How do I scribe a taper?

[DarrenUK]

Can anyone suggest a tool or a quick easy way that I can use to scribe a straight line down the centre length of a tapered bar?

I know I could measure and mark each end at the centre then just use a straight edge to scribe but would like to find a quicker alternative method.

Red line on image below is where I want to scribe.

[Pete.]

Mount it between centres on a lathe and use a height gauge scriber along the top of a piece of bar held in a toolpost at centre height.

[Stilldrillin]

Mount it between centres on a lathe and use a height gauge scriber along the top of a piece of bar held in a toolpost at centre height.

I like that idea Pete! 

David D

[DarrenUK]

Forgot to mention, I have no lathe, just a small SX2 milling machine and a few basic tools.

[angus]

how accurate does it need to be ???

use some marking out blue

dirty way put in a vice holding the ends, the holding a spirit level, and looking at the bubble drag it along the top edge

will be fairly close, but maybe not close enough for what you want ?

[ieezitin]

Darren

put on a surface plate build up smallest end with gage blocks (mill one since you have a mill)...you could use adjustable parallels,  You could use a sine bar get the angle and lay it top to tail on it.

Without some tooling its not easy to do.

Anthony.

[ausdier]

Reply #9 over here I think is a good simple answer.
http://www.modelenginemaker.com/index.php/topic,3285.0.html