Aligning a lathe to turn parallel

[bambuko]

Hi Harry,
I am not out to convince anybody
I am not one of these types frequenting interweb forums, who will argue to death, because they are right :big:
Forum format is not the easiest to conduct discussion anyway, so I am perfectly happy to agree to disagree and walk away
I have nothing against levelling. By all means do so, to the best of your available equipment, your ability and your desires.
Just give me one rational reason why a lathe with bed at an angle of 1 deg to horizontal will perform worse than the one at an angle of 0 deg and I might listen :bow:
Of course, within reason - I would not expect lathe with a bed designed for horizontal operation to perform well, when turned into slanted bed version...

BTW this subject has been done to death on other machining forums ... and it never lead anywhere apart from a lot of heat being created.

Chris

 

[Ken I]

O.K. let's throw some gas on the fire.

As an engineer responsible for the installation of hundreds of machines as well as the design and construction of dozens - as a person who was raised on the "level it - level it - level it" gospel - a gospel I practice simply because it IS good practice.

Machine builders build with their machines dead level - so that is how you should site them. Siting them otherwise might introduce stresses that will "change" the machine slightly - so for really precision work - it's mandatory.

Having said all that it (in most - not all) cases it doesn't matter if your machine is out of level slightly - most lathes would work fine if you bolted them to a wall. On a mill you might want to use an inclinometer or autocollimator - in which case the ground plane is your reference and it better be right.

You need to be more concerned about introducing a twisting moment into your equipment - by following good leveling pratice - you are less likely to screw it up.

So yeah - its really important - maybe.

Ken

 

[bambuko]

OK
Put three legged stool on the floor and it will be stress free, without you having to adjust any of the legs to prevent bending and twisting.
Put four (or more) legged stool on the floor and the chances are that without careful adjustment of the legs it will be bending and twisting introducing stress.
Now - you can adjust the legs to take out the stresses, without making the top level. It can be done, but it's not easy and it's difficult to know when you have adjusted it just right. On the other hand if you use levelling as a means of testing the adjustment - it's easy to do and you know when you have got the job done.
There may also be other, practical reasons why keeping things level is advantageous.
So, I am not against levelling - it makes perfect sense to use it, but it doesn't matter "per se". If you had means of accurate measuring of angles you could have lathe bed at an angle (providing it is not ridiculous) without stressing it, as long as this angle is the same along bed length

This discussion reminds me similar argument about wheel quartering on the steam locos - there will be some people who will tell you that "it has to be" at 90 deg exactly. B******s - anything close enough will do, as long as it is the same for all the axles.

So, as Ken says "...You need to be more concerned about introducing a twisting moment into your equipment..." How you achieve this is up to you - I prefer three legged stool, somebody else might prefer to adjust their many legged stool

Chris

and just to lighten up

 

[mu38&Bg#]

With all this said, does anyone inspect their hobby parts to the .0001"? I recently checked a paying part after that above mentioned alignment process and found it was ±.0001" on the OD and maybe ±.0002 on the ID over 5.5" length. Elsewhere, I posted I had a problem with the ID being tapered, but found after I parted it off, a ridge at the bottom of the bore where I measured about .002" smaller ID. I'm not sure if I got distracted and didn't finish boring. It pays to check alignment if you need to do accurate work. If you can't, or more likely the shop doesn't give you time in a production environment, you put in a 12" reinforced foundation and spend the money to have a machine installer to put in your machine so it doesn't need to be checked often. There is a difference between a production environment and hobby shop. Every individual has their taste in what they desire to enjoy the hobby, whether it meets ISO specs or not. An individual who desires accurate parts will listen when they need help. Had I access to a machinist level, my lathe would get the treatment. Even without one, I am happy with the parts.

 

[Ken I]

There is a difference between a production environment and hobby shop. Every individual has their taste in what they desire to enjoy the hobby, whether it meets ISO specs or not. An individual who desires accurate parts will listen when they need help. Had I access to a machinist level, my lathe would get the treatment. Even without one, I am happy with the parts.

Couldn't agree more - well put.

Ken

 

[ieezitin]

Im gonna be the asxxxle here.
If anyone who thinks there worth a shot the machine would not be the weakest link, just peruse the net and other hobby forums and see some of the most beautiful creations made on machines such as a craftsman 618 – 6” lathe and other temperamental small equipment including the Asian clan.

Getting your equipment dialed and zeroed in for business does not necessarily mean your work will reflect your machine capabilities, its you the operator who is responsible and to know its incongruities.

I have a 12” Atlas that I have used for 12 years now, its level and not twisted! But she cuts a slight taper, I know this and I build it in or I avoid cutting tapers on it, it heaves on knurling duties so I slightly angle the tool and dog it down on the tool post, 4” away from the headstock she rises .002 I accommodate that, it will not cut a 050 cut under power it will burst the half nut!, my Logan on the other hand will handle all of the above with no quirks with accuracy but!! Vibrates at high speed and everything turns to crap.

Machining is an art and knowing your boundaries is a part of the knowledge, we are hobby machinists our environments will not compare to industrial standards but saying that there are people out there who produce first class parts with simple practical tooling why because they are machinists and realists . know your frontiers and be in harmony with them.

If I have offended anyone so be it!. God bless Anthony.

 

[user 284]

I just got home from work and thought there was some interesting points raised. I'll have to reread them in the morning when I'm not dragging my butt.

Pete

 

[Ken I]

its you the operator who is responsible and to know its incongruities.

Well put - I once turned in a substandard part and blamed the machine for it - did I get a roasting - I was then tasked with doing it again on the "worst" machine in the shop - and no excuses would be accepted - it might take a little longer - but no excuses - guess what - I did it - lesson learned - I have never blamed the machine since.

If you can't fix your machine errors - you should at least know what they are.

Ken

 

[user 284]

Ken,
"If you can't fix your machines errors - you should at least know what they are." Very well said. It's pretty well impossible to compensate for something you don't know about. That's the main reason I started this thread. I have no industrial machining experience other than talking with various machinist's on different job sites. But in industry with their heavy, rigid equipment the first thing they do after getting a new machine is level it, Then bolt it down in a unstressed condition. Then do final alignments. Yet we hobbiests expect to take a really lightly built machine, Bolt it down to whatever surface is handy and expect it to perform dead true. It took me a lot of years of reading, thinking, checking my equipment, to figure out even some of this. The majority of hobby type lathe manufacturers do a pretty poor job about educating their customers in my opinion.

Pete

 

[dwentz]

So my buddy down the street has an old South Bend that came off a ship. I wonder if they kept it level?

Even my big lathe on concrete moves, and twists and bends under load. I have put an indicator on the bed while taking a heavy cut, and the bed does warp during the cut.

I was taught to align the lathe bed for square, and to do it use small wires from the left back to the right front of the bed, and from the left from to the right rear, Let them cross. If the wires touch both ways it is good enough. If they do not you have too much warp in the bed. The wire is very fine strands from multi strand wire. It gets the twist within a few thousands on a 3 or 4 foot lathe. I learned this from my buddy down the street with the South Bend. He was a Navy machinist, and the old South Bend in his basement is the same lathe he used in the Navy on board a ship. Looks like it just came off of the showroom floor too, he takes real good care of his stuff.

Dale

 

[Ken I]

That's a cute trick I've never heard of - make mental note for future reference.

Thanks.

 

[lordedmond]

they used the wire method to align the bearings on steam turbines before lasers were invented, stretch it tight between the end ones and take readings


Stuart

 

[user 284]

Dwentz,
I've been away at work so just read this, I'd certainly agree with Ken. That's a new one for me and very clever.

Pete