Author Topic: Help Needed for Research  (Read 3682 times)

Offline James Wilson Everett

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Help Needed for Research
« on: June 04, 2015, 02:05:56 PM »

I need some help with research on the HDTDT (How Did They Do That?) for gunlock making.  If anyone out there has information on this, let us know.

The following is an excerpt of a description for the manufacture of the 1816 Musket lock plate at the Harpers Ferry Manufactory

"In this die all the holes are drilled exactly in the position and at the respective distances from each other that they are required to be.  The workmen commence by marking the new plate with a drill.  This done, they finish the holes, slightly conical.  These holes they make cylindrical by means of a tool which they call a “false drill,” used with a conductor, in order that the holes shall be exactly perpendicular to both surfaces.  Finally, with a finishing bit they give them their finished size, and afterward “tap” such as are to be screw-threaded."

Durfee, William F. “The First Systematic Attempt at Interchangeability in Firearms.” Cassier’s Magazine 5 (1893-1894):469-477.

So far I know what the tooling looks like to drill the initial hole, I call the tool a "fish tail" drill bit.

The tooling to bring the fish tail drilled hole up to the correct diameter is a tapered square reamer which gives the
"slightly conical" hole described above.

So, my question is:  What is the "false drill" mentioned above along with the "conductor"?  Apparently this tool would ensure that the hole is truly perpendicular to the lock plate surface and to make the slightly conical hole from the tapered reamer "conical".

Next question:  After the fishtail drill bit, the tapered square reamer, the false drill/conductor, what is now the "finishing bit"?

Let us know your thoughts on this.  But, please categorize your thoughts as:  1. I know this for sure, 2. I think this is it, 3. This is a W.A.G.

« Last Edit: December 02, 2019, 04:35:05 AM by James Wilson Everett »

Offline Dale Campbell

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Re: Help Needed for Research
« Reply #1 on: June 04, 2015, 02:52:48 PM »
Jim, I don't have any direct input to the definitions of those tools. However, do you have access to the Oxford Dictionary of English? The full version usually has the first instance of any term in the language as part of the entry, as well as subsequent changes in meaning.
Best regards,

Offline ddoyle

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Re: Help Needed for Research
« Reply #2 on: June 05, 2015, 02:53:01 AM »
Total Guess:

A "conductor" is generally someone who directs/regulates traffic or means of linear conveyance (i.e electrical wire).
  I assume in this instance it is a jig or device for guiding the "false drill".

While it may be near impossible to find more detailed reference of a such named tool in relation to lock building it feels like a term/tool that you could turn up in a general reading of period engineering practice. Maybe watch making?
« Last Edit: June 05, 2015, 02:55:25 AM by ddoyle »

Offline Mark Elliott

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Re: Help Needed for Research
« Reply #3 on: June 05, 2015, 04:45:58 AM »
At the CW gunshop,  they made a drilling guide (die) for the metal (fishtail) bits which are used in a bow drill.  They them ream them to size, I had assumed with square reamers, but I never actually saw one, at least that I remember.   George could have showed them to me and I just didn't take notice.  You know, when you get old, you just can't absorb everything.  I guess it would make sense just to use the drill guide to mark the hole and then finish it outside the drill guide.   That way,  you don't wear out your drill guide so fast.  

Just from reading the description,  I would assume the "conductor" to be a pilot of some sort.  Perhaps the false drill is a counter-sink or counter-bore with a pilot.  It would help to know which holes they are using these tools on.   Some holes are counter-bored.  I really don't think they would be using all of them on all the holes.   That doesn't make sense to me.    

I bet that "false drill" is very similar to your breech mill.   Of course a picture in a tool catalog would be nice.

Just take the above as a guess, but I built an IT career off guessing.   I have always been a good guesser.   ;)
« Last Edit: June 05, 2015, 04:49:13 AM by Mark Elliott »

Offline Acer Saccharum

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Re: Help Needed for Research
« Reply #4 on: June 05, 2015, 05:44:59 AM »
Conductor is probably a drill bushing; a hardened bushing set in a fixture to guide the drill to a repeatable location.

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Re: Help Needed for Research
« Reply #5 on: June 05, 2015, 02:32:51 PM »
Conductor is probably a drill bushing; a hardened bushing set in a fixture to guide the drill to a repeatable location.

I think your onto something here......I conceive a jig of steel, with bushings for the drill bits. Clamp on ton the plate to be drilled, and the holes will be exactly drilled in each plate produced. The "pilot" holes could be reamed/coarse drilled with these spade type bit 1st, getting a lot of the metal out of the way.....

I made such jigs for making scale ribs for my R/C planes......

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Offline shortbarrel

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Re: Help Needed for Research
« Reply #6 on: June 06, 2015, 12:16:43 AM »
A conductor conducts something straight or curved, in this case straight. If I am correct they had vertical drilling machines, of some sort at HP at this time. I use a fish tale drill to drill the holes and  then ream and tap. I do it on a kind of bean drill and brace that I made. The tooling has to be made right and the screw grinders for sure.