Dovetail cutter???
 

Did someone here say they knew a vender that sold Luger/P38 dovetail cutters???

Smallest I can find hereabouts is 60º x .245"...the blueprint CD calls for 5.4mm/.212"...

...???...

I have never cut a dovetail for a Luger, P-38, or K98, but I have cut sight bases on custom barrels for sights from those guns... I always used a very small end mill to cut the correct depth that was just "close" to the size of the top of the dovetail, and then carefully hand cut the angles using a safe-sided triangular file that I made for that purpose by grinding one side flat... I think Brownells may sell similar files... I never cut enough dovetails to warrant buying a proper tool.

Here is an article on how to make one using cutting inserts that you can adapt to the size you want to cut.

You may want to braze the insert onto the tool body instead of using a mechanical hold down method considering how small the tool will be for your purposes...

http://cnccookbook.com/MTMillDovetail.htm

and Here is a photo:

http://cnccookbook.com/img/MillStuff...l/P6143491.JPG

-John

thanks for your reply, John! My mail tooling distributor, Travers http://www.travers.com/ sells just such a dovetail cutter...for very large dovetails...like lathe & mill ways...which looks like what your pic is...

Anything as small as a Luger front sight dovetail cutter is beyond my patience to make from scratch...Just too small... :(

I thought someone mentioned about a year ago that there was a vendor who sold dovetail cutters of that size...I think it is 55º instead of 60º...but with a slot that small, the 5º difference is unnoticeable...

If I had the cutter, I could re-use a Luger or P38 sight...Otherwise, I have to make the sight in-place, from scratch...

I do have small safe files, but the edges are pretty rounded...I might have to buy a couple new files...

I might try that first...Since the .245" cutter is bigger, it would cut away any filing mistakes... :p

Edit: Hmmmm...Here's a place...Not the Luger Metric cutter, but the 3/16" cutter with multiple passes should work...

http://www.harveytool.com/products/p...vetail+Cutters

I need to check the CD and confirm the angle...It's not given in degrees...have to drag out my trig tables and actually [gasp!] do some basic trigonometry...

...Or I could hold up a Luger sight to my thread gage and eyeball it... :p

Edit2: I eyeballed it to my 60º thread gage...It ain't no 60º... :mad:

OK; I did the math...It works out to 41º from the CD prints... :(

I may just go ahead and make my own sights...

Edit3: Harvey Tools makes a 40º dovetail cutter...

http://www.harveytool.com/products/p...&category_id=1

All is right in the world... :D

I ordered the 40º x 3/16" carbide dovetail cutter today...actually cheaper than listed on the web site...If anyone else is interested, they do not sell directly, only through their distributors...You can find the closest one on their site...and CC order from the dist...

FWIW, back in '69 when I worked for Twin Industries Inc (an aerospace subcontractor) dovetails were cut by a pieplate-shaped cutter on a horizontal mill...the workpiece was clamped at the desired angle, and one side of the dovetail cut...then the piece was rotated and the opposite side cut...

Something like this...I don't know if that is how the Luger was done, but it is a quicker and safer method than a teeny tiny dovetail cutter... :D

The Harvey Tool dovetail cutter came today...Looks like a good fit... :)

I don't have a barrel ready to fit a sight to at this time...but I will postmark this thread for further revision... ;)

Rich,
It does look like a good fit. Thanks for the photos and your "progress reports". Hope your dovetail cutter works great and you don't hear that dreadful "ping".

The horizontal milling machine with the cutter you described certainly looks like a fine solution and doesn't look as fragile as that tiny dovetail cutter...

Yes, it certainly is fragile looking...3/16" shank...3/16" across the base...Major pucker factor... :)

I'm more familiar with 3 and 4 flute dovetail cutters; I'll have to read up on speeds for the 2 flutes...

Looks like easy enough to be made in home shop, hmmm….

You can make dovetail cutters in your home shop??? :eek:

I'd like to order a .212" x 40º 4-flute dovetail cutter, please! :)

...Make that two!!! :thumbup:

YES, you can grind pretty much every mill bit into dovetail cutter.:thumbup:

All you have to do is grind away anything that doesn't look like a dovetail cutter! :D (But stay within the specifications you quoted if you want it to work) :D

Not really, but it should look like this when done with grinding. ::thumbup:

You two guys are much more experienced than me...Besides my poor eyesight and shaky hands, I don't have the necessary grinding skills either... :o

Post-WW2, Mauser used the following system:

First they milled out a square, 3.9mm across, 1.5mm deep.
Then they milled out the dovetails using a dovetail cutter with a base of 5.43mm and a 40 degree angle. This would open up the top gap to 4.18mm.

Hope this helps :)

I'll try the Harvey Tool dovetail cutter on a piece of scrap and see how it works out...

On those occasions when I needed to reform or create a sight dovetail, back in my formative gunsmith days, my tools were as many hacksaw blades that when stacked together and mounted on the same hacksaw frame carefully made the vertical slot to near dimensions, followed by a "safe" triangular file, or a standard file ground to produce the dovetail angle... used VERY carefully by my calibrated hand. If I made a mistake, and there were a few :eek: , we got the welder out and filled the dovetail and started over...

I did have a dovetail cutter for a 1911A1 rearsight dovetail at one time, but only used it once...

I thought you already tried it? I bought one just like it, and it worked great. I just made a straight cut with an end mill, and then I took about 2-3 thousands at a time with the dovetail cutter. It went straight through without any drama at all. :thumbup:

http://forum.lugerforum.com/attachme...1&d=1384732212

You bought a Luger dovetail cutter??? Do you remember where you bought it??? :confused:

I got the same one as you have, from Harvey Tool. Seems to work just fine.

And a stock Luger front sight blade has the same angle???

Argh...I can't find $%^& around here!!! :mad:

Ah! I found it! What kind of RPM did you use for the dovetail cutter, after making the base cut???

I tried a sight blade in it, and even if I didn't tap it in all the way it seemed to fit very well. This is a carbide cutter, so I cranked it up all the way (2500 rpm) and ran it dry. The only precautions I took was to set the cutter as deep in the collet as I could to reduce vibrations, and I also brushed out the chips after each cut. It wasn't even remotely as scary as I thought it would be, no vibrations, no funny noises, no nothing. Just go for it! :thumbup:

Simply Amazing!! I'm very impressed. Theres so much more thats never seen.. Luger art perfection!~~Eric..

I did as you suggested; ran a 1/8" end mill down to sight base depth, then cut with Harvey dovetail cutter. Low cutting speed; extremely low [hand] feed.

I had no problems with the cut; my problem was with my depth measurement. I used two different calipers, one Starrett dial and one digital, and could not get the same measurement twice. The two also differed as much as 10 thousandths on a single depth measurement. :mad:

This applied to the sight blade itself as well as the cut.

I'll have to re-think how I want to do this in the future. I've tried a magnetic base dial indicator reading directly off the spindle and that is not precise enough either (too much play in the 'headstock'). :(

This was matching a Luger sight blade with a 'new' dovetail; I've had no problems cutting dovetails and making my own sight blade for them & pressing the rough blade in and then finish machining it in place. :thumbup:

I didn't have any problems with the depth. I just indexed the end mill on top of the sight base, then I indexed the dovetail cutter on the bottom of the first cut. I hit it within 1/1000". Why are you using the spindle as a reference?

It's the part of the mill that moves up & down. :)

What do you use???

Ah, I usually call that the "head", and the "spindle" is on the lathe. I thouht you were trying to make every cut with the centerline of the barrel as a direct reference. I assume that you have a dial and fine feed on the Z-axis, so why do the cuts end up wrong?

My procedure for this (as well as plunge cuts, grooves etc) is to move down until the end mill touches the work, zero the DRO and then start cutting. The fine feed on mine is like a Glock trigger, very gritty, uneven and can jump too far if you're not careful. The DRO helps a lot, as I can see the actual position without having to rely on the dial.

Working on these mini-machines can sure be aggravating, once you learn their shortcomings you have to come up with a lot of workarounds to get the accuracy you need. It would be nice to have those zero back lash ball screws, that should eliminate quite a bit of error.

I should have said "quill". :)

Everything on this mill/lathe is crudely [Chinese] machined. One graduation of the 'quill' handwheel dial should be .040" according to the chart. But my dial indicator says .037". :(

But it's not the mill/quill I'm talking about. It's the dial calipers. The digital calipers is consistently .010" off in measurements under .100", compared to the mechanical calipers . Zeroing doesn't help. And I can't get consistent readings with the mechanical dial calipers. Starrett calipers. :mad:

Can't pin down the problem. The dial indicator method works pretty well for measuring the depth of cut, but trying to get a consistent measurement of say a front sight base is fairly unlikely. :crying:

Have you tried the Starrett with a standard, for example feeler gages? I have a Mitutoyo, and I try it with a known dimension now and then just to make sure that it's not out of whack. If it is, I'm sure that Starrett can recalibrate it for you.

I believe the small discrepancy in the dial setting could be due to the feed screw being metric. Seems like some older machines used metric feed screws, and for the US market they simply changed the dials to read the "closest standard equivalent". These are said to be a bit iffy sometimes, so if that's the case you may want to upgrade to true standard screws and dials.

Or the threads being tight at one point and loose at another. Just another reason to buy American. Interestingly, the same 3in1 machine is sold by Harbor Freight, Grizzly, and Smithy with different nameplates and colors... :rolleyes:

I have a short list of accessories I'd like to get for it from Grizzly; they import more accessories than the others...

Edit: Ha! Sears now sells the Grizzly 3in1 as well as Grizzly!!! :D

Here's the Harbor Freight [red] and Sears/Grizzly [green] 3in1 machines...

Since you guys resurrected this thread I will chip in as well. I am getting my cutters directly from Triebel one of the major gunsmith tools manufacturer for Germany. They are nice and they ship all over.

I have not yet found a way to accurately measure an existing dovetail. If anyone has a tool or instrument that will do this, please share. :)

A few days back, I needed to cut a dovetail for a Luger artillery rear sight base. I had an original base to work with (butchered LP-08 barrel, I think), but none of my dovetail cutters (including the Harvey front sight blade dovetail cutter mentioned previously) looked right...I even cut up small pieces of plastic to the angle of the dovetail and then extended the lines and measured them with a protractor...As far as I could see, it looked like 58º... :eek:

I ended up cutting the dovetail with a 60º cutter, the most common... :rolleyes:

2º doesn't sound like much, but I can assure you that when you're milling steel it can be a lot... :p

Not exactly what you guys are talking about, :rolleyes:but....be very careful of cutting a dovetail in a Mauser rear toggle, :eek:I ruined 3 expensive cutters before I realized that you have to grind off the surface hardening before attempting to cut a dovetail in it!:mad: No problems with the DWM & Erfurt ones!

Sheepherder,

Is it possible that the difference in the angles could be on purpose so as to result in a slight interference fit to help hold the sight blade in place?

Gunny John

Yes it could. :) You would want the top of the dovetail to be slightly less than the bottom, if that was the intent. IOW, to 'lean in' a bit. I'm not very well versed in dovetail design to say whether it is a common design element or not. :(

If it was, I would expect that both angled cutters would be generally available for quantity production. One for the dovetail itself, and one for the part to be dovetailed in place. Is that what is common in a production workplace??? :confused:

final fit!
 

Hi Rich, they may have been roughed out and broached to the final dimension?? If I was running production, that would be a real consideration for speed and efficiency?? And, I might add.. accuracy... It might explain some of the taper found in the original dovetail slots... I don't know for sure, but I would guess it could be so... best to all, til...lat'r...GT...:jumper::jumper:

I dunno...My broaching experience has been limited to cutting keyway slots in gears, pulleys, etc. While in a production job, I've never cut a dovetail.

We did our broaching with a 24" geared arbor press, with a hand lever, .010" at a time. I never saw a dovetail cutter until I got into gunhacking. I now have some big ones, but they're for cleaning up milling machine/lathe ways. And cutting the adjustment shims for the ways.

A tapered dovetail...I don't know if that's even possible...Is it??? You would have to stop the broach at a specific point of the broach stroke, to get the same size taper each time...And have some way to push the broach back out in the opposite direction...

Beyond my experience... :p

broaching
 

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! ....:jumper:.....til..lat'r...GT

Here:
http://homemetalshopclub.org/news/dec02/dec02.html

Scroll down near the bottom.

Then this:
http://www.neme-s.org/Model_Engineer...l%20Slides.pdf

and this video:

http://www.youtube.com/watch?v=0VGOa69sePo

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