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Calipers

R

Raif Harik

Joined
Jan 14, 2020
Messages
279
Likes
100
Location
Austin, TX
Hi, I've always had trouble with calipers. User error I'm sure. Where when I get down to where I want to measure, I then have to open up the calipers to get them out and look at the space/thickness.
I was going to just post that question but I did a bit of searching online and found that the term "breadth calipers" brings up basically the same calipers but with an angle measurement up by where you adjust it. They also come with little round circles at the ends rather than sharp points so you don't scratch what you are measuring (human beings by intent I believe). Pretty nifty.
Then I noticed the double end calipers. The ones that look like a figure 8. I guess I never realized that you could take a measurement on the one end and see the same opening on the other end, thus being able to measure before moving.
I guess I'm kind of slow to pick up on the advancements of engineering over the past 2000 years. But I thought I'd post here in case others were struggling like me. And/or to hear about other marvels of mankinds measurements.
 
I find this caliper very useful. Since the read out is instantaneous I can move it along the wall and see if the thickness is fairly uniform.


When I use figure 8 calipers, I keep a few old drill bits handy (1/8, 1/4, etc). Then instead of attempting to measure the gap, I can make a quick comparison to the drill bit that matches my target thickness.
 
One thing I do with calipers, and I think it was Al @hockenbery that first mentioned this way back when, is keep them open more than needed (enough space to stick a finger in between the caliper and exterior. Then, as I move the calipers down the wall, I can gauge relative thickness by how much the caliper squeezes on my finger. This also has the added benefits of 1) preventing the calipers from scratching/denting my exterior if they unexpectedly squeeze, and 2) having a lot of travel given their openness.

I also usually cover the tips of my calipers with a piece of tape if I'm worried about scratching a semi-finished surface.

That said, if price is not an issue, I'd get rid of most of my mechanical calipers in favor of a magnetic probe thickness caliper like this: https://www.metmusic.com/tools/calipers-gauges/2859-mag-ic-probe-wifi-thickness-caliper (alluding to your statement about engineering advancements).
 
Michael Anderson said:
One thing I do with calipers, and I think it was Al @hockenbery that first mentioned this way back when, is keep them open more than needed (enough space to stick a finger in between the caliper and exterior. Then, as I move the calipers down the wall, I can gauge relative thickness by how much the caliper squeezes on my finger. This also has the added benefits of 1) preventing the calipers from scratching/denting my exterior if they unexpectedly squeeze, and 2) having a lot of travel given their openness.

I also usually cover the tips of my calipers with a piece of tape if I'm worried about scratching a semi-finished surface.

That said, if price is not an issue, I'd get rid of most of my mechanical calipers in favor of a magnetic probe thickness caliper like this: https://www.metmusic.com/tools/calipers-gauges/2859-mag-ic-probe-wifi-thickness-caliper (alluding to your statement about engineering advancements).
Click to expand...
Ouch at $349. Plus you have to buy the software, it seems. But sure looks great.
 
Alan Weinberg said:
Ouch at $349. Plus you have to buy the software, it seems. But sure looks great.
Click to expand...
Right? There are a few other options, but all are relatively expensive. If I was more tech-/engineering-savvy than I am, something like this is probably not too difficult to build. I'm pretty sure @Luigi D'Amato uses something like this (that might be where I first discovered the tool).
 
Mark Jundanian said:
I find this caliper very useful. Since the read out is instantaneous I can move it along the wall and see if the thickness is fairly uniform.


When I use figure 8 calipers, I keep a few old drill bits handy (1/8, 1/4, etc). Then instead of attempting to measure the gap, I can make a quick comparison to the drill bit that matches my target thickness.
Click to expand...
That caliper works great when it works. The first one I purchased failed after a couple years so I bought another one and the same thing happened. I would be willing to pay more for that type if I could find a dependable one.
 
I usually use a stiff wire, bent into sort of a D shape
IMG_9458.JPG

I'll bend the wire so that the gap is wider than my desired thickness, maybe twice (so for a 1/4" wall, make the gap 1/2" or so).
I can usually get the wall thickness how I want near the opening, so I stick the "caliper" there and judge the space between the outer wall and the wire. Sliding down the form, if the space gets smaller, the wall is thicker. If it gets wider, the wall is thinner. With a 1/2" gap in the wire, if you have a 1/4" space then the wall thickness is 1/4".

The one on the right has a little brass tube on it that I can slide up to the wood, and I've scribed some lines on the wire so the end of the tube can give me sort of a measurement. That's sometimes easier to use on smaller forms.

If I cared more about the exact value of the thickness, I'd buy or make a larger version of that one with the tube (like this https://woodturnerscatalog.com/products/hollow-pro-caliper). But for me, consistency of the wall is more important than the exact measurement. And the wires work for me.
 
Made my own measuring double end calipers out of scrap wood, figure 8 shape cut on bandsaw and center bolt, but the outside end (where the points don't meet) I made longer 3/4 circle on one side and then applying calipers to known thickness, make marks on the overlapping side to note thicknesses - I should get a pic, but I need to make a new pair, as my old ones finally split along the grain.
 
Michael Anderson said:
Right? There are a few other options, but all are relatively expensive. If I was more tech-/engineering-savvy than I am, something like this is probably not too difficult to build. I'm pretty sure @Luigi D'Amato uses something like this (that might be where I first discovered the tool).
Click to expand...
Yes my calliper is Spexor
www.spexor.it

Home | SpeXor Measuring Tool

Spexor misura dello spessore del legno.Spexor is a magnetic system used in woodturning to measure thickness.
www.spexor.it www.spexor.it

Perfect misure,
Specialy in hollow
 
Dave Landers said:
I usually use a stiff wire, bent into sort of a D shape
View attachment 69522

I'll bend the wire so that the gap is wider than my desired thickness, maybe twice (so for a 1/4" wall, make the gap 1/2" or so).
I can usually get the wall thickness how I want near the opening, so I stick the "caliper" there and judge the space between the outer wall and the wire. Sliding down the form, if the space gets smaller, the wall is thicker. If it gets wider, the wall is thinner. With a 1/2" gap in the wire, if you have a 1/4" space then the wall thickness is 1/4".

The one on the right has a little brass tube on it that I can slide up to the wood, and I've scribed some lines on the wire so the end of the tube can give me sort of a measurement. That's sometimes easier to use on smaller forms.

If I cared more about the exact value of the thickness, I'd buy or make a larger version of that one with the tube (like this https://woodturnerscatalog.com/products/hollow-pro-caliper). But for me, consistency of the wall is more important than the exact measurement. And the wires work for me.
Click to expand...
Yep, I use exactly the same for measuring the thickness of my hollow form walls except I use the deluxe version!! "What's that", I hear you say. Well, I found that wire style bucket or paint tin handles that clip into the side have a half dome formed on each end. This makes them perfect for making calipers because the ends don't dig in and catch/scratch or mark the walls of the vessel when you are sliding them in or out. So the next time you are in your local hardware store and you find a bucket without a handle, hard luck, I got there before you 😉.
 
Raif Harik said:
Hi, I've always had trouble with calipers. User error I'm sure. Where when I get down to where I want to measure, I then have to open up the calipers to get them out and look at the space/thickness.
I was going to just post that question but I did a bit of searching online and found that the term "breadth calipers" brings up basically the same calipers but with an angle measurement up by where you adjust it. They also come with little round circles at the ends rather than sharp points so you don't scratch what you are measuring (human beings by intent I believe). Pretty nifty.
Then I noticed the double end calipers. The ones that look like a figure 8. I guess I never realized that you could take a measurement on the one end and see the same opening on the other end, thus being able to measure before moving.
I guess I'm kind of slow to pick up on the advancements of engineering over the past 2000 years. But I thought I'd post here in case others were struggling like me. And/or to hear about other marvels of mankinds measurements.
Click to expand...
First and foremost, I'm a staunch believer in the 'what works for you' woodshop. Ask a hundred turners the best bowl gouge and get 400 answers. I've tried several calipers over the years but for my money these have worked out the best for me:

Big Horn 19055 Woodturning Figure 8 Double Ended Bowl Caliper $19.00 from Amazon​


Simple and affordable. What I really prefer about these, besides the price, is I can run the calipers from the base to the rim repeatedly to discern high spots/dips.
 
I got the biggest inside/outside calipers that I could find. I would like bigger ones, but at least by reversing one leg on the ones I do have they are more versatile for use in hollow forms and very deep bowls...


Calipers.JPG
Max reach of about 10"
​
The hair tie keeps a gentle pressure towards the closed position so that I can use them one handed. I have also rounded off and polished the tips to reduce any scratching, which is necessary as I invariably have one finished surface when I get to use them.

I have reversed the screw adjustment mechanism on some spring calipers so that I can set a minimum distance, but as yet haven't got around to extending and reshaping the legs into a configuration similar to the Lee Valley ones, which would be fine but their 16.5" model would be a bit exxy by the time they were delivered down here.

 
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The Veritas calipers (mine came from Lee Valley) are my most used calipers. Since they can be set to just about any thickness, but are easily opened up wide to get past any thicker points without disturbing the thickness they are set for, they are really versatile. They are the only calipers I’ve found that can do that. If you adjust them to the thickest point then move to a thinner area the difference shows easily. You can set them for any wall thickness - say 3/16”, then open them up and move to the area you wish to measure simply. The way the adjusting nut works it is simple to adjust with the same hand you’re holding it with (hard to describe) They come in two sizes the large one will allow use in bowls 18 inches in diameter (possible a little larger. Not cheap at about $79 for the large size, but indispensable once you start using them.
1733360574874.jpeg
 
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I really like the Veritas calipers. When I bought mine, I purchased both the large and the small. Save your money and just get the large set. Once you use them a few times, you will love them. I have tried the figure 8 calipers, but do not like them as much as the Veritas. Lee Valley - $69.
 
IMG_1143.jpg
This is my collection the 2 digital calipers worked great until they failed. The direct reading calipers (black shown on a bowl work almost as good as the digitals but they do not have enough depth. The reshaped older calipers on the right I usually set for 3/4" and then judge by eye.
 
Wow, lots of great ideas. I think if I was going to buy something it would be the veritas they seem really well thought out. If I didn't then I love the various wire ideas. But what I have started to do immediately is stick my finger between the outside point and the wood. That works great.
Thanks all
 
JeffSmith said:
The Veritas calipers (mine came from Lee Valley) are my most used calipers. Since they can be set to just about any thickness, but are easily opened up wide to get past any thicker points without disturbing the thickness they are set for, they are really versatile. They are the only calipers I’ve found that can do that. If you adjust them to the thickest point then move to a thinner area the difference shows easily. You can set them for any wall thickness - say 3/16”, then open them up and move to the area you wish to measure simply. The way the adjusting nut works it is simple to adjust with the same hand you’re holding it with (hard to describe) They come in two sizes the large one will allow use in bowls 18 inches in diameter (possible a little larger. Not cheap at about $79 for the large size, but indispensable once you start using them.
View attachment 69562
Click to expand...
As Jeff says, these are great. I prefer the smaller size though, except for large work where I have to use the big ones.
IMG_4223.jpeg
These are my favorite thickness calipers. Made by Robert Sorby, no longer in production but occasionally available second hand. They work in much the same way as the ones above, but can be used with one hand
 
Isaac Fisher said:
These are my favorite thickness calipers. Made by Robert Sorby, no longer in production but occasionally available second hand. They work in much the same way as the ones above, but can be used with one hand
Click to expand...

I've seen Pat Carroll use a very similar looking scissor caliper during a few of his (great :cool:) IRD's. You can buy them on his site:

1733751199939.png
 
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@Darryl Fective Now, I ain't one with a lot of room to talk about names, but I gotta say, that is an awesome name. Especially when used with just the first initial, like in the picture above. Is that your real name or just a nom de plume or ... nom de chip
 
Raif Harik said:
Hi, I've always had trouble with calipers. User error I'm sure. Where when I get down to where I want to measure, I then have to open up the calipers to get them out and look at the space/thickness.
I was going to just post that question but I did a bit of searching online and found that the term "breadth calipers" brings up basically the same calipers but with an angle measurement up by where you adjust it. They also come with little round circles at the ends rather than sharp points so you don't scratch what you are measuring (human beings by intent I believe). Pretty nifty.
Then I noticed the double end calipers. The ones that look like a figure 8. I guess I never realized that you could take a measurement on the one end and see the same opening on the other end, thus being able to measure before moving.
I guess I'm kind of slow to pick up on the advancements of engineering over the past 2000 years. But I thought I'd post here in case others were struggling like me. And/or to hear about other marvels of mankinds measurements.
Click to expand...

The figure 8 calipers are handy. You can just glide along the bowl sides and watch the other end for differences.

On the standard divider type caliper, I grind one point down so it doesn't catch when marking my tenon.
 
Kent Reisdorph said:
On the standard divider type caliper, I grind one point down so it doesn't catch when marking my tenon.
Click to expand...

I've never thought of rounding one point of dividers.
I leave both points sharp, and with both firmly on the tool rest, just hold the point a bit away from the right-hand/uphill side of the wood.
I tell students to never let the right-hand point touch the spinning wood. Wear safety glasses, listen and learn. Or let the second point touch once - just once.


I size spindles and some tenons with this type of caliper, round and smooth both points so they slip easily into the parting tool groove.
This cheap vernier type is perfect, no need to read the numbers, just set the size by some method.

I've seen these on the wall in the cheap tool section at HD, and once I found them on Amazon for about $4 each and bought a bunch.
calipers_2MT.jpg

I mark these two for "small" and "large" and keep preset for turning #2 morse tapers on the ends of thin spindles. These make making MTs so quick: - between centers, turn a cylinder on the drive end about 3/4" in diameter and maybe 1" or so long, mark two lines 1/2" apart on the cylinder a little ways from the end, use the "S" caliper and parting tool to size the smaller MT diameter, use the "L" caliper to size the large diameter, then cut a taper that fits into the lathe spindle MT socket. I cut a shallow relief in the middle and twist in the headstock MT to test (with the lathe off!) - if it makes 2 burnished marks it's perfect. A quick and secure way to hold, and one that allows removal and remounting of the spindle without loss of registration!

This shows some finished turnings before the MT is cut away.
I used to make the taper shorter, like the one on the blank at the top, but now make it longer.
morse_taper_IMG_5054.jpg

I have no idea how I drift of on such tangents.

To get back on track, this is my favorite caliper for checking wall thickness of small work, made of brass, unusual shape, I can fit it into things I have a hard time measuring other ways (except by the wire technique, of course). I can't remember where I got it - I'd love to find a spare, might just have to make one. When configured as in the first pic, the gap on one side equals the gap on the other. When configured as in the second little picture, the wall thickness can be measured from outside to outside of the rounded tips on the right end. The nut in the center adjusts the tightness.


caliper_mini_comp.jpg
JKJ
 
Raif Harik said:
@Darryl Fective Now, I ain't one with a lot of room to talk about names, but I gotta say, that is an awesome name. Especially when used with just the first initial, like in the picture above. Is that your real name or just a nom de plume or ... nom de chip
Click to expand...

Somebody made the connection from my photos that I'm really Pete Meyer from the article in the July/Aug issue of American Woodturner. :cool:
 
I decided on the Kynup Digital Caliper from Amazon as it uses the 2032 battery which I have been told lasts twice as long as the LR44. Right now click the savings button and save $5, get it for about $24.
 
As for battery capacity, one 2032 has approximately 1.5 times the capacity of one LR44.
www.semiconductorforu.com

LR44 vs CR2032: Which Button Battery Do You Need? - Semiconductor for You

Have you been left trying to revive a dead device without success, yet searching for the ideal battery to revive it? This knowledge about true distinctions between LR44 and CR2032 can help you in saving time, money, and headache. It is the ultimate guide for understanding these batteries, their...
www.semiconductorforu.com www.semiconductorforu.com

I bought the iGaging 6" this past July, was $32.
The iGaging uses two CR2 batteries. One CR2 battery has 4 times the capacity of one 2032, but at the trade off of a larger size. Both are lithium based.

I bought it to evaluate. I find I never use it. Anyone want it come visit and take it home. I'll trade for a good joke.

Big caution about button cell batteries - keep them away from kids! I have a relative whose baby daughter found and swallowed a 2032 battery. An emergency rush to the ER prevented the need for serious surgery and possibly saved her life - discharge from the battery was burning a hole where stuck in her esophagus. All I've bought recently made by name-brand companies are in tough two-layer packaging that is difficult for even me to open, and the cells are now coated with a strong bitter chemical encouraging a child to spit it out.
 
I have been told that many small electronics (like calipers) continue to draw power when switched off. I pull the button battery holder partially out of the slot, disconnecting the battery, when not in use. This does seem to improve battery life.
 
Mark Jundanian said:
I have been told that many small electronics (like calipers) continue to draw power when switched off. I pull the button battery holder partially out of the slot, disconnecting the battery, when not in use. This does seem to improve battery life.
Click to expand...
Only when they are poorly designed.
There is a "fix" once it gets annoying enough.

20230110_224613.jpg
 
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