lathe mounted sine bar

[bob ward]

This isn't my idea, I first saw it over on practical machinist and I thought it was pretty neat, and best of all its made out of bits and pieces. The shaft is an offcut of 32mm hex, the plate is a piece of used 4" x 1/2" flat, the back fence and sine bar are 16mm square cold drawn, the sine bar rolls are 1/2" stainless rod out of a dead printer. The blocks to set the sine bar are made as required, so far that's been for an MT4 taper, an NT30 taper and 8° for an ER collet holder.

The thing I really like about this is that you don't have to have an original taper to set your compound to, just set your compound to the sine bar and off you go.

The fence is left a little short at the headstock end so you can put a small level on the plate. One of the fence's mounting holes is slotted so the fence can be trued up to the axis of the lathe.


2 views of the sine bar set at 8°, the block in this case is a piece of round turned to the required diameter.


I wanted the sine bar to be around 8" long, and its ended up with roll centres of 193.87mm

[cfellows]

Nice bit of kit, Bob.  Do you use this to set your compound angle for turning a taper?

Chuck

[Trion]

That is very neat! On the do to list

[bob ward]

 cfellows, at the moment I eyeball the compound to the required angle, then fine tune it by running a DTI up and down the sine bar.

While typing this, the thought occurs that its possible to reorganise the design to eliminate the DTI step. ie rearrange the components so one can, with the compound loose and the tool block fixed, set the tool block against the sine bar.

[AussieJimG]

Thanks Bob, I think this is exactly what I was looking for to set the angles on valve seats and heads. And it is so simple.

Jim