Dial bore gauge Q

[AdeV]

I'm considering buying a dial bore gauge, for the purpose of checking bore sizes/ovality in engines. So I reckon the 50-160mm ones will cope with most tasks.

The question is, it looks like it takes a standard plunger dial gauge, so could I use my Mercer 0.0001" imperial gauge in place of the one supplied by the manufacturer, for even more accurate readings? Or is the bore gauge mechanism itself likely to only be good to the nearest thou/0.01mm?

Here's the sort of thing I was looking at: http://www.ebay.co.uk/itm/Dial-Bore-Gauge-Set-Quality-NEW-Metric-50-160mm-/370751400320?pt=LH_DefaultDomain_3&hash=item5652816980

[redshift]

I use a 35-50mm version on my lads kart engines, I can't see a problem with a more precise dial gauge as the head of the unit is spring loaded and as a result the gauge should read the size precisely.
I use my gauge to check for piston fit and bore wear, mic the piston and set the bore gauge to zero in the mic and stuff it down the bore to check piston clearances.
Regards
Dave

[awemawson]

You will need some sort of standard setting ring to zero it I would assume

Andrew

[redshift]

Andrew, no I measure the piston skirt with the mic and set the bore guage between the anvils of the mic and zero the dial gauge, then stuff it down the bore and the difference from zero is the piston clearance.
Regards
Dave

[Pete W.]

Redshift:

I thought the bore gauges that have a dial indicator had three fingers, not two?

[redshift]

Pete, it's got three point contact plus the measuring plunger between two of the contacts, I'll put a picture up.
Regards
Dave

[redshift]

Pete, here you go

[AdeV]

Cheers chaps, much appreciated.

Dave - does the one I linked to look like yours - i.e. 3 point contact? If not, I'm guessing a 3-point is easier/more reliable than a 2-point (or 1 point + measuring plunger)?

e.g. the bore gauges I've got right now are the "T" shaped ones with spring loaded anvils, you stick it down the bore, lock the arms with the screw top, withdraw & measure; these rely on the spring loading to put them in the middle of the bore.

[redshift]

Ade, yes it's just like mine, should be perfect for your intended use. Plus you get real time readings as opposed to the ones you have been using.
Regards
Dave

[chipenter]

ARC have started selling bore gauges and have a brief description on how to use them , http://www.arceurotrade.co.uk/Catalogue/Measurement/Dial-Bore-Gauges


Jeff

[AdeV]

ARC have started selling bore gauges and have a brief description on how to use them , http://www.arceurotrade.co.uk/Catalogue/Measurement/Dial-Bore-Gauges

I'm glad you pointed that one out; I had a look and as far as I could tell, the 50-200mm one is, albeit the most expensive, also the best value pretty much everywhere. 

So I bought one. 


And today, it arrived 

So, now I'm off to find a bore to try it out in. I have just the thing on the workbench... (an old Lister LD1 barrel)

[DavidA]

The procedure we use to follow for bore wear measurement was to first measure the bore right at the top (above the top ring) as this area doesn't wear.  Set your measuring device at zero the proceed to take measurements down the bore to ascertain the wear.,

Dave.