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Who invented the first offset portable boring head, when?

By portable, i mean the non-machine-specific accessory that will fit any mill or radial drill so long as it has the correct shank.
As opposed to machine specific boring mill accessories.

Almost all "modern" boring heads have some form of dovetail ways and that seems intuititive.
I've seen a rare few with box ways, and have one somewhere (that came at the bottom of a box lot :) )but believe it to be shop made.

Recent use of one of the Universal Precision (brand) heads at any excuse got me wondering about what the first all purpose accessory boring heads might have looked like? The Universal's rectangular section slide is completely enclosed in the head. It apparently has internal gibs, but the slide essentially slides in a close fitting sideways mortise through the body of the tool. The Universal was patented in Dec, 1931. So it got me wondering what would have been the previous models or influence?

I have not taken one apart to fully grasp the method by which they work, so don't know if a dovetail slide would have given more extended travel in the same diameter. But for a 3-1/2" dia head, the slide has only 3/4" total travel. For smallish holes, sometimes you end up starting with a bar facing one direction, then as that runs out of travel, rotating it 180 deg in the slide, and going the other direction. I enjoy using the tool. Especially the way it is possible to keep dialing off radius witthout ever stopping the machine spindle until you either hit the target, or run out of travel and have to re-set the tool or install one with greater reach.

But it all got me thinking, what were the models that influenced Myers Conwell's thinking of the basic architecture, besides his own ingenious method of operation to effect precise slide movement while the tool rotates continuously?


Now that is interesting!
Per a Google ebook link, American Machinist takes the Casler back to 1917 at least, and it was made not too far from me in Canastota!

Vintage Machinery gets to the early teens:


Picture is also from Vintage Machinery. References a 1912 Machinery Ad.

If that tool was a reference for Myers Conwell/Universal Precision, he actually simplified the slide by omitting all the keys, and greatly expanded the slide/offset range.

Thanks Asquith!

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Herman Casler/Marvin & Casler apparently also invented (a rather complex initial version) of the spring loaded mechanical edge & center finder.

.....and digging further - it appears that various enterprises & combinations of the principals started in the 1890's in the very early movie business and machinery. It seems much of Marvin and Casler's business was based on "Mutascopes tm" (peepshow machines) which could be loaded with any subject including newreels, scientific and historical materials, local tourist information, and of course porn. Apparently Mutascopes tm specifically, became popular in Great Britain as "What the Butler Saw" machines.

Not to digress - they must have needed specialized somewhat small tools developed in house to facilitate building moderately complex mechanisms and found it profitable to market them, too? The sewing machine industry started roughly 50 years before the movie apparatus industry. Before that firearms and clocks. Were movie machines really the first inspiration for an offset boring head?

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What about Automotive Cylinder Boring Machine? Storm Mfc Co
Made in Minnesota?


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I was thinking specifically about "portable" boring heads with option for precision offset, held by one end, to be used in other machines.
Line boring equipment and bars with traveling heads do seem to have long preceded the more or less small, offset-heads. (HBM's)

A few days ago i was looking for something else in an old 1926 Carey (Baltimore) catalog, and there was a small boring head that consisted of a straight shank, and an L-shaped blade that pivoted on the end. The description mentioned something about accurate controll of position, but basically it pivoted from the top of the L which was bolted to the end of the shank, and the short leg was shop sharpened as appropriate. The amount of angle determined the amount of radius/offset. It did not look overly secure or precise, but the cut (engraving) was small, and a note about "inquire for details".