Rough finish.

[P. Waller]

Been a lot of discussion on this topic lately . A easy was to take the guesswork out of being on center ........... Take a piece of round stock and drill a 1/4" hole thru it , drill and tap 2 holes in it and put a 1/4" rod thru it . Set up a turning tool and find dead nuts center taking face cuts and adjusting . When you're there , set that little piece you just made on your tool tip and set it to a piece of flat stock across your ways or carriage etc . Lock it up and keep it on the lathe forever or until you can afford a height gage . It's an easy tooling aid .

You worry entirely to much about tool height, I set the tool in the video with an 18" steel ruler, on this lathe the spindle is 12 7/16" above the ways.
The ONLY time that I find it important to get the tool on center within .005" is when parting to 0 in the X axis.

This is a smaller lathe that is 2axis CNC (I should say that it is 2.5 axis because it will thread, it will also operate all 3 axes when taper threading) the C axis is not under full control however.
I set the turning tools with a ruler and the parting tools by trial.

 

[mmcmdl]

You worry entirely to much about tool height,

Not me , I don't worry about it at all ! Just giving free advise to someone asking to learn . I preset all my tools and never have to check them . Some people aren't fortunate enough to be able to do this , or work with a scale or obtain a height gage . This is a cheap alternative to all .

 

[Tony Pisano]

See images https://tse2.mm.bing.net/th?id=OGC....GDdGVDLa/giphy.gif&ehk=y75TL/voxygQZ04u4/zI3w

Not me , I don't worry about it at all ! Just giving free advise to someone asking to learn . I preset all my tools and never have to check them . Some people aren't fortunate enough to be able to do this , or work with a scale or obtain a height gage . This is a cheap alternative to all .

You worry entirely to much about tool height, I set the tool in the video with an 18" steel ruler, on this lathe the spindle is 12 7/16" above the ways.
The ONLY time that I find it important to get the tool on center within .005" is when parting to 0 in the X axis.

This is a smaller lathe that is 2axis CNC (I should say that it is 2.5 axis because it will thread, it will also operate all 3 axes when taper threading) the C axis is not under full control however.
I set the turning tools with a ruler and the parting tools by trial.

The quick easy way I find center is take a light face cut. You'll know right away where the center of the stock is.

 

[NortonDommi]

As T Bredehoft said there is some mild steel that is 'ropey' and extremley difficult to turn a good finish on. Good that you are playing around to see what works for you on your machine. Here's a couple of YouTube vidioes that may be of help:

 

[vimes1984]

Been a lot of discussion on this topic lately . A easy was to take the guesswork out of being on center ........... Take a piece of round stock and drill a 1/4" hole thru it , drill and tap 2 holes in it and put a 1/4" rod thru it . Set up a turning tool and find dead nuts center taking face cuts and adjusting . When you're there , set that little piece you just made on your tool tip and set it to a piece of flat stock across your ways or carriage etc . Lock it up and keep it on the lathe forever or until you can afford a height gage . It's an easy tooling aid .

I don't understand this, could you shoot me a photo?

 

[vimes1984]

To everyone else thank you SO much for enaging, I'd watched those vids before @NortonDommi,
"Their finger nail polish board, does a nice job honing HSS edges" this advice to gold now I don't have to buy anything I can just steal

 

[mmcmdl]

I don't understand this, could you shoot me a photo?

Sure will . I'm at work now though . Don't let anyone tell you that centering your tools isn't important . Yes , for junk work it may not matter much , but you're going to chew inserts and carbide to shreds if not on center or reasonably close . Give or take a few thou . I'm turning and facing 15-5 SS at 32 Rockwell C at the moment , and it don't like to cut without taking a good bite out of it . I'de be busting cemented carbide tools to bits if I wasn't on center .

As far as the tool aid , think of an in-movable depth gage . Once you establish the CL of your lathe , it never changes , so why anyone would just estimate with a scale is beyond me . Also , as you progress in the trade and use form tools , if you aren't on center , you can't get true form of the tool . This is advanced for some , but if you're working with engineers that need their part perfect , it matters . Learn the good traits of machining early , they'll save you aggrevation years down the road .

By the way , spent 2 weeks over in Ireland last years this time . Boy got his masters at U of Limerick . I would live there in a heartbeat !

 

[BaronJ]

Hi Guys,

The easy way ! Put a center in the spindle taper. Move the saddle up to the chuck. Put a block of material on the top slide and use the center to scribe a line on the block. Job done ! Simply adjust your tool hight to match the scribed line.

I have an "L" shaped piece of scrap alloy that I just sit on the top slide with a line scribed across it. Works every time

 

[vimes1984]

Well guys ( & gals??)
I've actually managed a decentish finish in the end
I'm really really happy with it!
It's not perfect but it's a start.

 

[mikey]

Vimes, I'd like to offer an opinion. I think the main cause of your issues is your tool. The pics you posted earlier give us some hints. The tool on the left has side and back rake, which is good. We cannot clearly see the relief angles but they look too small to my eye. The nose radius is too big so the tool will deflect big time. The tool on the right appears to have the rake angles inclined in the negative direction, and that tool's nose radius is also too big; this tool will not cut well. It will help to show us better pics of the tool.

Your tools need to be sharp. Buy some diamond stones and hone the edges. Working with dull tools doesn't work well.

I'm in the "get the tool on center" camp. For HSS tools, I feel it is important to get the tool dead on center, not above or even a little below. Go below and the work wants to climb onto the work. You might think this is just hobby guy BS but if you ever work on small diameter stuff to close tolerances you will understand why this matters. Make yourself a height gauge that is set to the exact centerline of your lathe spindle and use it every time you mount a tool.

If you can, find some leaded steel or aluminum to learn with. Using mystery steel or worse, stuff like 1018, will only frustrate you.

Finally, keep in mind that you're using a mini-lathe with very limited power, rigidity and speed. HSS is the best tooling choice for these little lathes. I suggest you spend some time learning to grind good ones.