dial bore gauge setting rings/fixtures

CNC BLOCKS · Post by **CNC BLOCKS** » Tue Mar 04, 2008 4:17 pm

stock z/28 wrote:Hello,

Carl, Im a bit confused by your statements about the inaccuracies of the Mititoya style bore gages in reading brgs clearances.

Could you explain it again, please?

I have a lot of different brands of bore gages, including some high end (atleast for me) Standard, Federal-Mahr, and others.

I have a pretty nice Standard bore gage setting fixture, but I get pretty comparable results using a mic in a micrometer holder.

Im not disputing your thoughts Im just trying to understand them better.

It seems to me gage is "reading" from the probe and the extension, and the "wheels" or "fingers" are just centering the device in the bore.

I can see where "if" the bore was very out of round the centering might be off?

It seems as long as you position the gage to "find" the largest (locating the largest diameter of the bore being checked) and then the smallest reading (locating the probes 90 degrees to the surface being measured) it would be pretty comparable, regardless of brand/style of gage used?

I hope I explained that about right!

Thanks

Jeff

Reread my previous post Like I said the cheaper bore gauges work fine in round bores and not having a setting fixture is not as accurate as a guy using a bore gauge with a setting fixture and with flexable fingers like the Sunnen gauges use.

n2omike · Post by **n2omike** » Tue Mar 04, 2008 5:18 pm

I have a Mitutoyo dial bore gage, and don't like it for use on bearings.

The spring on the little compressible tip is VERY stiff, which causes the tip to dig into the bearings. This gouges them out, and makes it look like the crank has more clearance than it actually does. Testing the clearance using different methods yields tighter results.

At least, this is MY experience. Personally, I'd like to have a little broader compressible tip with a slightly lighter spring tension.

Good Luck!

RW TECH · Post by **RW TECH** » Tue Mar 04, 2008 10:48 pm

n2omike wrote:I have a Mitutoyo dial bore gage, and don't like it for use on bearings.

The spring on the little compressible tip is VERY stiff, which causes the tip to dig into the bearings. This gouges them out, and makes it look like the crank has more clearance than it actually does. Testing the clearance using different methods yields tighter results.

At least, this is MY experience. Personally, I'd like to have a little broader compressible tip with a slightly lighter spring tension.

Good Luck!

Which gauge do you have? if it's the 511 that's absolutely NOT what you should be using on bearings. The 545 is a wayy different animal, but it costs more too.

Wolfplace · Post by **Wolfplace** » Wed Mar 05, 2008 1:12 pm

RW TECH wrote:
n2omike wrote:I have a Mitutoyo dial bore gage, and don't like it for use on bearings.

The spring on the little compressible tip is VERY stiff, which causes the tip to dig into the bearings. This gouges them out, and makes it look like the crank has more clearance than it actually does. Testing the clearance using different methods yields tighter results.

At least, this is MY experience. Personally, I'd like to have a little broader compressible tip with a slightly lighter spring tension.

Good Luck!
Which gauge do you have? if it's the 511 that's absolutely NOT what you should be using on bearings. The 545 is a wayy different animal, but it costs more too.

=
Ditto

I use the Sunnen gauge, as well as a number of Mitutoyo's, all are in my opinion excellent gauges if used correctly.

But the Mitutoyo 545 series is my favorite one for bearing clearance
The tips have a huge radius & do not damage the bearings like others
The one I use is the 545-135 with the 10" extension so you can get to the center mains
http://www.mitutoyo.com/TerminalMerchan ... group=1523

Side note:
You can set the 911 series in a Sunnen setting fixture with a 60 thou shim under the gauge if you wish

n2omike · Post by **n2omike** » Wed Mar 05, 2008 1:30 pm

I believe mine is the 511, which is the 2"-6" model that can be found for around $200. There are a lot of Chinese copies of this unit out there as well.

So.... no wonder that thing didn't give me a good feeling when using it on bearings! It would gouge lines in them, making the measurement appear 0.0005" to 0.0010" too large. LOL!

I could use a ball mic to measure the bearing thickness, the dial bore gage to measure the housing, and a 2"-3" mic to measure the crank... and get a different reading.

I also measured the front bearing directly, by placing bearing shells in the #1 and #5 mains, laying the DRY crank in place, torquing the #1 cap in place, and lifting up on the front of the crank to check it's clearance with a dial indicator placed on the crank next to the bearing.

I also checked with plasti-gage.

Using the three different tools, the dial indicator method and plasti-gage all gave similar clearances, with the dial-bore gage showing close to 0.001" larger. (This is how I ruled out using the gage for bearings.)

The dial indicator numbers seemed to come out really close to the ones derived from the various mics! It seems to be a good method for getting a quick measurement without special tools. I also like the fact that it's a DIRECT measurement, and doesn't involve the comparison of measurements from three different tools.

(Of course, I'll probably also be on the lookout for a good bearing mic like the 545)

Thanks for your input!

Patrick Harrington · Post by **Patrick Harrington** » Wed Mar 05, 2008 4:29 pm

I just use a mic set to a known standard! I never had a ring, seen a ring, cared much about a ring... Realy, use a good mic, check it often with a good standard. Your accurate zero reading with your dial bore gage in a mic is the tightest one .

RW TECH · Post by **RW TECH** » Wed Mar 05, 2008 9:04 pm

On that note,

What do you guys use to check your micrometers? If I buy a new one, I'll check it with carbide balls to ensure the faces are flat, and when I check them I like to use gauge blocks at different thicknesses through the mic's range.

That way I can see whether the threads are consistent or not. I've seen where checking with a 2" standard was OK, then checking at 2.255" showed inaccuracies.

Wolfplace · Post by **Wolfplace** » Wed Mar 05, 2008 10:22 pm

RW TECH wrote:On that note,

What do you guys use to check your micrometers? If I buy a new one, I'll check it with carbide balls to ensure the faces are flat, and when I check them I like to use gauge blocks at different thicknesses through the mic's range.

That way I can see whether the threads are consistent or not. I've seen where checking with a 2" standard was OK, then checking at 2.255" showed inaccuracies.

=
I do the same thing, I know of no other way to check & one point is taking a lot for granted

That said, if I am doing bearing clearance I could care less what the mikes say, it makes no difference as it is being used as a setting standard for the bore gauge rather than an actual measuring device

Ed-vancedEngines · Post by **Ed-vancedEngines** » Wed Mar 05, 2008 10:28 pm

I buy only Browne & Sharpe mics with slant line and friction thimbles and carbide faces. By my experiences with the and with LS Starret for over 40 years, I have complete confidence they are accurate at any measurement. I do calibrate with supplied standard.

On the other hand I also know that Dial Calipers can be off some just becuase of the way they work. So I will use mic standards to quickly calibrate dial calipers at different lengths as I feel the need.

I still can not in any way possible figure how you can use a ring guage for setting dial bore guages when just in one engine you may have several different measurements?

Ed

robert1 · Post by **robert1** » Wed Mar 05, 2008 11:01 pm

I agree with Carl (CNC BLOCKS) that the Sunnen is more accurate I have been using my Mititoyo for 20 years and used a similar bore gage for 14 years before that. I am currently working on a 1.850 dia rod journal and I went to measure the rod clearance with my trusty Mit. only to realize a 2.00 gage doesn't fit very well. At first I was going to use a ball mic and measure the shells but it is very easy to get off a .0001 or 2 per side checking a coated bearing like this so I borrowed a smaller Mit. bore gage. Any of these tools are only as good as the person interpreting them. And yes I would like ring gages to set up with but there are just too many combinations.

Bob G · Post by **Bob G** » Sun Mar 09, 2008 10:14 am

The problem with bore gages are they are a comparitive measuring device. Any size over or under the Zero set will get a slight error.The charts that come with bore gages are very important in setting the tool. These tools have linkage in the head, and can have inaccuracies. The tool needs to be set at the dimension you are looking for,very important! A height gage is a good way to set this tool, pricey! Gage blocks in a good toolmakers vise will work too!

robert1 · Post by **robert1** » Sun Mar 09, 2008 11:25 am

Bob G wrote:The problem with bore gages are they are a comparitive measuring device. Any size over or under the Zero set will get a slight error.The charts that come with bore gages are very important in setting the tool. These tools have linkage in the head, and can have inaccuracies. The tool needs to be set at the dimension you are looking for,very important! A height gage is a good way to set this tool, pricey! Gage blocks in a good toolmakers vise will work too!

Which is why it makes no difference how accurately you have set your mic. If you set the bore gage (correctly) with your mic you are tranferring the size of the target be it crank, piston, or whatever from the part measured to the bore gage.

littleben · Post by **littleben** » Sun Mar 09, 2008 12:24 pm

THe only real problem with using a mic to set a bore guage, as opposed to a ring. is that the mic will transferr a direct straight line deminsion to the bore gauge, but that doesnt mean the bore guage actuall measures straight accross the largest diameter of the cylinder. Wear on the shoes, and or any deformation inthe shoe frame can cause the guage to measure somewhat askew to the largest diameter. Neither problem will show up with a mike or micrometer setting fixture, where as a ring guage will acctuately duplicate the contact point of the shoes.

When you measure in a bore, You all rock the guage through an up and down arc, to get the smallest reading, try depressing the shoes manually and rock back and forth to get the largest reading and you will see if in fact you are measuring accross the largest part of the bore.

Bob G · Post by **Bob G** » Sun Mar 09, 2008 1:03 pm

There is no question the ring gage is a good way to set this tool. the problem is the gage has to be the target size. That will mean you need many rings to do all work.
If you take 5 different people on a mic, setting this tool you will get some different reading.
One more thing, if you hold this tool on the stem and not the plastic area that was meant to do this the the heat from your hand will cause the tool to get longer. Try this and you will be amazed at how the indicator will move. Comparitive measurment !!