Yellow Bullet Forums banner
1 - 20 of 34 Posts

·
Registered
Joined
·
8,147 Posts
Discussion Starter · #1 ·
I'm thinking of stepping up my metrology game. Is Sunnen the ONLY dial bore gauge to get, or are there others that are also good? How terrible an idea is it to buy a used instrument on ebay?
 

·
Registered
Joined
·
4,162 Posts
I'm thinking of stepping up my metrology game. Is Sunnen the ONLY dial bore gauge to get, or are there others that are also good? How terrible an idea is it to buy a used instrument on ebay?
If you going to bore gauge bearing you need gauges like Sunnen that have floating fingers, Rigid finger bore gauges show not to be as accurate from What I have tested against.

Here is a good link to look over

https://www.performanceboats.com/gn...michrometer-measuring-bearing-clearances.html
 

·
Registered
Joined
·
8,147 Posts
Discussion Starter · #4 ·
I have Standard bore gages which are sold by Brown&Sharpe these days.
They work very well.
That's good to know - there are quite a few Standard gauges on ebay.

If you going to bore gauge bearing you need gauges like Sunnen that have floating fingers, Rigid finger bore gauges show not to be as accurate from What I have tested against.

Here is a good link to look over

https://www.performanceboats.com/gn...michrometer-measuring-bearing-clearances.html
I read that thread, and bearing clearances are one of the reasons I'd like a dial bore gauge. Will I have to buy two gauges, a small one for bearings and a larger one for piston to wall, or can I use range extenders?


I'm looking at gauges like this:
 

·
The Phantom Machinist
Joined
·
1,916 Posts
I use Sunnen and I have some Mitutoyo. Both have centralization fingers. The Sunnen is great and has a nice set up fixture, while the Mitutoyo work great on ported cylinders and smaller stuff.
If you’re honing or checking longer cylinders, or with a torque plate installed, the Sunnen gauges are the best as they’re longer reach.
 

·
Registered
Joined
·
8,147 Posts
Discussion Starter · #7 ·
Unfortunately, I don't do my own machining, but I've read that a longer gauge is also more convenient for measuring main bearing clearances.
Does the Sunnen have roller tips on the centralizing plungers?
 

·
Registered
Joined
·
6,506 Posts
IMHO there is none better than the Sunnen. Their setup fixture is awesome but unfortunately has a not so awesome price tag. I bought a new 24" long gauge as my 1st and luckily had a friend with an extra setup fixture he bought at an auction and passed the savings on to me so I only paid 1/3 of the new price. While not 100% necessary it makes setting the gauge accurately only take a few seconds and spot-on every time.
 

·
Registered
Joined
·
4,162 Posts
Unfortunately, I don't do my own machining, but I've read that a longer gauge is also more convenient for measuring main bearing clearances.
Does the Sunnen have roller tips on the centralizing plungers?

Those do not have wheels but they float up I would say .500 and made for checking housing bores that are not round such as a housing bore with rod and mains bearings installed.
 

·
Registered
Joined
·
8,147 Posts
Discussion Starter · #10 ·

·
Registered
Joined
·
1,128 Posts
You can get used ring gages on eBay to use for calibration checks, but remember this is a comparative measurement so it doesn't really need calibration. I've had good luck with the Fowler and SPI units at work for those on the cheap side. You can always mount a higher quality dial indicator on a cheaper body if you want to. The Mitutoyo and Fowler/SPI type just clamp an indicator in the top.

That said I'll rarely tell someone NOT to buy the higher quality units when it comes to metrology!
 

·
Registered
Joined
·
1,048 Posts
What do you guys think about this one? I'd rather buy American, but I don't hate the Swiss all that much.
https://www.ebay.com/itm/EXCELLENT-...2-8-In-0001-EXTRA-LONG-30-In-OAL/223486259085
That looks like it uses the same principles as the Sunnen
BUT
1: There is no recourse to changing the balls when they wear.
Granted, you have to do a lot of measuring to wear them but.....
2: At that price point I would just get the Sunnen.
The long versions do show up in that price range now and again.
 

·
Registered
Joined
·
1,048 Posts
Yes, and you need the setting fixture also.
Ahh, but you can set them with a mic. It's just awkward as all get out.

I have the pre-setters and have also set the gauge with a mic from time to time.
The setting fixture is a great time saver for shops and individuals that do a lot of measuring but not absolutely essential.
 

·
The Phantom Machinist
Joined
·
1,916 Posts
Unfortunately, I don't do my own machining, but I've read that a longer gauge is also more convenient for measuring main bearing clearances.
Does the Sunnen have roller tips on the centralizing plungers?
The Sunnen has round centralizing locators, but they don’t roll. You can rotate them with an Allen wrench when they "flat spot" over time/use. The ball contacts can be popped out and rotated. The models with retractable centralizers have a tension adjustment for those as well, which is great for bearings.
 

·
Wart Remover
Joined
·
2,864 Posts
Whatever you do, don't buy Fowler or SPI anything.

Fowler mics, caliper, depth gages etc consistently fail calibration having never been used, even though they come with that nice little card that "claims" they were factory cal'd.

SPI is nearly as bad, especially on hard gaging. Their thread plugs/rings are made from extremely soft metal, and their hand gaging isn't much better. I've seen many bore gages from each brand that may check good at say 1", good at 1.25 and 1.5", but from 1.75-2" they can be 0.004" off. Usually if a bore gage/indicator is good at one part of it's range, it will be perfect all the way through. Fowler and SPI have managed to fuck that up entirely.

You have to watch out for even the new Starrett stuff, it's getting downright scary how much Starrett is bad right from the box, brand new.


While I won't claim Sunnen is the ONLY tool for the job, just buy it and the setting fixture and be done.
 

·
Registered
Joined
·
4,162 Posts
Whatever you do, don't buy Fowler or SPI anything.

Fowler mics, caliper, depth gages etc consistently fail calibration having never been used, even though they come with that nice little card that "claims" they were factory cal'd.

SPI is nearly as bad, especially on hard gaging. Their thread plugs/rings are made from extremely soft metal, and their hand gaging isn't much better. I've seen many bore gages from each brand that may check good at say 1", good at 1.25 and 1.5", but from 1.75-2" they can be 0.004" off. Usually if a bore gage/indicator is good at one part of it's range, it will be perfect all the way through. Fowler and SPI have managed to fuck that up entirely.

You have to watch out for even the new Starrett stuff, it's getting downright scary how much Starrett is bad right from the box, brand new.


While I won't claim Sunnen is the ONLY tool for the job, just buy it and the setting fixture and be done.



Those gauges are nice for round bores checking bearing clearances is another whole deal when your dealing with bearing eccentricity a lot of gauges are not designed for that.

I have had a lot of bore gauge wars at my shops showing the difference between rigid finger gauges and Sunnen gauges.
 
1 - 20 of 34 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top