Lathe unwanted taper

[Steve WithnellParticipant @stevewithnell34426]

Posted by ChrisB on 09/11/2017 10:40:24:

Thanks for all the replies, I spent most of this morning in the workshop adjusting bench feet and doing some test cuts on the lathe, also knocked out a spirit level out of some scrap I had around and a test tube – surprisingly it turned out much more accurate than a normal level,

Bit of a tangent – when I was a kid 10 or 11, Grandad asked me if I had a testube I didn't want. I gave him one to make a level – he knocked a hole in the end of the tube and fastened it to a long length of hose pipe. By filling the pipe at one end until water appeared in the test tube he could establish a level over a long distance.

Steve

[peak4Participant @peak4]

A friend of mine recently bought the WM290 complete with makers cabinet.

A rigid cast iron plinth, it certainly isn't. I loaned him my big crowbars and precision level, along with some basic instructions of what needed achieving. He has his own DTI. We has a play for a couple of hours together and I retired back home. The following day he went out and bought something to bolt it to the concrete floor of the garage.

The base of each of the two pillars on the stand has 4 mounting holes, so with careful shimming and the level, plus 8 Rawlstud anchors in the concrete floor, he was able to get both pillars level and vertical. Thus the lathe itself then has a rigid mount at both ends, independent of each other and firmly fixed to the floor, to allow differential shimming of the lathe mounting holes if required.

It was remarkable how just adding a single thin shim to just one of the 8 mounting studs under the cabinet changed the readings on the DTI.

I think it took him the best part of a day to drill the floor for the 8 anchors and shim it all up to get the cabinet bang on level.

Bill

[peak4Participant @peak4]

Posted by Steve Withnell on 12/11/2017 10:24:17:

Bit of a tangent – when I was a kid 10 or 11, Grandad asked me if I had a testube I didn't want. I gave him one to make a level – he knocked a hole in the end of the tube and fastened it to a long length of hose pipe. By filling the pipe at one end until water appeared in the test tube he could establish a level over a long distance.

Steve

For folks who've never used a water level;

I've just had a new garage built over in Buxton and made one of these myself to check various levels as the building progressed. The builder himself hadn't seen one since his apprenticeship and the guys working for him hadn't come across one at all.

In my case I used a spare gallon plastic container with a brass fitting near the base to accept a long length of 5mm bore plastic pipe. This leads to a 2' length of 2×1" timber, with a spare steel rule attached. I then plugged the plastic pipe into a length of translucent CO2 line from a mig welder, clipped that to the steel ruler, and terminated the lot with an old motorbike petrol tap. ( I added another one at the container outlet.)

The container can then be stood at any convenient place in the garage at about the level you need to measure.

Note that the container stays put, and you wander round with the ruler and pipe marking the walls accordingly.

To make the fluid more visible, the commercial ones seem to add a bit of flourescein to the water.
Not having such stuff to hand I took the filling wadding out of a normal coloured highlighter pen and squeezed the ink into the water. Seems to work fine.

Don't forget to open both petrol cocks and the lid of the container. A friend of mine didn't quite think it through and used a borrowed one of these water levels to set the RSJ when he was building his garage. He used the container at one end and the tube at the other, leaving the cap on the bottle. the end result was a lean to one side of about a full course of bricks after he'd cast the two concrete padstones for the beam.

[ChrisBParticipant @chrisb35596]

Posted by peak4 on 12/11/2017 10:29:48:

A friend of mine recently bought the WM290 complete with makers cabinet.

I got mine without the cabinet thinking it would be difficult to level without adjustable feet, so I built my own on leveling feet….still a hassle to line up tho!

Regarding the level, I filled it up with isopropanol and dyed it, the thinner the liquid the more responsive it gets and although it's homemade it's pretty sensitive, not pretending it to be a starrett, but I could read a 0.02mm shim with ease, good enough for me!

So yet again, this morning I had another go at leveling the lathe, as suggested I opted to start from scratch, so I loosened the lathe mount bolts all 6 of them, and proceeded with leveling the headstock and tailstock ends. There was so much adjustment  I could do via the bench adjustable feet as would have ended up with a seesaw, so I got as close as I could with the feet and the continued adjusting by tightening the 6 lathe bolts to the bench.

After a while I managed to get both HS and TS level, so I tried a test cut to see how close I was. I used the same test piece I had yesterday but reduced the overhang to about 4 inches. This time round there was no tool chatter, so proceeded with the test cut, result 0.1mm difference, wider part at the HS end 

Continued with test cuts and adjusting the level until I got identical readings on the test bar, that left me with a slight twist to the lathe bed, but I'm happy with it, I'll do a double check with rollies dad method

 

Leveled HS end before test cut

 

Leveled TS end before test cut

 

Final position of leveled HS end after test cut complete

 

Final position of TS end after test cuts complete

Edited By ChrisB on 12/11/2017 16:49:13

Edited By ChrisB on 12/11/2017 16:52:09

[Tim StevensParticipant @timstevens64731]

Quote:

If you have a boring head consider making a centre to fit one of the holes in it, put the boring head in the tailstock and use the diameter screw of the boring head to offset the home made centre; that way you don't need to disturb the tailstock offset, and you have a nice screw adjustment to set the amount of taper you're turning.

Exactly as described in my book 'Workholding for Machinists' – recently reviewed by a chap called Neil.

There is indeed, nothing new under the sun.

Regards, Tim

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