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Short Motor Rebore / Build - Measuring Tools


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#16 ACDodd

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Posted 12 September 2019 - 07:28 AM

Micrometers are needed for checking crank journal and bore dimensions.
The problem is these require a level of skill which needs practice to achieve a competence level to get accurate measurements. I still offer a FREE measure up service for miniforum members. I have only done this twice in all the time I have been on the forum. This goes some way to telling you how little effort people go to to check that their builds are going to be successful!



Ac

#17 JonnyAlpha

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Posted 12 September 2019 - 04:22 PM

Micrometers are needed for checking crank journal and bore dimensions.
The problem is these require a level of skill which needs practice to achieve a competence level to get accurate measurements. I still offer a FREE measure up service for miniforum members. I have only done this twice in all the time I have been on the forum. This goes some way to telling you how little effort people go to to check that their builds are going to be successful!



Ac


A service which I would happily use were it not for the distance :-)
Are you going to Castle Combe 28th? I could take out my front seat and get my block in for you to check :-)
I could also bring my Cam and Dizzy, Cam for a regrind and dizzy to be recurved? Would save on one way postage.

#18 ACDodd

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Posted 12 September 2019 - 04:36 PM

No, you would need to come to me.

Ac

#19 JonnyAlpha

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Posted 12 September 2019 - 04:54 PM

No, you would need to come to me.

Ac


Ok no worries

#20 JonnyAlpha

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Posted 13 September 2019 - 02:10 PM

Ok so can anyone recommend a suitable Piston Ring Compressor?

 

Need to change the title to Short Motor Rebore Tools :-)



#21 gazza82

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Posted 13 September 2019 - 04:09 PM

I have one of these, albeit over 40 years old!

 

Attached File  PistonRingCompressor0285.jpg   13.06K   0 downloads

 

https://www.lasertoo...uk/product/0285

 

You can get them cheaper than the price shown ..

 

Beauty of them is they cater for a wide range of pistons. A wipe down with oil, clamp gently around the piston/rings, and gently tap the piston down into the bore.


Edited by gazza82, 13 September 2019 - 04:12 PM.


#22 JonnyAlpha

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Posted 15 September 2019 - 04:36 PM

Anyone comment on this 0 - 3" set of Moore and Wright Imperial external micrometer.

£98.23

 

Also could anyone recommend the following:

 

Telescopic bore gauges

 

Feeler gauges (Imperial or Metric?)

 

Also need a set of imperial taps to run through the block threads - what type do I need?


Edited by JonnyAlpha, 15 September 2019 - 04:41 PM.


#23 GraemeC

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Posted 15 September 2019 - 06:31 PM

I don’t think there’s a huge amount of difference in feeler gauges, just get a set that has plenty of sizes.
If only for cleaning up threads then I’d look for a set of imperial sized thread chasers.

#24 DeadSquare

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Posted 15 September 2019 - 07:13 PM

If you take care of them, that Moore & Wright set will last you a lifetime.



#25 super6al

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Posted 15 September 2019 - 08:34 PM

I bought the bore gauge from the same company (Machine DRO) & for the price its a decent bit of kit -  especially if its just for occasional use.

Alan 



#26 mini-mad-mark

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Posted 15 September 2019 - 08:43 PM

The set you are looking at has a vernier scale to allow measurement expressed to the nearest 0.0001" (mentioned above by Moke spider)

You will need practice to actually repeatably measure to that nearest 0.0001" (you could say it was 2.7803" according to the mic but whether it actually was 2.7803"?)

 

This is at least the level of accuracy required for pistons, cranks etc

 

Of note  - metric kit gives better resolution as 0.0001" = 0.0025mm but a metric mic can have a resolution of 0.001mm but whether anyone can accurately measure to the nearest 0.001mm with a mic? 0.001mm = 0.00004" or  just about twice the resolution of a 0.0001" reading mic

 

 

Telescopic bore gauges can be relatively cheap and they are only a means to get something the same size as the hole that can then be measured with the micrometer BUT again getting the TBG to the same size as the bore needs practice and then measuring the TBG with the micrometer needs practice - better ones will have harder tips for longevity: 

 

 

I think there might be some confusion about the bore gauging as people might be talking about these:

 

 

What you actually need are some test pieces of known sizes to practice on.....

 

 

Feeler gauges - buy a reputable brand but some are harder than others (for longevity) but hence more brittle so can snap if bent too much so take care

 

 

Cleaning threads - agreed thread chasers or I heard a way was to grind a slot in the thread of a standard new bolt/screw and use that as a chaser?



#27 JonnyAlpha

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Posted 16 September 2019 - 04:28 PM

So I bit the bullet, more out of curiosity than need and bought the Moore and Wright 0 - 3" Set of Micrometers. Also bought a set of Draper Expert Telescopic gauges. The Piston Ring compressor needs to be ordered as Halfords, who are selling the Laser ones for £12.99, did not have any in stock. I also ordered a set of of Laser 32 blade AF/MM Feeler Gauges. 

 

Dummy Gudgeon Pins arrive today (courtesy of AC) but I was out so I'll have to pick them up Friday from the Post Office depot.

 

Thanks for everyones advice on here.



#28 JonnyAlpha

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Posted 16 September 2019 - 04:31 PM

The set you are looking at has a vernier scale to allow measurement expressed to the nearest 0.0001" (mentioned above by Moke spider)

You will need practice to actually repeatably measure to that nearest 0.0001" (you could say it was 2.7803" according to the mic but whether it actually was 2.7803"?)

 

This is at least the level of accuracy required for pistons, cranks etc

 

Of note  - metric kit gives better resolution as 0.0001" = 0.0025mm but a metric mic can have a resolution of 0.001mm but whether anyone can accurately measure to the nearest 0.001mm with a mic? 0.001mm = 0.00004" or  just about twice the resolution of a 0.0001" reading mic

 

 

Telescopic bore gauges can be relatively cheap and they are only a means to get something the same size as the hole that can then be measured with the micrometer BUT again getting the TBG to the same size as the bore needs practice and then measuring the TBG with the micrometer needs practice - better ones will have harder tips for longevity: 

 

 

I think there might be some confusion about the bore gauging as people might be talking about these:

 

 

What you actually need are some test pieces of known sizes to practice on.....

 

 

Feeler gauges - buy a reputable brand but some are harder than others (for longevity) but hence more brittle so can snap if bent too much so take care

 

 

Cleaning threads - agreed thread chasers or I heard a way was to grind a slot in the thread of a standard new bolt/screw and use that as a chaser?

 

Thanks for the videos. I did work out that Bore Gauges and Telescopic Gauges were different, but it took me a while.

 

With regards to your comment:

 

"Of note  - metric kit gives better resolution as 0.0001" = 0.0025mm but a metric mic can have a resolution of 0.001mm but whether anyone can accurately measure to the nearest 0.001mm with a mic? 0.001mm = 0.00004" or  just about twice the resolution of a 0.0001" reading mic"

 

Should I have bought the Metric set? The same set in Metric has a resolution of 0.01mm. 

Or are you saying I should have bought a Metric set with a resolution? 


Edited by JonnyAlpha, 16 September 2019 - 05:25 PM.


#29 DeadSquare

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Posted 16 September 2019 - 05:26 PM

 

The set you are looking at has a vernier scale to allow measurement expressed to the nearest 0.0001" (mentioned above by Moke spider)

You will need practice to actually repeatably measure to that nearest 0.0001" (you could say it was 2.7803" according to the mic but whether it actually was 2.7803"?)

 

This is at least the level of accuracy required for pistons, cranks etc

 

Of note  - metric kit gives better resolution as 0.0001" = 0.0025mm but a metric mic can have a resolution of 0.001mm but whether anyone can accurately measure to the nearest 0.001mm with a mic? 0.001mm = 0.00004" or  just about twice the resolution of a 0.0001" reading mic

 

 

Telescopic bore gauges can be relatively cheap and they are only a means to get something the same size as the hole that can then be measured with the micrometer BUT again getting the TBG to the same size as the bore needs practice and then measuring the TBG with the micrometer needs practice - better ones will have harder tips for longevity: 

 

 

I think there might be some confusion about the bore gauging as people might be talking about these:

 

 

What you actually need are some test pieces of known sizes to practice on.....

 

 

Feeler gauges - buy a reputable brand but some are harder than others (for longevity) but hence more brittle so can snap if bent too much so take care

 

 

Cleaning threads - agreed thread chasers or I heard a way was to grind a slot in the thread of a standard new bolt/screw and use that as a chaser?

 

Thanks for the videos. I did work out that Bore Gauges and Telescopic Gauges were different, but it took me a while.

 

With regards to your comment:

 

"Of note  - metric kit gives better resolution as 0.0001" = 0.0025mm but a metric mic can have a resolution of 0.001mm but whether anyone can accurately measure to the nearest 0.001mm with a mic? 0.001mm = 0.00004" or  just about twice the resolution of a 0.0001" reading mic"

 

Should I have bought the Metric set?

 

 

No.  you are measuring an imperial item and therefore need an imperial measure.

 

When you get your micrometer and play with it, if your eyesight is good, you will find that it is possible read to half of a .0001", which is splitting hairs with .001mm.



#30 mini-mad-mark

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Posted 16 September 2019 - 10:21 PM

Agree - after practice the half tenth (half ten thousandth of an inch) is possible but needs a fair bit of experience and is the same near enough as 0.001mm






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