Collars

[prof]

I'm looking for any info or calculations, books, charts for making collars for any projects in the near future. I've been making some but seems they are either to long to short it just takes me awhile to get the right size. Tired of wasting metal. Right now i need a few collars for two pieces of 1/2" square stock.

[John Martin]

A good way to measure a collar, is to measure the metal cold with a sewing tape measure. It's made for measuring collars. Well not really, but it works perfect. AS LONG AS the metal isn't HOT. The Backyard Blacksmith by Lorelei Sims is a real good book, and covers collars in depth. Hope this helps.

[Thomas Dean]

(Thickness of matrl' to be joined x 4) + (Height of matrl' to be joined x 2) + (Thickness of collar matrl' x 2)

Example: 2 scrolls joined with a collar 1/8"thick. scrolls are 1/2" sq stock.
(1/2 x 4) + (1/2 x 2) + (1/8 x 2) =
2 + 1 + 1/4 = 3 1/4"

Taken from Lorelei Sims' "The Blackyard Blacksmith" page 101

Hopes this help. Don't forget pictures when done!

[Mark Aspery]

The formulas are a place to start and none will ever take the place of a test piece or two.
The general formula is the perimeter of the stock to be collared plus 2.5 - 3 times the thickness of the collaring material.

This varies depending upon the collar thickness and shape, and the dimensions of the collared material.

I cut mine a little short and forge them on a mandril or collaring tongs to produce the correct length and get square corners to the collar.

I like the ends of my collars to butt up next to each other. The other style is to draw a taper to both ends which overlap when applied. The latter is a little more forgiving.

The joint should be away from the viewer and on the long surface of the collared stock if it is a rectangle.

[Mark Aspery]

Here is a picture of a forged collar with square corners and butt end joints.

[John B]

Make a mandrel the size of the pieces to be joined / held with the collar.

Place the mandrel on the end of the material you will be using for the collar, rotate the mandrel along the length of the material, (side, edge, side, edge [the perimeter of the mandrel]) and add twice the thickness of the collar material, mark and note this length. Use a pair of calipers or dividers to note this size,

Forge a collar on the mandrel using this length of material, it should be correct, if you need to make it bigger or smaller, any difference can be then made to the caliper/divider setting.

If you cut off the lengths on a hardy, cut on alternate sides, this gives an angled face that snugs up nicely, there is no need to forge a taper on each end using this method.

[evfreek]

Hi Mark. That is sure a nice looking collar, with well defined square corners. With square corners, they will have to be cut a little bit longer than the 2 x thickness rule. This is one of the lessons in my "Mathematics of Blacksmithing" talk. The 2x rule is appropriate if the corners are rounded off in a triangular fashion. It is 3x if they are rounded like quarter circles (actually closer to 3.14x). Finally, it is 4x for perfect square corners. You can calculate it with a volume balance, but if you draw a cross section picture, it becomes obvious. The next question is how long a piece of stock is required to great circle collar the earth . It is computed in a similar manner. One blacksmith reference I read suggested starting shorter than these amounts if you are a beginner. When I did my first few collars, I immediately figured out why. One gets too frantic trying to close the collar before it cools, and many errant blows are struck, especially at the "no-no spots" at the corners. This unnecessarily elongates the collar.

I look forward to seeing your workshop which is coming up soon at Oktoberfest.

[John B]

I feel I must respond to the "Mathematics in blacksmithing" thread, I have difficulty with fomulas, and so do others, hence the adjustment contingency using calipers to reference the length used,

Thats why I try to keep it simple, I have been using the "roll round the mandrel and add twice the collaring materials thickness" for many years now, as used in the attached thumbnails, all these collars were produced using this method, and some were made by students using this method, it works.

If I need a sharper corner, I may add a small amount to the original measurement, (But I have never added more than one extra thickess of material) then I forge it for longer on the mandrel to the required degree, this also works using shaped form collars.

If I am using a collar 3/8" thick, to add on an extra 3/4" in the collar length would be far too excessive,if you are only using thin material then it may be more appropriate,