pre boring reaming
- Thread starter michaelb
- Start date
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Jay Idaho
Guest
This ain't got nothing to do with chambering, but..... if the "headstock" is aligned with the ways I think that the spindle axis, center of the rotating spindle, bearings too, are what is actually aligned. Disregarding the "tool push preload", you would then bore a straight hole. If the spindle were pointing toward the operator, you would bore a tapered hole, small end furtherest from the headstock. If the spindle were pointing away from the operator, you would bore a tapered hole, large end fartherest from the headstock. That does not sound intuitive but that is how I see it in my head. Tool deflection would not really matter, the hole will be tapered even if you take "spring cuts".
You can get the same affect by using the compound to bore, if you wanted to prove that my theory is right or wrong. Simply tilt the compound a few degrees each way from being aligned with the ways and try it.
You get the same affect on the o.d. of a turned part if the lathe headstock is not aligned with the ways. Guess how I know that?
Fun mental exercises unless folks get frustrated and angry.
Jay, Idaho
You can get the same affect by using the compound to bore, if you wanted to prove that my theory is right or wrong. Simply tilt the compound a few degrees each way from being aligned with the ways and try it.
You get the same affect on the o.d. of a turned part if the lathe headstock is not aligned with the ways. Guess how I know that?
Fun mental exercises unless folks get frustrated and angry.
Jay, Idaho
Butch Lambert
Active member
Jay,
I guess that I just learned that lathes are not in line. How come then that I can bore a 2" hole with my carbide boring tool and show no taper? Did I knock my headstock in alignment?
Butch
I guess that I just learned that lathes are not in line. How come then that I can bore a 2" hole with my carbide boring tool and show no taper? Did I knock my headstock in alignment?
Butch
J
Jay Idaho
Guest
Butch,
I'd say that your spindle is very well aligned with your ways.
I have a test bar. It is about 2" diameter X about 15" long, hardened and ground on the o.d. and with ground centers in both ends. With it is an aluminum bushing with a number of slits coming from each end. That allows you to align the bar in a 4 jaw chuck while protecting the bar by using the aluminum sleeve.
Get this bar aligned in the spindle such that it is running true on the o.d. on both ends. This can be done rather quickly with two indicators on the bar.
Now you can really see if your headstock is aligned with your ways and if the headstock is pointing up or down, too. The centers allow it to be used to check the tailstock alignment, also.
Does this sound logical?
Jay, Idaho
I'd say that your spindle is very well aligned with your ways.
I have a test bar. It is about 2" diameter X about 15" long, hardened and ground on the o.d. and with ground centers in both ends. With it is an aluminum bushing with a number of slits coming from each end. That allows you to align the bar in a 4 jaw chuck while protecting the bar by using the aluminum sleeve.
Get this bar aligned in the spindle such that it is running true on the o.d. on both ends. This can be done rather quickly with two indicators on the bar.
Now you can really see if your headstock is aligned with your ways and if the headstock is pointing up or down, too. The centers allow it to be used to check the tailstock alignment, also.
Does this sound logical?
Jay, Idaho
Butch Lambert
Active member
Makes sense to me.
Butch
Butch
jackie schmidt
New member
Butch
I think my "BS" detection meter has gone completly off the scale.
.
For those interested, here is the short version. If something is not truly straight, you can only cause two points to run true at the same time.. What we do is decide which two points we wish to run true, then, by single point boring, make a third point run true with those two points.
The reason we core out thr chamber with a drill is so we can have access to the point in the throat that we wish to indicate.
After you indicate this point, you MUST single point bore the chamber so that it runs true with the two points that you have previously indicated.
Oh. The last thing is, you MUST be willing to check your work. If you do not, then you are just fooling yourself.....jackie
I think my "BS" detection meter has gone completly off the scale.
.For those interested, here is the short version. If something is not truly straight, you can only cause two points to run true at the same time.. What we do is decide which two points we wish to run true, then, by single point boring, make a third point run true with those two points.
The reason we core out thr chamber with a drill is so we can have access to the point in the throat that we wish to indicate.
After you indicate this point, you MUST single point bore the chamber so that it runs true with the two points that you have previously indicated.
Oh. The last thing is, you MUST be willing to check your work. If you do not, then you are just fooling yourself.....jackie
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Bill Leeper
New member
I turn a piece of cast iron (I like cast iron because it turns nice and is relatively inert) 3 inches in diameter and with about 5 inches sticking out to align the headstock with the ways. If it turns so it is the same at two points, the headstock is probably well aligned. Running a dial sitting on the saddle against the bottom of the turned piece verifies this. Mounting the dial on the tailstock quill and running it along the test piece will ascertain whether the tailstock quill is running straight or not but not whether it is co-axial. Sweeping the tailstock center with a gauge mounted on the test piece will verify the axis.
I've seen four jaw chucks with one set of jaws misaligned making the use of a true test bar a waste.
When I buy a new lathe, I don't want one of those crooked headstock models! Regards, Bill.
I've seen four jaw chucks with one set of jaws misaligned making the use of a true test bar a waste.
When I buy a new lathe, I don't want one of those crooked headstock models! Regards, Bill.
jackie schmidt
New member
Bill
We have bought 3 new lathes in the past five years, and all of the heastocks are adjustable. They are mounted on a pivot dowell that allows you to align the headstock dead on with the ways of the machine after you have the bed level and with no twist. SAfter you do this, you align the tailstock with these.
So are our two 18 inch Mazaks that we bought back in the 80's.
The last lathe we purchased is a 22 inch Kingston, which is a clone of the Mazak. When Mazak quit making manual machines a number of years ago, Kingston bought the rights to manufacture the design.
Anyway, after we had the lathe set in place, a technitian came out, and had all sorts of test bars and lazers. After he said the lathe was set up, it cut about .004 taper in just 6 inches. He played with it all day, and we finally just took a Starret 12 inch Machinist Level, got the bed right, adjusted the headstock to where the lathe cut and bored straight, then adjusted the tailstock to where it cut true between centers.
I don't know why he just didn't do that in the first place.
But this is all childs play. Try keeping a 44 ft lathe that weighs about 120,000 pounds dead level over the year, especially when you are sitting on a re-claimed swamp such as Houston.........jackie
We have bought 3 new lathes in the past five years, and all of the heastocks are adjustable. They are mounted on a pivot dowell that allows you to align the headstock dead on with the ways of the machine after you have the bed level and with no twist. SAfter you do this, you align the tailstock with these.
So are our two 18 inch Mazaks that we bought back in the 80's.
The last lathe we purchased is a 22 inch Kingston, which is a clone of the Mazak. When Mazak quit making manual machines a number of years ago, Kingston bought the rights to manufacture the design.
Anyway, after we had the lathe set in place, a technitian came out, and had all sorts of test bars and lazers. After he said the lathe was set up, it cut about .004 taper in just 6 inches. He played with it all day, and we finally just took a Starret 12 inch Machinist Level, got the bed right, adjusted the headstock to where the lathe cut and bored straight, then adjusted the tailstock to where it cut true between centers.
I don't know why he just didn't do that in the first place.
But this is all childs play. Try keeping a 44 ft lathe that weighs about 120,000 pounds dead level over the year, especially when you are sitting on a re-claimed swamp such as Houston.........jackie
JerrySharrett
Senile Member
The Brits may build their lathes with some built-in skew. I've never seen a US lathe builder do that and I have been in many of the big lathe builders in the US and Mazak in Japan. Workpiece and tool deflection is not a consideration mainly because the machine tool builder has no idea of the material or tooling the machine owner will use.
In the days when the most prevalent material to be machined was cast iron, some builders did build their engine lathes with the tailstock a few thousands higher to allow for wear. On turning and boring operations the tailstock being slightly higher does not cause problems
I didn't say I agreed with him!
I was just translating.......!!!!!!!!!!!!!!
Don't shoot the messenger.!!!
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JerrySharrett
Senile Member
N
NesikaChad
Guest
Last comment, then I'm popping smoke.
Someone made reference to reamer holders being only used in tail stocks.
Not the one I made:
Someone made reference to reamer holders being only used in tail stocks.
Not the one I made:
A
Andy Mass
Guest
Extremely interesting debate, I have to wonder just how much thrust is imparted on the saddle taking into account that (from my own perspective) cuts are no more than .005" deep and usually half this or less....over a total length of no more than 3 inches for the longest of chambers and just around an inch for tenons..
I too am wondering if a solution has been found to a problem that has yet to exist
Chad
envious of your machine...........
I too am wondering if a solution has been found to a problem that has yet to exist
Chad
envious of your machine...........
Gentlemen,
Jackie brings up a good topic that I think not everyone is aware of re: adjustable headstocks. As he says, a lot of them are adjustable. I have two lathes, both Taiwanese machines. One, a Cut King 15X36 that is a shrunk down copy of a Mori Seiki, and the other an Acra Turn 14X40 SVS, Both of which have adjustable headstocks.
I currently have the the Cut King cutting less than a tenth over 4 inches on a piece of aluminum with a good, sharp HSS tool bit. It got that way by doing what Jackie says to do. I got the bed as level as I possibly could with a 12" Starret machinist level, and then started tinkering with the headstock. I used HSS because you can get it sharper than, and deflects less than carbide. All of the above took some time to accomplish, and involved some pretty foul language...but I did it.
I haven't messed with the Acra yet, as it is not under power.
I've talked to a couple of people who were in the machinist trade who had no idea you could that some headstocks were adjustable. One was lamenting the taper his Mori Seiki cut, and when I told him that his headstock was adjustable and he could take the taper out, he looked at me like I had two heads. I showed him where all the adjustments were and he said "I'll be darned"...or something like that.
Justin
Jackie brings up a good topic that I think not everyone is aware of re: adjustable headstocks. As he says, a lot of them are adjustable. I have two lathes, both Taiwanese machines. One, a Cut King 15X36 that is a shrunk down copy of a Mori Seiki, and the other an Acra Turn 14X40 SVS, Both of which have adjustable headstocks.
I currently have the the Cut King cutting less than a tenth over 4 inches on a piece of aluminum with a good, sharp HSS tool bit. It got that way by doing what Jackie says to do. I got the bed as level as I possibly could with a 12" Starret machinist level, and then started tinkering with the headstock. I used HSS because you can get it sharper than, and deflects less than carbide. All of the above took some time to accomplish, and involved some pretty foul language...but I did it.
I haven't messed with the Acra yet, as it is not under power.
I've talked to a couple of people who were in the machinist trade who had no idea you could that some headstocks were adjustable. One was lamenting the taper his Mori Seiki cut, and when I told him that his headstock was adjustable and he could take the taper out, he looked at me like I had two heads. I showed him where all the adjustments were and he said "I'll be darned"...or something like that.
Justin
P
p17p14enflield
Guest
heads stocks !
hello there are lot of lathe that have adjustable heads and it nice to know there there are good machinest/smiths that use this usefull fetrue, but here are lathe like harrison m300 or smilar , where the head stock is set but been scarped in on the vee's of the bed way's , this is where core drilling chambers is problematric when tail stock is used ( you can adjust the tailstock to drill paralle to the haedstock bore but most as set a tha facorty will want to push of the drill off )
and as for boreing chamber out ( in my mind not good ) as when single piontin truning or bore the free movent in the baering is transfered to the work peace , buy this i mean it will not be truely round ( test with a tyloround machine or similar ) so if you where to find the mean axis of the rought out chamber and the bore the two would ont match!( i only biuld lathes so i well not go on any more about the thorey of how they work)
know lets be realistic to the tolarance's we try to hit ( few tenth of a thou )
both method will and do trun out rifles that shoot as good as the other ,
i my self just would not like to run the risk of missing up a fro the sack of buying a few more reamer in life time or ease indicating on the throat ( finger type d.t.i can be bourght with 3'' to 4'' styles) i use a vredict metric dti if one 2'' stylus and one with a 4''
hello there are lot of lathe that have adjustable heads and it nice to know there there are good machinest/smiths that use this usefull fetrue, but here are lathe like harrison m300 or smilar , where the head stock is set but been scarped in on the vee's of the bed way's , this is where core drilling chambers is problematric when tail stock is used ( you can adjust the tailstock to drill paralle to the haedstock bore but most as set a tha facorty will want to push of the drill off )
and as for boreing chamber out ( in my mind not good ) as when single piontin truning or bore the free movent in the baering is transfered to the work peace , buy this i mean it will not be truely round ( test with a tyloround machine or similar ) so if you where to find the mean axis of the rought out chamber and the bore the two would ont match!( i only biuld lathes so i well not go on any more about the thorey of how they work)
know lets be realistic to the tolarance's we try to hit ( few tenth of a thou )
both method will and do trun out rifles that shoot as good as the other ,
i my self just would not like to run the risk of missing up a fro the sack of buying a few more reamer in life time or ease indicating on the throat ( finger type d.t.i can be bourght with 3'' to 4'' styles) i use a vredict metric dti if one 2'' stylus and one with a 4''
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J
jGEE
Guest
<snip>"and as for boreing chamber out ( in my mind not good ) as when single piontin truning or bore the free movent in the baering is transfered to the work peace , buy this i mean it will not be truely round ( test with a tyloround machine or similar )"<snip>
Damn you guys can make a "cunt hair" look like a Pine Tree!! I never knew measuring could get this precise!! I chamber with a die grinder holding the bbl with my knees, lol! joe
Damn you guys can make a "cunt hair" look like a Pine Tree!! I never knew measuring could get this precise!! I chamber with a die grinder holding the bbl with my knees, lol! joe
I mean no disrespect, just helping the typos
hello there are lot of lathe that have adjustable heads and it nice to know there there are good machinist/smiths that use this useful feature, but here are lathe like harrison m300 or similar , where the head stock is set but been shaped in on the vee's of the bed way's , this is where core drilling chambers is problematic when tail stock is used ( you can adjust the tailstock to drill parallel to the headstock bore but most as set a the factory will want to push of the drill off )
and as for boring chamber out ( in my mind not good ) as when single pointing truing or bore the free movement in the bearing is transferred to the work piece , buy this I mean it will not be truly round ( test with a tyloround machine or similar ) so if you where to find the mean axis of the rough out chamber and the bore the two would not match!( I only build lathes so I well not go on any more about the theory of how they work)
know lets be realistic to the tolerance’s we try to hit ( few tenth of a thou )
both method will and do turn out rifles that shoot as good as the other ,
I my self just would not like to run the risk of missing up a fro the sack of buying a few more reamer in life time or ease indicating on the throat ( finger type d.t.i can be bought with 3'' to 4'' styles) I use a verdict metric dti if one 2'' stylus and one with a 4''
hello there are lot of lathe that have adjustable heads and it nice to know there there are good machinist/smiths that use this useful feature, but here are lathe like harrison m300 or similar , where the head stock is set but been shaped in on the vee's of the bed way's , this is where core drilling chambers is problematic when tail stock is used ( you can adjust the tailstock to drill parallel to the headstock bore but most as set a the factory will want to push of the drill off )
and as for boring chamber out ( in my mind not good ) as when single pointing truing or bore the free movement in the bearing is transferred to the work piece , buy this I mean it will not be truly round ( test with a tyloround machine or similar ) so if you where to find the mean axis of the rough out chamber and the bore the two would not match!( I only build lathes so I well not go on any more about the theory of how they work)
know lets be realistic to the tolerance’s we try to hit ( few tenth of a thou )
both method will and do turn out rifles that shoot as good as the other ,
I my self just would not like to run the risk of missing up a fro the sack of buying a few more reamer in life time or ease indicating on the throat ( finger type d.t.i can be bought with 3'' to 4'' styles) I use a verdict metric dti if one 2'' stylus and one with a 4''
P
p17p14enflield
Guest
dont mean to be bitchy
hay joe
i just like discussing the thorey's ( try making a lathes form some how makes airplane parts the discusion go on and on then)
and i dont think it make much defrance to the method
hay joe
i just like discussing the thorey's ( try making a lathes form some how makes airplane parts the discusion go on and on then)
and i dont think it make much defrance to the method
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Bill Leeper
New member
I would not buy a lathe which did not have an adjustable headstock. In setting up the bigger machines, I always leveled the bed first then set the headstock to turn parallel to the bed.
By the way, you can take a facing cut across a face plate to establish that the faceplate is parallel to the cross slide but this does not necessarily mean it is aligned with the ways. It should be but may not be. It is better to align with the ways and let the cross slide be what it is. One can always use the compound to cut a truly square face if that's necessary.
Jackie,
That big lathe should sit on it's own slab which is divorced from the rest of the building. If the slab is heavy enough and re-barred to hell and gone, it won't distort. If the whole thing, slab and all settles or tips, it doesn't affect the machine unless you are trying to set up tooling with a level!
I've seen the Mazak copies and used them. They are OK but don't last as good as the real thing. It always looked to me like the castings were copied from a blurry photograph. Still, they are what is available now and they are affordable. They are still a good, rigid machine and I like them. Regards, Bill.
By the way, you can take a facing cut across a face plate to establish that the faceplate is parallel to the cross slide but this does not necessarily mean it is aligned with the ways. It should be but may not be. It is better to align with the ways and let the cross slide be what it is. One can always use the compound to cut a truly square face if that's necessary.
Jackie,
That big lathe should sit on it's own slab which is divorced from the rest of the building. If the slab is heavy enough and re-barred to hell and gone, it won't distort. If the whole thing, slab and all settles or tips, it doesn't affect the machine unless you are trying to set up tooling with a level!
I've seen the Mazak copies and used them. They are OK but don't last as good as the real thing. It always looked to me like the castings were copied from a blurry photograph. Still, they are what is available now and they are affordable. They are still a good, rigid machine and I like them. Regards, Bill.