Koch test indicator

N

neilho

Titanium

Joined

Mar 23, 2006

Location

Vershire, Vermont

• Dec 29, 2022

• #1

Given to me by a friend, who inherited it from a neighbor 30 years ago, who got it dog knows where. Anyone have any experience with these, Koch specifically? I have a couple others in this style, one Starrett, but none like this.

Reads Koch Test Indicator, Nyack, NY. Pat July 17, 1906. The plunger operates the needle, as does the lever on the other end, but it's a bit sticky.
I may drive the cover off, which rides in dovetails, to clean it but mostly I'm just curious about it.

Sorry about the quality of the pix...

 

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I

IBLSKeith

Plastic

Joined

Oct 1, 2011

Location

Maine, USA

• Dec 29, 2022

• #2

The plunger end reads in thousandths on the scale.
The small lever has a reduction and gives a reading in tenths (0001”) on the scale.
I have one in my collection and I use it often.

 

N

neilho

Titanium

Joined

Mar 23, 2006

Location

Vershire, Vermont

• Dec 29, 2022

• #3

IBLSKeith said:

The plunger end reads in thousandths on the scale.
The small lever has a reduction and gives a reading in tenths (0001”) on the scale.
I have one in my collection and I use it often.

Click to expand...

Ah, good to know, the 10/1 reduction, especially.

In my reading on the forum, post-post as it were, Koch made a surface gage for use with this indicator, too. Rivett may still be looking for one

What do you mount it to? I may have the right fittings in my collection for this mount, but mostly I use dovetail test indicators.

 

I

IBLSKeith

Plastic

Joined

Oct 1, 2011

Location

Maine, USA

• Dec 29, 2022

• #4

I mount it anywhere I would use a dial indicator.

 

D

duckfarmer27

Stainless

Joined

Nov 4, 2005

Location

Upstate NY

• Jan 1, 2023

• #5

Neil -

I have the twin to your indicator. Got it with two tool boxes I bought at an auction about 6 years ago that came out of an estate - I entered a thread on here about the boxes and contents https://www.practicalmachinist.com/...s-from-an-old-tool-chest.325950/#post-2845155

The one I have has some old corrosion on one side but works smoothly, although I have never actually used it for any work. The top on mine slides easily in the dovetails. After reading Keith's comment I looked at it - knew there were two movements but had not realized the 10:1 reduction of the one.

Nice find.

Dale

 

rivett608

Diamond

Joined

Oct 25, 2002

Location

Kansas City, Mo.

• Jan 2, 2023

• #6

These were very successful as it is about the 2nd most popular test indicator behind the last word. I have seen them in about half of the early 20th machinists chest I’ve looked through.

 

N

neilho

Titanium

Joined

Mar 23, 2006

Location

Vershire, Vermont

• Jan 3, 2023

• #7

Thanks, Dale. Nice to know that cover is supposed to slide easily. It does need to come off, as the needle is bent up against the cover and sticks a bit at the end of its travel.

I wish I could say that I found it, but it was a gift from a guitar maker friend that I do occasional metal work for. He was given it by a 30-year-ago neighbor whose father was an amateur machinist, along with a set of B&S wigglers and misc other stuff. Surprisingly to me, there's only minor surface corrosion.

Keith - I'm intrigued by the fork-shaped attachment in the foreground of your photo. What's its purpose?

 

I

IBLSKeith

Plastic

Joined

Oct 1, 2011

Location

Maine, USA

• Jan 3, 2023

• #8

neilho said:

Keith - I'm intrigued by the fork-shaped attachment in the foreground of your photo. What's its purpose?

Click to expand...

I can’t say what the original purpose was….it came to me that way. I use it to clamp the indicator to machinery….but more often than not I just remove that piece and use it on a surface gauge.
Keith

 

N

neilho

Titanium

Joined

Mar 23, 2006

Location

Vershire, Vermont

• Jan 10, 2023

• #9

Finally got around to getting the cover off and oiling and adjusting it. And after a few trial and error minor bends, the needle no longer sticks.

And checked the indicator readings vs my DRO's. The plunger reading agrees with the DRO's, but the "side lever" reading is half what my DRO's say. Perhaps there were options for different ratios on that side lever.

 

I

IBLSKeith

Plastic

Joined

Oct 1, 2011

Location

Maine, USA

• Jan 11, 2023

• #10

so the side lever is showing .0002” per graduation?
Mine is .0001” per graduation

 

N

neilho

Titanium

Joined

Mar 23, 2006

Location

Vershire, Vermont

• Jan 11, 2023

• #11

That's the weird part about it - the DRO's show .002" per indicator graduation. Tested in both the x and y axis, plunger too, consistent in both axes.

I'm wondering if Koch made them with different ratios. Selling point and all that.

 

I

IBLSKeith

Plastic

Joined

Oct 1, 2011

Location

Maine, USA

• Jan 11, 2023

• #12

Patent can be seen here.

US825911A - Test-indicator. - Google Patents

Keith

 

N

neilho

Titanium

Joined

Mar 23, 2006

Location

Vershire, Vermont

• Saturday at 9:47 AM

• #13

Hmmm. Thanks for that link. Interesting reading. The indicator drawings in the patent application are different than any Koch I've seen.

Immediately noticable is the arc with the indicator divisions on it- not symmetrical about the ctrline of the length. The indicator needle in mine is straight, not a bellcrank, though the mechanism appears to operate similarly. And the plunger housing on mine is straight sided and isn't centered.

Safe to say we've different beasts than the patent app.There may have been some evolution in design, but not deemed worthy of another patent.