pre boring reaming

odd logic in the factorey set up for lathe's

bill ther some odd logic to the standerns lathes are made to!
the standard for facing is that it should be convex .013mm over a diameter of 150mm (for standard and tool room lathes) and this is so that face's well not rock when thay are clamped together!

wish i could figer out how they worked this out?
as for adjusting the facing the usally mean scraping or re doing the sadle beding compound with is big big job !
 
Bill

Don't you think that when we built our new building that the lathe is in, we did indeed include an independent pad for that machine. Although from the top it appears to be a single slab it is five feet of reinforced concrete.

We also have separate concrete pads for every large machine in all three of our buildings.

Bill, we have been doing this for a long time. I live in the real world of large job shop work. We tend to know what we are doing.........jackie
 
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Slow learner, eh

Butch:

Did Jackie just make a fo' pa?

Now changing the subject:

History repeats itself. I have been reading and posting on BRC for about 8 years. This topic drilling and pre boring has been hashed and rehashed year after year. Every year you guys sound like a sniveling bunch of children. That is putting it politically correctly. Do your barrels the way you think best. The best barrels and chamber jobs will win out at the matches. Whom evers technology is best will prevail in the school of supply and demand.

Nat
 
Nat

Many of these discussions are not for the professional who makes his primary living at this, they are for the hobbyist who might have limited skills, and limited equipment. For a seasoned craftsman such as yourself, all of this might seem mundane. But for lay persons who are ignorant of these concepts, this might be quite exciting.

These discussions need to be re-hashed because the population is not stagnant. New faces who are thirsty for knowledge are constantly becoming interested in the skills that are being discussed.........jackie
 
As to foundations for large machine tools, they are largely called independent bases. Most all machine tool builders recommend the size of the base and the mounting hardware. Some examples, the independent base for a particular 4-axis machining center required special mounting hardware that cost about $12,000 in addition to the independent base requirement.

A Giddings & Lewis floor type horizontal boring mill I bought with an X-Y travel envelope of 12' and with a 6" spindle bar, the foundation required 228 yards of concrete. The foundation drawings came complete with the bending instructions for the re-bar.

A 60" x 228" Monarch Engine lathe we installed required a base thickness of 6'. It also required the mounting/leveling bolts be left loose so the machine would not bind as the foundation changes with Winter/Summer temperature changes.

All these larger machines had specific foundation requirements based on what the builder thought best and they did not all think the same. American Lathe had different requirements than Monarch for lathes of the same size!!

One other comment, these machines and foundations all moved over time. We put re-leveling and re-alignment requirements in the PM programs for each.

I suggest it is also important on these small tool-room size lathes we use for gun work to recheck and re-level as needed to get the best machine life and best accuracy. There is more attention required to a precision machine tool than there is to a flashlight.
 
Jackie,
I figured you probably did and only brought it up as a matter of interest. I even poured a separate slab for my little 13x40 in the basement.
I wonder whether the challenges of trying to maintain a stable foundation are greater in a place like Houston (reclaimed swamp) or up here with the severe temperature extremes and sandy base. I guess no place is truly stable although I would guess the Canadian Shield comes pretty close!
Anyway, this has turned into a serious hijack of a thread but I think we've established that rifle barrels are different than hydraulic valve bodies and that pre-boring is the best way to establish a straight and true beginning for the chamber providing one takes the time to set it up properly to begin with. If the barrel is truly straight it probably doesn't matter so much and I don't necessarily think it is a reasonable method for a shop building lightweight magnums. This is benchrest.com though. Regards, Bill.
 
Faux pas..........

Rustystud said:
Butch:

This topic drilling and pre boring has been hashed and rehashed year after year. Every year you guys sound like a sniveling bunch of children.

Nat
Click to expand...

Nice! Nat

Well...to be honest...

You guys are a bunch of lordly, assuming, proud, swaggering, pompous, pretentious, stuck up ,cocky, contemptuous, blustering, imperious, overbearing, haughty, scornful, puffed up, egotistical, disdainful, self-important, presumptuous, high-handed, insolent, supercilious, high and mighty mean old farts.....

Yet I read every post, with a greedy hand on my mouse, waiting for a scrap of useful information to be thrown down to me....like a starving dog.

And love it.

Keep up the abuse....and tips for the novice.
 
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The result is what counts

I think many methods have been used to chamber barrels that
shoot well and I agree with Jackie, the result is what counts. In my way
of thinking, chambering a barrel that is not aligned as good as you can get it
is a waste of time. Having said that, I do know of bit and brase done barrels
that have defyed reason. A chamber that is out of round, or off center
is a constant and maybe when fed straight ammo, not much difference can be found on paper. Some of what those things cause can be seen as
guns with premature sticky extraction, scored chambers and excessive swells.
That you have shot a zero, does not mean that you indeed have a true chamber. I do prebore or use a carbide roughing reamer and recheck
alignment at various points. Given a true chamber does not complete the job,
shoulder fit and threads will make and break all that fast. I was once given
a barrel by a known barrel maker. It had been returned to him as a non shooter. I was told they could find no problem, and gave the shooter a new barrel. Screwing it into an action, I could see daylight thru the shoulder area
in one place. Seems the shoulder was cut with a parting tool and had a small
step. It turned out to be a great barrel. The quality control at that
smiths placed failed, kinda like the mechanic that didn't tighten the lug nuts.
But the brakes work. In any shop, there are machinists and there are
machine operators. There is a big difference
 
jackie schmidt said:
Many of these discussions are not for the professional who makes his primary living at this, they are for the hobbyist who might have limited skills, and limited equipment. For a seasoned craftsman such as yourself, all of this might seem mundane. But for lay persons who are ignorant of these concepts, this might be quite exciting.

These discussions need to be re-hashed because the population is not stagnant. New faces who are thirsty for knowledge are constantly becoming interested in the skills that are being discussed.........jackie
Click to expand...

Well said.

Fitch
 
Well said, Ben!!!

[/B]
Bnhpr said:
Nice! Nat

Well...to be honest...

You guys are a bunch of lordly, assuming, proud, swaggering, pompous, pretentious, stuck up ,cocky, contemptuous, blustering, imperious, overbearing, haughty, scornful, puffed up, egotistical, disdainful, self-important, presumptuous, high-handed, insolent, supercilious, high and mighty mean old farts.....

Yet I read every post, with a greedy hand on my mouse, waiting for a scrap of useful information to be thrown down to me....like a starving dog.

And love it.

Keep up the abuse....and tips for the novice.
Click to expand...


I'll second that. I'm another staving dog newbie!! Keep it up guys, thanks Med.
 
Bnhpr said:
Nice! Nat

Well...to be honest...

You guys are a bunch of lordly, assuming, proud, swaggering, pompous, pretentious, stuck up ,cocky, contemptuous, blustering, imperious, overbearing, haughty, scornful, puffed up, egotistical, disdainful, self-important, presumptuous, high-handed, insolent, supercilious, high and mighty mean old farts.....

Yet I read every post, with a greedy hand on my mouse, waiting for a scrap of useful information to be thrown down to me....like a starving dog.

And love it.

Keep up the abuse....and tips for the novice.
Click to expand...

Ben you left out arrogant.

I think the above must be a requirement to be a machinist, most of the ones around here fit the category.
I hope the above is not construed in a negative way, it is not intended to be.
Keep it up guys.

James
 
Novice viewpoint!!

As a novice, I can tell you these conversations are extremely valuable, not to mention humorous.

And I would like to add "generous " & "humurous" to the foregoing list.

Aloha, Les
 
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