Thread: WANTED: Precision ground test bar

Looking for a hardened and precision ground test bar that I can use to indicate out a lathe.

I have a spare one. Brand new, hardened and precision ground. It's 1" x 12" (IIRC) and has center holes for indicating between centers. In addition to everything, this will allow you to align/realign the tailstock or displace it precisely for cutting tapers. You can also use the bar to measure chuck or collet runouts.
I guess $150 including shipping will be fair.

What size? They mount to the spindle taper. I have two, MT5 and MT3. I found mine on eBay.

If you just want a ground shaft and don't need the taper, my choice is McMaster Carr....Look under linear shafting, the stuff used with linear bearings.
Comes in various ways...I usually buy the hardened and chromed version. The stuff comes in almost any length and in different diameters depending on your needs....
It is very straight and round right from the store....
Cheers Ross

Originally Posted by steve-l

What size? They mount to the spindle taper. I have two, MT5 and MT3. I found mine on eBay.

Precision ground test bar lathe | eBay

When setting up a lathe. The first step is the level and straight bed. The second step is checking headstock/ spindle alignment with the bed. Using a chuck of any description adds an unacceptabe variable. That is why the test bar must use the spindle cone.

Originally Posted by steve-l

The second step is checking headstock/ spindle alignment with the bed. Using a chuck of any description adds an unacceptabe variable. That is why the test bar must use the spindle cone.

Sorry, but if you're simply checking the spindle axis alignment with the carriage travel then any chuck that reasonably centers a round bar will do. All you're doing is to get the position of the bar relative to the indicator by averaging the high and low indicator reading by rotating the chuck. You want to do that even with a taper mounted test bar just in case there's some crap pushing the bar a little off axis.

But neither checks the alignment with the bed - it checks alignment with the path the carriage follows on the bed. On a new lathe with a well fitting carriage that should be the same as the bed, but with a worn lathe with a roller coaster bed it isn't, and that's where the fun comes in.

Miller Machine makes a variety of test bars for what seem like reasonable prices.

Miller Machine & Fabrication - Products