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help the rookie with a lathe fundamental question

rscott9399

Plastic
Joined
Jan 19, 2022
Hey all

So amateur hobbyists here with a fundamental lathe question that I have not been able to get answered through good old YouTube surprisingly.

I tend to work with a lot of old junk metal for practice. Most times there is a scale on the outside and the part is hardly ever round.

I am going to put forth a scenario and then explain what I am seeing and you all tell me what my best course of action is please.

So say I have some material that longish. 12-18 inches or so. Maybe 1.5 inches OD with an outside scale and isnt round.
I have a lathe with a 1.25 inch spindle bore. No steady rest. How do I true up the material?


I have tried so many things and cant get it to work.

My normal procedure has been, get as much in the chuck as I can. I have both a bison 3 and 4 jaw. Tried both doesn't make a difference.
I obviously cant do much in the way of centering the 4 jaw because the part has a scale on the outside and getting the 4 jaw indicated is impossible with the needle jumping all around. The first thing I have been doing is going to the far end of the work piece. Which sucks because that is where I have the most deflection. I cant drill a center hole for the tail stock yet because the dang part won't spin true and if I do it now it won't actually be the center. So I usually move to the far end and very carefully and gently take of the outside scale usually .005 at a time. Which takes for ever. If the part is very small diameter its a nightmare because of the deflection even with .005 DOC.

Once I machine a new surface, ill take the part out and flip it over and put the machined surface I just made in my jaws. This allows me to true up the jaws and the part at least very close to the chuck. The far end will still be wobbling all over.

Once I get to this point sometimes I try to gently drill a center to I can finally get the damn tailstock in and then I clean up the piece for real.
However, the issue im having is, TAPER!!!

Because of this wack procedure I'm doing, the center drill never is actually in the center. So when I put the tail stock in its usually not perfect. and then im stuck with taper on the part for forever because no matter how badly I try to get it out I never can.

If the part would fit in the spindle bore I would stick it far far in so I could get a proper center with no deflection.
So the issue seems to lie with the following problem.
Spindle bore to small. Material is junk yard rust crap stock and I am a rookie.


Can someone suggest a procedure to help me? I am tired of my parts having taper. I have a machine capable of holding 10ths over feet however my setup is all wrong.
I am running on a fryer easy turn CNC with sinumerick control. I use it manually with the exception of single point threading.

any help much appreciated.
 

Joe Gwinn

Stainless
Joined
Nov 22, 2009
Location
Boston, MA area
You will need to turn the raw stock between centers. Carbide tooling may be needed to cut the scale and other trash on the surface away without wearing the cutter out too fast.
 

john.k

Diamond
Joined
Dec 21, 2012
Location
Brisbane Qld Australia
Find the centre of the bar end with dividers,mark and centre punch,then drill a centre.....a very basic skill on the way to actually being allowed to operate a lathe.
 

52 Ford

Stainless
Joined
May 20, 2021
Hey all

So amateur hobbyists here with a fundamental lathe question that I have not been able to get answered through good old YouTube surprisingly.

I tend to work with a lot of old junk metal for practice. Most times there is a scale on the outside and the part is hardly ever round.

I am going to put forth a scenario and then explain what I am seeing and you all tell me what my best course of action is please.

So say I have some material that longish. 12-18 inches or so. Maybe 1.5 inches OD with an outside scale and isnt round.
I have a lathe with a 1.25 inch spindle bore. No steady rest. How do I true up the material?


I have tried so many things and cant get it to work.

My normal procedure has been, get as much in the chuck as I can. I have both a bison 3 and 4 jaw. Tried both doesn't make a difference.
I obviously cant do much in the way of centering the 4 jaw because the part has a scale on the outside and getting the 4 jaw indicated is impossible with the needle jumping all around. The first thing I have been doing is going to the far end of the work piece. Which sucks because that is where I have the most deflection. I cant drill a center hole for the tail stock yet because the dang part won't spin true and if I do it now it won't actually be the center. So I usually move to the far end and very carefully and gently take of the outside scale usually .005 at a time. Which takes for ever. If the part is very small diameter its a nightmare because of the deflection even with .005 DOC.

Once I machine a new surface, ill take the part out and flip it over and put the machined surface I just made in my jaws. This allows me to true up the jaws and the part at least very close to the chuck. The far end will still be wobbling all over.

Once I get to this point sometimes I try to gently drill a center to I can finally get the damn tailstock in and then I clean up the piece for real.
However, the issue im having is, TAPER!!!

Because of this wack procedure I'm doing, the center drill never is actually in the center. So when I put the tail stock in its usually not perfect. and then im stuck with taper on the part for forever because no matter how badly I try to get it out I never can.

If the part would fit in the spindle bore I would stick it far far in so I could get a proper center with no deflection.
So the issue seems to lie with the following problem.
Spindle bore to small. Material is junk yard rust crap stock and I am a rookie.


Can someone suggest a procedure to help me? I am tired of my parts having taper. I have a machine capable of holding 10ths over feet however my setup is all wrong.
I am running on a fryer easy turn CNC with sinumerick control. I use it manually with the exception of single point threading.

any help much appreciated.

I have a couple YouTube channels that I think you can learn a LOT from. So, in no particular order:
Keith Fenner
This Old Tony
Abom79
Vintage Machinery
ROBRENZ
Stefan Gotteswinter

Those are just the ones that come to mind right now. Most of these channel's videos aren't "how-to" videos per se, but these guys know what they're doing and you can pick up a LOT of knowledge just watching over their shoulder, so to speak.
 

rscott9399

Plastic
Joined
Jan 19, 2022
Find the centre of the bar end with dividers,mark and centre punch,then drill a centre.....a very basic skill on the way to actually being allowed to operate a lathe.

Care to explain the process? Allowed to operate the lathe? sounds pretty condescending.
I also dont see how you are going to do that on a part that is not round as I stated the material was.
 

rscott9399

Plastic
Joined
Jan 19, 2022
already watch them all. Abom79 is by far my favorite. I have yet to see someone perform the operation I am talking about.
 

henrya

Stainless
Joined
Jun 25, 2008
Location
TN
Another thing to improve your work is to take a belt sander to the piece and clean it up before you put it in the lathe. Knock all the crap off until its mostly clean metal.

Also, its easy to make a center for the chucks by simply turning one in the lathe. Until you take it out of the chuck, its as perfect a center as you can get. But because you made it you can give it a clean-up pass next time you chuck it up. This home made center should have a shoulder on it to stop it from sliding into the chuck.

As written above, center punch the ends of the shaft and mount it up between centers. Look up “lathe dog” if you don’t know what that is. Make or buy one. Look up “turning between centers”
 

henrya

Stainless
Joined
Jun 25, 2008
Location
TN
You won’t see many people cleaning up old rusty crap metal because after they try it a few times they realize its mostly worth the money to start with clean stock and not fight this battle over and over.

You should get a copy of Southbend’s “How to Run a Lathe”. It will help you a lot.
 

kustomizer

Titanium
Joined
Aug 17, 2007
Location
North Fork Idaho
You won’t see many people cleaning up old rusty crap metal because after they try it a few times they realize its mostly worth the money to start with clean stock and not fight this battle over and over.

You should get a copy of Southbend’s “How to Run a Lathe”. It will help you a lot.

Material and tools in Alaska aint just a call away, getting shit up there takes some planning though there are little junk yards all over as stuff that goes to Alaska tends to stay there
 

rscott9399

Plastic
Joined
Jan 19, 2022
Another thing to improve your work is to take a belt sander to the piece and clean it up before you put it in the lathe. Knock all the crap off until its mostly clean metal.

Also, its easy to make a center for the chucks by simply turning one in the lathe. Until you take it out of the chuck, its as perfect a center as you can get. But because you made it you can give it a clean-up pass next time you chuck it up. This home made center should have a shoulder on it to stop it from sliding into the chuck.

As written above, center punch the ends of the shaft and mount it up between centers. Look up “lathe dog” if you don’t know what that is. Make or buy one. Look up “turning between centers”

Yes I am familiar with turning between center. I have never tried it but im familiar with the idea and using a dog. Not sure how that would look on my CNC machine haha
 

rscott9399

Plastic
Joined
Jan 19, 2022

dalmatiangirl61

Diamond
Joined
Jan 31, 2011
Location
BFE Nevada/San Marcos Tx
Care to explain the process? Allowed to operate the lathe? sounds pretty condescending.
I also dont see how you are going to do that on a part that is not round as I stated the material was.

You use a combination square, draw 3 lines 120 degrees apart, it will give you a little triangle in the center, drill into it with a center drill. Do this on both ends then mount it between centers. I'm pretty sure this is explained in detail, with pics or drawings in "How to run a lathe", which is REQUIRED reading for anyone wanting to learn how to operate a lathe correctly, and keeps you from having to ask such a basic question.

P.S. Quit using rusty non round scrap, its miserable to work with. Look for hydraulic rod scrap, you get a know material (chrome plated rod is 1045, sometimes you might find polished 304SS), and its round.
 

52 Ford

Stainless
Joined
May 20, 2021
already watch them all. Abom79 is by far my favorite. I have yet to see someone perform the operation I am talking about.

I just meant you can learn a lot from them in general - since your new to turning.

I saw a similar question about getting rough stock true in a lathe not that long ago.

Find your center with the stock on the workbench, in a vise, or whatever. Take some calipers, measure your your Dia, half it, mark the center, rotate and so it again a few times find your center, punch it with a centerpunch, and either use that divet as a reference or go ahead and drill a center.



Not sure how much of This Old Tony's videos you've watched, but Adam (Abom) is actually in a few of them. Pretty funny cross-overs. Same with Stefan and Keith Fenner. TOT's lathe leveling video is really funny.
 
Joined
Apr 14, 2018
Location
Airstrip One, Oceania
Care to explain the process?
You take this (most basic tool for even a beginning machinist), use the dividing head (left hand end), scribe three or four lines across the center at different angles, average them out, put the thing in a drill press and make a center with a center drill.

5UAP9_AS01


Put the other end in your three or four jaw, skim the outside.

Or if you want to get fancy-pants put centers in both ends and turn between centers.

Taper is a different problem entirely, your tailstock is probably out of adjustment.
 

52 Ford

Stainless
Joined
May 20, 2021
You use a combination square, draw 3 lines 120 degrees apart, it will give you a little triangle in the center, drill into it with a center drill. Do this on both ends then mount it between centers. I'm pretty sure this is explained in detail, with pics or drawings in "How to run a lathe", which is REQUIRED reading for anyone wanting to learn how to operate a lathe correctly, and keeps you from having to ask such a basic question.

P.S. Quit using rusty non round scrap, its miserable to work with. Look for hydraulic rod scrap, you get a know material (chrome plated rod is 1045, sometimes you might find polished 304SS).

You got it. I kinda like rusty scrap... it's CHEAP. Given, I forge with it, so the rust just flakes right off.
 

52 Ford

Stainless
Joined
May 20, 2021
You take this (most basic tool for even a beginning machinist), use the dividing head (left hand end), scribe three or four lines across the center at different angles, average them out, put the thing in a drill press and make a center with a center drill.

5UAP9_AS01


Put the other end in your three or four jaw, skim the outside.

Or if you want to get fancy-pants put centers in both ends and turn between centers.

Taper is a different problem entirely, your tailstock is probably out of adjustment.

Does you gotta have all them extra bits on the ruler? Looks like it'd make it hard to center up big rounds.
 

eKretz

Diamond; Mod Squad
Joined
Mar 27, 2005
Location
Northwest Indiana, USA
There's more than one way to skin this cat.

First, the aforementioned center punch. You use a center head or similar method to roughly lay out the center of the shaft and then lay into it with a big old center punch and hammer until you have enough of a punch mark to use for a center. Put your part in the lathe and set the center into the punch mark and turn the shaft. Alternatively you can use the punch mark to start a center drill, insert the center, then turn the shaft. At this point you can try to turn the shaft complete, then spin it and attempt to get it centered while it's sticking way out there or you can spin it around, set up a steady and roll on the fresh turned surface and center the second end then finish turning. This is not the best method for a beginner.

Another way is to set the shaft up on a mill with the end of the shaft facing the spindle, then mill the end and center drill, reposition to the other end, mill that end and center drill. Then move the part to the lathe and start turning.

One more: make an end cap with centering set screws and a center in the end or use a live chuck in the tailstock to cut spots on the OD for the steady rest. Set up the steady and run on the spots, then face and center the first end. Spin the part around and face and center the second end. Remove the steady and turn the shaft.
 








 
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