You are very right Alan a 125mm sine bar will give you a different result to a 5". Not innacurate, just different. You could not use 5" sine bar tables but find 125mm tables or do a bit of trig.

Just multiply the sine of angle required by 125 then divide the answer by 25.4 Now you will have an imperial size to use your imperial slips.

As long as you know the roller centre distance of the sine bar it's simple trig to work out an angle.

Tony

I’m with J.H. I have sine bars and slips plus a wixey gauge, I’ll let you guess which one gets used the most!!!

I have a sine bar that I made. It was in the magazine a couple of years ago.

Made from gauge plate and silver steel easy to make. 45mm centers so I could use it in a small vice as well.

David

I've never seen one, or a photo of one, but I believe that Hardinge made a 'double' sine bar or table. The principal was that, instead of having the stack of gauge blocks on the milling table etc. and the sine bar forming the hypotenuse of a right angle triangle, there were two hinged bars and the gauge blocks were clamped between them, forming an isosceles triangle.

The calculation was sin(angle/2)=(gauge stack length/2)/bar length. While the calculation is slightly more complex, the advantage of the system was that the gauge blocks would not have any tendency to be squeezed out of the assembly, even for large angles, since they were clamped between the tangents of two cylinders, not a cylinder and a flat.

If one ends up making a sine bar, this system might be worth considering.

I bought a 5" one years ago. It has only ever been used to hold things down whilst the glue sets. Much more useful is a set of angled bits of steel bought from Chester years ago

Duncan, I have a couple of sine bars, never get used, use the Wixey instead. However, I occasionally use a home made device copied from somewhere on the internet. It's a thick rectangular block of steel with an arm pivoted near a bottom corner, which swings to different angles and secured by another screw. Angles are 90, 60, 45, 30 degrees. Set up in machine vice like an extra and loose jaw, I've used it successfully a number of times.

John

I have a 5 inch sine bar and have used it a very few times.

I am intrigued by Mark Rand's description of the Hardinge double sine bar .I cannot see why the slips would tend to get squeezed out of a conventional sine bar when they are held betwen a flat and a tangent to the roller- which tends to a flat at the point of contact. There is a limit to the size of the angle which a particular sine bar can be set up for, determined by the amount of metal cut away to give clearance near the roller but I would have tthought that would equally apply to a "double" sine bar.

Rod

I have a 5" sine bar, a 5" sine plate, and a 3" an 2.5" sine bars plus a compound angle magnetic chuck with 5" roll distance. While I do have gauge blocks (slips) I often use an adjustable parallel or a shaper gauge to set the height instead of using the gauge blocks. The 2.5" bar has an integral base. Once the angle is set the bar can be locked to the base to maintain the angle. The integral base incorporates a magnetic V. It works great on the lathe for setting the compound to exact tapers.