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techtalk:ref:tools109 [2019/05/28 05:27] hippysmack [Telescoping Bore Gauge (snap gauge)] |
techtalk:ref:tools109 [2019/08/01 22:55] hippysmack [Telescoping Bore Gauge (snap gauge)] |
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| Each arm snaps toward opposing sides in the bore (hence the slang 'snap gauge'). \\ | Each arm snaps toward opposing sides in the bore (hence the slang 'snap gauge'). \\ | ||
| The arms are rounded on the ends and they will self center in the bore. \\ | The arms are rounded on the ends and they will self center in the bore. \\ | ||
| + | They usually come in a kit. This one's from Harbor Freight and works great. \\ | ||
| + | The ends are curved as to not catch a corner or thickness of a flat end as in a caliper. \\ | ||
| + | {{:techtalk:ref:tools:telescoping_bore_gauge_kit_by_hippysmack.jpg?direct&300|}} ((photo by Hippysmack)) {{:techtalk:ref:tools:telescoping_bore_gauge_by_hippysmack.jpg?direct&300|}} ((photo by Hippysmack)) | ||
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| * The measurement is found by forward and backward movement in the bore with the gauge loose and with a slight drag. | * The measurement is found by forward and backward movement in the bore with the gauge loose and with a slight drag. | ||
| * When you feel you are at the correct distance, (pulling straight in the bore with a slight drag on the tool), tighten the nut to keep that arm length. | * When you feel you are at the correct distance, (pulling straight in the bore with a slight drag on the tool), tighten the nut to keep that arm length. | ||
| * Before removing the tool from the bore, continue the movements to make sure you still have the same drag as you did before tightening the tool. \\ Then remove the gauge tool from the bore. | * Before removing the tool from the bore, continue the movements to make sure you still have the same drag as you did before tightening the tool. \\ Then remove the gauge tool from the bore. | ||
| * Next, use a caliper to measure the length of the gauge arms to find the internal diameter reading. \\ | * Next, use a caliper to measure the length of the gauge arms to find the internal diameter reading. \\ | ||
| + | * Take several measurements instead of just one and at different points around the bore to check for equal roundness. | ||
| It takes practice and patience to get used to using this tool. \\ | It takes practice and patience to get used to using this tool. \\ | ||
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| * Snap gauges are notorious for closing in (slightly) when the nut is tightened. This will give you a bad reading. \\ You should feel a slight drag in the bore with the arms loose and the same when tightened. \\ Continue with the forward and back motion until you feel like the tool is perpendicular to the bore (with a slight drag). \\ Then tighten the nut and double check that you still have drag on the tool BEFORE removing it from the bore. | * Snap gauges are notorious for closing in (slightly) when the nut is tightened. This will give you a bad reading. \\ You should feel a slight drag in the bore with the arms loose and the same when tightened. \\ Continue with the forward and back motion until you feel like the tool is perpendicular to the bore (with a slight drag). \\ Then tighten the nut and double check that you still have drag on the tool BEFORE removing it from the bore. | ||
| * It's also easy to turn the tool sideways (even slightly) and feel drag. \\ Then while double checking the distance when tightened, you get even more drag. \\ Since a sideways measurement is longer than a straight thru measurement, this will give you a bad reading. | * It's also easy to turn the tool sideways (even slightly) and feel drag. \\ Then while double checking the distance when tightened, you get even more drag. \\ Since a sideways measurement is longer than a straight thru measurement, this will give you a bad reading. | ||
| + | * Evo cylinders will naturally not be perfectly (a few thousandths variance in circumference). \\ To measure cylinder bore, the heads have to be off which releases the torque on the cylinder and distorts the bore. | ||
