this one out to Me fairly recently USA Address & Mail Forwarding (http://www.shipito.com/) I haven't used them as Yet.

Did You see these Levels eskimo ?Amazon.com: TTC Precision Machinist Spirit Level - Model: SL-279 SENSITIVITY PER 10": 0.0005" (10 seconds): Industrial & Scientific (http://www.amazon.com/TTC-Precision-Machinist-Spirit-Level/dp/B0057PP7YC/ref=sr_1_8?s=industrial&ie=UTF8&qid=1328000207&sr=1-8) ,they come from France according to the Travers Website they also have a 20 second to the foot one. I am Tempted, but the Starret levels look to be better made.



Hi Steran

I was going to install plastic roof sheets to save on power..might not now
never thought of whirly vents...I might give one or two a try.

I was using a the standard 3 jaw feurda chuck that came with the lathe

No I didnt see them...but they are dearer than that Starret

The level has been shipped direct to me so Amazon says..at AU$92.26
No need to use the US address. But I have used it for telescope stuff from US as the dealers wont ship Celstron, meade and some other stuff direct...so I use the us address and all works out about the same as if the stuff was shipped straight to me...but its still a whole lot cheaper than what they want here for the same stuff

[eskimo]

So tell us how you did it. After all the discussion I'd love to hear the details.

Graham

Hi Graham

At first I started out going round in circles as every time I made an adjustment to the set screws to swivel the headstock it didnt seem to want to go where I thought it should have.

I then deliberately put it out in one direction..this way I knew that I needed to keep moving the headstock in only one direction...this removed a tendency to ask myself..which way do I now need turn that set-screw...kept moving it bit by bit using RDM until it got close ...then watched for movement in the head stock when tightened it all down..made allowances for this and tightened it all up when I thought it was close to the mark.....

did a test cut and still half thou smaller dia at far end...closer than what it was

put bar back in exactly same spot ( bar was indexed to chuck) and did another small adjustment...pulled down head and noted how far head altered DTI...made allowance and did test cut...still 0.00025" (I reckon) out...still could be better I thought

Repeated previous step and a few more times making ever increasing smaller adjustments ....creeping up to its final resting place so to speak

The DTI was only moving at 0.001" at the far end of the test bar which was about 18 inches from the chuck in these final adjustments

when it hit 0.0001" on a test cut I thought that was reasonable.

[eskimo]

Out of Interest what Chuck were You using to do this 3 or 4 jaw ?.

Due to lack of knowledge,would it be of any importance if a 3 or 4 jaw chuck was used for alignment?

I dont think so Pipeclay...I stand to be corrected on this tho

my thought is/was :
I was trying to align the spindle to the carriage movement along the bed so that I was getting a cut which didnt have a taper..it should not matter if the chuck is not running true...your goal is to have a cut which is parallel to the bed

is this correct guys?

[Stustoys]

Hi Eskimo,
Sounds like you've done a great job.
Did you loosen the middle bolts right off or leave them tightish when making the adjustments?
RDM? Relational Database Mining?

Stuart

[eskimo]

I kept that one firm..and to the opposite end to the one I was adjusting

RDM...Rollie"s Dad's Method for aligning the lathe

[Stustoys]

You can't really give Rollie's dad credit for this one. You were aligning the headstock to level(untwisted) ways. As I understand it Rollie's dad's method is really about twisting a level lathe to make it cut straight(parallel).

Stuart

[GDD]

Thanks for the description, Eskimo. This thread, and in particular RC's post -



Also I think the two collar test is really only applicable on light short bed lathes like a Hercus... Not a lathe that is metre between centres..

That is why I would precision level it to remove twist...... Then adjust the headstock to suit..I have adjusted the headstock on two lathes now... it is not hard, just time consuming..

got me thinking and mucking about with my AL960. I have got it cutting parrallel but the bed is slightly twisted to achieve this. So I conclude that my headstock is misaligned after all. The smart thing to do now is leave it alone because it is doing the job, but the perfectionist in me wants to start on that headstock. .....

Graham

[Dave J]

Good work Eskimo,:2tsup: Now was the lathe leveled spot on before you did this?

It has always been recommended to use a large diameter thick wall pipe to take a test cut on. This way it's still nice and rigid 200mm+ out from the chuck.

You will need to check how it faces now and see whether it a faces concave or truly flat.

Dave

[simonl]

Hi Eskimo,

Just caught up on this thread. The taper of 0.0001", was that over the length of 18 inches? :)(

My god I have a lot to learn! I was puffing my chest out when I got my lathe to turn 0.0001" in 6 inches! :woot:

Simon

[simonl]

Good work Eskimo,:2tsup: Now was the lathe leveled spot on before you did this?

It has always been recommended to use a large diameter thick wall pipe to take a test cut on. This way it's still nice and rigid 200mm+ out from the chuck.

You will need to check how it faces now and see whether it a faces concave or truly flat.

Dave

Hi Dave,

How flat does truly flat have to be? Don't all lathes turn slightly concave, albeit very small?

[Dave J]

Hi Dave,

How flat does truly flat have to be? Don't all lathes turn slightly concave, albeit very small?

Hi Simon
They should cut concave and no more than about 0.02 / 300mm seems to be the maximum from manufacturers. As for truly flat it was just the way I worded it.:doh:

Dave

[Bryan]

You can't really give Rollie's dad credit for this one. You were aligning the headstock to level(untwisted) ways. As I understand it Rollie's dad's method is really about twisting a level lathe to make it cut straight(parallel).

Stuart

I think what RDM does is establish what you might call a proxy for the spindle axis. And I think aligning a headstock to a straight bed is a far better use for it.


I have got it cutting parrallel but the bed is slightly twisted to achieve this. So I conclude that my headstock is misaligned after all. The smart thing to do now is leave it alone because it is doing the job, but the perfectionist in me wants to start on that headstock. .....

Graham

I disagree about leaving it alone being smarter. A twisted bed is not what you want, except maybe as a last resort on a worn out lathe.

[pipeclay]

Yes ,not seeing any significance in what method was used to hold work piece was the reason for chuck question.

[Dave J]

Hi Graham
I agree with Bryan and think it would be time well spent trying to align the headstock as good as possible with the lathe perfectly leveled.

I went through your posts to see what lathe you had as there are that many members with different machines it's hard to remember them all, and see you have had it for 18 years. I am not sure how much you twisted it or how long ago but if it was twisted a bit and long ago it might have a permanent twist to it now. If it was something done in recent years you should be able to get it back.

You have a fail safe if you get into trouble, Eskimo will come around to do it for you as it's a 5 minute job to him.:D

Dave

[eskimo]

Hi Eskimo,

Just caught up on this thread. The taper of 0.0001", was that over the length of 18 inches? :)(

My god I have a lot to learn! I was puffing my chest out when I got my lathe to turn 0.0001" in 6 inches! :woot:

Simon
no Simon
it was .0001 over only 2 inches...so still leaves room for improvement if yours is doing that over 6 inches

I might have another go later when I have more time

[eskimo]

Good work Eskimo,:2tsup: Now was the lathe leveled spot on before you did this?

It has always been recommended to use a large diameter thick wall pipe to take a test cut on. This way it's still nice and rigid 200mm+ out from the chuck.

You will need to check how it faces now and see whether it a faces concave or truly flat.

Dave

I had leveled the lathe across the bed at both ends..I reckon about .00025 difference going the bubble..is that good enough?

My material was only short Dave, but non the less better than what it was

So should I follow you guys opinions and do it on a longer piece further out from the chuck and over a longer piece?...what should I be striving for...Simon says his does .0001 over 6 inches..is this my target or should I have a target of say = or <.0001 over 8 inches ( with out tailstock support ).... and would that also be at 8inches out from the chuck?

[eskimo]

You can't really give Rollie's dad credit for this one. You were aligning the headstock to level(untwisted) ways. As I understand it Rollie's dad's method is really about twisting a level lathe to make it cut straight(parallel).

Stuart

yeah..but the method of measurement still works doesnt it?

doesnt matter now cos it cuts .0001 over 2 inches.. but going by Simon his does better than this so maybe back to measuring some more eh?

[eskimo]

Hi Graham
I agree with Bryan and think it would be time well spent trying to align the headstock as good as possible with the lathe perfectly leveled.

I went through your posts to see what lathe you had as there are that many members with different machines it's hard to remember them all, and see you have had it for 18 years. I am not sure how much you twisted it or how long ago but if it was twisted a bit and long ago it might have a permanent twist to it now. If it was something done in recent years you should be able to get it back.

You have a fail safe if you get into trouble, Eskimo will come around to do it for you as it's a 5 minute job to him.:D

Dave
yeah ..5 mins....wrong !!!:oo:

i even had to stop drinking so i could remember what I doing

[simonl]

Hi Eskimo,

That figure I quoted was with a 50mm solid bar held in the 3 jaw with no support.

Only reason why I know this figure is from when I decided to make a cylindrical square and I wanted as parallel as possible. This was the best I could get and figured I was happy with the result given the lathe and my skills.

Last year I completely stripped the headstock and removed it for cleaning, when I put it back I took great care to align the headstock to the best of my ability (using RDM). My aim was to have it better than when I bought it, which I think it is going by the test results it came with.

Also if I wanted to get better accuracy then it would have been difficult for me as my most accurate mic is a 0.0001. I don't have a 0.001mm mic so I would have had to make the bar protrude longer. Also once you get to the pointy end of accuracy, those adjustment bolts get very touchy, even tightening the headstock bolts once you are happy with the alignment is a delicate process.

Anyway, not sure what the standard is but 2.5 microns over 150mm is good enough for me!

Cheers,

Simon

[Stustoys]

yeah..but the method of measurement still works doesnt it?
Hi eskimo,
Sure the method of measuring two points still works but I doubt Rollies dad can take credit for that.

Its the distance between your measuring points you want to increase, not the distance out from the chuck. (if you feel you arent close enough already).
Do you have a 0.0001" DTI?
Which end is big now?

Then the real problem.... how close is close enough....

Stuart

[GDD]

I'm not worried about the bed twist; its only about half a bubble on my level which measures to 0.02 mm per metre.

As for how good is good enough, attached is the accuracy standard for a British Colchester lathe of about 30 or 40 yeas ago. These were highly regarded then. Also, I expect the limits set were in accordance with some accuracy standard of the time. Please ignore the scribbles.

Graham

[Stustoys]

got me thinking and mucking about with my AL960. I have got it cutting parrallel but the bed is slightly twisted to achieve this.


I'm not worried about the bed twist; its only about half a bubble on my level which measures to 0.02 mm per metre.

How much taper was it cutting that moving it half a bubble fixed it?

Those specs call for +0.0012" max a foot(sort of, not exactly the same thing) . Eskimo has his set up to something around half that(maybe, depending on which end is big.)

Stuart

[Dave J]

Eskimo,
I had a look in my test report that came with my lathe and it states that in 300mm from the chuck 0.02mm is the maximum tolerance allowable.

When I made my cylinder squares I could not detect any difference on my 0.001mm mic"s over there length (180mm I think they where) both by measurement or comparing each end by feel with the mic.

How good you get it is up to you, but as you know the closer to zero the better.

I thought of something that may help you guys with fine adjustment.
Get 3 grub screws to replace your original alignment bolts, you will probably have to anneal them depending on how hard they are.
Drill down the centre along their length and tap for metric 3-4mm and put some metric 3-4mm bolts in them that are a bit longer.

This will allow you to screw the grub screws in the original holes, but be able to use the finer M3-4mm thread for adjustment. Once it's adjusted and the headstock is tightened down you can take the metric 3-4mm screws out and firmly tighten the grub screws in the original threads.

Dave

[pipeclay]

The 3/4 mm set screw done the centre of the grub may be a big ask for most blokes on here to tap without breaking a tap let alone the amount of load that may need to be applied to the headstock to get it to move.
Generally you would only crack the headstock hold downs and apply a reasonable amount of torque to the setting screws.
It may work if the hold downs were loose but I think a lot hard if just cracked if possable at all.

[Stustoys]

Hi Dave,
There maybe one other problem. With an M8's root dia of 6.466mm an even an M3 doesn't leave a lot of meat in the bolt(found that out the hard way myself :(. But then I'm the heavy handed git that didn't see it coming). Of course you could swap back to solid bolts once you've finished(assuming you don't move something).

I wonder if leaving the center bolts loose so the headstock isn't seesawing on it would make the screw half an sensitive?

Stuart

[Dave J]

You both are probably right, it was just a thought off the top of my head so I thought I would throw it out there.
With the tapping you could clearance drill most of the way and just tap the end 4-5mm, but like Pipeclay said, you would want a bit of torque on the headstock bolts so the M3-4 probably wouldn't move it.

Stuart, I think that would be plenty of meat for the M3, and if they where changed over at the end it should be OK. The M8 would only be there to hold the M3 while adjusting it, it would be like a helicoil.

The factory should have tapped them at least M8 fine for the adjustment.

Dave

[GDD]

How much taper was it cutting that moving it half a bubble fixed it?

Stuart

It didn't unfold like that. I realigned it with my "two collar tool" then checked the bed twist.

Graham

[Stustoys]

It didn't unfold like that. I realigned it with my "two collar tool" then checked the bed twist.

Graham
Hi Graham,
Seems like you headstock must be pretty close then. The problem I have with RDM is that is assumes either 1. everything else is set up correctly so any error is twist in the bed or 2. there is nothing you can do about the problems that are making the lathe cut with a taper other than twist the bed.

Stuart

[Dave J]

If it's only a small amount of twist it shouldn't matter to much, and if it's doing the job accurately and you don't want to play with the headstock alignment I would just leave it.:2tsup:

Dave

[simonl]

I'm not worried about the bed twist; its only about half a bubble on my level which measures to 0.02 mm per metre.

As for how good is good enough, attached is the accuracy standard for a British Colchester lathe of about 30 or 40 yeas ago. These were highly regarded then. Also, I expect the limits set were in accordance with some accuracy standard of the time. Please ignore the scribbles.

Graham

Hi Graham,

Those accuracy tests are an eye opener! I dare not post mine up here from my 12x36. how embarrising!.......... Except my headstock alignment thats exceptional! :biggrin2:

Simon

[eskimo]

Eskimo,
I had a look in my test report that came with my lathe and it states that in 300mm from the chuck 0.02mm is the maximum tolerance allowable.



Thats what it says for the AL960

The near end (chuck end) had the larger dia over the two inches