For measuring inside bores I have been relying on a telescoping gage set and inside micrometers for quite a while. I finally bought a dial bore gage set, but I'm kind of lost as to it's use. I assume I need a set of calibrating ring gages and I also need to read the indicator backwards?
cheers T.Alan
If you've got the kind of dial bore gage which uses a pair of centralizing plungers on either side of the measuring plunger I don't think you really need to use ring gauges to calibrate it, it's only the center plunger which takes the measurement.
You should be able to use an appropriatly sized outside mike you trust to establish where "zero" on the bore gauge's dial is.
Jeff
Jeffry Wisnia (W1BSV + Brass Rat '57 EE) The speed of light is 1.8*10^12 furlongs per fortnight.
On Fri, 20 Apr 2007 10:44:59 -0700, "T.Alan Kraus" scribed:
T.Alan:
Special size ring gauges are quite pricey. Nice to have if your making a few thousand of one thing, but I reckon you want the gauge for day to day use.
If you have a set of gauge blocks, you can use them with inserts and a holder that will let you set any size between the pinion and back plunger, just make sure the centalizing points are somewhere in the range of where you want to be. There are special kits that you can get to do this exactly.
Depending on your accuracy or tolerances needed, you might want to invest in a short set of blocks, with the holder and bore setup goodies... Certainly a good investment anyway for the future.
As always,
Phred
How many anvils? Our bore gages have three spaced 120 degrees.
Wes
Depending on how close you are trying to measure, you can use a new ball bearing race as a gage. Much cheaper than a ring gage but a little less accurate.
John
If you have the type with three anvils at 120-degree orientation, then you WILL need a ring-gage.
However, if you have the type with the measuring anvil directly opposite a fixed (usually ADJUSTABLE) anvil, make sure the centralizing plungers work to keep the thing centered in the bore, and then you can set the gage with a reliable OD micrometer, and be quite well assurred of accuracy. Depending on the make and model of the gage, tenths are easily within expectation. You usually set the dial to read "0" at your desired setting and then read "+" or "-" as you measure the bore.
There are many good ones on the market, and at different price ranges, as well. In the past few years, even the knock-offs are about as good as the Name-brands, and often the parts are interchangeable, as well.
Flash
Just a tip on that: If you adjust the micrometer, press the mic's anvil outwards with your finger and use the ratchet to adjust. Then, while keeping the pressure, lock the spindle. Micrometers need some force to be precise.
Nick
In fact I've been using gage blocks to set a small precise vice jaw and then using that as my final gage. I thought that the multiple transfer of a primary standard reduces accuracy considerably, but maybe not if I'm striving just for + - .0005 accuracy.
Phred wrote:
Just two.
T.Alan
Thank you all for the replies. It's excellent to be able to get all this info.
T.Alan
Good tip!
I'm sure I wouldn't have thought to do that because I'd have been focusing my attention on the dial bore gauge.
Jeff
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