Re: Reamer holder idea
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dave Tooley</div><div class="ubbcode-body">It's all about feedback from the reamer. You can't get that unless you have a hand connected to the reamer through that little tailstock. Using it I can tell when a reamer is getting dull, I can tell if starts to load up with chips, I can tell when it's personality changes. By that I've had reamers that cut fine when new and then went downhill after 15-20 chambers and I've seen just the opposite. Not so good for the first few chambers but then between changing speeds on the fly and some age they settled down and cut fine. You don't get that feedback when holding a reamer either rigidly or in an independent floating reamer holder and pushing with the carridge. This statement is not to offend anyone but machinist removes metal. As a precison riflesmith I have an affair with every barrel. I have a different perspective that has severed me well for over 27 years. I know without a doubt that each barrel I pull out of the lathe has the best finish possible,the most concentric chamber I can cut. I don't have to check the barrel after I'm done. The barrel in some ways has talked to me while I was cutting the chamber. It's just the way I do things.
Not saying it can't be done but trying to use a Bald Eagle reamer holder while at the same time using the jog wheel will get very tiring. I have an image of a Cormoran drying it's wings in my head. And I agree the tailstock is a POS. I've heard they've changed it but it's still a big piece of steel to wrestle. </div></div>
No disrespect intended but I have to disagree on a couple points.
I used to work in "job shops" in southern California and the Colorado Springs area prior to this whole gun thingy. I made parts for General Atomic, various aerospace companies, etc.
Not saying "I'm the man". What I'm saying is I ran machines and made a pile of parts held to tolerances that far exceed 90% of what a guy will ever see in a bolt gun.
Not once was I ever encouraged or told to hold onto a chucking reamer while sizing a hole. Nor was I ever told to put my hand anywhere near a spindle, chuck, or tool.
If I put my hand on a chambering reamer and I feel it buzzing (chatter) as it plunges into the barrel I AM TOO LATE. The damage has already been done. At that point it becomes a function of damage control.
I've found it works far better if I examine the process before and take measures to prevent it prior to the tool ever touching metal.
I've come to realize mass means quite a bit when cutting metal. Heavy stuff resists unwanted movement. In my case I went to extremes with the turning center I have. It's close to 9,000lbs. The second part is work holding. The more clamping surface area you have (without distorting the part) the better chances you have to making an accurate part.
If we were to mill a 3x3x3 pocket in a steel cube measuring 5x5x5 would you support the part in a vise via two parallels that stood the part off the vise to where only say 1/4" was captivated between the jaws? Most wouldn't. You'd grab onto as much of the material as you could. Barrels, in my opinion, are no different. Hold onto as much as you can via any means necessary. This isn't crazy stuff. It's fundamental machine shop practice.
Next is tool rigidity. What's better? A pair of vise grips/tap wrench or a purpose built ream holder that doesn't allow the tool to wander all over the place. Floating holders obviously work as many use them, however I can't help but think its a bandaid fix to an underlying problem. If I was making a pile of lathe turned parts would I really sit there and hold onto the tool for each one? No. Neither does any other shop making large production runs. Yet the holes manage to come out right on size.
In most drilling/reaming operations its understood that you need around 2.5 x's the tools major diameter in depth of cut for it to begin to track straight and continue straight.
Bore the hole slightly under the tool's OD prior to chambering and you'll likely never have a wandering tool issue again. (assuming you followed the other little rules and have a machine reasonably tight) We've proven this in my shop to the point that we don't even use the floating pilots anymore. This sucks cause I spent over a thousand bucks buying every pilot David Kiff makes from 17-338 caliber. We don't need them. Boring the hole prior was the key to pulling this off.
The increase in coolant flow down the bore is far greater with it removed. This brings up the next "trick", chip evacuation. The gullets in a reamer will pack very quickly. You have to get rid of the swarf. Tooling companies spend zillions each year in research to develop better ways to get crap out of the way so the tool can do its job. Solid carbide through coolant drills representing prolly the most exotic efforts. Try drilling a 3" deep hole in 300 stainless at 3500 rpm and .005"/rev without this once. It'll resemble a cooling rod at Chernobyl in short order.
A drizzling pee streak of oil weeping out of a barrel doesn't do this the way high pressure will. I don't use oil. I use water based coolant. 300PSI worth. It's like a Wet n Wild water park inside the machine when we chamber. So much that I can't even see the chips coming out. They are quite small. If the tool never compacts with chips its much less likely to chip weld, load up, and cause rings.
I encourage others to consider the same.
C.
