PDA

View Full Version : Interesting situation with my Starrett Last Word #711



scmw
12-09-2010, 02:12 PM
I just trammed one of my mills after doing some clean up on it. I used a Starrett #711 Last Word DI. I managed to get the mill trammed but I noticed some interesting actions on the part of the DI.

Note: Prior to tramming, I marked off the X and Y axis points with a sharpie to insure that I was measuring 180 degree opposites each time that I took a reading.

As an example when tramming in the Y, I set the DI bezel to zero on the back side of the table nearest the column. I would then rotate the spindle CW to the front of the table. I then split the difference and rotated CW back to the point of origin (column side). After I had the Y axis to where I thought it should be, I rotated the DI CW between front and rear. Each time that I checked the dial, it would show -.0005" consecutively. I.E. The first time the back of the table read 0. The next rotation showed -.0005". The third rotation showed -.001 and so on. It did the same thing with the front of the table.

Keep in mind that the table was stationary during the tramming process.

I did switch to another DI which confirmed that the mill was correctly trammed but I suspect that my Last Word has done it's last tram.

Has anyone else experienced something like this?

TGTool
12-09-2010, 02:35 PM
Something's shifting. Either the indicator holder is drooping or the indicator point isn't holding its position or it's getting bounced crossing the slots in the table. I wouldn't conclude that the indicator is headed for the last roundup yet.

Carld
12-09-2010, 02:46 PM
Your going to get some deviation on any dial indicator and the reason is the slop in the shaft the linkages. The way you can see it is if you turn the spindle back and forth you will see the indicator needle go up and down. That is, in one direction the needle will show .000" and the other direction it will show .0005".

That is why I always try to take a reading in the same direction but even that can be an issue because when you stop moving the indicator it may change the reading. Sometimes I move the indicator in one direction very slow and take a reading then move to the opposite point and do the same.

With all that said, just how accurate do you want a Bridgeport type mill that has more slop than that in the quill to head and spindle to quill? Think not, push on the side of the spindle nose and watch the dial indicator.

If you get the head in showing inside .001" it will be just fine. You may get it to show .000" at all four points, which I doubt you will, but when you move the X and Y and/or the knee things will change.

Keep using the Last Word but only load the indicator with about .010" to .020" travel while reading each position. Any more is not needed. Get it within .001" at all four points and be happy. It will never be perfect no matter how hard you try.

scmw
12-09-2010, 06:20 PM
All points taken. When rotating the spindle CW, I took care to rotate it slowly as not to offset or disrupt the ball point when going across the slots.

I did obtain have readings of 0.0 on the X axis surprisingly enough. The Y has me puzzled. And yes, it's a B'port. Series II with the 4HP head. Heavy little beast!

Thanks again,

Rich Carlstedt
12-09-2010, 07:07 PM
Any change of rotation direction produces an effect on the Dial linkage
Try to always go in the same direction (ie CW) to prevent this.
A very common issue with worn indicators
Rich

strokersix
12-09-2010, 09:17 PM
I put my spindle in neutral and spin the indicator (usually held in a drill chuck with a suitable extension bar) with a light touch. Work it back and forth over the surface to get a feel (visual as opposed to tactile) for the needle motion will uncover hysteresis and average surface irregularities.

J Tiers
12-09-2010, 10:01 PM
Your basic problem is that you are using a Starrett last word.....

Get a decent chinese DTI and use that instead. it should work better. I am NOT joking....... not one little bit.

As for anyone else experiencing something like that... YES. About every time I use a "Last Word" indicator I experience something like that. I have two LWs, both of which suck. Bought another figuring the first (both are used) had an "issue". yeah, it did, and the second has the exact same issue.

I borrowed a NEW one at work to align a high speed shaft and motor, and IT sucked too. I brought a decent indicator in and did the job the next day.

darryl
12-09-2010, 11:22 PM
Here's Neil Youngs last word-

http://www.google.ca/url?sa=t&source=web&cd=4&ved=0CCsQtwIwAw&url=http%3A%2F%2Fwww.dailymotion.com%2Fvideo%2Fxjo 08_neil-young-piece-of-crap_music&ei=IpsBTZKSG4OqsAP93MjaAw&usg=AFQjCNFW-9Q6_MNjsqQphBJM_aw6ZcwRmw

gwilson
12-10-2010, 12:44 AM
The last word's feeler is not easy to move as it should be. Get an indicator that has an easier to move tip.

scmw
12-10-2010, 03:08 AM
OK, so there are those who don't believe in the LW. I have no problem with that as I'm not married to it. What would be a good substitute?

Thanks,

JoeLee
12-10-2010, 09:20 AM
When I tram my mill I never run the point of the dial directly on the table surface. I always set a long ground paralell across the table and indicate off that. All the little nicks, scraping marks and jumping the T-slots will make the dial jump all over the place.
After I indicate off the table I mount the vise and check the surface of the vise as well. I always wanted to make a circular paralell for this job so I could just set the ring down on the table and swing my dial around it without having to slide a paralell around under the dial point.

JL..........................

j king
12-10-2010, 09:56 AM
As already stated the last word is JUNK. I bought a new one also and it was a POS! Starrett should give one to everyone for free and include a ball pein so you can smash it and the world would be a better place.Get a best-test Love it except the mount. Hate it.Pain to set up and adjust as easy as the LW..