How are your contact points fellas?

[Anorak Bob]

Not in the EJ Holden but on the ends of your indicators.

Before I committed myself to boring one hole I thought it might be pertinent to have a look at the indicator point I intended using to help locate that hole. Viewed through a 7x loupe I noticed a flat worn on the end of the ball contact. I then decided to check all of my indicators and a set of contact points I have. Some of my second hand indicators, whilst in exceptional cosmetic condition, have scratches, burrs and flat spots on their contact ends. A check of the points in my set revealled two that I had ruined while determining grinding wheel runout.:doh:

Being aware of this will encourage me to either use the couple of beater indicators I have for rough stuff or use a less than perfect contact for the same work and keep the pristine points for special occasions.

A bunch of blokes have raced out and dropped 3 dollars of their hard earned play money on 60x and 100x pocket men's fertility testers. At that magnification you'd see past the damage and wear. I tried to look at something a couple of days ago at 43x when I removed the head from my microscope and attempted to hand hold it. I couldn't hold it still enough to bring anything into focus.

The last paragraph is an aside. It's worth checking the condition of those points.

BT

[Abratool]

First thought was "I dont have a car with points"
But still have the equipment to test points cam angle etc I liked fiddling with my EJ, those years back.
I am looking forward to getting my mens $3 fertility tester,Never know what the results could be. For $3 not expecting an Electron microscope.
The dial indicators I have are...
A Tesa brand 1/2 thou graduation
A Starret brand Last Word 1/2 thou graduation
A Mitutoyo brand 0.01 mm which I dont use much because always mentally converting to .0004"
I just checked the points & they all look good under a hand held magnifier.
That may change when I get the expensive $3 job
Thanks for the reminder Bob, I have noticed some indicator points get wear flats which would give false readings
regards
Bruce:)

[Dave J]

You bring up a good point Bob as I have never checked and I am sure a lot of others haven't either.

Dave

[Stustoys]

I'd always thought all my "standard" points were carbide. I'd better have a look see.

Stuart

[steran50]

HI:),
I thought that they were carbide too. I will have to have at look at mine to check their condition. Thanks for bringing it up Bob:2tsup:.

[pipeclay]

Is it really worth the effort for a backyard show?

[Anorak Bob]

It comes down to what you and we aspire to Peter.

[Greg Q]

As an aside I bought a Mitutoyo micrometer calibration set a couple of years ago when no one else was looking*. I think I paid $12.00. It has the optical flat and the set of gauge blocks in the genuine non-organic rosewood box. My point is (and I do have one) that it is surprising how non-flat micrometer anvils can be by the time they bob up to the surface on ebay. A little judicious repair can go that extra couple micron towards a reliable measurement.

And I am with Bob in the pursuit of excellence. Sure, variables creep into the equation: temperature, concrete pad stability, etc etc. But the purposeful elimination of variables is the path towards enlightenment and less doubt. Less doubt is self-evidently a worthwhile goal in a world chock-a-block with uncertainty.

* I mention this solely in the interest of perpetuating the myth of the BargainSlayer™:U

GQ

[Anorak Bob]

I got a rude awakening when one of my vintage micrometers met Alan"C-47"s optical flat. Not much flat going on.:no: Any chance of an expansion on the judicious repair GQ? Long Island Indicators will undertake a relap but with their shipping costs a new mike could be a more economical solution.


And thanks for the backup..

[Greg Q]

Well, in my case I have mostly one brand of mic. I happened across a box of 12 Etalon anvils for my imperial mics...My Tesa metric set was purchased new from Italy for a song...and to my regret, at a price so far below retail as to invite thoughts of stolen goods:(

That's not to say that you could not lap them with a bit of diamond paste given a truly square set-up. Then again, I was astonished at my new 0.01mm micrometer anvils being about 0.002 out of flat-a happenstance that gives pause to the claim of absolute 0.01 precision. (Since it is an article of faith that a metrology instrument needs to be an order of magnitude, that is: 10 times more precise than the feature that it is called upon to quantify.)

It's a good thing that at these unreal levels we can often use comparative measurement as opposed to absolute...once you get into the realm of truly legendary precision you cross the threshold into climate control, daily levelling, monthly calibration, and the little known anal breathing exercises.

GQ