Looking for an advise on caliper type.

[AlexK]

What type of outside calipers are most handy for all around shop.
Starett has two types of outside calipers:

Classic

and
Firm-Joint


When do you use one type vs. another? Is it just a personal preference?

BTW MITUTOYO also makes calipers that sell for a little bit less than Starrett. Are they as nice as Starrtett?

Thanks,
Alex

[The Artful Bodger]

I have both and use the classic style when I am setting the calipers to a scale and I use the firm joint ones when I am taking a diameter (or thickness). I would say there is a place for both, mine are dollar store purchases and seem to be adequate but maybe the name brand ones are better, if only a better feel.

[Your Old Dog]

I've got both and find the former have more spring to them and used when my lathe is spinning to see if I'm getting close to my target diameter. The latter I use to carry a measurement from one place to another but more of an optical or eyeball comparison as they don't lock but slip voiding your measurement. To my mind these are purely yard sale and flea market items. I would never pay full shot for my home shop for something tools like this unless I needed them today.

[hawgwrench]

I've always just used the cheapos Alex,not because I dont appreciate quality,but I never pick these up when I need critical dims,these get it "pretty close" so cheap is close enough.If it needs precision then its time for dial calipers or micrometers,in that order.

[oldtiffie]

Calipers

I've got - and use - both types.

It doesn't matter who made them or where or when they were made - with a bit of judicious "fine tuning" just about any of them will work very well - providing you have the patience needed to "learn" them and to get the "feel" of them.

If I want to "spring" them over a size or diameter, I opt for the "spring" version. If I want them left "as is" I use the fixed version.

They are after all, the "external" version of the "stick" (internal) version that I posted earlier. The principles and math are pretty well the same in all cases.

I can still set mine to half an etched division line width - or better - on a good rule.

I always make sure that I put cutting or tapping oil on the job as a lubricant for the calipers.

I use them while the machine is running.

Both are excellent for diameters of narrow grooves which are hard to measure otherwise although I use the "depth guage" feature of a common digital caliper for that as well.

I use "inside" spring and friction calipers for bores and for lengths of turned parts and depth of "steps" but the digital caliper "depth" feature is hard to beat there too.

In my mind, digital calipers are all but useless for internal diameter work but they are really good for measuring between parallel faces - as are spring and friction calipers.

Short of using slip guages, sliding parallel strip guages are pretty hard to beat for work in slots etc:

http://www.littlemachineshop.com/products/product_view.php?ProductID=2552&category=

[JCHannum]

I've got both and find the former have more spring to them and used when my lathe is spinning to see if I'm getting close to my target diameter.

Bad advice. Neither type should ever be used on a part with the machine turning. It is as dangerous as wearing gloves. The caliper can be wrapped around the workpiece and drag the hand in or be launched into the operator.

What are being called classic are properly called spring calipers tha other are firm joint. Either can be used in the same manner. The firm joint tends to be more useful for larger dimensions, the spring caliper has a more delicate feel.

[oldtiffie]

Standing still

Bad advice. Neither type should ever be used on a part with the machine turning. It is as dangerous as wearing gloves. The caliper can be wrapped around the workpiece and drag the hand in or be launched into the operator.

.................................................. ...

Hmmm.

In retrospect, I think you are right Jim, as used incorrectly in the wrong way or inexperienced hands - so I guess that using while the machine is running is a no-no for a novice and has to be used with due diligence by the more experienced.

That is the reason I used the caveat of lubrication - cutting/tapping oil and the like. "Suds" - soluble oil - is OK as well although I use it "dry" on brass and cast iron.

Every job should be pre-assessed for risk before starting and if it looks risky it probably is - so use the calipers with the machine stationary.

Used dry is asking for trouble - as is careless use in slots.

[JCHannum]

Hmmm.

In retrospect, I think you are right Jim, as used incorrectly in the wrong way or inexperienced hands - so I guess that using while the machine is running is a no-no for a novice and has to be used with due diligence by the more experienced.

That is the reason I used the caveat of lubrication - cutting/tapping oil and the like. "Suds" - soluble oil - is OK as well although I use it "dry" on brass and cast iron.

Every job should be pre-assessed for risk before starting and if it looks risky it probably is - so use the calipers with the machine stationary.

Used dry is asking for trouble - as is careless use in slots.

The use of calipers on a moving part is extremely dangerous. If you choose to do it yourself, that is your decision. Recommending it to others, regardless of experience or lubrication is irresponsible.

[oldtiffie]

Caveat

Jim,

again I agree - so far as it goes.

I did not recommend anything - just said how I do it.

Every one of the four paragraphs/sentences in my post that you refer to had a warning and/or caveat in it.

If people want to ignore them or be gung ho about using machines, there is sweet FA that I can do about it.

[Wess]

Measuring part diameters with the work revolving is SOP on a wood lathe, whats the difference?

[JCHannum]

Measuring part diameters with the work revolving is SOP on a wood lathe, whats the difference?

There is no difference at all, unless somehow, the loss of a body part or other resulting injury is less painful or devastating when done on a wood lathe. An unsafe act is an unsafe act no matter how it is done or who is doing it.

[Kirbot]

I have both kinds and only use the firm joint ones when the classic style ones are too small.

[Wess]

There is no difference at all, unless somehow, the loss of a body part or other resulting injury is less painful or devastating when done on a wood lathe. An unsafe act is an unsafe act no matter how it is done or who is doing it.

Like I said it's done by wood turners all the time and I don't hear stories of death and mayhem resulting. Sanding or filing is much more likely to grab you. Obviously if you don't feel you have the skill to do it then don't, but your opinion on the subject is not the be all end all answer.

[BobWarfield]

Putting aside the relative mayhem that may result from such caliper use on a moving workpiece, it has just not appealed to me to do so.

I am familiar enough with my lathe that I know what it can and can't cut accurately, and I know how much to leave for a finish pass. I don't seem to have a problem running it down to the finish allowance of 10 or 15 thou without taking lots of measurements.

The dials on the lathe tell me where I am at. If I had a DRO that would be nice, but by this time I've just trained myself to keep up with it. For about the first year I would punch it up in a calculator or jot it in a notepad each pass. Now its automatic.

Makes the work go a lot faster. Now my various calipers are largely used for markup, and even that less and less.

Cheers,

BW

[JCHannum]

Like I said it's done by wood turners all the time and I don't hear stories of death and mayhem resulting. Sanding or filing is much more likely to grab you. Obviously if you don't feel you have the skill to do it then don't, but your opinion on the subject is not the be all end all answer.

It is an unsafe act no matter how many people choose to do it. It is not my opinion, it is mentioned in many texts as presenting a danger both to the tool and the operator back as far as 1911, the oldest I have at present.

Improper or unsafe use of tools does not denote a high degree of skill. As Bob points out, it is a simple matter to calculate the amount of material to be removed, zero out the infeed dial and make your cuts. In the long run, that is much safer, faster and more accurate.