# Newbie Sticker still unremoved from my forehead.. Here we go.. with both left feet!



## Learning Curve (Mar 21, 2017)

I have an older Atlas... 12 x 24  101 07403 model... 3/8 bed material... Love the old machine and am not sure what anyone is talking about when it comes to any "flexing" while cutting..  I swear that is some point made 60 years ago by someone trying to sound like they knew what they were talking about...and people have repeated it with no evidence of it.. as at the speed I cut at there has never once been any thread or shaft that has any mishape to it due to any flexing not at all.   Anyway I digress.... (Newbie remember... I do actually have a question...)  I have however been very been disappointed that I could not pass a barrel through the spindle that was larger than the ... 25/32 bore would allow.   So recently an opportunity came up for me to buy a much larger Atlas 12 x 36  model 111 "War lathe" Industrialised, in comparison to the 101.... Heavy V rails 7-1/2" wide All 1/2" material everything beefed up and about 130% in overall size and weight.  I am totally surprised that they still used that same Shaft and timkin Bearing spindle... They still have that same 25/32 pass through in this much larger machine....  ?  I am past trying to understand why other than production costs....   So I got looking at it closer and considering I only need 7/8 of an inch...   It seems to me there is plenty of thickness on this spindle to bore out just 1/16th"....   I'd have the 29/32 I am after and all would be right with the world... Right? ....  And I just do not see any way removing just 1/16th would weaken anything enough to cause problems..  So I wonder if anyone ever tried this?     That is my question..... and I do beg forgiveness in advance.  This could be sacrilege to suggest it or even dangerous if there is some engineering principle other than conjecture against trying this.    Thanks for any input.


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## Wreck™Wreck (Mar 21, 2017)

Shoot it if it displeases you.


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## ghostdncr (Mar 21, 2017)

I have heard and read of this being done, but have no source material to offer for verification. You are talking about removing a very small amount of material, after all. I've got a 101.07380 and the thought of running a few reamers through that spindle has crossed my mind a time or two, but I've never gotten serious about it.


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## scwhite (Mar 21, 2017)

Learning Curve said:


> I have an older Atlas... 12 x 24  101 07403 model... 3/8 bed material... Love the old machine and am not sure what anyone is talking about when it comes to any "flexing" while cutting..  I swear that is some point made 60 years ago by someone trying to sound like they knew what they were talking about...and people have repeated it with no evidence of it.. as at the speed I cut at there has never once been any thread or shaft that has any mishape to it due to any flexing not at all.   Anyway I digress.... (Newbie remember... I do actually have a question...)  I have however been very been disappointed that I could not pass a barrel through the spindle that was larger than the ... 25/32 bore would allow.   So recently an opportunity came up for me to buy a much larger Atlas 12 x 36  model 111 "War lathe" Industrialised, in comparison to the 101.... Heavy V rails 7-1/2" wide All 1/2" material everything beefed up and about 130% in overall size and weight.  I am totally surprised that they still used that same Shaft and timkin Bearing spindle... They still have that same 25/32 pass through in this much larger machine....  ?  I am past trying to understand why other than production costs....   So I got looking at it closer and considering I only need 7/8 of an inch...   It seems to me there is plenty of thickness on this spindle to bore out just 1/16th"....   I'd have the 29/32 I am after and all would be right with the world... Right? ....  And I just do not see any way removing just 1/16th would weaken anything enough to cause problems..  So I wonder if anyone ever tried this?     That is my question..... and I do beg forgiveness in advance.  This could be sacrilege to suggest it or even dangerous if there is some engineering principle other than conjecture against trying this.    Thanks for any input.


Why do you need to run your gun barrel through the Spindle bore ? 
      Can't you run it in the steady rest


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## 3strucking (Mar 22, 2017)

I saw a YouTube video where a guy done just that. I think he made a couple of pillar blocks with bronze bushings that clamped on the ways. He bored and then honed.


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## Learning Curve (Mar 22, 2017)

scwhite said:


> Why do you need to run your gun barrel through the Spindle bore ?
> Can't you run it in the steady rest


Not sure how to make that work.    Need to spin the barrel and need room to thread the end. 12x 24"  Perhaps I am missing something.. I am a newbie afterall.


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## Learning Curve (Mar 22, 2017)

Wreck™Wreck said:


> Shoot it if it displeases you.


Would rather problem solve or learn some new trick from the group.  But thanks "shooting it" is an option I did not consider...


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## Learning Curve (Mar 22, 2017)

rightway1974 said:


> I saw a YouTube video where a guy done just that. I think he made a couple of pillar blocks with bronze bushings that clamped on the ways. He bored and then honed.


Again being new to machining, I am figuring I must just not understand my options as I have not built up and experience but taking that 4/32 out of the bore and ending up with 29/32 is actually all I need for the time being.  If I need larger than that I will have to look for another machine someday. SB or I think I was told some of the Logans have large bore spindles...  Any chance of finding that video?   And thanks for the help guys...  These old lathes are really cool and ys get a sense of pride in ownership of  them, I'd hate to hurt the machine, but my proposal seems doable and an improvement if done right.


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## Learning Curve (Mar 22, 2017)

ghostdncr said:


> I have heard and read of this being done, but have no source material to offer for verification. You are talking about removing a very small amount of material, after all. I've got a 101.07380 and the thought of running a few reamers through that spindle has crossed my mind a time or two, but I've never gotten serious about it.


Yes Sir, and if not for the limitations of the shorter bed on my small lathe I might not want to try this but now that I planned on doing it,  it is hard to dismiss the curiosity.  I was hoping someone here has done this or has information that is solid as to way I can/t before giving it a go. So many of you guy's have been at this for years and I actually appreciate the fact that you still enjoy this hobby/business enough that you all take the time to check in here and share advice.  It's the "machine" that is addicting to me and "fun"... I have to admit I really still do not like working with metal... I am a wood carver and gun stock kinda guy... my recent engraving techniques and my new machinery acquisitions have me as a fish out of water for sure.


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## scwhite (Mar 22, 2017)

Learning Curve said:


> Not sure how to make that work.    Need to spin the barrel and need room to thread the end. 12x 24"  Perhaps I am missing something.. I am a newbie afterall.


I thought you said you bought a bigger 
36" cc lathe


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## Learning Curve (Mar 22, 2017)

ghostdncr said:


> I have heard and read of this being done, but have no source material to offer for verification. You are talking about removing a very small amount of material, after all. I've got a 101.07380 and the thought of running a few reamers through that spindle has crossed my mind a time or two, but I've never gotten serious about it.


It does not keep me up nights.... yet..   but I am really thinking of just doing it....  I was hoping someone in here would have done it and can tell me it's wonderful or warns me DON'T Do IT you'll ruin your lathe..


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## scwhite (Mar 22, 2017)

Learning Curve said:


> Again being new to machining, I am figuring I must just not understand my options as I have not built up and experience but taking that 4/32 out of the bore and ending up with 29/32 is actually all I need for the time being.  If I need larger than that I will have to look for another machine someday. SB or I think I was told some of the Logans have large bore spindles...  Any chance of finding that video?   And thanks for the help guys...  These old lathes are really cool and ys get a sense of pride in ownership of  them, I'd hate to hurt the machine, but my proposal seems doable and an improvement if done right.


I would not bore out the Spindle on the lathe
It could forever change the taper in the Spindle
And  render the lathe useless
     As for as running anything between centers .
  All engine lathes have a  precision taper on the inside of the Spindle . This taper is for a dead center.
Which becomes a live Center when it is run in the lathe spindle .
   And it is perfectly ground ture to the Spindle .
  If you bore the Spindle you will loose this taper .
       I think you would be better off to buy a
Lathe with a longer bed and a Center to center
That is longer than the longest gun barrel you
Will ever run .
      Then run your barrels in the steady rest


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## scwhite (Mar 22, 2017)

Learning Curve said:


> It does not keep me up nights.... yet..   but I am really thinking of just doing it....  I was hoping someone in here would have done it and can tell me it's wonderful or warns me DON'T Do IT you'll ruin your lathe..


I am saying don't do it you  will most likely
Ruin the lathe


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## tq60 (Mar 22, 2017)

Another thought is the material thickness of the spindle is what it is and is in a stress relieved natural state so to speak.

Side stepping...Just out of high school we worked at an engine machine shop straightening crank shafts and cam shafts and tools used were chisel and hammer to change surface stresses to cause shaft to "bend" in the direction needed.

Back to point. ..drilling or reaming the I'd of the spindle MAY cause internal material stresses in the graining of the steel resulting in bending of the shaft which would cause wobble at the chuck ruining the spindle.

These small "hobby" lathes get good money due to small size and easy to move weight.

Clean up the old one and sell it then look for a suitable lathe and upgrade...It is a disease....

Sent from my SAMSUNG-SGH-I337Z using Tapatalk


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## Learning Curve (Mar 22, 2017)

scwhite said:


> I thought you said you bought a bigger
> 36" cc lathe


I did, but I still wonder if I could fix the problem on the other one that I had for so long.   Point being my question is can I bore out the spindle.   Simple enough question but not as simple an answer.... that is why I came here any thoughts on this possible fix and not the "why"of it?   I am glad to see other s have considered it themselves so I am not alone and this might perhaps be a good topic (assuming it has not been discussed previously) as these Atlas LAthes only have a few weaknesses....  The Spindle Bore being one of them.   Now I realise even my simple proposal only will allow the use of 7/8 stock at best as I do not think I could take more than 1/16th from the bire...., but hey...  that's better than 3/4 and if it is an easy enough process Why not make the modification....?  I realise I muddied the waters mentioning the larger lathe.  My bad.  I guess I want to enlarge the bore on that one as well, how's that..  Again...  I will have more than one project in the future that would be possible with a larger space.  I really am curious to know what you guy's think.   And many Thanks for doing so.


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## ghostdncr (Mar 22, 2017)

Other options would be either make a new spindle for it (many mod options there!) or keep your eye out for a used spindle and bore that one, thus retaining your original.


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## Learning Curve (Mar 22, 2017)

scwhite said:


> I would not bore out the Spindle on the lathe
> It could forever change the taper in the Spindle
> And  render the lathe useless
> As for as running anything between centers .
> ...


Excellent observation and again....  lets forget the gunbarrel... this fix is for everyone and anyone who has material of any type larger than 3/4"  I see your point exactly but please take a second look just for the heck of it with me...  I am measuring this taper as best I can now and from what I can see in a preliminary check.... this taper begins at the Working end of the spindle @ 1" but this is an 11" long shaft.. 3/4 Inch is achieved at the loading end....  I think we can all assume the taper is an exact instrument and continues undisturbed through the full 11"  Now I have never seen an 11" dead center, chuck or tool of any kind that takes up the entire 11" to be accurate.   From what I measure .....and logically we should all assume that 7/8" bore would be found in the center of this opening... Or @ 5-1/2"  Dead Center in the bore...  All I am going to be removing is 1/16th from the inside of the back half or "gear end" of this spindle.  The working end will still maintain it's tapper as far as I can see... at least 5" of it... to hold any tools....  If you see my point..  I'f wanted to bore the whole shaft out to the full 1" through the bore,  I'd loose any working taper and ruin the machine in this way as you warned.  Yet @ 7/8th I think I am safe..?  Does any of this make sense?  For what it's worth I hope your not done looking at this and have spoken and moved on.... this is a good discussion to at least hash out a bit more... I think it would enhance many old machines if it works and there are those who want to try this.   I certainly do not wish to propose madness here.  Forgive me if I am...  Your point is the best one against it but I really think they could have cut that spindle slightly larger at the factory years ago but they just didn't.


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## Learning Curve (Mar 22, 2017)

ghostdncr said:


> Other options would be either make a new spindle for it (many mod options there!) or keep your eye out for a used spindle and bore that one, thus retaining your original.


Excellent Point..  I am looking as we speak..   I do believe this is completely doable but I do not wish to ruin anything..  My measurements right now seem to show no loss of any taper at the working end of this bore.  I have to find my old millwright tool box I think I have some bore gauges in there that will reach through the shaft and verify the tapper and my 29/32 goal beginning near the midway point... Where's that old bunch of long calipers when I need them?   I will try this soon once I find another shaft to experiment on. And there's one of the GREAT POINTS of these lathes.   Parts are everywhere..!


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## Learning Curve (Mar 22, 2017)

tq60 said:


> Another thought is the material thickness of the spindle is what it is and is in a stress relieved natural state so to speak.
> 
> Side stepping...Just out of high school we worked at an engine machine shop straightening crank shafts and cam shafts and tools used were chisel and hammer to change surface stresses to cause shaft to "bend" in the direction needed.
> 
> ...


Of course the engineering weaknesses are in play here.  If I wanted to ream this out drastically I would not even have proposed it... but thanks for the observation... it was not lost on me at all.    But we are not talking the stresses of a crankshaft on a car... this small lathe is opened to 1" on the working end for the taper already... and my bore would only begin near the center of the shaft and work toward the loading end of the shaft and we are talking about removing 4/32" of material.. not a 1/4 of an inch... No way to answer the engineering stresses without a total mathematical workup...


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## ghostdncr (Mar 22, 2017)

I don't know what grade of material the original spindles were made from but if one were to make a new one from something like 4140, it wouldn't take much wall thickness to match the strength of the original. In doing the self-cleaning thread modification to the spindle nose, the original material files much like 1018 or some similar mild steel, if I remember correctly.


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## Learning Curve (Mar 22, 2017)

ghostdncr said:


> I don't know what grade of material the original spindles were made from but if one were to make a new one from something like 4140, it wouldn't take much wall thickness to match the strength of the original. In doing the self-cleaning thread modification to the spindle nose, the original material files much like 1018 or some similar mild steel, if I remember correctly.


Yes I remember reading it is a mild steel.    But the attachment of the Driven Gear on the outside is over an area I will not even be touching with my proposed Bore work...  Please take a second and realise I am not trying to OPEN the WHOLE SPINDLE to 1 inch... I think everyone is looking at this like I will cut the entire bore..  The taper that opens to 1 " on the working end lies directly between the drive gear and the Chuck end threads.... The section I want to cut 1/16th out of begins in the shaft somewhere below the pulley and runs out to the change gears end of the shaft...  I seriously do not see any real strenght issues here not in the small amount I wish to remove..   And 7/8th opening is an improvement and partially solves one of the notorious long standing comments about the limitations of these lathes.  I have checked now and I will not lose ANY taper at all.... as the 29/32 I am going to go for begins in the center of this shaft... I will not be touching the working End (HALF) of the bore at all.     I will try it on another shaft when I get an extra...  I think this is worth the effort.    If there is any reason for the bore taper to run 11" and that benefits me in some way I would like to know what it is.. And please stop me from ruining a perfectly good spindle.   As it stands I will have 5" of taper..  I think that will hold any tapered tool I know of well enough and straight enough. Right?


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## scwhite (Mar 22, 2017)

Learning Curve said:


> Excellent observation and again....  lets forget the gunbarrel... this fix is for everyone and anyone who has material of any type larger than 3/4"  I see your point exactly but please take a second look just for the heck of it with me...  I am measuring this taper as best I can now and from what I can see in a preliminary check.... this taper begins at the Working end of the spindle @ 1" but this is an 11" long shaft.. 3/4 Inch is achieved at the loading end....  I think we can all assume the taper is an exact instrument and continues undisturbed through the full 11"  Now I have never seen an 11" dead center, chuck or tool of any kind that takes up the entire 11" to be accurate.   From what I measure .....and logically we should all assume that 7/8" bore would be found in the center of this opening... Or @ 5-1/2"  Dead Center in the bore...  All I am going to be removing is 1/16th from the inside of the back half or "gear end" of this spindle.  The working end will still maintain it's tapper as far as I can see... at least 5" of it... to hold any tools....  If you see my point..  I'f wanted to bore the whole shaft out to the full 1" through the bore,  I'd loose any working taper and ruin the machine in this way as you warned.  Yet @ 7/8th I think I am safe..?  Does any of this make sense?  For what it's worth I hope your not done looking at this and have spoken and moved on.... this is a good discussion to at least hash out a bit more... I think it would enhance many old machines if it works and there are those who want to try this.   I certainly do not wish to propose madness here.  Forgive me if I am...  Your point is the best one against it but I really think they could have cut that spindle slightly larger at the factory years ago but they just didn't.


The taper don't go all the way through the Spindle 
Bore . It just goes deep enough to get the full Dead center in full contact of the center .


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## scwhite (Mar 22, 2017)

Learning Curve said:


> Excellent Point..  I am looking as we speak..   I do believe this is completely doable but I do not wish to ruin anything..  My measurements right now seem to show no loss of any taper at the working end of this bore.  I have to find my old millwright tool box I think I have some bore gauges in there that will reach through the shaft and verify the tapper and my 29/32 goal beginning near the midway point... Where's that old bunch of long calipers when I need them?   I will try this soon once I find another shaft to experiment on. And there's one of the GREAT POINTS of these lathes.   Parts are everywhere..!


That taper is not very long . It is just long enough
To get a full fit on a # 3 MT .
     That taper should be in the  neighborhood
Of 3-1/4 long .


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## scwhite (Mar 22, 2017)

Learning Curve said:


> Of course the engineering weaknesses are in play here.  If I wanted to ream this out drastically I would not even have proposed it... but thanks for the observation... it was not lost on me at all.    But we are not talking the stresses of a crankshaft on a car... this small lathe is opened to 1" on the working end for the taper already... and my bore would only begin near the center of the shaft and work toward the loading end of the shaft and we are talking about removing 4/32" of material.. not a 1/4 of an inch... No way to answer the engineering stresses without a total mathematical workup...


That taper will almost completely be lost if you
Bore out that machine .
       You are talking about boring it out
.125 on the Dia.
        The taper is only .150 you want have anything left .
        The large end should be .938 Dia. And the Small end is .778 Dia.  On a # 3 Morse Taper


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## Reeltor (Mar 22, 2017)

Learning Curve said:


> Not sure how to make that work.    Need to spin the barrel and need room to thread the end. 12x 24"  Perhaps I am missing something.. I am a newbie afterall.



How long is your gun barrel?  I think I'm missing something,


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## RJSakowski (Mar 22, 2017)

The reason the lathe has the current bore diameter is to accommodate the MT3 taper.  If you open the diameter to 29/32 or .906", you will lose all but 1/2" of that taper and it will be destroyed.  As has been previously mentioned, a very useful function of an engine lathe is the ability to work between centers.  For short work pieces, you can, of course, mount a bar in a 3 jaw chuck and turn a driving center in situ.

But the bottom line is that the lathe is yours to do with as you please.  We all have our opinions as to the wisdom of seriously modifying a piece of machinery (some time ago a thread was posted where a lathe was turned into a barbecue spit to roast a steer; check the posts to see the comments made there) but they are our opinions not directives to you.  As a wise old farmer was said to me "I'll give you some free advice; take it for what it's worth".


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## Learning Curve (Mar 22, 2017)

scwhite said:


> The taper don't go all the way through the Spindle
> Bore . It just goes deep enough to get the full Dead center in full contact of the center .


OK, so again considering it


scwhite said:


> That taper is not very long . It is just long enough
> To get a full fit on a # 3 MT .
> That taper should be in the  neighborhood
> Of 3-1/4 long .


Well then that might cause me to loose quite a bit if it only 3 - 1/4 long... but I have not found my tools yet and I need to verify with actual numbers to be sure.  If this is the case you may be quite right and removing the 4/32 of material will perhaps not eliminate the taper but reduce its seating qualities as there will be some loss on the narrow end....  Again I will verify soon. 

YEP.  it's verified....   I bet this would still take a live center % that it might even still work...but for the small gain in size it's just not worth risking the damage if those centers don't run perfectly true.   I'll just read the threads and enjoy learning now...  my bad.


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## Learning Curve (Mar 22, 2017)

Reeltor said:


> How long is your gun barrel?  I think I'm missing something,


Longer than the bed will handle.... and again the barrel is NOT the only consideration...  I was wondering if This could be done so many other applications could fit in that bore hole...   So far the consensus is I will damage the taper to much for it to be of worth..  I will verify with good measurements soon enough...  If this is the case that's too bad, as it would be a fun and easy modification to increase the capacity of many old machines....  But then I suppose if was this simple someone would have thought of it before.    I noticed this thread says  it's being "watched"  what does that mean?  Sounds ominous...  lol  !


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## Learning Curve (Mar 22, 2017)

RJSakowski said:


> The reason the lathe has the current bore diameter is to accommodate the MT3 taper.  If you open the diameter to 29/32 or .906", you will lose all but 1/2" of that taper and it will be destroyed.  As has been previously mentioned, a very useful function of an engine lathe is the ability to work between centers.  For short work pieces, you can, of course, mount a bar in a 3 jaw chuck and turn a driving center in situ.
> 
> But the bottom line is that the lathe is yours to do with as you please.  We all have our opinions as to the wisdom of seriously modifying a piece of machinery (some time ago a thread was posted where a lathe was turned into a barbecue spit to roast a steer; check the posts to see the comments made there) but they are our opinions not directives to you.  As a wise old farmer was said to me "I'll give you some free advice; take it for what it's worth".


Yep.... Damn .. you guy's were right.  That's too bad... I thought this would be a nice little modification...  I verified it... the taper is just as you say it is... and although I will not remove it all I will remove just under half of it... leaving about an 1 - 1/2" to seat on any centers I use...  Not worth doing if I risk losing that much taper.    Well, I suppose us newbies get all excited about things then find out it's been done or  just won't work.  It's what hooks us into this madness to begin with I guess!   Sorry for the time expenditure with such small return.    I will just get used to the larger lathe... and probably end up selling the smaller lathe in the future..   Right now it's just too much fun...!


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## 3strucking (Mar 22, 2017)

You are being watched by the man. You are now on some list somewhere like the rest of us. 

It means that you are watching it since you posted in it.


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## Learning Curve (Mar 22, 2017)

rightway1974 said:


> You are being watched by the man. You are now on some list somewhere like the rest of us.
> 
> It means that you are watching it since you posted in it.


LOL///////// tooo funny...  I am watching myself...?   Now I am totally paranoid how do I get away from the man when I am the man!?  !


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## scwhite (Mar 22, 2017)

Learning Curve said:


> Yes I remember reading it is a mild steel.    But the attachment of the Driven Gear on the outside is over an area I will not even be touching with my proposed Bore work...  Please take a second and realise I am not trying to OPEN the WHOLE SPINDLE to 1 inch... I think everyone is looking at this like I will cut the entire bore..  The taper that opens to 1 " on the working end lies directly between the drive gear and the Chuck end threads.... The section I want to cut 1/16th out of begins in the shaft somewhere below the pulley and runs out to the change gears end of the shaft...  I seriously do not see any real strenght issues here not in the small amount I wish to remove..   And 7/8th opening is an improvement and partially solves one of the notorious long standing comments about the limitations of these lathes.  I have checked now and I will not lose ANY taper at all.... as the 29/32 I am going to go for begins in the center of this shaft... I will not be touching the working End (HALF) of the bore at all.     I will try it on another shaft when I get an extra...  I think this is worth the effort.    If there is any reason for the bore taper to run 11" and that benefits me in some way I would like to know what it is.. And please stop me from ruining a perfectly good spindle.   As it stands I will have 5" of taper..  I think that will hold any tapered tool I know of well enough and straight enough. Right?


No you want have 5" of taper after Boeing out the Spindle . You will you might have about 1" of taper left


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## scwhite (Mar 22, 2017)

Learning Curve said:


> Yep.... Damn .. you guy's were right.  That's too bad... I thought this would be a nice little modification...  I verified it... the taper is just as you say it is... and although I will not remove it all I will remove just under half of it... leaving about an 1 - 1/2" to seat on any centers I use...  Not worth doing if I risk losing that much taper.    Well, I suppose us newbies get all excited about things then find out it's been done or  just won't work.  It's what hooks us into this madness to begin with I guess!   Sorry for the time expenditure with such small return.    I will just get used to the larger lathe... and probably end up selling the smaller lathe in the future..   Right now it's just too much fun...!


I am glad you decided not to bore out the bore .
   That would put a future buyer of the lathe in a very bad  predicament , if you sold it to someone with a Spindle that had been bored out . When they get ready to put something between centers . That's 
Most likely when they would find out the lathe had been tampered with .


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## RJSakowski (Mar 22, 2017)

Here is a drawing of a no. 3 Morse taper plug, specs courtesy of Little Machine Shop.  If the socket is bored out to 29/32 or .906", only .638" of the plug will be in contact.


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## scwhite (Mar 22, 2017)

RJSakowski said:


> Here is a drawing of a no. 3 Morse taper plug, specs courtesy of Little Machine Shop.  If the socket is bored out to 29/32 or .906", only .638" of the plug will be in contact.
> View attachment 229478


         That's a great drawing . I am glad you posted it .
I know it would not be much left . 
        Less than I was guessing 1"


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## jbmauser (Mar 25, 2017)

Why don't you just buy another spindle on ebay for under $100 and bore that out.  If it works you are gold if not you still have your lathe in proper order.  I guess boring it from the rear might preserve the Morse taper and just shorten it a tad.  Advice given by someone who knows little.  Being honest.... JB


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## scwhite (Mar 25, 2017)

jbmauser said:


> Why don't you just buy another spindle on ebay for under $100 and bore that out.  If it works you are gold if not you still have your lathe in proper order.  I guess boring it from the rear might preserve the Morse taper and just shorten it a tad.  Advice given by someone who knows little.  Being honest.... JB


No it would be lost regardless how or where you bore 
The Spindle


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## Learning Curve (Mar 25, 2017)

RJSakowski said:


> Here is a drawing of a no. 3 Morse taper plug, specs courtesy of Little Machine Shop.  If the socket is bored out to 29/32 or .906", only .638" of the plug will be in contact.
> View attachment 229478


Excellent, I came up with about 1 -1/2" left in a rough measurement... and even that was not worth the gain to begin with.    No As I posted yesterday I am no longer going to try this..  I thought it was far less intrusive than it is.  Thanks again for the actual numbers.   this helps put  it to rest for sure.


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## Round in circles (Mar 25, 2017)

Learning Curve said:


> Again being new to machining, I am figuring I must just not understand my options as I have not built up and experience but taking that 4/32 out of the bore and ending up with 29/32 is actually all I need for the time being.  If I need larger than that I will have to look for another machine someday. SB or I think I was told some of the Logans have large bore spindles...  Any chance of finding that video?   And thanks for the help guys...  These old lathes are really cool and ys get a sense of pride in ownership of  them, I'd hate to hurt the machine, but my proposal seems doable and an improvement if done right.



  Any idea how much of the Morse taper you would remove by doing it  ?  That may be the reason for the tube size or perhaps the spindle was made from standard stock size & turned to size ,   then Morse tapered & threaded for the chuck & threaded at the opposite end for the gear & retention nut .

 Once you start thinking about the gears , length of shaft & the weight of the chuck & gears perhaps it's been engineering tested to find a size with enough meat in it to absorb the cutting harmonics ie the tube is " tuned " . If that's the case , taking out the 4/32 might affect things considerably .


 Ha ha , I've just discovered the posts that are in agreement .  I  must read all the posts before replying in future .


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## Round in circles (Mar 25, 2017)

Learning Curve said:


> Longer than the bed will handle.... and again the barrel is NOT the only consideration...  I was wondering if This could be done so many other applications could fit in that bore hole...   So far the consensus is I will damage the taper to much for it to be of worth..  I will verify with good measurements soon enough...  If this is the case that's too bad, as it would be a fun and easy modification to increase the capacity of many old machines....  But then I suppose if was this simple someone would have thought of it before.    I noticed this thread says  it's being "watched"  what does that mean?  Sounds ominous...  lol  !




 Being watched ..    It's  the ghosts of the long departed engineers , machinists & tool makers looking after Atlas & Sphere lathes


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## Turnaround (Mar 25, 2017)

tq60 said:


> Another thought is the material thickness of the spindle is what it is and is in a stress relieved natural state so to speak.
> 
> Side stepping...Just out of high school we worked at an engine machine shop straightening crank shafts and cam shafts and tools used were chisel and hammer to change surface stresses to cause shaft to "bend" in the direction needed.
> 
> ...



Just out of high school we worked at an engine machine shop straightening crank shafts and cam shafts and tools used were chisel and hammer to change surface stresses to cause shaft to "bend" in the direction needed. 

I too ran a crank grinding shop. I soon caught on to the stress riser created when you chisel smack a shaft in a filet (straightening it).  Magnafluxing before and after proved the point, and worse, racing those straightened parts usually resulted in broken parts right where the chisel marks were.


Sent from my iPhone using Tapatalk


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## MetalMuncher (Mar 27, 2017)

Post #37 is what I was going to suggest as I got halfway through reading this thread.  If you had a secondary spindle you could bore out, you could preserve the tapered stock spindle for use when you need it, or to install if/when you sell the lathe to someone else. I've never used a lathe bigger than my 7x10 mini lathe, but I HAVE often wished I could run larger round stock through the bore! And I don't make gun barrels. Even with the less than 10" projects I have turned, I have wished for this ability many times. For one thing, it consumes less material when you can just turn the end of a long rod, pull out the remainder after your part is made,  and save it for next time, rather than having to cut a blank to the length you need + the depth of the chuck jaws, ending up with that extra chuck jaw length left over. Yes, I may need it for something small "someday", but I have a whole box of those leftovers, so "someday" doesn't seem to come that often. 

One of the things about being a newbie is the "all things are possible" frame of mind, simply because you have not yet encountered reasons they are not possible. It drives creativity and unique solutions.  Were I in your position, and could find a spare spindle, I might try boring it out. As much as I'd like mine to be bigger, I have a hunch it isn't made from all that thick of a rod to begin with in this little lathe, so likely would not hold up if it were bored out. I suppose I could also mention that in 15 years of using and modifying this lathe, I have never put a center in the spindle bore, I've always used a lathe chuck on that end of the work piece. But I suppose that varies a lot with the kinds of things we all make.  Overall, I agree with the advice not to bore the spindle you have now. But it might prove interesting to try on a secondary spindle if you feel the experiment is worth the cost of another spindle. As one member mentioned, it is your lathe in the final analysis, to do with as you see fit. If you feel it would be more to your liking to have the bored spindle, why not put one in it?


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## ghostdncr (Mar 28, 2017)

I mentioned making a new spindle from 4140 earlier in this thread and the idea has been rolling around in my head in the days since. Using a much stronger alloy than the originals would allow for a thinner wall wall thickness while still retaining comparable strength, right? Well, I've never had the spindle out of my 12" Craftsman and finally got around to doing some research this morning. I have the occasional job where a bigger bore would completely change the setup and allow for much easier and faster turning.

This idea soon evaporated when I realized the scope of such a project. Here's a photo I found of a 12" babbitt-bearing spindle. There doesn't appear to be much difference between this one and one designed for the Timken roller bearings, as near as I can tell:




In making a spindle to allow pass-through of larger OD stock, the reduced diameter to the right would need to be brought up to near the same diameter as the portion on the left. Looking at the number of parts that sit to the right of that shoulder, we would be looking at extensive modification to a host of components to successfully implement this change. If I'm interpreting the schematic correctly, the small back gear is the last component that rides on the larger diameter. A collar with set screw butts up against the shoulder and changing it's bore diameter wouldn't be much of a problem, nor would several of the various spacers, baffles, dust cover, etc. that sit along this smaller diameter. On the roller bearing headstocks, I'm pretty sure p/n 10A-11C is that lipped bearing that, when found, carries a price tag between $800 to $1600! I was reading about this in another thread but can't seem to find it this morning to use as reference. Now, we're most likely into line boring the headstock to accept an alternate bearing with a larger ID, which may not be a bad idea considering the scarcity of the original part, but still. I think the other components fitted to the smaller OD of the shaft could be modified to fit, but the scope of this project has grown quite rapidly and we're no longer in "swap spindles back and forth" territory. It would be a permanent modification requiring lots of time and money, and probably enough to fund the purchase of a more modern lathe that already has a larger bore.

With the idea fairly-well researched, I can scratch it off my list and move on with my life.


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## Scott.S (Mar 31, 2017)

You have discovered that these machines were designed for certain ranges of use...if your machine has a MT3 taper you will have larger i.d. on the spindle.  Kinda like trying to haul a ton on rock in the back of a half ton pickup...it isnt just the rear springs you need to think about.  Maybe you need to find a second operation lathe to keep tge footprint small.  Good luck


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