Author Topic: Novice question Re lathe  (Read 8212 times)

Offline piper1

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Novice question Re lathe
« on: August 25, 2013, 07:21:59 PM »
Hi i wonder if some one could advise me on an issue I'm  having regarding my lathe and the quality of the cuts.

Iíve tried cutting Stainless steel, Brass and alloy rods and the quality of the cut appears to be very rough.

I pretty sure the fault is me and the way I'm setting the machine up or possible using incorrect cutting tools.
Any help would be greatly appreciated.

Thanks
Kev       


Offline Bangkok Mick

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Re: Novice question Re lathe
« Reply #1 on: August 25, 2013, 09:59:33 PM »
Hi Kev,

I am also new to using the lathe and I am sure if you post a couple of pictures of your tooling and set up you will get great advice from the experienced form members here.

There are also many beginners tutorials available on U Tube, I goggled lathe turning, facing etc. and watched a few of these and found them very helpful when getting started. In fact there are many levels of good practice available via u tube on the internet including thread cutting etc. and when I am practicing a new skill I ask advice here and look for tutorials posted on U Tube.

Hope this helps.

Cheers Mick

Offline Bradley Simmonds

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Re: Novice question Re lathe
« Reply #2 on: August 26, 2013, 08:46:27 AM »
Pictures of tool-carbide,hss, cobalt, material finish, tool set up, part setup and held in chuck, speeds and feed information, depth of cut...

If carbide...nose radius of carbide...

Offline piper1

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Re: Novice question Re lathe
« Reply #3 on: August 26, 2013, 01:31:10 PM »
Thank you for the replies

Offline Pete.

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Re: Novice question Re lathe
« Reply #4 on: August 26, 2013, 02:08:09 PM »
Whenever I get a poor finish it's almost always that I ave got the cutting edge wrong when grinding my tool. You can get all the angles right but have a slightly dull edge - a tiny slip on the grinder - and it just won't cut. I use a 30X loupe to inspect them now and you wouldn't believe how rough a 'perfectly good looking' edge can be.

Offline hopefuldave

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Re: Novice question Re lathe
« Reply #5 on: August 26, 2013, 05:40:26 PM »
Some good points re tool sharpness, and recommendations for YouTube videos, Mr Pete has produced some good beginner's tutorials.

Beyond that.... More info please! What lathe, tools, workpieces and what rpm, depth and feed of cut, etc.?  What's the length/diameter ratio of the work, long slender workpieces will need extra support to avoid chatter/vibration and a poor finish, etc.
Rules are for the obedience of fools, and the guidance of wise men.

Offline piper1

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Re: Novice question Re lathe
« Reply #6 on: August 27, 2013, 03:50:21 PM »
Whenever I get a poor finish it's almost always that I ave got the cutting edge wrong when grinding my tool. You can get all the angles right but have a slightly dull edge - a tiny slip on the grinder - and it just won't cut. I use a 30X loupe to inspect them now and you wouldn't believe how rough a 'perfectly good looking' edge can be.

Thank you for your reply but I'm not that advanced to be able to re-sharpen my tools at the moment so the probability of them being blunt tools is high.
I know that this is something that I need to learn how to re-sharper cutting tools sooner than later.

I really need to get myself of some sort of course. 

Offline piper1

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Re: Novice question Re lathe
« Reply #7 on: August 27, 2013, 03:58:47 PM »
Some good points re tool sharpness, and recommendations for YouTube videos, Mr Pete has produced some good beginner's tutorials.

Beyond that.... More info please! What lathe, tools, workpieces and what rpm, depth and feed of cut, etc.?  What's the length/diameter ratio of the work, long slender workpieces will need extra support to avoid chatter/vibration and a poor finish, etc.

Thank you for the reply

The lathe is a Smithy mill/ drill lathe CB-1220-XL

At the moment I'm trying to make Drip tips out of 10mm SS and Brass rod, pretty much able to achieve the aim but the quality of the finishes is poor and requires lots of sanding.

The tools are very similar to these.
http://www.ebay.co.uk/itm/360423893257?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2648

Speed, sorry for my ignorance I don't really know.
 

Offline colin563

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Re: Novice question Re lathe
« Reply #8 on: August 27, 2013, 05:02:04 PM »
I struggle sharpening tools as I've only got the use of one arm

My solution was the diamond tool holder from eccentric engineering really easy to do

But the tool is on the expensive side but it does work as good as the video

Cheers Colin

Offline garym

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Re: Novice question Re lathe
« Reply #9 on: August 27, 2013, 06:36:24 PM »

....The tools are very similar to these.
http://www.ebay.co.uk/itm/360423893257?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2648.......


I'm a relative beginner also, but from my limited experience I would say there is a good chance it could be the tools. When I got my mini-lathe about eighteen months ago I had similar problems with the finish, even on free cutting MS. I wasn't confident with grinding my own tools but after lots of encouragement on another forum I had a go and was amazed that my first attempt gave a better finish that the purchased ones. Since then I've ground all the tools I've needed apart from a small diameter boring bar which I couldn't get right so bought an insert-tipped one.

Gary
Workshop activity resumes now ankle improving :-)

Offline Fergus OMore

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Re: Novice question Re lathe
« Reply #10 on: August 28, 2013, 05:54:54 AM »
I think that you are dead right and dead wrong :doh:

You have a set of brazed carbide tools or so I assume. At some point, they would be sharp but the question is how sharp are they now- which is what really matters. You have been using stainless steel which is a quick way to blunt whatever tooling you possess. Somehow, I doubt that you have facilities to recondition them as you will need diamond wheels and possibly finish the last bit of the work using diamond laps. So where do you go from there?

Frankly, if it was me, I'd either change my material or change my tooling. I'd probably do both but if you are stuck with stainless, I'd head off to buy the correct carbide inserts and tools and swop them when they got blunt.

Me, I'm a mean old Sassenach-  and use almost entirely high speed steel tooling  on ordinary steel or cast iron.

Oh and for the record, I've  made a set of pipes- Northumbrian of course!
So re-think please and let me help sort out my missus with her sopranino saxophone, eh?
 

Offline hopefuldave

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Re: Novice question Re lathe
« Reply #11 on: August 28, 2013, 04:14:33 PM »
I worked for q well known UK importer who insisted those.brazed carbide tools were Just What A Novice Needs ( high profit margin...), they are in fact the machining equivalent of the Chocolate Fireguard...

Straight from the box, the edge geometry is unlike any tool I've known, they need sharpening and honing before use, once ready and used the edges crumble and.shatter in no time.... Decent (non-Chinese) indexable tooling is.worth the money, the Chinese stuff is really one-use disposable, in my humble opinion - great for taking the skin off an iron casting, but swap to HSS for finish /  accurate cuts.
Rules are for the obedience of fools, and the guidance of wise men.

Offline vtsteam

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Re: Novice question Re lathe
« Reply #12 on: August 28, 2013, 10:07:21 PM »
If you're a beginner, I think it's helpful to start out with the basics before moving on to specialized stuff.

High speed steel lathe tool blanks are inexpensive, and by grinding your tools instead of buying inserts or ready made tools you will learn a lot about what is needed for different materials and cuts. If you goof up sharpening HSS, you can adjust it until it works better.

Mild steel is all you need, for practice blanks rather than stainless, and it will teach you a lot. True, it isn't easy to get a fine finish on some of the lesser grades, but that kind of difficulty is a blessing in disguise because it allows you to see improvement when it happens. You will learn a lot about feeds and speeds and chatter, etc. as you try to improve the finish on practice bars. These things are all important to experience first hand. It gives you the background to understand by feel almost, what is needed. It is very much more instructive than looking up inserts in a catalog.

High speed steel lathe tools can be made very sharp. It's not necessarily a lesser choice. HSS may not have the wearing qualities of carbide, but is easily re-sharpened and to a high degree. It is true that for some uses carbide is a better choice. But for most everyday use for common steels brass and aluminum HSS is an excellent choice. I think it is ideal for learning, inexpensive and flexible in application.

The first week I started eleven years ago after months of building a lathe and having a lot of expectations and anticipation, I had trouble getting anything but a rough edge on work and was appalled at what I had vs what I hoped it would be. Don't get discouraged by that. It happens to everybody -- particularly with a small lathe. I gradually learned to sharpen better, adjust speeds and feeds, increase work holding stiffness, too, by many small changes to what I was doing -- long overhangs of thin stock don't work well. Turning work between centers helped greatly for some things, etc. etc.

You need to learn your lathe and its capabilities, and don't worry too much if you can't at first get the same results you see in photographs online and in magazines. You will eventually get there as you improve your methods and understanding. Experience is the best teacher.

One place I found helpful for my initial sharpening of tools back then (and is still online today) was Varmint Al's website. He shows lots of interesting stuff for a newcomer and a first lathe. The diamond toolholder also mentioned above is nice (but pricey) if you are trying to achieve a nice finish with relatively easy tool grinding.

Whatever you choose, don't worry too much. You will work it all out in time!  :thumbup:
I love it when a Plan B comes together!
Steve
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Offline piper1

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Re: Novice question Re lathe
« Reply #13 on: August 29, 2013, 04:49:28 PM »
Thank you so much for the constructive replies, i really do appreciate the time you have given to me by explaining some of the fundamental points  .
I do realise that the more i get to know my machine the clearer and easier things will become.

I think that one of the best ways for me to learn how to operate a lath apart enrolling on a machine course is to try and find some one who is local to me and willing to show some of the basic points of getting started.

Thank you once again   

Offline sparky961

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Re: Novice question Re lathe
« Reply #14 on: August 29, 2013, 09:00:04 PM »
Piper,

I bought my first mill/drill in around 2002, thinking I'd be running production parts and making money with the shiny machine I knew very little about.  (I see lots of nodding heads out there, so read on)  Fast forward to the future, where I'm now solely responsible for the machining operations of a fairly large metal fabrication business.  Now, I'll be the first to admit that most of what I do isn't that complex, mostly drilling, tapping, and some profile milling.  But the important parts is what happened in between, or maybe rather what didn't happen. 

I've had neither formal nor informal instruction.  I have had quite a few failures of my own, and learned from many hundreds that other people have made.  But I'm entirely self taught, which is exactly the mentality that I believe one needs if they want to become successful with machining as a hobby or career.  I remember going to the public library, while those were still fairly early days in terms of the Internet, and sitting at one of the basement tables hand copying some sketches of how to grind various tools.  The 3-ring binder of paper that went with me got heavier and heavier as I added this and that article in my relentless pursuit to having both skill and confidence in transforming "unyielding" lumps of steel into the parts floating around in my imagination.

You need to be respectful of your machines but not afraid of them.  You need to be observant and constantly adjusting this and that while seeing what kind of effect your changes have.  You need to ask questions on respectable forums like this one, and learn to "separate the wheat from the chaff" when you get replies.

You're well on your way to figuring things out if you manage to stay engaged and focused on getting through every challenge that's tossed your way without trying to take the easy way out.

The worst possible attitude that one could take is to think that someone else is going to teach them how to do things.  No, you need to teach yourself, using the multitude of resources at your fingertips.

Offline Fergus OMore

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Re: Novice question Re lathe
« Reply #15 on: August 30, 2013, 06:00:46 AM »
This is not intended to be a definitive  or exhaustive reply but------------------- :doh:

Go into Aldi or somewhere similar and buy a cheap sh1te double ended grinder. Throw the wheels at the local Moggy. Go into Cromwell Tools and get a pair of replacement white wheels perhaps 60 and 80 grit and make up a pair of rests - from B&Q wood. Get a hold of old Ian Bradley's book on Shaping and Lathe Tools ( Map) and follow up his words and music.


It isn't wonderful stuff as it was written way back in 1949 but you should have tools which will cut metal.

Offline Anzaniste

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Re: Novice question Re lathe
« Reply #16 on: September 01, 2013, 02:30:07 AM »
Amongst all the invaluable advice offered I notice that no one has mentioned the importance of setting the height of the tool tip.
One of the simplest methods is trapping a thin ruler between the tool tip and the work (apply just enough pressure to hold up the ruler). If the tip is too high the top of the ruler will lean away from you and if it is too low it will lean towards you. When it is spot on the ruler will be vertical.
Alternatively line the tip up with the tail stock centre.
There are other methods that require equipment that is very simple but I guess that at this stage you do not possess. As you gain your experience you will come across a method that takes your fancy and that's the way you'll go.
Always set the tool height before you start turning. If you have a quick change tool they have built in height adjustment. Failing that have a selection of packing pieces to put under the tool. Funnily, when I first started out my "bits and pieces" box never seemed to yield the right packing pieces but it did not take long to accumulate a good collection. The arrival of a quick change tool post solved that .:thumbup:
Good sharp tool at the correct angles are essential but the cutting angle is only true when the tool point is exactly on the centre height of the lathe.
Scrooby, 1 mile south of Gods own County.

Offline piper1

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Re: Novice question Re lathe
« Reply #17 on: September 03, 2013, 04:02:09 PM »
Thank you so much for all the great advice now time to put them all into practice  :beer:

Offline Fergus OMore

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Re: Novice question Re lathe
« Reply #18 on: September 04, 2013, 03:16:00 AM »
I've just taken a moment to open my battered copy of 'Bradley' and yes, he constantly keeps showing 'centre height' in his diagrams  of set ups
One trick that he doesn't show nor have anyone else in this post is the humble black felt tipped waterproof pen which if carefully used will show where tool edges have become blunt.

I really think that that as a beginner- with only distance learning that you should make a Bradley honing jig. OK it is dated and was written for a bygone age( Mine) but it can be altered to touch up a carbide tool which probably needs different angles than high speed steel.  A so called fine 'diamond' file will work wonders on a blunt tool.


Offline piper1

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Re: Novice question Re lathe
« Reply #19 on: September 04, 2013, 11:09:02 AM »
I've just taken a moment to open my battered copy of 'Bradley' and yes, he constantly keeps showing 'centre height' in his diagrams  of set ups
One trick that he doesn't show nor have anyone else in this post is the humble black felt tipped waterproof pen which if carefully used will show where tool edges have become blunt.

I really think that that as a beginner- with only distance learning that you should make a Bradley honing jig. OK it is dated and was written for a bygone age( Mine) but it can be altered to touch up a carbide tool which probably needs different angles than high speed steel.  A so called fine 'diamond' file will work wonders on a blunt tool.

Hi is any of this information available on the internet, done a little search but I didn't really find anything.

Thank you 

Offline Fergus OMore

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Re: Novice question Re lathe
« Reply #20 on: September 04, 2013, 12:11:45 PM »
Bradley and most of the good authors demand a 'wee sporran spanner'  :hammer:

The bit about using a felt tip is 'me' or someone that I've forgotten :doh:

If you want to do a series of 'competences', I'd reckon that Advanced Machine Tool Work by A H Smith is as good as any and free on the net. It would probably cost you more for ink and paper than something secondhand from perhaps Amazon, to down load. I gave my copy of Smith away to another newcomer- so sorry.

What you will find is that buying castings now prohibits making tool grinders, cheaper to buy a 6" one and kit it out properly. Others will disagree which is their prerogative!

Meantime, regards

Norman


Offline The Steamer

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Re: Novice question Re lathe
« Reply #21 on: September 04, 2013, 08:21:38 PM »
pictures of your set up's ect would help us narrow down whats going wrong ;-)

Offline piper1

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Re: Novice question Re lathe
« Reply #22 on: September 05, 2013, 12:10:15 PM »
Bradley and most of the good authors demand a 'wee sporran spanner'  :hammer:

The bit about using a felt tip is 'me' or someone that I've forgotten :doh:

If you want to do a series of 'competences', I'd reckon that Advanced Machine Tool Work by A H Smith is as good as any and free on the net. It would probably cost you more for ink and paper than something secondhand from perhaps Amazon, to down load. I gave my copy of Smith away to another newcomer- so sorry.

What you will find is that buying castings now prohibits making tool grinders, cheaper to buy a 6" one and kit it out properly. Others will disagree which is their prerogative!

Meantime, regards

Norman

Thanks Norman

Offline piper1

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Re: Novice question Re lathe
« Reply #23 on: September 05, 2013, 12:11:12 PM »
pictures of your set up's ect would help us narrow down whats going wrong ;-)

I will take some pic's and upload them, thank you.

Offline kwackers

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Re: Novice question Re lathe
« Reply #24 on: September 05, 2013, 12:44:06 PM »
My experience of starting out was trying to turn a piece of old steel with one of the carbide tips I got free with my Chinese lathe. It looked as if the dog had chewed it, disappointing wasn't the word, I thought I'd wasted my cash.

Someone recommended I tried using insert type tools so I bought one on the basis that it was at least one less thing to get wrong. The difference was amazing, my machine was cutting properly, with little effort and the finish was pretty good (and that was just eyeballing the tool height).

Can't say I've ever looked back, I've since learned to sharpen HSS for those times when one off 'form' tools are required but most of my turning is with tipped tools.
Among other things they don't seem as fussy about center height, I've deliberately tried moving them above and below to see what effect they have but find they need to be significantly off before the finish starts to suffer (size of work dependent). This is even true of my tipped parting tool, only once have I had parting go wrong and that was because I was running the lathe the wrong way! (I still got half way through the bar thinking that the tool had gone blunt before the cut threw the tip out of the holder!)

Bit long winded, but overall if you reduce the number of things that can be wrong it's much easier to find out what is...