9mm PAK Blank Firing Gun - Page 2
21/02/2016 - February
It took a couple of days to get my tools through the post but I could finally get the slide finished. Using the collet chuck again I placed the slide in the middle of the chuck, this should prove to be accurate. I first faced the slide to the correct length and then used a centre drill to get a good start. I had to drill to a depth of 129mm as the drill deviating was a major concern. All I could do was run the lathe really slow and feed the drill very slow, once I had gotten a fair way in I could turn up the speed.
Once I had managed to drill it which a succession of larger drills I proceeded with the reamer, again with a very slow speed I started to bore it out using plenty of cutting oil. My tailstock could only move a maximum distance of 90mm so I had to stop the lathe and move in the tailstock half way through. I also think that due to me buying a machine reamer with spiral cutting flutes the whole length probably made the job a lot easier. The reamer I had bought was also used, costing me about £10 which was considerably cheaper than a new one. The finish looked to come out ok, well as far as steel goes, it doesn't matter too much as it shouldn't wear with the little use I'm going to give it.
I chose to press the insert into the back of the slide, it was a very tight fit and then it was TIG welded, then faced and sanded in the lathe. I placed the slide into the miller ensuring to clock it flat and then used a dowel to set the coordinates on the DRO. A carbide end mill was used to cut the ejection slot.
I turned the slide upside down in the vice to first cut a slot in the back for the hammer to sit it, I chose to do this operation first as I could set the "X" coordinates on the millers DRO. A slot at the other end was cut that will be used for the slide return assembly. A groove was cut using a progression of larger milling cutters, this is so the barrel can link through the slide to the rest of the gun.
Another slot was milled for the blank to pass through, this will be used in the Mk2 but while I was set up it was stupid not to mill it. A hole for a grub screw was drilled and tapped at the end of the slide, this will hold the firing pin in place.
All that now needs to be done to the slide is weld on a part for the slide return, give it a good sand to remove the turning marks and then give it a paint. I'll be honest I'm not sure if it counts as a realistic imitation firearm as it's not based on any other gun and neither will the Mk1 represent a gun, but it's better to be safe than sorry, by painting it at least 50% of a bright colour to make it comply law, normally bright orange.
22/02/2016 - February
First on the list was to make the insert that bolts into the recess of the barrel, this was made from stainless again. A flat and then a hold drilled into the side of it, as will be clear later.
A shaft from stainless was turned to suit the hole in the pin I made earlier, it was TIG welded on both sides to hold it in place.
The pin was placed back in the lathe to drill some holes, one for the bolt to the barrel and the other to attach to the slide return spring guide. The purpose of this part is to connect the barrel to the body of the gun.
A bush made from PTFE will stop wear between the pin and the slide, it is the easiest part to replace when wear occurs. It also acts as a damper to reduce the shock from metal hitting metal which could lead to shock fatigue.
The spring guide for the slide return was turned next, I had to be careful by turning it in two steps to reduce deflection, sanding removed any traces of an overlap.
The guide is not doing much effort as it's only guiding a spring, the hole was slot drilled as close to one end as possible, the reason for this is that this end pushes into the barrel pin, the further I drill into the pin the further I weaken it, so I drilled just far enough for the spring guide to fit.
The end of the slide needs something for the spring to push against, this was next and machined from the same steel as the slide.
The pictures are pretty self explanatory, the last showing this insert TIG welded into the end of the slide.
The gun is almost ready to fire a blank, I first must drill out the barrel pin so I can secure it to something as will be shown in my next post. I will then test a blank inside of it to make sure it fires and ejects the blank, then hopefully the Mk1 will be complete. And of course the slide will be painted bright orange after I have given it a quick test.
23/02/2016 - February
The barrel pin was clocked, drilled and tapped. This pin will be used to fix the barrel to the rest of the gun.
I cut out a piece of polyacetal to suit the barrel pin and then pressed it in place, I chose not to bolt it in as it was a tight fit. I chose to drill into the barrel further and then drill a port into the top of it as the law requires it to be "top venting". It turned out that I drilled the hole too big so had to use the TIG welder to make the hole smaller.
The picture taken is before I drilled out the top vent in the barrel. Once I got the diameter of the port right the gun ejected the shells perfectly, I made quite a few videos, some in 240fps to watch the blank eject from the port. The video provided shows that the shells are ejecting properly by firing two blanks. I sought out some professional advice, due to this not actually representing a gun yet due to various reasons it does not imitate a firearm and therefore doesn't require painting yet. Although the next stage will be to make an imitation firearm so before doing so I must paint the slide bright orange.
The next project was supposed to be the following, due to a change in lifestyle I chose to sell all of my workshop and therefore I did not continue with this project.