reamers vs drill bits?

[blind ear]

Exposeing my vast ignorance as usual. Where can dimensions for chambers, reamers, go - nogo guages etc be found? I searched the gunsmithing thread for such and did not come up with dimensions. I know tollerance above cartridge O.D. deminsion must be more than press fit but I don't know what that would be.

With the description of free handing the chamber extension of a 357 to a Max length being a "feel" proceedure requireing care, paitence,cutting oil and cleaning, I was wondering if a quality drill bit of the correct O.D. could be used to do the job? A special order of the correct demension, quality bit would be cost effective vs a reamer for this simple task if plausible. Flats could be ground at 120 degrees on the tang for the hand chuck.The leading edge has an angle between the cutting edge and the cleaning edge of the flute but is that critical?

What about it guys? eddie

[kennyd]

A reamer has multiple flutes.  The two flutes on a drill will cause a wobble and a poorer finish: when one side catches, the other side will make a gouge.  Usually a reamer also has the "lead" different and sometimes staggered flutes to keep chatter down.  It is expensive to replace a gouged barrel.  To just extend a bore, you may be able to use an off the shelf reamer, but let someone who has tried it weigh in.  The other problem is reamers are special order in special sizes.  I don't find .379 or .357 in the usual lists.

[blind ear]

Thanks kennyd.

 Maybe the flutes could be filled to oversize a little distance behind the cutting edge then turned or ground to a good demension to avoid chatter.

The cleaning edges on the flutes could be ground to the correct O.D. to the cutting edge and some distance back from the cutting edge. Then reduced the cleaning edge to undersized behind that on up the shaft and then fill the flutes to oversized and grind to a good following pilot size.  A trap space for debree would be left before the flute fill and clean every turn. With hand turning perhaps chatter could be avoided. ? ? ? maybe, eddie

[trotterlg]

I use a drill bit for a roughing reamer for my 17 FB rechambers, however I did grind a pilot on the front of it to keep it centered in the bore.  Also, turning a barrel around a drill or reamer is a lot different than turning the drill or reamer in the barrel, know it is hard to believe but it is true.  Larry

[mitch132]

Here is where I found some chamber dimensions.

http://www.leverguns.com/dimensions/Default.htm

Doesn't cover most chambers, but it is a good start. A drill bit that is smaller than the desired chamber is ok for a rougher, but for finishing a chamber, I would rather use the tool for the job, a finishing reamer.

For just lengthening a .357 Mag chamber, you could make a D reamer if you have access to a machine shop and take careful measurements. Google "D reamer" or "half reamer" as there is some information out there on them.

Here is a quote from Mr. Gale McMillan:

"Turn the shape you want on a lathe out of a good oil hardening tool
steel like Ketos.  Put it in the drill press and turn it in slow speed
while heating it with a torch.  When it reaches a bright red 1550
degrees lift a can of oil up and quench it while it is rotating.  This
prevents warpage as it is heated evenly.  Then grind it in half being
sure not to over heat it The arc of the wheel will give you a hollow
ground effect which will make stoning much faster.  On any shoulder that
is square to the axis has to be backed off so that it doesn't rub.  With
care a good reamer can be made that will cut slowly but well.  It is not
critical that it be ground exactly in half as long as it is ground at
least in half.  If a pilot is used grind only half of the pilot and
leave half to be a guide.  -Gale McMillan"

Just go into this knowing full well you could ruin your barrel, or at least have to ream it out to something bigger to remove the messed up region if you are not careful.

[blind ear]

Thank you Mitch132

Do you have the title of a book that teaches how to grind a reamer? Any other books on barrel making ?anyone?

Trotterlg: I believe you.

thanks, eddiegjr

[mitch132]

Sorry I don't. Most of my knowledge of this has come from my computer and trial and error. Barrel making I leave to those with the specialized equipment to do so, I merely adapt and fit them as a hobby. I do remember seeing muzzleloader barrel making in one of the old Foxfire series of books.

[briannmilewis]

OK, this may be Handi heresy, and I am a shade tree mechanic about some things, but why would anyone go to the trouble of making a reemer that they could rent for $35 or so, or buy one for $100? OK I will grant you if you have the equipment and don't have the money that would explain it. I do understand there is "because it is there" explanation, so there does not have to be any other reason for doing it. I hope it is worth the fun and trouble.

[blind ear]

Because it is there,yep. But I did get my order in to 4D today for a reamer.  After I use the reamer and get to study it some I hope I get some more ideas. (wild hairs)

Also ordered 'The Machinist's Bedside Readers',vol #1, #2 & #3.