Gunsmithing: Machining a dovetail

[IndyGunworks]

I am in the process of trying to learn all the machining skills required for gunsmithing. This is a long term goal and not something I expect to achieve overnight. This is a dovetail I cut into a piece of conduit because I didnt want to take a chance of 1. destroying a 50 dollar dovetail cutter before I even knew what i was doing, and 2. the material is softer and easily replaced if I had goofed something up.

I had a front sight sitting around that measured around .330 w/ a 60 degree dovetail, and around .075 high, which happens to be what dovetail cutter i had laying around, so thats what i decided to use. I dont know what it came off of but that doesnt really matter.

I started off by tramming in my vise to make sure the dovetail was going to be square. I used a .0005 test indicator and got the vise trammed in to w/in a half though of square.

Then i squared the end and sides of the conduit to make it look feel and act like a 1911 slide in the vice and during fitting/machining.

then i took notes down, and wrote a plan of action on how everything was going to work. (this kind of changed mid plan because i had not calculated center correctly. but it still all worked out.

I was lucky that all three tool, edge finder, end mill, and dovetail cutter all used the same collet (3/8) so i wouldnt have to do a ton of swapping of collets.

Then i leveled the piece

After i found the edge, and moved back as far as i needed to, i found the top of the work piece using a piece of paper that measure .003. this is the only measurement that i messed up on a little bit. I think when i found the top of the paper i went an extra thou or two down because when i was fitting the sight i had to remove a few thousands to keep it from rubbing on the top of the "slide". I need to find a better way to find the top of my workpiece more precisly and i think this issue will go away.

After lopping out most of the material I ran the dovetail cutter through. I dont have any pictures because this is where i thought i was really going to mess up after hearing lots of horror stories.

Per my math the sight was going to be about .001 undersized w/ one pass of the dovetail cutter, but the cutter was VERY hard to measure. so i made a pass and tried the sight. It wouldnt fit! oh well, removed another .002, and tried again, then another .001, then another .001. after that last pass the sight went about 1/3rd of the way into the dovetail so i knew i had hit the mark perfectly.

A little bit of fitting and here she is.

 

[IndyGunworks]

I also have a scrap 1911 slide that i will be practicing this cut on some hardened steel, as well as attemping front cocking serretions, slide lightening cuts, bomar rear dovetail, french cuts, and flattopping on, but thats more to come. I need to get around another bajillion dovetails cut so i can become proficient, and proffesional about it. As well as being able to cut one in less than the 2.5 hours this one took me.

 

[the1kidd03]

good job.......get a "machinists reference bible"...they are usually like a little black pocket book...it'll help you with proper speed settings for different materials and such......I think harbor freight has them, and most other industrial supply places..........practice is good, but it will at least allow you to make the mill last as long as possible

 

[IndyGunworks]

good job.......get a "machinists reference bible"...they are usually like a little black pocket book...it'll help you with proper speed settings for different materials and such......I think harbor freight has them, and most other industrial supply places..........practice is good, but it will at least allow you to make the mill last as long as possible

I have the machinist bible. Most of the tooling i used for this came with its own speeds/feeds instructions though. I turned the dovetail cutter at 600 RPM. and fed at 3-6 inches per minutes IE.... SLOW

 

[the1kidd03]

LOL...yeah....it's one thing when you work somewhere and they can provide tooling...it's another when the tools come out of your pocket...lol....... is that an older JET mill?

 

[IndyGunworks]

LOL...yeah....it's one thing when you work somewhere and they can provide tooling...it's another when the tools come out of your pocket...lol....... is that an older JET mill?

No its an american made wells index from 1956. Still in as close to new condition as an mill that old comes. Less than .020 backlash in all travel. original scraping still visible throughout. Needs some table locking bolts, and an oil gun w/ a zirk fitting for way oil. right now i just sqirt it on the ways.

3 axis magnetic scale DRO gets delivered tomorrow for it

 

[the1kidd03]

No its an american made wells index from 1956. Still in as close to new condition as an mill that old comes. Less than .020 backlash in all travel. original scraping still visible throughout. Needs some table locking bolts, and an oil gun w/ a zirk fitting for way oil. right now i just sqirt it on the ways.

3 axis magnetic scale DRO gets delivered tomorrow for it

NICE.....what other equipment you have setup?

my uncle was a well accomplished smith and I always wanted to apprentice for him, but he retired before I was old enough......but then I got into doing industrial work for a few years before working for uncle sam and was able to really hone my technical skills that I inherited...........I'd like to setup a home shop, but it'll will have to wait for now as I think the "boss" is hell bent on moving somewhere else, and I don't want to have to move a bunch of heavy equipment......a friend of mine owns a couple machine shops and lets me use his stuff when I need it until then though

 

[IndianaResident]

I'll let you practice front serrations and lightening cuts on my G26.

 

[lovemachine]

Next time, you should put some 1-2-3 blocks under your work like that. With it hanging out that much, you're going to get vibration and knocking, which you don't want. It'll even be off.

And usually, you don't need to use a level to "level" your work piece. As long as the head of your mill is indicated with the table, that floor of the vise is level and square.

 

[IndyGunworks]

Next time, you should put some 1-2-3 blocks under your work like that. With it hanging out that much, you're going to get vibration and knocking, which you don't want. It'll even be off.

And usually, you don't need to use a level to "level" your work piece. As long as the head of your mill is indicated with the table, that floor of the vise is level and square.

In that picture i was just machining some flats along the sides of the conduit to make it so when i clamp it it wouldnt roll if i did something wrong. I have leveling support jacks less than a foot away from the machine, i just didnt think to use them. Good advise for the future as i was getting a bit of chatter at the end of the cut, i just didnt care to much about it in this case.

 

[Lock n Load]

Good job and nice pics too.

Now I know who to contact for some smith work, due to Govt work I cannot perform my own govt work at work !!!

 

[NHT3]

I have 2 years experience in tool room work (lathe, mill and grinder) that was required of me to become a Machine Repair Journeyman. Over 30 years in my trade along with carrying the trade of Machine Builder and a couple of years experience being a Glock Armorer.. It looks like VERY competent work to me.. Like most jobs, time and patience is what is needed most.. Also I might add that I'm jealous that you have all that machinery at your disposal at home. As a previous post noted, I can't get to Government work during the day for the "Company" work I'm expected to complete.

 

[DaKruiser]

Nice! That looks great for being your fist one and on a piece of pipe!

 

[bluewraith]

I am by no means an expert.. or even up to novice level yet imo, but heres a couple tips that I've been told at work (Tool and die for orthopedics)

If you indicate the back jaw of your vice in between the bolts, you'll get a much more true reading. It's not hard to put enough pressure on the vice jaw bolts to warp the jaw out a half thou or so and will give you a headache trying to figure out where the dip is.

Paper is ok to find the top, but I've read that you can turn the cutter by hand and listen/feel when it hits the top of the part. I'll check with the bossman(tmkr) tomorrow(unless he pops in here) but it sounds like it would work to me. If the work will allow it, you can take a very light cut and use that as your new zero.

Draw an india stone along any surface that you'll be clamping onto. Just a light pass will tell you if you have a burr that'll need attention. Along the same lines, any time I take a piece out of a vice and return it, I make sure the jaws and parallels are clean. Brush it out with a paintbrush, then double check with my fingers for any small chips. Cutting oil attracts small chips that can throw you out of square.

 

[David]

No its an american made wells index from 1956. Still in as close to new condition as an mill that old comes. Less than .020 backlash in all travel. original scraping still visible throughout. Needs some table locking bolts, and an oil gun w/ a zirk fitting for way oil. right now i just sqirt it on the ways.

3 axis magnetic scale DRO gets delivered tomorrow for it

I'm jealous!! I'd like a DRO for mine but the machine really doesn't get used enough. Gotta love the old American machinery, mines an old Gorton, about the same age as yours, and i've got a mid 40s South Bend 9" lathe too.

You're dovetail looks nice, now I want to see you machine that round stock into a slide. Looking forward to part II.

 

[drillsgt]

And usually, you don't need to use a level to "level" your work piece. As long as the head of your mill is indicated with the table, that floor of the vise is level and square.

Great work on that dovetail and great way to practice. It looks like you got a nice snug fit going on with no gap under the sight which is key. Anyone can cut a dovetail but doing it with precision is the difference which it looks like you did. As for the level, in 1911 slides there is a taper from the back end to the front end, might not make that big of a difference for a sight cut but if you try to flattop a slide without taking that into account it would be immediately evident so leveling won't hurt anything.

 

[David]

As for the level, in 1911 slides there is a taper from the back end to the front end, might not make that big of a difference for a sight cut but if you try to flattop a slide without taking that into account it would be immediately evident so leveling won't hurt anything.

Or just indicate it off the top of the slide.

 

[jmdavis984]

Would you want an actual barrel to "practice" on? I have a cheap airgun that the front sight mounts in a dovetail, and they were so poorly machined that the front sight keeps falling out.

 

[drillsgt]

Or just indicate it off the top of the slide.

If you are doing something like flat topping the slide than indicating it along its entire length is essential, for a sight cut you usually don't have to go to that extreme but you can.

 

[IndyGunworks]

Or just indicate it off the top of the slide.

The level is more than satisfactory for what needs to happen for that cut. Indicating it in would take more time than necessary.