Bearing clearance

[JSeery]

I have never had much luck with the telescoping two point inside gauges or mics. The problem I have experienced is consistency. When your looking for .0005 differences they are just not consistent enough (at least not when used by me, LOL).

 

[Bored&Stroked]

I have never had much luck with the telescoping two point inside gauges or mics. The problem I have experienced is consistency. When your looking for .0005 differences they are just not consistent enough (at least not when used by me, LOL).

Exactly my point . . . and exactly my problem! LOL

 

[flatheadmurre]

3 point micrometer is the thing for measuring...dial bore gauge is great for checking your result against a std...but if i´m going to measure a few pieces and trying to do the math what the +/- readings on the dial gauge means in real world it takes triple checking before i trust my calculation...

 

[Kohnke Rebabbitting]

I have never had much luck with the telescoping two point inside gauges or mics. The problem I have experienced is consistency. When your looking for .0005 differences they are just not consistent enough (at least not when used by me, LOL).

You are right Mr. JSWeery, telescoping gauges should never be used on anything, unless .002 thousandths is as close as you need.

The best, and most accurate, to a .000-10, of a thousandths, is a post mic, also called an inside Mic. You will get the same reading every time.

When you get it set, don't read the post Mic, but read the OD, of the post Mic, with an outside Mic.

We build bearings every day, and can't afford to be wrong, even once.

They make smaller ones also, that we use, and also other designs, that are a 3 leg type, spendee, but so are mistakes.

Last point, There has never been an instant, for us, in 54 years, that any kind of cylinder bore mike, reading, has been accurate enough, to read bearing sizes, or oil clearance, and there has been countless instances.

Thanks,

Herm.

 

[Kohnke Rebabbitting]

More info on bearing clearance. The machine shop that checked and assembled the crank and main bearings measured the OD of the crank with a mike, and the ID of the installed bearing & cap with bore gauge. They said the bore gauge was more accurate than plastigauge. Bore gauges are too costly to invest in where plastigauge is good enough.

Don't believe what he said about, plastigauge, Mr. Russcc, or a bore Mic. he is wrong about both.

Many people do not know how to use plastigauge. They try to use it dry, and that will give you a bad reading. You have to use oil on the shaft, and bearing, or the plastigauge will NOT spread. With oil, you will get its full expansion, and, correct reading.

Thanks,

Herm.

 

[outlaw]

Don't believe what he said about, plastigauge, Mr. Russcc, or a bore Mic. he is wrong about both.

Many people do not know how to use plastigauge. They try to use it dry, and that will give you a bad reading. You have to use oil on the shaft, and bearing, or the plastigauge will NOT spread. With oil, you will get its full expansion, and, correct reading.

Thanks,

Herm.

I for one did not know this, which means that I have been doing it wrong for years. I will try this next time. Thank you. Bill

 

[40 Deluxe]

Don't believe what he said about, plastigauge, Mr. Russcc, or a bore Mic. he is wrong about both.

Many people do not know how to use plastigauge. They try to use it dry, and that will give you a bad reading. You have to use oil on the shaft, and bearing, or the plastigauge will NOT spread. With oil, you will get its full expansion, and, correct reading.

Thanks,

Herm.

Yeah, I've even seen it leave a small impression in the Babbitt layer in an insert when used dry.

 

[40 Deluxe]

You are right Mr. JSWeery, telescoping gauges should never be used on anything, unless .002 thousandths is as close as you need.

The best, and most accurate, to a .000-10, of a thousandths, is a post mic, also called an inside Mic. You will get the same reading every time.

When you get it set, don't read the post Mic, but read the OD, of the post Mic, with an outside Mic.

We build bearings every day, and can't afford to be wrong, even once.

They make smaller ones also, that we use, and also other designs, that are a 3 leg type, spendee, but so are mistakes.

Last point, There has never been an instant, for us, in 54 years, that any kind of cylinder bore mike, reading, has been accurate enough, to read bearing sizes, or oil clearance, and there has been countless instances.

Thanks,

Herm.

Any thoughts on how much "drag" there should be on an inside mike when at the correct setting? This seems to be a variable for me.

Thanks

 

[Kohnke Rebabbitting]

Yeah, I've even seen it leave a small impression in the Babbitt layer in an insert when used dry.

Yes, Sir., Mr. 40, Exactly!

 

[Kohnke Rebabbitting]

Any thoughts on how much "drag" there should be on an inside mike when at the correct setting? This seems to be a variable for me.

Thanks

I go with a light feel, on the inside Mic, and the OD, of the outside Mic, also light feel.

With the inside Mic, I move the top of the post back and fourth in the bearing ( the Bottom of the Post should always remain Stationary ) lightly, side ways, and ending up in the middle, and see if it will fit through the Top Dead Center, length ways.

If the fit is to loose, it will fall through, if it to tight, it will want to dig in slightly, which you don't want either.

I work from the right side of a bearing, as I am Right handed, but if I have to, I can also measure from the left.

So the correct feel is, not fall through, and not forced through.

When your feel if right, you will be right to the .000-10 of a thousandth, every time.

Do not make to course of an adjustment, at a time, as a lines width, is about a 1/10.

Thanks,

Herm.

 

[GOSFAST]

In order to effectively use a bore-gauge to check brg clearance you need one that does NOT use any type washers along with the mandrels to get to the size you need!

The various adjustments for different hole sizes MUST be able to be set by adjusting the mandrels, and not with any washers (shims). This setup allows the user to be able to set the "load" (seen at the brg surfaces) by adjusting the tension on the "fingers", this cannot be done with washer-type mandrels!

Sunnen's are the only ones we use here, we always have 3 at our disposal. This brand is by far the best bore-gauge in the marketplace for this type work.

We do have less expensive gauges but not for checking any brg clearances! We use these gauges on pin/rod clearances, machined hole sizes (with harder materials), etc.

I put a shot below here of one of our older Sunnen gauges, this particular one was mfd over in England for Sunnen back when. Later on Sunnen mfd them here in the U.S. If you look very closely at the mandrels, each has it's own lock-nut for adjusting desired length/tension.

Thanks, Gary in N.Y.

P.S. There is absolutely no issues with using "Plastigage", it's good for checking when a gauge isn't available! There is one other method (also accurate) that hasn't been mentioned anywhere up here and I'm sort of surprised! We used it many, many, years ago to get 15 units per week out the door! We had no bore gauge at the time and still managed well! Maybe somebody here will figure it out???

 

[40 Deluxe]

In order to effectively use a bore-gauge to check brg clearance you need one that does NOT use any type washers along with the mandrels to get to the size you need!


Thanks, Gary in N.Y.

P.S. There is absolutely no issues with using "Plastigage", it's good for checking when a gauge isn't available! There is one other method (also accurate) that hasn't been mentioned anywhere up here and I'm sort of surprised! We used it many, many, years ago to get 15 units per week out the door! We had no bore gauge at the time and still managed well! Maybe somebody here will figure it out???

Shim stock?

 

[GOSFAST]

Shim stock?

Absolutely correct!

When building 15 units per week this was the safest method for the assemblers, and it was "dead" accurate! It was really more simple for some of the guys than trying to get them accustomed to using a micrometer!

Thanks, Gary in N.Y.

P.S. Today we have a total of about 12 bore gauges at last count, various ranges, many are used for "dedicated" purposes but the Sunnen is the one we use most times for brg clearances and bore sizing, both rods and mains. Occasionally for checking cam brg clearances also (depending on size)!! All the Sunnens to the best of my knowledge have the adjustable anvils, no shims/washers involved.

 

[vilanar]

Very informative post. Thank you all that have contributed your knowledge.

 

[flatheadmurre]

Doesn´t matter if it´s a sunnen or a mitutoyo diallbore gauge from precision or performance point of view...sunnen use the measuring finger and a lock nut to adjust the zero on the dialgauge...others use fixed fingers and adjust the height of the dialgauge.
Not sure why a boregauge with fixed fingers(washers) would be any less accurate...tell that to mitutoyo
For measuring inside a round hole and not just checking it against a std a 3-point micrometer is the way to go !

 

[GOSFAST]

Doesn´t matter if it´s a sunnen or a mitutoyo diallbore gauge from precision or performance point of view...sunnen use the measuring finger and a lock nut to adjust the zero on the dialgauge...others use fixed fingers and adjust the height of the dialgauge.
Not sure why a boregauge with fixed fingers(washers) would be any less accurate...tell that to mitutoyo
For measuring inside a round hole and not just checking it against a std a 3-point micrometer is the way to go !

Hi "flathead", the difference is you cannot set the amount of "tension" using a "fixed" anvil (washers/shims) tool, can't happen!

The Sunnen's allow you to set the amount of tension. The "higher" tension at the "fingers" allows for "deeper" marks in the brg surfaces, in effect this MAY actually give a false reading as to the actual clearances??

Thanks, Gary in N.Y.

P.S. As for the accuracy of the dimensions either type/brand gauge is just as accurate! We use the Mitutoyo's for pin/rod and pin/piston checking, our gauges for these procedures measure in "tenths", not 1/2" thousandths!

 

[Lawrie]

Gary I just bought a Mitutoyo 10ths bore gauge ,not cheap ,but need for me to get my finished bore right,
Also got some new imperial dial gauges as I dropped my good one,I spent so much on tools the last month I my need to go back to work,Lol
Lawrie

 

[Bored&Stroked]

I spent so much on tools the last month I my need to go back to work,Lol
Lawrie

Yes - but just like flatheads, don't fine precision tools make yah happy! I remember as a young man when I bought my first set of Lufkin outside mics - made me happy just to hold them and put them back in their purdy little wooden boxes.

I have both Starrett and Lufkin mics - for some strange reason I am still fond of my original Lufkins. (Must me a strange attachment that we get for certain tools!).

 

[FL&WVMIKE]

Tight is dangerous, a little loose is safe.

To run tight clearances, machining has to be SPOT ON. ANY incaccuracy in the rods, bearings or mains... and you'll have contact. Most machine shops have a tolerance limit of half a thou accuracy... 0.0005"... and some cannot even achieve that consistently. With the crank, rods and bearings all coming to the tolerance party, it doesn't take much for there to be a problem. I like AT LEAST 0.0020" if not 0.0030" clearance. 0.0010" gives pretty much zero room for error... and we haven't even mentioned crank flex.

The crank runs on a layer of oil. With looser clearances, as long as they are not excessive, you're a lot safer. Tight clearances are what spin bearings.

Good Luck

 

[Bored&Stroked]

Tight is dangerous, a little loose is safe.

With looser clearances, as long as they are not excessive, you're a lot safer. Tight clearances are what spin bearings.

Good Luck

Exactly!