Month: September 2011

The Four Jaw Chuck

Posted by on September 30, 2011

I have published an e book entitled “The Four Jaw Chuck – the hidden secret of precision lathe work.”  

The three jaw chuck is a convenience tool.   It is quick to use because all three jaws move in unison, so that round stock can be chucked quickly, more or less to centre.   I say “more or less” because there is a built in ”inaccuracy” in three jaw chucks.   It is not really inaccuracy, it is that, because of  inevitable tolerances in the scroll, they seldom close dead to centre, usually one or two thousandths out ( 25 – 50 microns).   Also, the error is different at different diameters, and often, if  a piece of work is removed from the chuck and later returned, it will not be exactly on centre.  Three jaw chucks are thus quick and convenient for repetitive round work at one setting, but not for much else.    

The four jaw chuck is much more accurate and versatile.   That’s why most books recommend that, if only one chuck is to be purchased, it should be a four jaw.  Most mention that it can hold rectangular work, and can do eccentric turning work, but the full extent of its versatility is seldom explained.

On its own, its only advantage is that it can hold rectanguler work.  But if the work can be set in the chuck to exact measurements, it opens up a whole world of versatility and precision that can’t otherwise be imagined.   That measurement is provided by the dial test indicator.   The four jaw chuck and DTI should therefore be considered a two-piece combination tool, each as important as the other.

It is the most important lathe accessory, more versatile and useful than all others combined.  It is indispensable for serious work, and makes possible a variety and complexity of work, and a degree of precision that cannot be achieved otherwise.

My book is not big at 52 pages, but with 13500 words and 77 illustrations, it explains in detail the advantages of the four jaw, with several working examples.   It is not armchair theory – the four jaw chuck was the vital tool for the many parts, jigs and tools I made in my gunsmithing work. 

It is a E book, available direct from me, boothroyd@polka.co.za, and will be sent by e mail.   I will gladly send sample pages to anyone who wants to see the quality of the content before buying.

Payment will be credit card via www.gunownerssa.org.   Price is $20.   Payment instructions will be sent with the book.

Posted by on September 16, 2011

My buddy, Richard Bowman, and I have often discussed making bullet moulds, so that we can make experimental moulds and save some bucks as well.  But its not easy, and needs some special equipment when you get past the first rough attempts.  Last week, Richard showed me a mould he had made.  He’d be the first to admit that it’s a bit rough, but it was made only to test the method, with the better build quality coming later.  It works very well.  The blocks are aluminium, dimensioned to fit RCBS handles.  The alignment pins have matching bushings in the soft aluminium blocks.  It was made for a very big bullet, for a 4 bore rifle.  Bullet diameter is almost 19mm (3/4″).   It is too big to weigh on my scale, but measurements indicate about 800 grains.  Big cavities are easier to cut, which is why Richard chose a big calibre for his first effort.

The cavity was drilled out with a series of ordinary twist drill bits of increasing diameter, and finished with a twist drill bit that Richard had ground to desired diameter and shape.   Again, a bit rough, but creditably good for experimental use.  The driving bands were cut in the four jaw chuck with a suitably ground boring tool. 

It casts  creditably good, perfectly shootable bullets, considering its experimental nature.  Making moulds as good as factory moulds will need a lot more work, but this is a good start and proves that it can be done.  Professional mould makers naturally don’t publish their trade secrets, so intending mould makers have to figure it out the hard way.

Bullet Casting for Beginners

Posted by on September 8, 2011

I have published an e book entitled “Bullet Casting for Beginners.”  There are many books and articles about cast bullets, but most say little about the actual casting, and how to do it efficiently and well.  One book says that a high temperature furnace is needed for melting antimony, and that multi cavity moulds are no faster than single or double cavity.  And how often have you read that tin and antimony will separate from the lead if not fluxed and stirred ?  All are untrue.

Then there are the things they just don’t tell you.  Like the fact that bevel base bullets can’t be lubricated in RCBS, Lyman and Saeco lubricators.  Well, they can, but so slowly and with such difficulty that it’s not worth the struggle.  How many guys have bought moulds they can’t use, but can’t return because they’ve used them once ?

I am a commercial bullet caster.  I have hand-cast handgun and rifle bullets for quality conscious customers for many years.  In doing so, I have found what works and what doesn’t, and have encountered and sorted out every imaginable hitch and glitch. 

My book is not big at 55 pages, but with 21500 words and 75 illustrations, it is packed with the sort of “how to” detail you need to cast quality bullets.  It covers equipment selection and use, alloy blending, hardness testing, casting methods, temperature control, sizing & lubricating, gas check seating, and much more.

It is an e book, available direct from me, boothroyd@polka.co.za, and will be sent by e mail.  I will gladly send sample pages to anyone who wants to see the quality of content before buying.  As far as I know, it is the first bullet casting book written by a commercial bullets caster, with the wealth of experience that implies.

Price is $20.  Payment will be credit card via www.gunownerssa.org.   Payment instructions will be sent with the book.