MT5 Test Bar

[Just for fun]

I purchased an MT5 test bar made in USA. It was advertised as "Each piece is inspected for concentricity within 0.0001”

Acugauge MT5 Lathe Alignment Test Bar, Length 17-1/2 in. + Hooray, Your Item is in The US, not in India!: Amazon.com: Industrial & Scientific

Acugauge MT5 Lathe Alignment Test Bar, Length 17-1/2 in. + Hooray, Your Item is in The US, not in India!: Amazon.com: Industrial & Scientific

www.amazon.com

After installing it I'm not sure what I am looking at. I don't thing bar is concentric. I'll try and explain without a video, hopefully the photos will be enough.

I first checked the concentricity for my spindle. With my dial indicator zero run out.



On one side of the bar, I zero the indicator and without spinning the spindle I move to the tail stock end. It still reads zero or very close. For this test I think this indicator is going to be close enough.





Now at this point when I spin the bar 180° it almost 2 thousand out. And if I move back to the head, it doesn't come back to zero it is still 1 thousand out.





I hooked up two indicators, I can't say that I have a handle on it yet. My thinking is the bar is the problem. Why would one side pretty much be straight and then when I rotate it 180° it reads off.

I zeroed both indicators at the spindle then move to the tail stock end, about .5 thousand off maybe.





Rotated the shaft/spindle 180° and the indicators read 2 thousand out. Move back to the spindle and they both read about 1 thousand out.



Without rotating the spindle again, I zeroed the indicators and moved back to the tail stock end, they read 1 thousand out. What am I missing? By the way I marked the bar and the spindle with a felt pen and then rotated the bar to different locations in the spindle I can repeat all these measurements on the bar at the same locations.

 

[benmychree]

Blame the machine or the messenger? Check the spindle taper for even the tinyest nicks or dirt that could deflect the test bar. Finally, if the machine preforms adequately, why worry?

 

[Just for fun]

I have checked for nicks and dirt, cleaned both surfaces more than once. Even after that no matter how I install the bar in the spindle, I can repeat all these measurements on the bar at the same locations each time. I marked the bar and the spindle I have rotated it every 45° in the spindle.

Since the measurements follow the bar and not the spindle wouldn't that indicate that bar is ground correctly.

 

[Winegrower]

Finally, if the machine preforms adequately, why worry?

Because it's a hobby.

 

[ddickey]

Wow that Amazon add is deceitful. Your bar was not made in the USA but India. But at least it was in the US when you ordered.

 

[ddickey]

You're rotating the bar then returning to your origin, there is runout in the bar it won't return if you rotate the bar.

 

[Just for fun]

Wow that Amazon add is deceitful. Your bar was not made in the USA but India. But at least it was in the US when you ordered.

Yeah, After I posted that it was made in the USA, I was looking for the manufactures address or phone number and seen that it says the bar is in the USA there is nowhere that says it is made in the USA.

 

[Just for fun]

You're rotating the bar then returning to your origin, there is runout in the bar it won't return if you rotate the bar.

I agree, the bar is defective in my mind. How am I supposed to line up my headstock with a bar that has run out?

I did a couple more test using dead centers and my DTI. It looks like right at the taper there is (I'm not sure how to type it) I little less than one thousand run out. That can't be good.

 

[pontiac428]

Time to chuck up the bar in a 4-jaw and turn that taper true. Opportunity to use the tool post grinder.

 

[Just for fun]

Time to chuck up the bar in a 4-jaw and turn that taper true. Opportunity to use the tool post grinder.

That's above my pay grade at this point....