Center Punch Callipers

[Josh.Sampson]

I had the idea of making a pair of callipers similar to the Golden Mean callipers I forged but to measure the halfway point instead. When working out the numbers, I realized the center point would be dead center of the bottom rivet.
 

I had the idea to make the bottom rivet of tool steel (Atlantic 33 in this case) and make a center punch of the rivet. It works well though I would make the tool steel rivet differently next time. I think this will prove to be a handy tool. 
 

Sorry I didn’t get progress pics this time but the process is nearly identical to the Golden Mean process I documented in an earlier post. But I did get a video showing how well it works. Hope you enjoy. 
 

 

 

 

[Frazer]

I'd be interested to hear if the rivet tightens up over time and locks up the movement.

Regardless: 1. Even if it does that's an easy fix 2. I really like the idea and 3. That's some very clean forge work. 

[Josh.Sampson]

9 hours ago, Frazer said:

I'd be interested to hear if the rivet tightens up over time and locks up the movement.

Regardless: 1. Even if it does that's an easy fix 2. I really like the idea and 3. That's some very clean forge work. 

Time will tell. I think since it is hardened it will take a while to cinch up. We shall see. Thanks for the compliments. 

[ThomasPowers]

You saw my post about making a center finder from 1 short bar and 3 posts?

[Josh.Sampson]

3 hours ago, ThomasPowers said:

You saw my post about making a center finder from 1 short bar and 3 posts?

Yes. From what I picture from your description, I’d imagine it would only work on fairly wide stock or you would need a few different sizes of the tool. I could be misinterpreting. Do you have a picture of one?

[ThomasPowers]

A few different sizes will do a wide range of sizes.  So one with 5/8" offsets will handle everything from 1" down to 1/8"---if the piece being scribed is long enough. 1.125" offsets will handle 2" down to 1/4", etc.  5/16 offsets is great for 1/2" stock.The neat thing is that it works with oddball sizes as long as the bar sides are parallel. 

Try it; drill 3 holes, drop in rods with a very short, pointed, middle one and see how it works.  if you can't get the holes spaced correctly it will still work by scribing one way then rotating the tool so the rods now bear on the other sides and rescribing the exact center will be between the lines.

The two outer rods need to be the same diameter; the scribe can be a tungsten tig electrode.

[anvil]

nice tool, nice design. Should hold up forever. I wouldn't make a center punch out of the bottom rivet, I'd do a scribe instead. That way you could mark your center line along a whole bar. 

I have a far simpler solution. It may be what Thomas is talking about, not sure. I'll see if i can get a pic of it. Its 3 pieces with 2 legs riveted to the ends of the third one. Then drill a small hole dead center between the two rivets for your scribe tip to fit thru in the center of the middle piece (centered length and width). The outer legs will pivot and fit flush and parallel with the two sides of your flat bar. The hole in the middle bar is always on the center line of any sized stock as long as the legs are parallel with each other and your drilled hole is centered.  Dirt simple for a blacksmith to make and use..     The length of the cross bar determines the max sized stock you can use and it will work on any sized stock smaller than this.

[ThomasPowers]

Nope; my tool doesn't have any moving parts to it.   I'll have to see is I can move my drill press over to an outlet and get it back working and make a couple to show here. (Been sitting over a decade since there was no power in the shop...)

[Frosty]

I made mine with a tig torch tungsten for the scribe but you have to keep the scribe short, 1/16" tungstens are brittle. 

The first time I saw one of these work it was made from a popsicle stick a couple finish nails and pencil stub on the spot. 

The things are silly easy to make a center punch and compass to lay it out and a drill press. EZ PZ.

Frosty The Lucky.

[ThomasPowers]

At last someone else that has used this simple device!  I've been tempted to move my drill press in where the active 220 plug is just to make a couple before the next NMABA meeting.

[Josh.Sampson]

On 3/20/2022 at 1:22 PM, anvil said:

nice tool, nice design. Should hold up forever. I wouldn't make a center punch out of the bottom rivet, I'd do a scribe instead. That way you could mark your center line along a whole bar. 

I have a far simpler solution. It may be what Thomas is talking about, not sure. I'll see if i can get a pic of it. Its 3 pieces with 2 legs riveted to the ends of the third one. Then drill a small hole dead center between the two rivets for your scribe tip to fit thru in the center of the middle piece (centered length and width). The outer legs will pivot and fit flush and parallel with the two sides of your flat bar. The hole in the middle bar is always on the center line of any sized stock as long as the legs are parallel with each other and your drilled hole is centered.  Dirt simple for a blacksmith to make and use..     The length of the cross bar determines the max sized stock you can use and it will work on any sized stock smaller than this.

From what I’m picturing, I can’t imagine this one tool working well with a variety of lengths and cross sections. Say you have a piece of 3/8x3/4 at 12.75” long and a piece 1/2” square at 6” long. If you had just one of the tools you speak of, would it work on both of these? If so, I need pictures because what I’m picturing would not. 

[Frazer]

The tool they are describing seems to find the center of the width of a piece of steel. Not the length. Perhaps I too am misunderstanding.

I suppose it could do the length as well, but that's were you run into sizing issues.

[ThomasPowers]

Right, its for the width not the length.

To find the middle of a length of sq stock, I just balance it.  I work to the tolerance of the thickness of a worn late 18th early 19th century shilling. (If I need to find a more exact middle of a length a pair of dividers works well.)

[Frosty]

Before I saw this center finder I used my dividers, eyeball center then scribe from one side and back on the other and interpolate center between the marks. 

If you want a pretty precise center lengthways brush the stock off and balance it on a sharp edge like your hardy. If you want silly accurate check with a bubble level. Over a finger or piece of round stock is good enough in most cases I don't have a tape measure handy.

Finding center lengthways is so easy I use different methods just for fun say stretch a piece of string full length and fold it in half to find center. Remember to mark from both ends!

I use string to mark divisions on a cylinder more often than using dividers you just have to keep track of how many times you fold it. EZ PZ.

Dad was a tricksy one he was.

Frosty The Lucky.

[anvil]

correct, center of width, not length. 

If you are trying to find the center of length, well, Its still a pretty tool, and a very nice forging to look at, but a 6' metal folding ruler is far more functional, or any of the ways Frosty mentioned. 

Lol, you would need to have a bridge crane to handle your tool form any lengths that are commonly used in an architectural shop,,, 36" pickets, for instance. I'd imagine your tool would work for lengths a foot or less.

For what its worth, I do nearly all my layout from centers, not an edge, length or width.

Thomas, thats quite a way to measure tolerance! Baring a worn shilling, you can be within a 64th" quite easily with a 6' metal folding ruler. 

[anvil]

I didn't watch your vid, so misunderstood it's purpose. A beautiful forging and a joy to use for it's use. It may need periodic maintained to keep it's accuracy for the reasons given. I think a heat treated center punch/rivet would not be easy to do, and the hardened punch may wear the mild steel hole it lives in. Worth a try 

Here's my ultimate " center finder", width or length. It lives in my back pocket, works for any length or width and has a myriad of uses.  My 6' metal folder.

And a drawing of my very simple center finder for width. The size of stock is determined by the length of the middle piece.

However, I rarely use anything but my ruler for linear measurements. 

Thomas, I would like to see a pic or drawing of what you describe. I don't know how to search for it 

[Josh.Sampson]

On 3/23/2022 at 1:20 PM, anvil said:

correct, center of width, not length. 

This is geared toward things like hammers, horseshoes, finding center on things between 4” (pretty easy to eyeball) and 20ish” quickly. Just an idea I had and brought to life. I too have used many methods of finding center of length. 

I keep a 3’ steel folding rule in my back pocket all day every day. Love it. 

Edited March 25, 2022 by Mod30
Excessive quoting

[JHCC]

On 3/24/2022 at 12:11 PM, anvil said:

My 6' metal folder.

I think you mean 6", not 6'.

For finding the center of something's length, this beastie is very handy. Also works well when you're finding the center of something that can't be balanced on your finger, like one section of a bar or the middle of a line drawn across a piece of plate.

Just slap it on the workpiece, set it so that the measurements are equal on both sides, and mark the center point:

[anvil]

On 3/25/2022 at 2:20 PM, JHCC said:

I think you mean 6", not 6'

Naa, 6' metal folder. I use the primary number lines as a straight edge to be able to locate centers and to scribe center line if needed. I can also open up one of the 6" sections and it makes a pretty good angle finder. Also, note it is steel. Dont use aluminum as it will expand when measuring hot iron. Steel won't. Primary tool. Couldn't be without it.

[Frosty]

A 6' folding steel rule isn't too heavy or bulky to carry in a pocket either. They're certainly more durable than a tape.

Frosty The Lucky.

[anvil]

Yup,, mylar tapes dont do well measuring hot iron,, poof up in smoke. I rarely use a tape. Its pretty easy using this even to measure and layout ling lengths. 

[Will Brouwers]

I would like to see what the other center finding tools were. I tried measuring halfway when making split crosses. But never seemed to truly find the center, the end of the ruler and trying to mark center with a center punch made for some inaccuracies.

[George N. M.]

Will, the easiest way to find the center of a piece of steel of uniform width and depth is to find the balance point.  balancing it on a narrow edge is more accurate than just on the side of your hand.  Mark that point with a felt tip and then, if necessary, a punch.  This eliminates the need for rulers, proportional dividers, arithmetic, units of measure, fractions, etc..  Of course, it doesn't work if your piece is not uniform along its length.  Then, you get a center of gravity.

Merry Christmas.

George

"By hammer and hand all arts do stand."

[Will Brouwers]

Thanks for the reply George. I should’ve clarified which measurement. I meant by width, hotdog way. How best to find the center/middle of a 3/4 square bar without getting a tape measure out and struggling to find 3/8.

[George N. M.]

if you are trying to divide it in half lengthwise the easiest way, IMO, is to lay a piece of 3/8 square (cold rolled is best because of the sharp edges) on the 3/4," line up the back and mark the center with a fine tip felt marker or a scribe.  You can keep a bucket or rack of about 12-18" pieces of various widths to use for measuring stock twice their size.

Still, Merry Christmas.

GNM

"By hammer and hand all arts do stand."