Re: 7.62x39 Question
Posted: Thu Sep 10, 2020 6:25 pm
the Gordy rods are fine however they do require a reasonably well set up machine to start with. Here is a good test, take a 20" length of bar stock. centre drill one end and lock it in place between the chuck and the tail stock centre. Now take a cut for the full length, take a couple if needed. Now measure the diameter at both ends of the cut. How much does it vary by? This will give you an idea of how far out of line our tail stock is, or if your headstock is canted if it is separate to the bed. This error/taper is going to be on most machines, even CNC. The only thing is you can tell the CNC what the error/taper is and cancel it out. There will be an error, in fact if there is no error why buy a floating reamer holder (OK, ignore that!)
I thought the viper was just a multi-point spider that clamps into a 4 Jaw? I see absolutely no point in it personally. I either use a low profile 4 jaw Pratt Burnerd chuck and spider at the drive end, or my own D1-3 Spider/Cathead and a drive end spider.
My reasoning is as follows:
A Barrel, in a spider in a 4 jaw can lead to quite a mass whirling around, especially when it is an off-set mass (Out of balance) Supporting it all outboard of the chuck is poor practice in my opinion. This is why I use the spider I have posted pictures of in the past, it is locked in place instead of being dependant on someone not under or over tightening something, or trying to perform a task at the wrong speed/feed.
Building your own is the easiest way forward. I have all of the drawings in the workshop if you would like a copy, I may even have something on this forum. The advantage of doing it this way is only one set of clocking in. The spider/cathead is already concentric to the lathe bore so that is one less operation to consider. The cost of making one is way less than buying something in and probably of a better quality. I routinely use mine for re-machining bolt faces and adding bushings for myself and for trade customers and I have to say it is remarkably easy to set up.
I thought the viper was just a multi-point spider that clamps into a 4 Jaw? I see absolutely no point in it personally. I either use a low profile 4 jaw Pratt Burnerd chuck and spider at the drive end, or my own D1-3 Spider/Cathead and a drive end spider.
My reasoning is as follows:
A Barrel, in a spider in a 4 jaw can lead to quite a mass whirling around, especially when it is an off-set mass (Out of balance) Supporting it all outboard of the chuck is poor practice in my opinion. This is why I use the spider I have posted pictures of in the past, it is locked in place instead of being dependant on someone not under or over tightening something, or trying to perform a task at the wrong speed/feed.
Building your own is the easiest way forward. I have all of the drawings in the workshop if you would like a copy, I may even have something on this forum. The advantage of doing it this way is only one set of clocking in. The spider/cathead is already concentric to the lathe bore so that is one less operation to consider. The cost of making one is way less than buying something in and probably of a better quality. I routinely use mine for re-machining bolt faces and adding bushings for myself and for trade customers and I have to say it is remarkably easy to set up.