Precision Level or Precision Frame Level

[Neil WyattModerator @neilwyatt]

Posted by JasonB on 03/05/2019 10:11:50:

Coplanar ( in the same plane) is probably a better description of how each end should be.

Bloomin' swot

Neil

[Antony PriceParticipant @antonyprice56876]

Hi JB

I’ve just spent the last week sorting out my Harrison T300 lathe…I tried using the Rollie Dads method but found the accumulation of errors (taper adaptor, test bar etc) difficult to resolve, so went for levelling the lathe. Having levelled the lathe, I did a test piece and had an error of 1/1000” over about 6”. Tweaking the relevant lathe foot, now gives me no error over 6”

If you would like a recommendation: the level I used was a Moore And Wright Machinists Spirit Level. 12”/300mm. I found it perfect for the job required. My level was second hand, from the well known auction site. I’ve just checked and there is one currently available (buy it now £79.99)

Hope this helps

Tony

[Rod RenshawParticipant @rodrenshaw28584]

Hi Clive

Many thanks for your prompt and comprehensive reply to my question.

I just have to find one like yours now!

Even if I can't find an adjustable one, I now have an idea of the sensitivity I am looking for.

Thanks again.

Rod

[Clive FosterParticipant @clivefoster55965]

If I didn't already have mine I'd be seriously tempted to make something functionally similar. Start by strapping one of the short, inexpensive, import bar levels to a sine bar style pivoting plate on a flat base. Add a vertical screw to adjust the pivot. For quick and dirty I'd probably have proper full circle pivot pins at each end of the bar. Then drill and tap the one at the moving end for the screw. Put another pivot in the base at the moving end and drill part way through to form a location for the end of the screw. 5° movement should be plenty. Being able to go an extra couple of degrees below horizontal.

Proper calibration like mine is handy but only necessary if you are using it to measure things.

For levelling the screw adjuster is just there to keep the bubble in view whilst you get close. Finish off by switching end for end until the bubble stays in the same, or near enough the same, place. Always remember that the objective is to get the thing bolted down, or standing on its own feet if its a bigger beast, with no extraneous stress on the bed. The level just tells you when making an adjustment or tightening a bolt is straining things.

100 mm long levels seem to be in the £30 range so could be sat on a pivoting bar from 4 to 6 inches long. Close to 1° per turn is 10 tpi for 6", 11.5 tpi for 5" and 14 tpi for 4" between pivot and screw. I'd probably go for 11 tpi on 5.22" between pivots as being very close as one of my lathes has 11 tpi on the screw cutting box. Or if you are metric 2 mm pitch on 115 mm between pivot and screw is very close to 1°.

If you do go that way don't be tempted by the 0.02 mm / m ones. Unless you can stop breathing!

Clive

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