3 point (scribing) centre punch

Attachment 48561


I downloaded a pdf copy of “Modern Toolmaking Methods” ed. Franklin Jones, published 1915. On page 49, there is a photograph of a tool which can be used to centre punch where 2 lines at right angles intersect. The 2 points slot into one scribed line and the third point is moved along the work until it engages with the line scribed at right angles, “ with an audible click,” I read.

I have balked at the cost of an optical punch, but I thought that this was a good tool to have. But was unable to find one, even in a 1935 catalogue.
Of course this is not up to the accuracy needed for making accurate jigs, relying on it does on pegboard and those little brass buttons which you see. These buttons have been salvaged from telescopic frames, such as walking aids. They are attached to v-shaped springs inside the aluminium tubes and engage with one of a series of holes. I have kept them to use as dowel markers. These happen to be 1/4” diameter, same as the pegboard. I drilled 3 of them through as a tight fit on these hardened picture-hanging nails and the central one, the punch, just slightly larger, to make a single light mark, to be enlarged subsequently.

I have kept a square of pegboard around for many years since it’s handy to locate a point to drill holes in 4 corners.

I hope you toolmakers might like to make a precision version. The book is free to download, and very interesting. Other old methods may have been forgotten, but might save from buying an expensive tool.

Happy New Year.

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Thanks Philip Davies! We've added your Three Point Center Punch to our Scribes, Awls, and Marking Knives category,
as well as to your builder page: Philip Davies's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/homemade-three-point-center-punch"> <img src="/uploads/273361/homemade-three-point-center-punch.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/homemade-three-point-center-punch">Three Point Center Punch</a> <span> by <a href="https://www.homemadetools.net/builder/Philip+Davies">Philip Davies</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/punch'>punch</a>, <a href='https://www.homemadetools.net/tag/scribe'>scribe</a> </div> </div> </div> </div>
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Thank you, Phillip, great post. Also, excellent reference to Jones' publication.

It certainly is a quick and simple jig but I'm a little confused about the "slots". I can see using this on dykem blued scribed lines or pencil-on-paper lines as demonstrated. Either case, there are no slots and alignment of the pins on the lines seem to be tedious by having to look around or underneath to locate the pins exactly on the lines. What do you think of maybe a lucite or clear plastic bushing instead of brass so you can see the point contact the lines? (Although there may be parallax error)? Or drilling viewing port holes at an angle aligned with the contact on the surface?

I understood from the text that the points would engage with fairly deeply scribed lines. Which most would not want. But for making a jig, it might not matter. I relied on the pegboard geometry, so it was a really easy, quick tool to make, but a clear plastic, as you suggest, would be good. Are you going to make one?

Yes, probably with a modification. I want to easily see very light, thin lines, as in scribed dykem blue lines. Some kind of viewport (or slot) is interesting. Busy time of year now but I will post here any follow up. Many thanks.