Dial Bore Gage

[Retired Wrencher 4,909]

:USA: Hi I have been to my Auto parts store and look into a D/bore Gage and $325 later I said I will think about it. I have been on E-Bay tons of Gauges there. So the Questions is what would u pay for this Gauges. I am only a weekender. I do not need the best and do not want junk ether . would $150-200 sound good for this. found a vintage set for $70.00 in a nice wooden box,but it was only up to 3" the K301 are 3.375/3.250. Thanks for any info. Gary B......................

[specialwheelhorse 174]

A dial bore guage is great but if you learn to use a set of telescope guages and

micrometers are just as accurate. Talk to your local Machinist buddy and he can show you.

I have a long handled telescope guage that covers nearly every size bore.

Those might be out of the question the way things are now.

Jim in Texas

[JamesBe1 80]

A dial bore gage will not give you an absolute measurement. You will need a micrometer to set it. I have one of the cheap sets from ebay (the ones in the red plastic case), and it works fine.

The critical piece is the dial indicator which needs to be linear over the narrow range you are going to be using it for. I've never had the least problem with that.

The accuracy limiting piece will be the micrometer that you set it with. The bore gage will only tell you how much the cylinder is over or under the distance at which you set the zero at.

If you don't already have a micrometer to set it to the desired distance, then it would probably be easier to go with the telescoping gages as Jim mentions. They aren't that expensive or hard to use. I'm sure that you can find someplace on the internet to give you a quick and dirty primer on their use.

[gregg'shorses 77]

This is a quality British made set instead of the Chinese junk. ebay item 350534895818

[Retired Wrencher 4,909]

thanks every one I will going to sears they have eather KD or Centeral Tool set of six. From $50 to $!00 unless I get Staret or Brown/Sharp for big $$$$$$$ . This looks a lot eayser than a B/Gauge Take care all. Gary B................

[wheelhorse656 20]

Get a good set of of .0001 micrometers and teloscopic bore guages and you will be set! I bought my set of bore guages for around $30 micrometers are a diffrent story I have no a couple hundred $ in the micrometers but it was worth it to have a good quality set.

[Keith 21]

I am using an telecoping bore gauge, not so successfully. I have measured a cylinder bore that is smaller diameter than its new spec. Wouldn't it be great if they wore that way? I am using a Chinese gauge set but its my lack of familarity with the tools that is the problem.

On this motor I have a slight ring ridge that is only on the flywheel side of the motor. What might that mean? There is no carbon buildup in this motor.

[JamesBe1 80]

There is a minuscule chance that the bore is actually smaller than spec, but very, very doubtful. Barring that, the only two things that I know of that could be affecting your reading are, technique or instrument error.

Consider looking on youtube for videos that demonstrate the proper use of telescoping bore gages. This may reveal a hidden flaw in your technique. There is a wealth of good knowledge (and some bad) on there.

If you are sure enough of your technique, then that leaves instrument error. Unfortunately, you are going to have to find a standard to measure it against. Any chance that you have, or have access to a 3"-4" micrometer? If not, then you are going to have to hunt down something with an accurately known distance and measure it.

That's just my 2C worth.

Many cylinders develop a small ridge around the lip of the bore. I have never heard of one was only on one side of the bore. I'd love to hear from some of the more experienced members here on that point.

James

[Keith 21]

The motor is an aluminum Briggs & Stratton 190434 from an 800 Special. I got it from someone who said it was running badly, but the spark plug threads were stripped and glued with JB Weld. Motor is clean inside, no carbon. Piston top is shiny. I have another cylinder head. I'll check the compression. Top of bore is smooth on the PTO side, a ridge on the flywheel side.

I have a set of digital calipers that I will use to verify results, when I find it

[TT-(Moderator) 1,129]

Another option: inside micrometers. :thumbs2:

[Callen 64]

Keith,

That means your bore isn't in line with the crank.

[MalMac 1,328]

Small word of advise, any of you machinist will know that whether you have a so so Gage or mike, or a high dollar one. The measuring instrument is not worth anything till it is calibrated. I have a box full of Starrett and I have had to calibrate right out of the box new. They may leave the factory in perfect calibration but handling while it's being shipped can knock the daylights out of them. Don't make the mistake of taking for granted that they are perfect right out of the box. It could cost you alot in time and money.

[SousaKerry 500]

Very well said the best guage in the world only measures as acuratly as the master it is calibrated to. I was a calibration technician in a former life and can write volumes on this but to boil it down buy a set of mics with a standard included.

Also I use 3 pronged internal mics They are much easier to use for the novice but you have to have a master ring to calibrate them.

[JamesBe1 80]

Keith,

That means your bore isn't in line with the crank.

Not sure what you meant but this, but it does bring up a good point.

My dial bore gage will center itself perpendicularly in the cylinder by virtue of it's spring loading mechanism. That is, the outward pressure from the springs will cause it to find the widest point across the cylinder. Not sure if this is the case with telescoping bore gages or not, but I don't see any spring loading mechanism from pictures on the net. If that is the case, and the gage is out of line (perpendicularly) from dead center in the cylinder, the reading will be smaller.

Add to that the possibility of - if the points of the telescoping bore gage are not exactly parallel (laterally)across the cylinder, the readings will be higher.

I can see that technique is very critical to obtaining an accurate measurement with telescoping bore gages.

Looks like this is a modicum of virtue for the plain old dial bore gage.

Also, MalMac is absolutely right. I've been doing calibrations and precision measurement for over 20yrs, and can say that he is spot on perfect. There are a lot of variables that can add up for or against you to the final measurement - temperature, cleanliness, accuracy, precision, linearity. Most of these sources of error are small, but can sometimes stack up against you instead of cancelling each other out to various degrees. Not saying that this is the case, here, but thought I'd throw that out for people to chew on. But it is really important to have accurately calibrated equipment. A calibrated set of micrometers to check the telescoping bore gage against would give you a much higher degree of confidence in your readings.

j

[JamesBe1 80]

I guess I was mistaken about telescoping bore gages. I was under the impression that they were direct reading instruments. That was not the case, and I guess that explains whey I have never worked on them. According to this, you still need a set of micrometers to obtain the actual measurement:

http://youtu.be/qDNP25PtBqM

[Keith 21]

My micrometer set come from Harbor Freight. It is missing the standards that are supposed to be in the kit. It might be cheaper to buy another HF set to get the standards. Who sells "standards"? I saw some on Ebay but not the right size. I am thinking that they might also go by another name. Professional machinists have told me the HF set is okay, that they use them along with their Starrett sets.

Not the hijack the thread, but what causes the cylinder bore to be not inline with the crankshaft? I assume that this was okay when the alloy B&S motor was new.

[JamesBe1 80]

The standards you need to check your micrometers are called gage blocks. Ebay has tons of them, but I would guess that most of the cheaper ones are not certified (calibrated). But then again, the standards in the HF set probably have a dubious certification (just my humble opinion).

You might consider a digital caliper to measure your bore gage:

http://www.harborfreight.com/4-inch-digital-caliper-47256.html

it has an alleged accuracy of +/- 0.001"

Don't worry about hijacking the thread. The threads tend to wander around here. Nothing wrong with that as long as we are all sharing knowledge.

I'll have to defer to some of the more knowledgeable experts around here regarding the cylinder alignment question.

[Keith 21]

I found several gauge blocks on Ebay. I ordered a cheap set. I'll ask a machinist to measure my "standards". I want to measure close enough to determine whether I have at a worn STD bore or whether its .010 etc oversize already. I am attempting to shop around to order a piston/ring to save myself some money. I want to restore this B&S as we have had this tractor since 1971.

I am also looking for a bigger Horse with cast iron Kohler or Onan..

Tim