A few trammel point questions

I'm helping a friend sort through some drafting tools and have a few questions.
I really like the set in the green case. They are from Theodore Alteneder & Sons and very well made. Do you think they had their own factory beam or did you make your own beam any length you want from wood?
The set in the blue case are from Alvin, an economy set, and they do have their own long and short beams.
Can anyone tell me the maker of the brass set? They are unmarked and do have a wooden beam.
Thanks for any insights.

You may get a "closer" guess if you consider the slot for the beam. Trammels that I have seen for a wood beam usually have a bigger slot, close to something nominal, than a custom beam.
I have a "cheapo" set that was made to fit a standard yard stick.

Pete

For some reason the photos don't show up.

As shapeaholic said, the size of the slot gives a clue. Most yardsticks are 1-1/2 x 3/16 or smaller, most combination square blades and similar rules are 1 x .1 or smaller, and trammels for user supplied wood are usually something like 3/4 x 1/2, 3/4 x 1/4 or similar so beams can be ripped from 3/4" stock.

A while back I bought some new trammels (Wood River Brand) on sale at Woodcraft. They fit nothing I owned so I milled the slots wider to fit nominal 1 x .1 rules. I don't know what they were thinking - the slots were so narrow they would only fit maybe 0.050" or so but every thin rule I own (or have ever seen) is at least 1.5" wide. The slots were barely 1" long and I had to mill a little past the existing end.

Thank God for machine tools!

Generally these companies, T & A, K & E, Ditzen, etc. sold their drafting trammel points in small fitted cases or included them with the larger set. Their catalogs show they offered bars, often made of pear wood or some other hard wood. They tend to have a wider rib on the top that is rounded and a little ridge on one side of the bottom to keep the trammel in place while loosening it for adjustment. I don't think a lot of folks bought the bars, why spend that kind of money when a yardstick will do fine? They were also included in some of the largest sets, that is the only place I have ever seen them. They are rare but not valuable.

i always use a piece of cold rolled steel for trammel points, wood is soft and flexes.
.
weight not a problem but if it was then i would use aluminum bar

Another vote for a length of good quality aluminium bar.

Regards Tyrone.