Cylindrical square from a lathe tailstock.

[tonyfoale]

I had a spindle from the tail stock of a large lathe which I used as the basis for an accurate cylindrical square. Although the spindle was hardened it had some wear due to years of use on the lathe. This video shows how I lapped it true and checked it for squareness.

here is a link to my Youtube playlist of more workshop videos.

https://www.youtube.com/playlist?lis...O1hdmUIYO28Def

I had an old aluminium bearing housing in the scrap box which had a bore of 50 mm and the tailstock cylinder was 54 mm so I made a lap by boring out the housing and then splitting it with a bandsaw. I added a couple of clamping screws for adjustment during lapping.

Click for full size.



I had machined the bore for a nice slip fit on the cylinder, but for the initial lapping I spread the diameter a little so that I could charge it with the lapping grit and some thin oil. I worked the lapping over the areas which were the largest. The cylinder varied in diameter by only 2 tenths of a thou. prior to lapping. Pretty good but I like perfection where possible.

Lapping.

After lapping I could detect no difference in diameter over its working length. So that left the squareness to the base to be checked.



I suggest watching the video for more details. Please like and share it and subscribe to my video channel if you have not already done so.

[tonyfoale]

Finally I cut a short length off the top to eliminate an undersize area.

Attachment 32877

[DIYSwede]

-Wow! Thanks, Tony for yet another inspiring and educational video!

You really got the point across regarding the necessity of having a cylinder square:
its self-checking ability for establishing its own squareness:
-As even a leaning cylinder have 2 perpendicular lines somewhere around its perimeter...

For years I've been on the lookout for a 1-ish ft long, 2-3" dia hydraulic piston at scrap yards for precisely this purpose.
I'll personally try to aim for a 4-5:1 length to dia ratio.

I was initially a bit hesitant about the compressability of your bearing housing lap,
but you killed two birds with one stone when slitting the inside, also providing grooves for the slurry...

Q: I wonder about your sequence of lapping and the grits chosen - any info to share on that, please?

Turning and lapping in the bottom of the newly sawed-off end will probably be another video of yours?

All the best for the coming new year!

Cheers
Johan

[tonyfoale]

-Wow! Thanks, Tony for yet another inspiring and educational video!
For years I've been on the lookout for a 1-ish ft long, 2-3" dia hydraulic piston at scrap yards for precisely this purpose.

An hydraulic piston shaft should be good, but are they usually hardened or chrome plated? I have never tried lapping chrome.

Q: I wonder about your sequence of lapping and the grits chosen - any info to share on that, please?

I do not know the grit size. I have some 1200 grit diamond but that was a bit fine for removing much metal, great for a mirror finish but my concern in this case was not a shiny finish. I had several lots of valve grinding paste and one tube emphasised that the grit was all one size (it did not say what that was), so I used that one. Not a scientific choice but a practical one.[/QUOTE]

All the best for the coming new year!

Cheers
Johan

Thanks, and the same to all inmates of this forum.

[Toolmaker51]

DIYSwede, and Tony Foale; very clear you both familiar with geometry that makes Cylinder Squares dependable standards, whether comparison or direct measure.

To the General Population [inmates], I'll add three, carrying the process off in useful ways.
Brown & Sharpe [+ others] make a cylinder where ends vary intentionally. One end square isn't any surprise. Their 6" x 2"ish #558 product is OUT OF SQUARE on the other end! What? Yes, intentional! The exterior is marked with ellipses, interpolating out of squareness at given heights. Rotated in proximity with piece being inspected, the tilt goes from possible full contact to less than, regardless. Just as Tony demonstrated and DIYSwede observe, a cylinder [tilted] has two [minimum] perpendicular lines of contact. The #558 can relay needed correction quite accurately; greater angles are likely planned and better verified by sine tools.

Another fine square, especially popular setting up in accordance with horizontal [vertical plane] locations is the Magnetic Cylinder. Constructing one wouldn't be out of range for many private shops. They are non-magnetic stainless with epoxied Nd magnets [usually 3] with a small gap less than flush from the base. The broad base supports the smaller cylinder readily, as they are machined one piece. Careful handling would make brass, bronze or aluminum rather acceptable.

Finally, pic might disclose a rarity, the cloverleaf square.

Some tools arise out of utility.
Some tools born out of imagination; may not gain interest outside that realm.
Some go away when processes get outmoded.
Some disappear, thankfully. We call those gimmicks.

https://www.google.com/search?q=brow...w=1600&bih=736
https://www.google.com/search?client...4dUDCAY&uact=5

[tonyfoale]

Thanks for adding that toolmaker51.

[tonyfoale]

For years I've been on the lookout for a 1-ish ft long, 2-3" dia hydraulic piston at scrap yards for precisely this purpose.
Johan

Your comment reminded me that I happened to have a couple of 20 ton bottle jacks open. i measured them to check what the were like.

Click image for full size.

The item on the right is my new cylindrical square, the other two are from the bottle jacks. The longer one measured up with the ends of equal diameter but around midway was 0.001" large. The shorter one had a gradual taper of 0.003" over its length. Careful setup in a lathe or grinder would allow bringing them up good enough to lap to an accurate shape. Not the ideal donors but they are readily available. The shorter jack was obviously built to lower quality standards, with rougher machining and twisted gaskets etc.

[DIYer]

Thanks tonyfoale! We've added your Cylindrical Lapping Tool to our Machining category,
as well as to your builder page: tonyfoale's Homemade Tools. Your receipt:

Cylindrical Lapping Tool by tonyfoale

tags: tailstock

[DIYSwede]

Thanks Tony & Toolmaker51 for good comments,
unfortunately my usual scrap sources don't seem to carry any
heavy equipment or machines that could carry 3" hardened pins or sleeves.

I've yet to find a 20T bottle jack or a tailstock spindle...

Lapping a chromed piece would most certainly "forge my character".

Cheers

Johan

[tonyfoale]

Thanks Tony & Toolmaker51 for good comments,

Lapping a chromed piece would most certainly "forge my character".

Johan

Yes it probably would.