Jim
As usual I hit the wrong button for my reply post. My comment was not directed at you rather ALL OF US including myself. When I heard Clay talking about this new relm of precision I new I had to go and see for myself. Recently Jim Borden, no newcomer in the exteme accuracy game, went to Clays as well. He has ordered the same Lathe and Clay is headed to PA to make the modification required. Why would a guy spend another $35,000.00 unless he saw a possible edge?

It is very easy to bitch about advancement of any kind, until it's a proven reality.

All I can say is WOW !



Clays website. http://spencerriflebarrels.com/



Regards,

Dave

I've used okuma and Mazak CNC machines for years and some over $500,000.....and would be lieing thru my teeth to say that I could control .0001 without secondary operations such as lapping, grinding, or honing.

I see Clay's website.
He has a barrel in a 6 jaw chuck.
I have a 6 jaw Buck Chuck about the size that is about .004" off from barrel to barrel.
To get anything centered, I have to use a 4 jaw chuck and dial it in.
Am I lost here?

Thanks AJ.

How an existing chambered barrel is indicated off the bore for rechambering, or what have you, without a really long indicator is what I have been wondering.

I like the way you think, DArcy.

Pat Byrne

Clark, some of the Buck chucks have 4 adjusting screws which you can dial it in. Can't tell by the picture if thats the case here.

Brent, I've never tried to rechamber a barrel. From my machining experience, the reamer will follow the existing hole (chamber). If your modifying it to an AI shoulder and the existing chamber is offset to the bore axis, the reamer won't center the chamber no mater how close you indicate the bore in. Tooling flex will push the reamer.

you know you dont need to spend 1000's to chamber a rifle. as i said before you can look at the holder i use to chamber my rifles. i also a tapered bore rod with to gages on it that read tenths.then i open the bore up but leave the hole still smaller then the reamer.i put my tapered bore rod back in to the point were the bullet and the case neck is going to be. then put both gages back on the rod and dail it in to 1-tenth. then i take my boring bar and make a clean up pass after that i go in with my reamer.but stop about 100-thousands from the data line on the reamer.then i will thread the barrel under the same set up now my threads are true to my bore.then i go back in with the reamer to finish the chamber.if you have a true hole going in the reamer will follow the hole.heres the holder that i use. www.parrysgunsmithing.com

Mr. Echols, the beauty of using a CNC lathe are not lost on me. The ability to turn a barrel contour, or turn and thread a barrel tendon in 1/4 or less the time of a manual machine is of great benifit. When it comes to chambering with a reamer a manual machine will produce the same results IF the operator pays attention to details. Only thing I could see the CNC would be more efficient in the process. You could set up the cycle to say advance the reamer .100" with a feedrate at .006" per rev, either have the reamer dwell or retact a minor amount to allow coolant to flush out the chips, and continue this for a given depth. Yes, the CNC will do it faster than a manual machine. Then again, with you being a great craftsman (I say this with great reverence, I admire your work) It's all in the final product, regardless of the time consumed.

My point of view, I program and run a 4 axis CNC mill. I could turn out a completed Rem action clone in a little over an hour, only if I could find someone to EDM the bolt raceways into it for me, for cheap While I find Clays machine interesting, I've been involved with CNC's costing 10 times that amount and more.

Kregg, do you make your own range rods? I'd give my left nut to have access to a Brown & Sharpe #13 grinder again.

Muzzle end, how do you locate it in the spindle?

Ever shoot against one of the Prathers in benchrest?

dave kiff who makes reamers also makes tapered bore rods at any taper you want. i do the same thing when i crown a barrel i use my tapered bore rod and dail it in then crown it. alot more time to do it this way but that is the last part of the barrel before the bullet leaves it. so i like it to be as perfect as the chamber also.

kregg,
Like aj300mag, I can see myself doing what you wrote, except for the tapered bore rods.

All I have is 2" pin gauges in .001" increments. And I don't see anything longer or in smaller increments off the shelf from Enco, J&L, or MSC.

So I put the test indicator stylus in the bore and center with the reading in the grooves.



My system means there is degradation in centering if the barrel is removed from the lathe and then put back in, OR if the barrel is already partially chambered, OR if the barrel flexes instead of pivoting with the spider adjustment.

Where / how did you get those tapered bore rods?

Jim,
Allow me to end this discusssion.... especially when the article say .000005 or even .00005

the cnc lathe he has pictures of measures to .0000 period.. end of discussion... it's either an eggargration or misquote



that's all there is to say... anything else is just BS rather than admiting an error

jeffe

you can buy them at pacifie grinding from dave kiff the reamer maker, his phone number is 541-826-5808 when i frist started making my own rifles i did it your way with a pin at each end of the barrel and used the 4-jaw and a spider at the other end.but now i do it this way and i like what i get. because now you can get in the bore with your tapered rod where the bullet and neck is going to be and true that point up before chambering. but you still need to use your boring bar to make the hole true to that point. and you also need to make the holder that i use, i use the same holder for trueing actions.

J&L industrial also offers plus and minus pin gauges in half thounsanths (.0005) increments, under and over by about .0002". By the way, in order to even get a plug gauge into a bore of, say .2240001 (twomilliontwohundredfortythousandone millionths on an inch), the plug gauge would have to be at least a tenth (.0001) under that size. Hmmmmmmm. I still someone is passing a lot of gas here and I think I know who it is.

I don't Jim, care to fill me in.

Some are so full of themselves there's no room for learning!

I am learning, perhaps someone will answer this for me. The digital readout, which must get its readings from some type of electronic signal, is a separate unit from the lathe correct? You could take that digital readout off the lath and bolt on one from another maker or even a different model from the same maker correct?

Assuming that to be the case, and I think it is; what does the digital readout have to do with the accuracy potential of the lath? Just because the measuring device is capable of only four digits to the right of the decimal doesn�t mean that�s all the machine is capable of.

Carcano,

Unfortunately, in publishing these days, the editorial department very nearly is the ad sales department.

Howard,
Because this is the control FROM the manufactoror...

Do you than Romi would buy controls from fanuc , would put LESS precise controls than the machine could do? This is not a kludge bolt together CNC, as you can tell by this picture




In fact, howard, in a full cnc machine, the resolution IS the accuratey potential. It's not like a manual machine where you can say ".001 and a little bit"... this machine in an order of maginitude from that...

and 3 orders of magnitude from being about to get into .0000075.

Does every understand what an error of this catagory is? an order of magnitude is a factor of ten.

take, oh say $1000.00 us

an order of magnitude error $10,000

two of the same, $100,000

THREE orders of magnitude $1,000,000

what is .0000075? oh, just 190 nanometers...

jeffe

jim these tapered bore rods you can get 7-inches long they are not the same size as the pin gages. these are made for gunsmiths

Kregg,
The rod is tapered. So, does it take a pilot at the small end?

Any pictures and explanation of how it'd held parallel in the bore if it's a tapered rod?

Is the part of the rod you're indicating off of tapered or not?

What rate of taper are yours?

Using the holder you made, you use two tapered rods, one in each end to dial it in, yes?

Two indicators spaced apart on one rod - Why two indicators?

Just getting into this here shortly for nearly the first time, and a lot of this is still new to me unfortunately. I remember very little from machine shop class in high school, and it was basic stuff at that. Would have helped a lot to have finished it too, instead of dropping out to go commercial fishing where the money was. $1000 a week was just too hard to resist back then.

This is pretty much off topic, so I'll start a thread about tapered rods and indicators to continue.

yes the rod does have a bushing at one end of it but there is still a tenth of movement in the bushing because it needs to side on and off so you can get the tightest bushing on it for your bore. now once you got the bushing on it that fits tight to the bore you slide the tapered bore rod into your barrel it will get tight aginst the lans because of the taper. you only use one rod with two gages on it one at the end of the rod and the other one at the base of the rod now the two gages need to be able to read tenths. spin your head stock with your hand intil both gages only have 1-tenth of runout if this is your frist time trying this it could take you awhile to tune it in. but the more you do it the faster you will get at it. the reason why you only use one is because with two gages on it when they are running with in 1-tenth that bore is pretty much dead on at that point. then i use my boring bar to open the hole up. to the size of the reamer at the shoulder as far as the taper on my rods for my 30-cal it starts at 0.29685 and 6-inches from that is 0.30085 i will try to put a picture of the rod on here but if i cant go to www.parrysgunsmithing.com and you will see a picture there what it looks like. [image]BORE ROD[/image]

triggerguard1 i think you got me mixed up with the post about the cnc that,s not my machine i was just telling some follow's how i did my set up for chambering with dave kiffs bore rods his tools has nothing to do with the cnc post.

After it's dialed in using the one rod, do you check for runout at the muzzle on the grooves to double check it? You're cutting the threads and squaring the barrel to this axis, so if the bore were to be off in the least where your rod is centered up in, the muzzle end could be out by quite a bit, true?

Bushing slop - The pivot point in any rod movement because of the .0001" slop in the bushing would be at the breech, and .0001" slop in the bushing could mean a lot, or little at the muzzle. If 4 inches of the rod is inserted for dialing in, and the barrel is 6 times longer than that, that would mean .0006" runout at the muzzle is guaranteed with .0001" slop in a bushing that's used, also assuming the bushing and tip have .0000" runout.

Considering that you are chambering, and also squaring and threading the barrel tennon, and that the muzzle end could be even further off if the bore was not perfectly straight, is this as accurate as one can get? Would dialing in at the muzzle, and at the breech with the tapered rod be more accurate, or less?

Just exploring the various methods employed for setup of chambering, threading etc. to understand which is most accurate and what to go with. I've got 3, 4 and 6 jaw chucks, my smith used the 4 jaw mainly. My Dad, Brother and I just bought my smith out, so I've got a bunch of stuff already. Still lots of stuff to work out to get where I'd like to be. Hopfully by this winter, after the road construction season is over, we can get serious about things.

I find this thread interesting, as I was wondering what to "expect" from this JET GH10x40T for accuracy.

This is my last post on the subject of Clay Spencer's or Gary Ocock's runout of chambers. PLEASE read Mr. Echols (a famous gun builder himself), and perhaps you will take his word for the precision with which Mr. Spencer works. All kinds of numbers have been thrown around on this forum, and I have been accused of everything from being full of BS to not knowing .7 from .0007. Some say that the numbers have been exaggerated for commercial gain. What gain could I possibly have by exaggerating any of these men's precision. THE NUMBERS REPORTED IN THE ARTICLE WERE EXACTLY AS GIVEN TO ME BY THE GUNSMITHS. If you can't live with that then quit reading the magazine or better yet, call the men in question and challenge their numbers. I have never seen so many people jump on the bandwagon which assumes that I made up these figures. It reminds me of the Democrats in the feeding frenzie that they had over President Bush's National Guard record. As a final note, none of these gunsmiths have done any work for me, nor have I received any financial rewards for praising their precision. I got the standard fee for writing this survey of these fine 'smiths. Thanks to Mr. D'Arcy Echols for taking the time to really check this out before jumping to conclusions that I am full of $#!^. Good shooting and goodbye. James

With CNC equipment, as with any other, the precision of the finished product is as much a function of setup and operator input as it is the CNC system. Materials still act a certain way when machined. This is why one can't simply set up the tools in his CNC lathe and turn it loose guarateeing the resulting dimensions. Generally test cuts are made, tool offsets inputted (is that a word?), and then the machine is ready to, hopefully, produce the desired dimension with that tool cutting that particular material. The machine is still limited by the accuracy potential of the chassis or the base machine. It is possible to use the controlling system to compensate for a certain amount of mechanical error but there are limitations.
I do believe that with proper setup it is possible to cut chambers which are essentially perfect. I think this can be done with good equipment, good technique, and careful workmanship. I think the big advantage of a system like that employed by Mr. Spencer has to be in the area of repeatability.
I don't believe that I can measure to much better than .0001 under normal circumstances simply because I can only do as well as the tools I have available to me. This does not mean that others cannot however. If they can then it gives the rest of us something to reach for. Regards, Bill.

Howard, you have two basic systems that drive a CNC machine. One system has the encoder attached to the ball screw and counts the revolution of the screw. Inexpensive system because as the screw wears it doesn't have a clue to where its at other than how many times it turned the screw. You have to input correction factors to mantain accuracy. With the second system, you have the encoders on the screws, plus you have a readout that employs a glass scale and a pickup attached to the moving table. The reader sends feedback to the computer, working togeather with the encoder on the screw. This system is a closed loop system that checks its position to minimize error. No, you can't swap readouts unless you change the scales also. And then you have to make sure the readers are set to the proper resolution.

Jim,
I am not a machinest at all, but I do have a Clausing lathe and a Bridgeport in my basemant. As someone that knows what he is talking about, what is the best way to true the tailstock to the headstock. I have a .0001 indicator mounted on a rod that I chuck up and run around the I.D. of the tailstock taper, or around the outside of a floating reamer holder that I use{a JGS and it works great}. I align the tail stock in the same spot that it is in when I chamber. I have had to raise the tailstock the thickness of three layers of aluminum foil. Do you use a better system, if so ,would you mind posting it? Thanks. Bob

BBeyer,
I used shim steel between the parts of my tailstock in my Clausing 5419.
I ground off the burr from cutting the .005" metal.
Then I cut myself on the tailstock.
Watch out for that, don't have any sticking out.

Also, the two ends of the tailstock need to be shimmed a different amount. I had to put something long, staight, and round in the tailstock, and then with the tail stock clamping in place, move the carridge with the indicator on it along the long thing in the tailstock. The height is easy, put the mag base of the indicator on the chuck and spin it around with different shims until the tailstock is dialed in.

Just a thought. Do you think his indicator tip is so big thats its dampening the reading? Ya can't tell me there was no movement of the needle, it would be bouncing around from the surface finish. Could have used an indicator like that a few years ago

Clark
Thanks, that is a bit of improvement on my way. Thanks again. Bob