Newbie and turning metal

[Richard.]

How much of it have you got sticking out of the chuck unsupported? Drill a centre into the exposed face and run your tail stock up its backside to see if that helps. On mine it will not turn nicely at all if I have any more than 3" of bar that diameter unsupported from the chuck. Obviously other things can contribute to a finish like that.
Tool condition, tool centre, feed speed over rpm, material hardness as mentioned above.

 

[Richard.]

Send me a lump of it if you like.
If I can turn it on my poxy little thing then there is something wrong with your set up.

 

[God mode restorations]

I have got a centre on the way. I will gear it down to minimum and start again. It must be something I doing because all was ok yesterday...if all else fails then will send a lump Richard with a drawing..

 

[dab4318]

Try and get under that "skin".

It could be that.

 

[Richard.]

I have got a centre on the way. I will gear it down to minimum and start again. It must be something I doing because all was ok yesterday...if all else fails then will send a lump Richard with a drawing..

I don't need a drawing mate I'm not asking you for work that your geared up to do yourself, I'm just curious as to whether I could or couldn't turn it on my lathe

 

[KMP]

A piece of hot rolled black bar by the look of it and therefore almost impossible to identify carbon content just by looking at it. The surface scale if it is a higher carbon content can be very hard indeed and if so you will need to get below that. MBB, Richard and dab4318 have given good advice and I would agree that most likely culprits are, too fast, lack of support and flexing of the tool away from the work or vice versa, lack of front or side clearance. A way to try and get below the surface is to turn the tool post slightly clockwise to present an angled rather than a perpendicular edge to the work, increase the depth of cut to get below the surface layer, reduce the speed and feed very carefully by hand maintaining a positive force on the tool. Check the corner of the tool to see if it has flat spotted thus removing the front and side clearance at the cutting tip.

 

[God mode restorations]

I don't need a drawing mate I'm not asking you for work that your geared up to do yourself, I'm just curious as to whether I could or couldn't turn it on my lathe

I was joking mate...its cool. I having a bad day so am putting down to frame of mind.

 

[Seadog]

I've some 1" hot rolled that is a real bugger to turn. I've never been able to get a consistent surface finish even with inserts. The consistency varies as you traverse the bar. I usually resort to emery to finish the job is it needs look nice.

 

[WorkshopChris]

I have a length of 2" that looks similar waiting to go back to a customer.
Killed a new bandsaw blade in 5 mins in that time it went down 3/4" absolutely no idea what it is, was given it to make a spacer.
Thats the problem with unknown material sometimes you hit a rough bar.

 

[brightspark]

try another piece of steel it may be hardened or just a lousy piece ive had a few of unknown origin

 

[addjunkie]

I have a couple of bits chopped out of half shafts that look like that, hard as hell on the outside, soft in the middle. Chuck it in the bin and use another piece.

 

[God mode restorations]

Going to get some new fresh mild stock..have a nice revolving center coming. Will set everything up and try again..

 

[Richard.]

Case hardened metals most likely. It's a wonderful thing if you don't have to machine it. Best of both worlds (nice hard abrasion properties from the crust with a lovely soft ductile core that will bend not snap). Generally it's less than 1mm thick but even that can be a pig to get through.
You could anneal it spencer which will soften it a lot in order to allow you to turn it. Get it glowing cherry red and slow cool it. You can also have it re hardened if required when done.

 

[God mode restorations]

Case hardened metals most likely. It's a wonderful thing if you don't have to machine it. Best of both worlds (nice hard abrasion properties from the crust with a lovely soft ductile core that will bend not snap). Generally it's less than 1mm thick but even that can be a pig to get through.
You could anneal it spencer which will soften it a lot in order to allow you to turn it. Get it glowing cherry red and slow cool it. You can also have it re hardened if required when done.

Good point Richard. .didn't think of that.

 

[WorkshopChris]

Another problem with using any odd bit of bar is you never know what it is.
I was once given a short length of bar to make a replacement pin for a mini digger bucket.
It turned ok but had a few hard spots.
3 days later the guy came back as the new pin had sheared in two, turns out the odd bit of bar was at some point in its previous life 2 parts welded together probably as a temp repair.
Customer payed for a replacement as he had provided the original material.

But just makes you think what if i had had to turn it down smaller, it would of parted company while spinning round at a few hundred rmp between centres.

I am now very wary of used or unknown material.

 

[God mode restorations]

The box of off cuts I have had for ages..but as you guys say ya never know what type. So will pop out this week to my local and get some new mild...

 

[God mode restorations]

Some new bits arrived today. Some more tomorrow.
In the mean time I started making a temporary adjustable motor bracket.

 

[Richard.]

Some new bits arrived today. Some more tomorrow.
In the mean time I started making a temporary adjustable motor bracket. View attachment 121752 View attachment 121753 View attachment 121754 View attachment 121756

Why is it a temporary motor bracket? That’s a great job it should get a few stitches, a splash of colour and be a permanent motor bracket.

 

[God mode restorations]

Why is it a temporary motor bracket? That’s a great job it should get a few stitches, a splash of colour and be a permanent motor bracket.

I was going to use the ml7 myford motor bracket because I might have to gear it down more.

 

[eLuSiVeMiTe]

My plan was to mount the counter pulley where the motor is and have the motor mounted on the back of the cabinet on a similar mount powering the counter pulley.
I recon its too fast too. The digital tacho I bought was DOA so never confirmed.