Dovetail cutter???

[SIGP2101]

Originally Posted by sheepherder

They taught me that in shop class. I'd like to know how to determine the dovetail angle.

Once I measure dimensions I use mm paper to make large drawing and then just measure angle.
European angles are 60, 65, 70 and 75 for most of the gun industry. So if you measure 63.5 for some reason that should be actually 65.

Or you can use known dimensions to calculate angle with given formula which brings us to 67.5 angle for the front post male dovetail.

[Olle]

Originally Posted by G.T.

Yes, beyond my experience as well... but, I think a big massive broach with the dove tail cut on the length face could be used on a very fast production scale... just too much leisure time is my excuse! .........til..lat'r...GT

When I was experimenting with the sight leveling tool, I realized that the size of the dovetail can vary well beyond the tolerances for a press fit. I can't remember how much of a taper I put on it (3-4/1000" in 4"?), but it was still just barely enough for the barrels I tried it on.

I'm not sure how they solved this in the factories, but one or two quick strokes with an angled file would cut a taper wide enough to start the sight blade. This is what I would do for a DIY job, and it might be what they had to do in the factories as well. Unless it's the sight blade being tapered... It's kind of difficult to measure, so I don't know for sure.

[sheepherder]

Originally Posted by SIGP2101

Or you can use known dimensions...

That sounds the simplest way. Could you please post the dimensions of the Luger artillery barrel, especially the rear sight base dovetail?

Originally Posted by SIGP2101

Once I measure dimensions I use mm paper to make large drawing and then just measure angle.

That's pretty much how I do it. I don't use paper, I use plastic sheet. I label the triangles so I can hold them against an unknown angle and see how close they are, then lay out what I think the angle is and cut it out and compare it. These are some I use to set my compound rest and/or set my fixture to mill a feed ramp [first pic]. It works good enough for my work. I don't demand perfection.

I use the plastic template to get my angle, then use the machinist's level to transfer that angle to my fixture [second pic]. This is a Luger feed ramp being cut.

The dovetail dimensions are less than a tenth of an inch in any direction; hard for me to see light under the template. 60º seems to be the closest I can come, so 60º it is.

[John Sabato]

Originally Posted by sheepherder

I'd like to know how to determine the dovetail angle.

Trial and error is probably best. 60 degress/58 degrees will probably work the best for an interference fit if you don't have a setscrew to hold the sight in place. If you do, the 2 degrees difference won't make much of a difference with a setscrew.

alternative 2. You can also use a CAD program to draw a variety of dovetails, then print them out, and cut them and see how they fit in the dovetail you are using as your example.

BTW, did you check the Luger blueprints to see what angle is actually specified on the P.08 for the sight dovetail?


The same measurement is probably used for the LP.08, and since you are talking about a sight for NAMBU, which never had an artillery version before, I don't think the dovetail police will visit you if you freelance the dovetail size.

BTW, Dimensions shown on the front sight blade above are IDENTICAL on the blueprints to the dimensions for the dovetail that sight fits into

Also, Someone recently posted the blueprint of an artillery barrel from a published reference book. I don't remember who did it, or what the subject of the thread was, but if you can find that posting, the angle of the dovetail on an artillery barrel is probably in that drawing...

[Olle]

Originally Posted by sheepherder

That's pretty much how I do it. I don't use paper, I use plastic sheet. I label the triangles so I can hold them against an unknown angle and see how close they are, then lay out what I think the angle is and cut it out and compare it.

Have you had any luck with the CAD yet? It's great when you want to determine an angle, and only have the side dimensions to go by. Just draw it and snap the angle, and you'll get an accurate number without having to do the trigonometry. I have made some templates by printing them and transfering to cardboard or acetate, it works well if you're lazy like me.

[sheepherder]

Originally Posted by John Sabato

BTW, did you check the Luger blueprints to see what angle is actually specified on the P.08 for the sight dovetail?

If you mean your CD, there's no print for the LP-08 rear sight dovetail.

Originally Posted by John Sabato

Also, Someone recently posted the blueprint of an artillery barrel from a published reference book. I don't remember who did it, or what the subject of the thread was, but if you can find that posting, the angle of the dovetail on an artillery barrel is probably in that drawing...

Ed posted some free-hand sketches & dimensions of a Luger carbine, maybe that is what you mean? I don't see any LP-08 barrel drawings...

Originally Posted by Olle

Have you had any luck with the CAD yet?

I have it installed and have tried a few simple images. What I did isn't all that different from PSP. There is a long tutorial and I'll try to print out the simple sample and see if it is in any way intuitive [to me!].

[Olle]

Originally Posted by sheepherder

I have it installed and have tried a few simple images. What I did isn't all that different from PSP. There is a long tutorial and I'll try to print out the simple sample and see if it is in any way intuitive [to me!].

It's actually more like MS Paint to me, simple and intuitive once you learn where the right command buttons are located. I used it every day when I worked for a cabinet factory, and it took just a few days to get the hang of the basics. You'll really see the benefits once you have built up a decent library of drawings. No more anxiety over that sketch you found wadded up in the pocket of a pair of jeans you just washed, or the one that got destroyed when you flipped over a container of quenching oil on the work bench. You just print a new one and go on.

[sheepherder]

Originally Posted by Olle

It's actually more like MS Paint to me, simple and intuitive once you learn where the right command buttons are located.

Right now I can't find any 'delete' button. I have points & lines that need deleting, but the Point/Edit functions don't list any Delete function. (This is in the tutorial). Until I can delete my mistakes, there's not much usefulness to it. I'll play with it a while more. I don't have a lot of patience. I do have lots of envelopes.

[Ron Wood]

Here is a dumb question, but can you click on the point/line in your drawing to highlight it and then just hit the "delete" button on your keyboard? Just asking because I do not have that program and have never used it.

[Olle]

You go to the "Edit" tab at the top, and hit the "Er" button. This will put you in erase mode, so any object you click on will be deleted. You can also do it like Ron suggested: Go to the "Select" tab, select the objects you want to delete, then hit "delete" on your keyboard. After that you hit "enter" to confirm, and the selected objects will be deleted.

You can select multiple objects by "drawing a rectangle" with the mouse (i.e. clicking two corners), but the most useful way is to hold down "Ctrl" and pick the objects by clicking on them. If you select the wrong object, just click on it again and it will be deselected. Once the correct objects are highlighted, hit "delete" and "enter".

Originally Posted by sheepherder

I don't have a lot of patience.

...says the man who is painstakingly building an Artillery Nambu. Yeah, right.

[sheepherder]

Originally Posted by Ron Wood

Here is a dumb question, but can you click on the point/line in your drawing to highlight it and then just hit the "delete" button on your keyboard?

Short answer is that the delete key does nothing inside the program (so far). There must be another way to delete points, lines, whatever; I just haven't found it and the tutorial hasn't mentioned it. Yet.

The delete key would be intuitive, wouldn't it???

I think I found how to delete text [it's the Er key]; now I just need to get rid of that pesky point I mistakenly added...

I'm drawing the calculator, slowly...It's not very easy...Hey, my IQ is only 103...

OK, I got through the tutorial. I now have a printed-out stick drawing of a calculator outline.

Envelopes are much more intuitive.

[sheepherder]

Originally Posted by SIGP2101

Or you can use known dimensions to calculate angle with given formula which brings us to 67.5 angle for the front post male dovetail.

IIRC, I got 41º for that...(first page)...

The Harvey 40º dovetail cutter works pretty good...I think I found my problem, G.T. - I have to knock off the sharp edge before trying to fit the sight blade...

Too late now on three dovetails here...That edge seems to hold the blade up...

[Olle]

Originally Posted by sheepherder

Short answer is that the delete key does nothing inside the program (so far). There must be another way to delete points, lines, whatever; I just haven't found it and the tutorial hasn't mentioned it. Yet.

The delete key would be intuitive, wouldn't it???

I think I found how to delete text [it's the Er key]; now I just need to get rid of that pesky point I mistakenly added...

I'm drawing the calculator, slowly...It's not very easy...Hey, my IQ is only 103...

OK, I got through the tutorial. I now have a printed-out stick drawing of a calculator outline.

Envelopes are much more intuitive.

The delete key does work, but you also have to confirm by hitting "enter". Look at the bottom of the screen when you hit "delete", and you will se text saying "press ENTER to erase selected objects". There are some commands that have to be confirmed with the enter key, so if nothing happens: Just look at the bottom of the screen and see what it says.

[SIGP2101]

Still, easiest way is to use mm graphing paper. Draw what you want and read values directly of the paper. Substitute mm with cm and you accuracy reading could be within 0.01 mm/0.0004 in.