3/4 Round Gage

[Bob La Londe]

I'd like to know who has made one of these and any tips you would care to share for making one. In the past I have made "special" angle blocks that capture an over all rectangular part at a particular angle. It has a clearance where the edge of the part is located assuring burrs, dings, and chamfers have little or no affect in the location of the edge in relationship to the angle block. This allows me to indicate/probe/touchoff the angle plate/block and use the math to tell me where that edge is. It works, but its cludgy, requires some math (or cad to do the math) when often what I want/need is the location of the exposed edge.

Recently a YouTuber posted a tool they had made. It is basically a cylinder of known diameter with a clearance hole bored down its central axis. Then 1/4 of the round is machined away. When its placed over the exposed edge it can be probed to find center and height of the edge more easily than my previous method. In addition it doesn't matter what angle the work piece is mounted at to find that edge. It should work for most work piece angles of any angle between 90 and 0 where the widest point of the tool is accessible with the probe or edge finder. Of course 90 and 0 would not require the tool.

P.S. Its such a simple elegant solution I am sure the YouTuber wasn't the first one to think of it. Does this tool have a proper name?

P.P.S. I have made "other" similar locating tools and I know how to make one. I'm asking more if there are any tips to get it better or gotchas to avoid that might not be obvious.

[mklotz]

It's also handy for placing the punch mark on the intersection of two layout lines...

https://www.homemadetools.net/forum/prick-punching-aid-39225#post54767

[reggie_obe]

Very simliar to a Toolmakers chair.

https://www.practicalmachinist.com/forum/threads/accurately-locating-angular-holes.75689/post-38985

https://www.practicalmachinist.com/forum/threads/accurately-locating-angular-holes.75689/post-39001

[Bob La Londe]

It's also handy for placing the punch mark on the intersection of two layout lines...

https://www.homemadetools.net/forum/...5#post54767

I didn't think of that. Now I have to consider drilling/boring/reaming the center accurately now too. I was just going to slap a quick and dirty hole in it on the lathe to start. Maybe size it to match a particular transfer punch.

[Randy]

I saw James Clough's video, then Stefan Gotteswinter's, which is what inspired James. As you know, James is rather anal retentive and exhaustive in his videos, so you might watch his if you haven't already.

As for what to call it, that's a good question. I don't recall if either of them had a name. I googled "corner gage" for images and got no hits, but "corner finder" brought up a photo from Practical Machinist, as well as some other similar gages. Corner finder seem like a good candidate to me. Someday I'll make me one.

It just occurred to me, it must have been James's video you saw. Stefan made a metric one, IIRC.

[Dan Dubeau]

I made a similar one years ago, 1" od, but it doesn't have the through hole, and is not machined all the way through. It comes in very handy every once in a while.


I don't know what you'd "call it" but everybody in the shop that wants to borrow mine calls it "hey can I borrow that angle block pickup thing that you made" "hey, can I borrow your corner bar edgefinder thing", "hey can I borrow your half milled corner dowel thing" or something similar. That's the problem with taking the time to make special tools in a small shop. You can't keep them hidden for long

Do you have a surface grinder Bob? Can't remember if you did or not. I'd rough machine everything to within 0.005" and drill/ream the center then heat treat. Grind the faces flat/parallel, then mount on a pin in a punch grinder to grind the od concentric and to size after heat treat. Then I'd grind in the step faces in one setup. You can use a gauge block against the face to bring it out far enough past od to mic directly, otherwise it's tough to measure in place as it's right on centerline, and the anvil won't hit the od correctly. I should make another one and do it better this time. I never hardened mine, and it's only milled. Still fine for how I use it, and it's served me well but I'd like a nicer one. I want to remake a bunch of old shop made tooling I made years ago.

[Bob La Londe]

Well, I made it. I just ran seat of the pants and measured as I went. I blew one dimension totally. The other is okay. Checked by stacking gage blocks and locking a caliper. about .0004 under in one dimension and totally trash .004 under in the other. I'm going to have to make it again. A multiple anvil micrometer would be better, but I don't have one. Atleast the caliper can reach past center so it will measure as good as a caliper can. I ran dead reckoning with the DRO and hosed the measurement at the end.

Yes, I have a baby 6x12 surface grinder, but no coolant setup yet... and low skill level with it. Someday when I have time.

[Bob La Londe]

Three tries... it took me THREE FREAKING TRIES to make one that will get me by for the current job.

I wound up using a square collet block and then taking it off the mill to measure on a surface plate with a height gage. I also cut the final surface height cut on both faces with the end of the endmill.

Its not so good where I would try to teach somebody else how to do it, but it's good enough for the current job. Now I need to go throw the other two away so I don't get them mixed up.

[boslab]

What I have done, two rollers, dowels precision rollers held together with elastic ( the part must be small to clear the elastic) then clock off the rollers
and a vee block on the edge, indicate the faces
but the notch guage is more elegant to be sure
finding missing corners is always a challenge!
mark

[ChazzC]

Late to the tread, but reading through it I thought of Jame’s (had forgotten about Stefan’s input), but then saw that Randy beat me to it. Now I have to go back and watch them again because I can’t remember why they made them!

[Bob La Londe]

Late to the tread, but reading through it I thought of Jame’s (had forgotten about Stefan’s input), but then saw that Randy beat me to it. Now I have to go back and watch them again because I can’t remember why they made them!

I need to drill through wire holes at 45 degrees to the parting line in a mold. The first of 8 holes has been drilled using a stubby 1/16 carbide drill for my pilot.

[mklotz]

...
As for what to call it, that's a good question. I don't recall if either of them had a name. I googled "corner gage" for images and got no hits, but "corner finder" brought up a photo from Practical Machinist, as well as some other similar gages. Corner finder seem like a good candidate to me. ...

I just call mine the "cheese wheel" gauge...

https://www.mashed.com/1096646/the-structure-of-a-cheese-wheel-is-more-important-than-you-may-expect/