Dial test indicator on a mill question.

Parlo said:
Does anyone ever need to set their indicator stylus not parallel to the spindle?
Click to expand...

One must understand the COS() effect when performing metrology.

One can neglect its contributions when only using it as a null reference device. 0×cos(angle) == 0
 
Let's look at this subject from a different angle.
In a chuck on a vertical mill, a lever indicator is constrained to being permanently aligned with the spindle axis and the stylus movement always tangential to the spindle axis. Like the Metrinch for example where it has a pivoting spigot. See image.metrinch.jpg
This indicator remains aligned with the spindle axis & on centre, regardless of the swing. Would this cause any issues?
 
Not that I can think of, seems like common practice. Watching the dial with a mirror on the back side of the sweep is "FUN!"
I finally bought a Co-Ax indicator. Very fast to use. The only down side is needing to lower the knee to use it and then bringing it back up, if you don't have power on the knee. The Co-Ax is longer than the dial test indicator. The Co-Ax indicator works just like a dial test indicator except the dial stays in one place while the interchangeable tips can swing around with the spindle. All the interchangeable parts allow sweeping large holes and to a lesser extent the outside of a round work piece. All of which can be accomplished with cheaper tools but slower.

I have a well known brand made in China. It works OK but the threaded part, that the tips mount to, stripped very soon. I made a new part with more thread engagement and a knurled knob instead of needing to use an Allen wrench.
 
Thanks Larry.

I can't think of any situations either that can't use an indicator set correctly to the machine. There may be odd times, but Engineers are paid to solve these situations. In 40+ years since I was introduced to the pivoting stem I can't think of a situation where it has been a problem. Which leads me to the reason for the initial question, does an indicator ever need to be set in any orientation to the spindle other than as the Metrinch image shows.

I posted a video about two weeks ago that shows how a pivoting stem indicator in a tailstock chuck made indicating on a lathe simple. I now intend to look into indicating on a mill, specifically finding the centre of holes a little larger than the stylus tip using commercial indicator holders. This is a situation where it is crucial to have the geometry aligned with the spindle. A pivoting stem indicator will immediately be set correctly once the chuck is tightened.

Having satisfied myself that there are no circumstances where an indicator set correctly is a disadvantage, I will see how many commercial indicator holders can automatically set the indicator geometrically correctly to a machine spindle. I suspect none; yet it seems that it is advantageous, almost crucial & certainly 99% beneficial. I have my own very simple solution and I welcome any other solutions the members use to guarantee alignment of a dti stylus to a machine spindle.
 
Well it seems that the principle of keeping the indicator aligned is catching on. There is already a video posted mentioning alignment & defending the indicol holder whilst demonstrating its disadvantages at the same time. I'll have to get my skates on making my demonstration before too many buy an Indicol. Remember you saw it here first lol.parts 2.jpgvertical.jpg
 
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My slideshow on YouTube seems to have been caught up in the ongoing beef between the video of an indicator holder by Blondihacks and Joe Pie's video confirming the topic here. The Blondihacks naive attempt did blatantly highlight the issue with dti alignment to the spindle which encouraged me to clarify here the importance of correct alignment which I have not ever seen covered on social media. However Joe Pie wanted to quickly highlight Blondihacks design failure to have an open side to the indicator holder.

Due to the timing of the 3 videos, my research has been singled out as " absolutely false " by Joe Pie and my second favourite troll, Shop Tech.
I firmly believe that my unique hexagonal spigot replacement used with my slotted arm is a simple valid upgrade and offers the only non rotating mount for a dti. This truly unique and extremely robust holder, offers indicating from 0 to 150mm swing using only a 100mm long arm.

Sadly, Joe has once again invited me to comment on his channel to justify my design, knowing that he will historically block any suggested improvements. So just to give the heads up, you won't find a response appearing in any of his comments from me or perhaps many many others?

Here are the three videos for comparison.

Blondihacks dti holder -
Joe Pie's response -
My simple slideshow that I believe is the best solution -

Please enjoy all 3 and please let me know if there are any improvements that I could incorporate.
My design is free: post here or on YouTube comments if you need further info to manufacture..
 
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The Arch Indicol style in the picture for your video automatically aligns the indicator to the spindle. You just have to orient the angle of the indicator when you set it up. I have an Insize copy and it works just fine. I just bought a vertical face Interapid 312b-1v to use with it.

I use a good Japanese Indicol copy and I don't seem to have any real problems getting everything in line with the spindle. I run my test indicator with the face vertical with the needle dropping a bit less than straight down. This makes the face 10 times easier to see. It doesn't always work but it works often. This is what it looks like and I really like using it this way.

20220706_094154.jpg
 
Thanks for the image. It does show that the indicator spigot can be rotated in the holder clamp which will move the stylus away from the ideal alignment. Due the the number of joints in the Indicol style, the incicator can easily be moved out of alignment even when using the dovetail. My principle is using an hexagonal spigot in a close fitting slot to prevent this rotation and guarantee automatic alignment without having to set anything.
I seldom need a swing greater than 1/2 the width of the bed, the 4" model in the video can swing from zero radius to over 5". This compact unit has no joints making it extremely rigid and therefore accurate. It is nice to rotate the bezel without the needle flickering.
When I finish my spindle mounted prototype I will use either a vertical face dti or an adjustable mirror fixed magnetically to the ball on the end of the arm.
 
Parlo said:
Thanks for the image. It does show that the indicator spigot can be rotated in the holder clamp which will move the stylus away from the ideal alignment. Due the the number of joints in the Indicol style, the incicator can easily be moved out of alignment even when using the dovetail. My principle is using an hexagonal spigot in a close fitting slot to prevent this rotation and guarantee automatic alignment without having to set anything.
I seldom need a swing greater than 1/2 the width of the bed, the 4" model in the video can swing from zero radius to over 5". This compact unit has no joints making it extremely rigid and therefore accurate. It is nice to rotate the bezel without the needle flickering.
When I finish my spindle mounted prototype I will use either a vertical face dti or an adjustable mirror fixed magnetically to the ball on the end of the arm.
Click to expand...
The Indicol allows for the vertical indicator face with any standard test indicator. It takes 2 seconds to align the indicator to the spindle on only one round axis.

I totally get what you are trying to do. I just like the Indicol set up like in the picture better than anything I've tried so far. No more chasing the indicator face around the machine. I'm too old for that...lol!

Maybe you can do a variation of your holder with an arm that hold a standard dti the same way as my Indicol?
 
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