By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Allendale Jan 24th

my first lathe.

All Topics | Latest Posts

Search for:  in Thread Title in  
jamie creighton 110/12/2019 18:44:53
15 forum posts

im a great believer in just having a go,you learn from your mistakes,well some people do lol

Howard Lewis10/12/2019 22:34:49
3361 forum posts
2 photos

HSS is probably best for a newbie. Throw away tips are intended to run at high speeds and feeds are such that the metal is heated to the point of being softened. This is useful for turning hardened materials, where HSS will not cope,

Start by taking small cuts. with light feeds. Deep cuts and higher feed rates, (for roughing ) can come later when you have more experience.

Find a local Model Engineering club if you can, and join. You will get advice and help, face to face, and probably hands on, one to one, either on your machine, or someone else's.

Exact clearance angles are probably not too vital. Most folk will grind a knife tool with about 5 - 10 degrees clearance angles. (Cue howls from the perfectionists! )

It is unlikely that you will get on well with HSS tools with negative rake. I sometimes (mostly through sheer idleness ), use zero top rake.Too great a top rake will weaken the tool and shorten the life between regrinding. Softer materials, such as Aluminium, will accept greater top rakes than hard material.

Various books will show how to grind tools.

For a better surface finish, a radius on the edge of the tool can be stoned d or ground on. Too large a radius can induce chatter.

The most important thing is to ensure that the cutting edge is on the centre height of the job. Too high and the tool rubs instead of cutting, too low and it does not cut properly, and effectively has much too great clearance.

Both these faults will meant the tool does not cut to the centre, leaving a pip in the middle when facing.

If you do not yet have one, make a centre height gauge, and set the tool to it, always. There are various ways of finding the centre height. As a starting point, keep shimming a freshly ground tool until a facing cut leaves no pip in the middle. The set your gauge to that. All other tools can then be set to the gauge.

For tools in the front toolpost, the blade of the gauge is above the tool. Subsequent tools are then shimmed until they just make contact with the underside of the blade.

When / if you fit a rear toolpost, the gauge will need a second blade fitting below the original one. For this, fit the lower blade, loosely, set the upper blade, to the centre height cutting tool, again, The lower blade can then be brought up to contact the upper blade and locked in position. You are then ready to set tools in either the front or rear toolpost to the centre height. Tools in the rear toolpost will be mounted inverted, with the cutting edge facing down, hence the use of the upper surface of the lower blade.

You will make mistakes, but you will learn from them

Howard

Nigel Graham 211/12/2019 00:57:10
665 forum posts
15 photos

I wonder if that odd-looking tool-post had been made for some very specific work, not general-purpose turning, though I can't imagine what. A lot of brass machining perhaps?

'

A note on grinding tools: you can obtain satisfactory results grinding HSS tools on a straightforward off-hand grinder, but it takes quite a bit of practice. Without going to the extent of building an elaborate tool-grinder, many people replace the rather crude, as-bought rest on an ordinary grinder, with some form of fairly simple but effective, wider table with adjustable stops or fences. Harold Hall's book on the subject gives designs for such accessories.

'

I don't seem to have noticed very much difference in finish quality between HSS and carbide tools, all other things being equal. The inserts are indeed designed to rip the metal off at alarming rates, but that's on massive industrial production machines; and they seem perfectly happy at our modest speeds and feeds. " Can " does not equal " must ", here.

I think what would really matter is selecting the right tip for the material, though "our" stockists do try to sell ones best matched to our needs. (A tip manufacturer's full catalogue is a mind-boggler of work-materials, tip geometries, chip loads and nonchalant remarks about tip lives of 20 minutes. We hope for nearer 20 hours!)

For example, recently my band-saw took literally hours to cut a slice of 2.5"dia stainless-steel of unknown grade but once on the lathe - a Myford 7 - the metal cut beautifully with both HSS and carbide. Having turned a short length down to 2" and drilled and tapped the centre hole as required, I parted the disc off with an insert tool in the rear tool-post. I'd found the wider HSS blade was unhappy with the task. It was a slow process, a lot of very careful, patient feeding, clearing and lubricating, and experimenting with speeds; but gained a very good finish indeed. That was at no more than perhaps 100rpm for most of the depth (low pulley, back gear, inverter turned down a bit but still in the green speed sector).

I needed a decent finish, not so much for appearance though I wanted that too, as function. The disc is a thrust-washer against the end of a Nylon roller.

I think the crucial aspect is not tool material, but tool setting, so the cutting geometry is spot-on. I set the parting-tool height by the facing marks, before centre-drilling. (Parting-off and deep grooving also means ensuring the tool is at right-angles to the axis. I use the chuck face for alignment by gently pushing the tool-holder against it while tightening the post clamps.)

Hopper11/12/2019 07:10:07
avatar
4634 forum posts
101 photos

That is the most bizarre looking toolpost on a small lathe I have ever seen. And no amount of Googling around reveals anything even remotely like it. It has way too much negative rake for general purposes.

You need to put that toolpost to one side and use the standard one that holds the tool in the normal flat position.

SillyOldDuffer11/12/2019 10:00:07
5894 forum posts
1280 photos
Posted by Hopper on 11/12/2019 07:10:07:

That is the most bizarre looking toolpost on a small lathe I have ever seen. ...

I agree. My guess is it's an unsuccessful quick-change tool-post and those angled slots are meant to take a tool-holder which holds the cutter at a normal angle. My other thought was it's angled to take a tangential cutter, or both sides are used with a missing ball-cutting attachment. Doesn't make much sense though.

Buying second-hand can be confusing. Not unknown for lathes to come with accessories meant for different machines entirely. Although Jamie's strange tool-post looks as if goes with his lathe, perhaps that's just coincidental!

Dave

Michael Gilligan11/12/2019 13:39:19
avatar
15852 forum posts
693 photos
Posted by SillyOldDuffer on 11/12/2019 10:00:07:
Posted by Hopper on 11/12/2019 07:10:07:

That is the most bizarre looking toolpost on a small lathe I have ever seen. ...

I agree. My guess is it's an unsuccessful quick-change tool-post and those angled slots are meant to take a tool-holder which holds the cutter at a normal angle. My other thought was it's angled to take a tangential cutter, or both sides are used with a missing ball-cutting attachment. Doesn't make much sense though.

[…]

.

I wonder if it was designed to have a tall spacer under it ... and to be a rear toolpost.

MichaelG.

jamie creighton 111/12/2019 17:15:55
15 forum posts

well all i know is it came already mounted on the lathe and as i said previously the original oem one has been put back on

Roderick Jenkins11/12/2019 18:31:50
avatar
1891 forum posts
485 photos

The original Hobbymat mounts the tools directly onto the top slide:

$_86.jpg

Jaimie's tool post looks like a brave attempt to make a rotating tool post that will allow a selection of tools to be presented at the correct height. If the tools are ground appropriately then I think it will work.  It also has the advantage that the tools can be adjusted to centre height without the use of shims,  just by the projection of the tools

Rod

Edited By Roderick Jenkins on 11/12/2019 18:41:22

Michael Gilligan11/12/2019 23:01:16
avatar
15852 forum posts
693 photos
Posted by Roderick Jenkins on 11/12/2019 18:31:50:

The original Hobbymat mounts the tools directly onto the top slide:

$_86.jpg

[…]

.

I’m not questioning your description, Rod ... but I’m bewildered

How is one expected to use the round plate ?

MichaelG.

Roderick Jenkins11/12/2019 23:30:30
avatar
1891 forum posts
485 photos

Michael,

Just like this:

hmat toolpost.jpg

It's a bit crude frown

Cheers,

Rod

(Both photos grabbed from the web)

Michael Gilligan11/12/2019 23:41:12
avatar
15852 forum posts
693 photos

Sorry, Rod ... I didn’t ask the question clearly blush

I realise how one tool is clamped, but I’m struggling to see the benefit of having multiple ‘stations’ when the tool-post is just a static plate.

MichaelG.

Paul Kemp12/12/2019
503 forum posts
18 photos
Posted by Michael Gilligan on 11/12/2019 23:41:12:

Sorry, Rod ... I didn’t ask the question clearly blush

I realise how one tool is clamped, but I’m struggling to see the benefit of having multiple ‘stations’ when the tool-post is just a static plate.

MichaelG.

Fair point, I have used the front pair for boring bars, the side pair for normal tools and occasionally the rear pair when turning a large diameter, never used the pair on the tailstock side myself - but supplied with the lathe as std is an angle plate which mounts to the cross slide onto which the top slide bolts to give you a vertical slide for milling. Also provided was a small machine vice for work holding on the top slide in the vertical position. I suppose you could leave the tool post in position as another way of clamping the workpiece in which case the screws on the tailstock side may be used? Before I got the micro mill I did a fair bit of milling using the supplied vice but I have never used the tool post to hold milling jobs, never occurred to me before! Agreed the standard tool post is a bit unconventional as well but it has served me well and I think they are great little machines, the only real limitation is the slow speed is not slow enough for coarse thread screw cutting unless you are quick and brave! This was addressed by Essel Engineering who produced an additional set of pulleys, I don't have this though.

Paul.

Michael Gilligan12/12/2019 00:04:48
avatar
15852 forum posts
693 photos

Thanks, Paul

It’s bedtime now, so I will ‘sleep on it’

Perhaps it will be obvious in the morning.

MichaelG.

fizzy12/12/2019 08:16:50
avatar
1716 forum posts
116 photos

Made for a tangental tool I think. No idea why you would bother though.

Howard Lewis12/12/2019 20:56:03
3361 forum posts
2 photos

A tangential tool is very useful item for most turning and facing jobs.

And dead easy to sharpen, only needing one face to be ground. Easy to set on centre height, if you have a centre height gauge, of some sort.

Howard

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Support Our Partners
ChesterUK
emcomachinetools
cowells
Allendale Electronics
EngineDIY
Warco
Eccentric July 5 2018
Eccentric Engineering
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest