Who the hell inveted the LATHE!!!

[erasma]

Well as the title says.... what a scrappy tool who thought it would be a good idea to make things round in the first place!!!

I tried to turn down some aluminum yesterday and well lets just say the first few passes were so rough it could as well have been a heavy threaded screw!!! by the time things were still rough I was aiming for 12mm and ended at 11.... something & I was sure I was no where near 12 when I did the second measure.

any good advise? tips and or tricks? on how to use these THING

Thanks

 

[Munkul]

Did you centre-line your tool? If it's high or low, then you're always gonna get crap results.

 

[Seadog]

First things first:

Are the slides adjusted correctly?
Is there a lot of backlash in the feed screw?
Is the tool post rigid?
Is the tool sharp?
Is the tool on centre?

 

[Dr.Al]

What lathe have you got? What type of tool were using? Was the tool sharp? Was there any radius on the tip of the tool? Was the tool mounted rigidly with the cutting edge on the centre-line of the lathe? Did you move the carriage roughly with the carriage hand-wheel or did you use the power feed on a very fine feed rate?

There are loads of things that can affect the quality of finish, but you probably want a sharp HSS tool with a slightly rounded tip (sharp in the vertical plane, slightly rounded in the horizontal plane). Using the power-feed on a fine rate will give you a better finish until you get used to the "feel" you need for using the carriage hand-wheel.

Also does the cross-feed dial on your lathe read radius or diameter? If it reads radius, then you may be reducing the diameter twice as fast as you expect and that might be why you overshot the target dimension. Lots of people have a strong opinion on whether radius reading or diameter reading is best, but either can work just as well if you understand what it's telling you.

 

[RaceDiagnostics]

 

[erasma]

The lathe I own comes from the land of the coronavirus & all those many suggestions all sound brilliant it seems there is a lot more to learn then a piece of round stuff spinning and a tool shaving bits off it. There is just something about a lathe I don't fully understand and I need to get my head around it.

it's a little larger then a desktop lather but not as big as a Colchester. I am busy turning it into a electronic screw thread which sort of worked my stepper motor needs an upgrade which I have.

 

[Newlands]

You probably need to post a photo of the lathe, and another closer one of the toolpost and tool, along with the speed and feed. If there are any glaring errors folks on here will let you know!
For 12mm aluminium you probably need to be running fairly fast, somewhere near 800-1000rpm if your lathe can go that fast. With a sharp high speed steel tool you should get a mirror finish provided everything else is right (tool geometry, centre height, depth of cut, feed rate, decent condition of slideways etc).

 

[frank horton]

join ur local "Model engineering group" there will be someone there who'll come to ur place to show u how to set up and turn ur project.....
If I was local I'd be happy to do it.....
all u gotta do is ask......
if ur having that kind problem on ally it can be dangerous when u start turning steel.........
get some help please.....

 

[slim_boy_fat]

The lathe I own comes from the land of the coronavirus & all those many suggestions all sound brilliant it seems there is a lot more to learn then a piece of round stuff spinning and a tool shaving bits off it. There is just something about a lathe I don't fully understand and I need to get my head around it.

it's a little larger then a desktop lather but not as big as a Colchester. I am busy turning it into a electronic screw thread which sort of worked my stepper motor needs an upgrade which I have.

YouTube will be your friend, search out @doubleboost's SSS series of videos.

 

[pressbrake1]

I don’t believe it, you’re good on a mill!

 

[rikrobson]

so what size is the work piece in diameter?
What speed was the lather turning at?
what was the depth of cut?
how fast was the feed down the bed?
do you know what type of aluminium it was?
what type of too were you using?

 

[God mode restorations]

Put a picture up of the machine you have.
Get some good shots of the compound slide. Cross slide .tool post ect.

 

[gaz1]

Well as the title says.... what a scrappy tool who thought it would be a good idea to make things round in the first place!!!

https://www.gracesguide.co.uk/Early_Lathes

 

[erasma]

I will take some pics over the weekend - I work away from home during the week.

 

[erasma]

I don’t believe it, you’re good on a mill!

It's sad but true my son was watching and I could hear him laughing inside

I have used my lathe before to good affect just have not been on the round wheels in a long time, I turned it on looked at the stock turned the wheels and well it looked as rough as a bears ass - as my father would say

It's one of those things you can read all you want how it should be but until you do it you have no idea how it works - reading how to play a sport a professional it does not make one

 

[grim_d]

What type of aluminium was it?

I got a hold of some bits of bar a while ago, general purpose stuff for general fabrication.

Nothing I did make it turn nicely. It was all chewy and horrible.

 

[Barking Mat]

@RaceDiagnostics , thanks for sharing that fascinating video, I look forward to watching the rest of his stuff.

I'd never heard of Vaucanson, or the Paris museum of 'Arts et Metiers', a French version of the science museum. I'll have to find and excuse to go visit, looking forward to watching videos of it. I was wondering the other day how long lathes had been around for.

Love finding good stuff to watch on YouTube. Thanks again.

France as well as Britain produced some first class engineers, one local to me was Francois Hennebique 1842 - 1921, widely reputed to be godfather of reinforced concrete constructions, built buildings and bridges all over (some) of the world, Wales, France and America come to mind. Never heard of him, till I found myself working next to a decaying mill near Nantes which they couldn't tear down as it was being classed UNESCO or similar, quick Google and he was incredibly prolific.

Thanks again.

 

[zx9]

Any appreciable length of 12mm aluminium will need some support, either from the tail stock or a steady together with a sharp HSS tool or a polished insert designed for aluminium.
Like the others have said, post more details or pictures of your set up.

Edit: Sorry post crossed with your last two posts, note to self: Don't read a thread then wander off for half a hour before replying

 

[Barking Mat]

Who the hell invented the lathe?

Apparently the ancient Egyptians in roughly 1300 bc.

They too had the same problems turning aluminium as you have.

That last line isn't actually true.

 

[Dr.Al]

They too had the same problems turning aluminium as you have.

The problem being that aluminium wasn't going to be discovered for over 3000 years? That's a hell of a lead time to be quoted when you order material!