Reamer Malfuction

[cuutter]

Hello Guys,
I've never had this happen before in the many barrels I have chambered. I would appreciate any input you can give me. Brand new reamer, 2/3rds. the way through the chamber, oiled everything up, seated the reamer and just started to move it in (0.010"-0.015") and it like caught and broke the handle off of my Bald Eagle Reamer Holder. I removed the reamer and it didn't look like it was damaged. Bore scoped the chamber and couldn't see anything really out of place. Sanded the chamber, fixed the handle on the reamer holder and inserted it again and that's when the reamer caught again and broke. I ream at 90 rpm and feed it pretty slow, lots of oil.
Any input would be much appreciated. I have enough room to cut the tennon off and start again, but don't know if that's the fix.
Thanks for the help.
Wayne

 

[shortgrass]

Who made the reamer?

 

[cuutter]

PTG. Bought it through Midway.

 

[sinarms]

You know I had the same thing happen to me last week, but mine never bound or anything and I use a flush system too. I have cut hundred of chambers too. I was pretty surprised. Mine was a PT&G too

 

[sj-pratt]

I was cutting a 375 H&H Improved a while ago and the exact thing happened to me.
Dave replaced the reamer no charge and when the flute broke off it didn't marr up the chamber it just took 3 months to get the new reamer.

 

[Trickymissfit]

I've managed to do the samething when step reaming holes more than I'd like to remember. Looked at all sources for the trouble, and it always came back to two or three things. Excessive tool pressure due to the coolants breaking down, and chip build up. My boss told me once to actually take an Arkansas stone and dull the reamer a little bit, and that helped. On production lines you often see this, and almost everytime it's surface speed related with an excessive chip build up in the flutes. Remember that your really cutting with the entire surface of the reamer instead of simply reaming a strait hole. You didn't say what material you were reaming, but one has to think stainless steel, and that stuff can often get kinda gummy like like (like reaming 1010 thru 1020CRS). An undersized hole your following will also cause you havoc.
gary

 

[shortgrass]

TM, I think they pump those reamers out so fast, the get the rake and clearance angles screwed up. I had a new, customer supplied PT&G in .270 Win. 'stall' 2/3 of the way in to a SS Shilen Match. I removed the PT&G from the holder and put my Manson .270 reamer in and finished the chamber with NO problems.

 

[J E Custom]

Re: Reamer Malfunction

TM, I think they pump those reamers out so fast, the get the rake and clearance angles screwed up. I had a new, customer supplied PT&G in .270 Win. 'stall' 2/3 of the way in to a SS Shilen Match. I removed the PT&G from the holder and put my Manson .270 reamer in and finished the chamber with NO problems.

+1

I use 4 different brands of reamers and prefer the Manson reamers. (I don't know why but I just like the way they cut).

Some reamers have very large relief cuts for clearing the shavings and it can weaken the flutes also
different makers sharpen there reamers differently making them more or less aggressive.

J E CUSTOM

 

[Trickymissfit]

I'm not aware as to what the grinding processes are for a reamer from Dave Kiff or Mr. Manson, but I do know somethings about grinding similar reamers.

The better grinders are from Walter and Starr. They use a generic step reamer program that allows you to plug in all the needed data. The actual grinding operation takes about 1.5 hours from a raw blank (rough, semi finish, and finish). Accuracey wise we're looking at +/- .0001". A typical resharpening of that reamer will take longer to plug the data in than to regrind it. The days of using a Cinn tool and cutter grinder are long gone
gary

 

[shortgrass]

Those that rely on CNC in place of skilled people and strict inspection procedures are kidding themselves. As for CNC, "garbage in = garbage out"! They are not infallible. The days of the manual tool and cutter grinder are not gone! That's where 'alterations' take place.

 

[Trickymissfit]

Those that rely on CNC in place of skilled people and strict inspection procedures are kidding themselves. As for CNC, "garbage in = garbage out"! They are not infallible. The days of the manual tool and cutter grinder are not gone! That's where 'alterations' take place.

Next door to me was a tool and cutter grind shop. I probably had them grind 250 reamers a year in all sorts of oddballs shapes and sizes. They had the good old Cinn tool grinders (about a dozen of them), and right accross the aisle were a Walter and a Starr grinders. About the only thing they did on the old machines was odd shaped end mills and a few step drills that were one up deal we were experimenting with. A completely rebuilt Cinn will not grind any closer than a Starr, and when dealing with multi steps with several radiuses the Starr was far better. Now if I wanted to get a reamer that was well less than a tenth in runout I ran it accross a Studer, and then hit the reliefe on a Cinn tool grinder (the Studer will not cut the reliefe and back off very well). I've seen reamers come off a Studer that had less than .000075" error a lot of the time. But that process is slow, and takes an act of congress just to get into one of those machines.

Cutter grinding be gone? I hope not! We had several large grinders just for sharpening broaches alone. A Red Ring and a Magg gear grinders for doing nothing but shave cutters (these are ground as accurate if not more accurately than any reamer). A half dozen or more drill grinders that were always in a back log (we ground a lot of multi step drills). And a pair of custom built web grinders to redo the web on drills (I built them). Plus two grinders for nothing but gun drills. These were kept covered up unless thyey were using them as the processes were very secretive. There was even a couple of lapping machines to take another half tenth off a reamer when needed. But the inovation of the indexable insert certainly has taken it's toll on cutter grinding, and the TIN coating processes have greatly increased cutter life. I hate to think about how many tons of cutters we sent out for replating a year!
gary