So I made a "real" spider - threaded end is 1-5/8x16, and I used 4 1/4-20 brass bolts for the clamps, in 2.125" (roughly) OD 6160 Al.
I often get partway through one of these and then go "shoulda made a youtube video for other beginners like myself" but then...well, I'm not going back to the beginning and there are plenty of so-so YT vids on things like this - and a few good ones.
So I just took a couple of pix. My main use for this is chambering rifle barrels with the chamber not just concentric with the bore, but also angularly aligned. Maybe there are people out there who don't know that blanks often come with the hole not in the middle, not straight, and not the same offset at both ends. And that's the good high pricey ones.
if you're trying to make a hyper accurate rifle (what other kind is interesting?) on the cheap - because, you know, cheap - getting this part right really matters a lot, and it's the sort of thing that's really hard to go back and fix later.
So, this amounts to a 4 jaw second chuck for the end of the barrel not in the main lathe chuck so you can adjust all of that and just cut things perfectly after that.
So, here's a 2.3" long piece of stock partly prepped. Showing my new toolpost - I really like this thing and the new tools I also go (all Accurite brand). Chatter go bye-bye, and repeatability is no longer a dream.
- Part turned down to the desired OD for threads, a nd a gutter cut for the threading tool to run out into.
Yup, even this got a center, because I needed to have very little in the chuck for other clearance reasons.
The carbide insert threading tool worked well. I haven't yet set up like Joe Piezynski to do it on the backside and work away from the chuck. I'll have to make a reverse-side insert holder for that.
Had some adventures in making boring tools work right...The usual "why does this obviously small enough for this hole thing rub anyway?" kind of stuff. But I got there, to a 1.35" bore to hold big stuff, like this:
- Fast-twist Kreiger 6.5mm bull barrel
- 1::7.5 like the original swede - for super heavy, high BC projectiles.
Which I'm going to be really tempted to put into this good old 6 mm ppc rifle, since - amazing - the case head size fits the bolt perfectly with no mods (so I can have interchangeable barrels) and...wow. That's it's original custom scope underneath - 30mm tube, fixed 35x (very clean internal optics).
