Working at Northrop Grumman as a Tool & Die machinist with some of the best machinist in the world sometimes got pretty boring when you have to be by a machine for hours machining a part. The company discouraged you from reading a newspaper while operating machinery. There were always the football pools and handicapping the horses. And little home projects. These guys were always building something and getting a patent on it. But it had be something that you would not get caught building at work.
My project was to make a drill bit that would drill a square hole.
The entire machine shop was helping and over a two year period I bet we tried fifty different designs that did not work. We even had top engineers involved.
The conclusion was that it is impossible to drill a square hole with a round drill bit. And it sort of became a saying around the shop.
Years latter I’m in this old tool crib at General Dynamics in San Diego that probably had not been use since WWII. Guess what I found, yep, a round drill bit that drilled a square hole. It was patented in 1910.
Point being, I think, is that, what we accept as fact based on the available evidence and for practical purposes, is subject to revision in the face of new information.
With a 3D printer you can build the object around the hole but I presume they cannot do that with metal.
YET!
psik
TimB
The shoe fits.
Did you pick that up somewhere or come up with it on you own. Boy, it great!
Years latter I’m in this old tool crib at General Dynamics in San Diego that probably had not been use since WWII. Guess what I found, yep, a round drill bit that drilled a square hole. It was patented in 1910.Come on, produce some pictures :smirk: I know I can drill a square hole in wood, but it takes multiple drill bits and a little cleaning with a chisel. I want to see this drill bit that can drill a square hole :coolsmile:
Is it truly a square hole, or are the corners rounded? >-D
Citizenschallenge.pm Post #4
I really wanted to take it home. The setup was in a big wooden box. I know its wrong, but I did think about it. I would have had pictures, but this was before we had cell phones like today. It was before I even had a cell phone, but like other classified project, cameras and cell phones are not allowed in the buildings.
Today we just broach square holes.
This method required tooling setup. You’d have to be a better machinist than me to do it on a drill press. So a mill would have been required.
- Step one would be to attach the drill block.
- Place the round drill bushing attachment for round hole.
- Insert the proper drill bushing for your bit size.
- Do steps 2 & 3 until you got the size of hole needed.
- Remove round drill bushing attachment.
- Place drill bushing attachment for square hole. This attachment turned in a off center movement.
- Insert the size of drill bushing for the special square hole drill bit.
- Note; this was a one flute bit.
- Turn slowly with small bite.
The basic method.
The box contained about fifty round and fifty square drill bushing sizes, one drill block, two drill block bushing inserts (one round, one square), fifty one flute drill bits. It did not contain any round drill bits.
Note; the square drill bushing inserts turned off center and on roller bearings.
TromboneAndrew Post #5
At the time I was General Dynamics Air Force Plant #19 as a Jig & Fixture Builder. They had no machine shop there. I was trying to figure out a reason to have them send me to the machine shop at the main plant so I could try it out, didn’t happen.
My guess is that the hole would have been ruff and any good machinist would have cleaned up the hole with a file.
But yes, it would have been a square hole with square corners. I came to that conclusion by turning the off center square bushing attachment. It seemed to have a cam like movement, but without dissembling the unit I’m not sure. I forget to add the drill chuck to the list in the box, the chuck turned off center and the drill bushing attachment moved with the chuck. So you would put the Chuck in the mill after you drilled the round holes.
I’d love to see a YouTube video of the thing in action.
Although it seems to me a series of bite sizes starting with the smallest drilling the initial hole in each corner,
then establishing each corner with a series of those holes in line,
then come in with the bigger bits to cut out everything in-between,
finish with chisel… or file.
somehow sounds simpler than that gizmo {IMHO}.
I would have had pictures, but this was before we had cell phones like today. It was before I even had a cell phoneOh my gosh... :ohh: are you from those days when people used to be out of voice contact with each other for hours at a time... on my. No camera on the phone... :ahhh:
Me too, this was before home computers. Holes one-half inch and less would only require you to drill one round hole and then one square hole.
Broaching a square hole would be faster, you would use this setup where a broach would not work, like for example a square hole that would not go all the way through the part.
The system was patented in 1910 but the bits were made of high speed steel. And the grinding finish on the harden drill bushings and chuck was of a fine finish which leads me to think that the kit was most likely manufactured in the late 1930’s.
Used in wood or plastic only one round hole and one square bit would be required and it would be much faster that using a broach. And wood or plastic less than one inch, I would bet all you need would be the square bit and no drill block and should be able to work on a drill press.
I should note that in the posting I used Northrop Grumman because that is the name of the company today. Back then they were two separate companies.
If you have an interest in the tooling and machine shop I have gone several times to the Los Angeles Machine Tool convention that is held once a year. They always have some unbelievable stuff there.