Selecting an Engineer's level

All,

I've decided to level my lathe and although there are various methods to achieve this, I'm going to employ the use of an Engineer's level in this process. Now you can pay crazy money depending how accurate you want to go. A google offers up a number of options and I'd like to solicit people's thoughts on them:

1 - Moore and Wright ELS range (165mm - 0.3mm/m) ~£150

2 - Level developments 61R-0.05-140 (140mm - 0.05mm/m) £205

3 - RDG tools brand (150mm - 0.05mm/m) £58

Now what I find strange is the cost of #1 with an accuracy of only 0.3mm/m. Seems a high price for such an accuracy. Then we have the polar opposite for #3 which is very cheap for a reasonable high accuracy.

Does anyone have any thoughts / advice? Do I need something more accurate than #1 for leveling my lathe (Murad Lathe)

Thanks in advance

It matters not that the lathe is level but rather that the bed has no twist. The engineers level is one way to check that the bed is twist free. There are other cheaper and probably quicker methods to achieve the same outcome. Unless in a toolroom environment I cannot imaging that the level would find much use in the home workshop, a bit of overkill to make sure the shelves are straight.

John

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Hi Journeyman,

What other methods would you suggest?

For what it's worth I'd say:

• 0.3mm/m is a little insensitive for levelling a lathe, and 0.05mm is maybe over the top. The problem with sensitive levels is they take an age to settle, making them a little hard to use. Patience!
• I'd go cheap because an Engineering Level is rarely used! Once a machine is levelled, that's it. So unless levelling is part of the day job, don't throw money at a tool that's doomed to live in a drawer until the end of time.

Expensive tools tend to be more reliable and easier to use than cheap ones. A level that changes with temperature or when tapped on the bench, or gradually drifts is a time-waster. The quality is in the way the bubble is mounted.

But lathe levelling can be done without spending a fortune on fancy kit. Provided it's sufficiently sensitive the level doesn't have to be unilaterally accurate. It can be 'calibrated' for the job in hand by turning it end to end and noting the difference between readings. More fuss and bother than just plonking a true level on the machine, but not massively so. So I'd happily spend an extra hour of my time with the £58 level, which might be completely satisfactory when new, rather than cough up £200 for a better instrument that never gets used again.

Finally, no point in levelling unless the lathe is known to be cutting wrongly. If it ain't bust don't fix it!

Dave

Edited By SillyOldDuffer on 16/04/2020 17:17:21

I used a couple of 12 mm HSS tool stock & a digi level to check for any twist on my lathe...

Headstock end...

Tail stock end...

along the bed... rear shear...0.1mm off...

Front shear...

Same as rear shear, obviously, 0.1mm off length wise, but no twist head stock to tail stock, good enough for me. Pay a £150 + for an engineers level for home check maybe twice a year, I think not.

I have used Eng' box levels, DTI's & electronic alignment equipment when I used to instal / realign turbines / pumps & gearboxes etc, when I was in the middle of the desert a few times but they had to be spot on, including adjustment & offsets for thermal expansion. Save your money for some useful tooling is my thought.

George.

The wear on an 80year old lathe could well throw the readings off anyway, 5microns of wear on one of the ways would be equal to 0.05/m if they are 10mm apart.

Is the lathe not cutting true? if it's OK then save your money.

Thanks for all of your thoughts. Much appreciated! Looks like I need to reconsider my approach leveling given the cost and alternative approaches.

It isn't cutting true although i haven't measured yet but I can see it isn't.

The classic method I suppose is often referred to as Rollie's Dad's Method but there are plenty of threads on here covering how to do it. (The link is to a pdf file detailing the method.)

John

Your level is only resolving to 6 minutes of arc - that's not even it's accuracy, but it's resolution. A typical engineer's level will measure 10 seconds of arc or better, 36 times more sensitive to a change in angle.

In real terms it means that your electronic level won't register 6 thou of twist in a bed 4" wide (approx. the length of that HSS bit). It's not sensitive enough.

How many feet are supporting this lathe?

Mine is supported on just three. I consider using an expensive level an utter waste of time, effort and money for my example. I suggest you, perhaps, start by counting yours before proceeding to do anything, particularly shelling out for an unneeded item such as you are proposing.

Just adjust the lathe until it is cutting parallel. Plenty of information on the net

Tony

You can spend money on "levelling" using the most sophisticated and expensive means, but only actual comparison of machined diameters can tell you if the lathe is cutting correctly. Of course that result can be obtained without any resort to levels.

A digital level which resolved to 0.1 degrees is accurate to no better than 1.74533mm per metre.

Edited By old mart on 16/04/2020 19:38:44

Hi GingerLathe

I bought mine from Rotagrip. 0.0002/10". Comes in at around £70. I did have to set it up which was pretty straight forwards and it's not the beautifull object you saw in toolrooms of yesteryear but it does the business at a reasonable price.

regards Martin

I can just see the chief engineer on a ship trying to use spirit levels to get the lathe in the workshop level.

Although the machines in a machine shop would be installed to be level it is not essential as the ship example illustrates. It can be useful on things like large mills to have level as a reference in some setups. It is quite possible that the slab we usually build a home workshop on will move depending on the weather so the machine level would need checking if using as a reference. Rollies dads method will sort out a lathe not cutting true if the bed is not true.As most people use a level once in a blue moon it might be worth just borrowing one. I have a couple if you are anywhere near Oxford.

Mike

Sometimes I could strangle Rollie's Dad. If folk don't pay careful attention to what they are doing and keep the brain properly engaged the poor lathe can end up wound tighter than the spring in my alarm clock yet still turning taper. Factoring in the relative torisional stiffness of lathe bed and bench is way to complicated!

With smaller machines i've found that being very careful with shims et al to get the bed resting nicely on its feet with no stress and no clearance before being snugged down works as well as messing around with with levels or endless iterations of Rollie's Dad. Easy enough to use a torque wrench and dial gauge to verify that each foot moves down the same amount when tightening. Dial type torque wrench is best for that sort of thing. Naturally if you have a Myford or similar with a motor and other gubbins hung out the back its much easier if they can be removed temporarily so the bed is reasonably close to being balanced.

In general levels sufficiently sensitive to get a lathe bed accurately aligned are a monumental faff to use and well capable of driving even the most mild mannered to profanity, drink or serious investigations into achieving orbital velocity by arm power alone. Best compromise I've found is the old British WW2 Gunners clinometer.

About half the sensitivity of an engineers precision level at 30 seconds of arc per division, 0.14 mm / m, its easy to work to 10 seconds of arc or better. I recon 5 seconds of arc is realistic by exploiting the screw adjuster. The screw adjuster makes life much easier if you level actually isn't going to be a true level. Compact, being barely 6 inches long its easily switched end for end.

Clive

Edited By Clive Foster on 16/04/2020 22:58:31

If you still decide to purchase one, good brand name ones are often available on ebay for less than £30; e.g. Starrett, M&W, Rabone etc.

Bill