A day in my shed barrel spiders impact casts etc.

[Alpha1]

I have a whole day of tomorrow and her indoors has given me the go ahead to spend it any way I like. The xmas shopping is done. I managed to get all her birthday stuff right this year. So I am in the good books. I don't often get a full day to just do what I like. So to morrow Sunday I'm going to build a barrel spider for the lathe. I have measured up done the drawings so its all systems go. What I have discovered is the spindle on my lathe is threaded at the end with the gear train on and there is quite a bit of threaded end sticking out so the spider will be a screw on jobby held in place by a grub screw. I'm not sure about cutting the internal thread because its quite large so I may have to sublet that bit. But we will see. After that I'm going to do some more impact casts of barrel chambers/throats I'm quite happy to have a go with any rifle chamber now using this method its not as difficult has it sounds. I much prefer it to cerosafe. I had a look on the NOE web site for a chamber length button for the AIA they don't do one of the right size so I feel justified in making one as a one off. So we will see how that goes. I'm looking forward to it should be a interesting day.

[ovenpaa]

If you are going to sub out the internal screw cutting leave the bore undersize/smaller than needed and take some pictures as you proceed with the job!

[Alpha1]

It did not go quite according to plan. I ran out of time. I had to make decision what material to use. I was quite keen to use aluminium because its easy to work with. I have some mild steel round bar in different sizes that would of done but it meant cutting it to length with a hack saw etc. Any way I decided to stick woth aluminium in the end. The only piece I had was a oblong block so it meant machining the block into a piece of round bar stock. Phew it took a while. I'm glad I don't have to make a living at this.

Any way here we go.
The first thing I did was remove the 3 jaw chuck and replace it with a four jaw. I then centred the block of aluminium in the 4 jaw and drilled a small pilot hole in the opposite end so I could support it with a live centre.
I then machined a portion of the block round. When this was done I removed the 4 jaw chuck and refitted the 3 jaw. I fitted the now round bar into the 3 jaw and machined what was left into a round bar.

[Alpha1]

Once the bar stock was round I drilled a pilot hole through the centre then opened it out going up in drill sizes until I had a hole in the centre to allow me to get a boring bar to allow me to bore the hole through the centre large enough to match my spindle bore.

[Alpha1]

I started to bore the hole through the centre but I'm not happy with internal finish I am getting so I have stopped for now to have a think. My boring bars are to small for this kind of work I'm thinking they are not rigid enough I might have to up grade them. I suppose a mill would be better for this kind of job but unfortunately I don't have one. To morrow Ill drill and tap the spider on my bench drill and fit the grub screws to hold the barrel. The end that goes onto the spindle will need internal threading Alan at work has agrred to do this for me providing I do the rest of the work my self. (I think he's been talking to ovenpaa )

[Alpha1]

Anyway that's it for now Ill post the rest of the pictures as I progress. The case overall length button was a lot easier and so was the impact cast.

Just a word of warning have a look at this picture and notice how far back the drill chuck is wound back into the rest when I wound the drill back it came out of the taper could of been nasty. These things are not toys they can bite back if you are not careful.

It was good fun though I enjoyed the day but unfortunately its back to work tomorrow.

[Alpha1]

Drilled and tapped the spider to take grub screws. The grub screws were squared of then bored out to take soft inserts I did not have any brass so I used a type of nylon.
The spider is finished it just needs boring out to the correct inside diameter then a internal thread screw cutting on the opposite end to the grub screws. The spider will then just screw onto my lathe spindle.
So this is version one I may do another I noticed after I had drilled and tapped it that most spiders actually have four locking down bolts as opposed to the three on mine. don't know if it makes a difference. Ill post some more pictures after its bored out and the thread cut. Probably showing it mounted on my lathe.
So all I need now is a barrel or a barrel blank to try it on.

Hmm what's next.

[ovenpaa]

Looks like a cracking job there. Deep boring is not as easy as people think, a good rule of thumb is bore twice the diameter of the bar or in other words a 20,0mm boring bar is good for boring a hole 40,0mm deep however in practice this does not always work out. My largest boring bar is 20,0mm diameter however I will bore considerably deeper than 40,0mm on occasion and I have some customised bars for particular applications. Oddly enough my favourite is a 20,0mm stepped down to 16,0mm - a job I did in a 4 jaw one Friday afternoon. I use this bar far more frequently than the correct 16,0mm bars I have simply because it is a little more rigid and I like it.

With boring light finishing cuts are the order of the day and check with a gauge (It can be home made) as it is possible to machine a tapered bore due to the deflection of the bar at the far end of the cut.

[Alpha1]

I'm worried that my boring bars might not be up to the job mine are all small more for hobby use. I worry that they might not be rigid enough. But we will see.

[Alpha1]

I expressed my concerns about my boring bars to Allan at work his reply was. Dave you are just making excuses you know damn well you are capable of finishing this job your self. No I am not going to do it for you. I came home from work that evening with every boring bar in every size known to man along with a bucket load of HSS cutting tools with every profile you would ever need.

Its finished and a lovely job it is to. Iv been sat staring at it mounted on the lathe ready to go for the past half hour. I think I would like to make a couple more actually. Any way I have put a shipping order in for boring bars the ones I borrowed have to go back. I have to say that this exercise has taught me a lot about HSS tooling as well. My new years resolution is to learn how to grind the tools properly.

All I need now is a shot out barrel or a barrel blank to practice on any old one will do.