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

[Learning Curve]

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..

 

[scwhite]

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

 

[scwhite]

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

 

[tq60]

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

 

[Learning Curve]

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.

 

[ghostdncr]

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.

 

[Learning Curve]

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

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.

 

[Learning Curve]

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..!

 

[Learning Curve]

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

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...

 

[ghostdncr]

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.