What sort of tooling are you using Jamie, and is it bang on centre height?

A photo of the tool and work would help. Though I doubt it's the problem the temporary mounting balanced on boards may not be helping. Shouldn't be necessary to tighten the gibs until they actually grip.  Bolting down my mini-lathe didn't make any difference – it was OK on rubber feet.

One thing that jumps out at me is the tool-post with angled slots:

How are you holding the tool in it?

Various possibilities:

Tool blunt or wrongly angled.
Poor steel (Rather a lot of metals don't machine well. Don't test lathes with unknown scrap!)
Tool point extended too far and bending under cutting pressure
Work bending under cutting pressure.
Swarf getting trapped under cutting point. (This causes most of my finish problems.)
Wrong speed & depth-of-cut combination.  (Experiment)
Wants lubrication, especially if tool is HSS.
Bed and or headstock bearings worn. (Should be obvious.)

Dave

Edited By SillyOldDuffer on 08/12/2019 14:09:56

100% the oddest toolpost I have ever seen, I suggest going back to the original round one for the moment.
I take it you are doing auto feed when the problem occurs because if you are manual feeding even changes is speed of hand movement can show up. There is always some backlash on the cross-slide however tightly the gibs are set and well the screw is adjusted. On the final cut lock the cross and top slides.

Jamie,

Thanks for the bigger picture. Never seen a tool post like that before! Can't imagine what advantage it gives, disadvantage I would say is the large negative top rake, not really what you want for steel. I think you will get better results with the conventional round tool post that came as standard, that will give you a zero or positive rake depending how the tool is ground. I get a decent consistent finish without locking slides on mine.

Paul.

Beware of plastics and metals difficult to machine! My start as a total beginner was dogged with problems caused by me assuming a metal-working lathe would obviously cope with anything. Not true! Plastics are usually gummy, pliable and easily damaged by heat. Many metals from finished products will have been carefully selected to suit a particular purpose and manufacturing process; zero consideration is given to chaps wanting to turn it on a small lathe! For example, aluminium window frames are made from an alloy intended to be extruded, too soft to machine well. There's a lot to learn about machining different materials.

I wasted months as a beginner. I may have been unlucky because my entire collection of scrap metal turned out to be carp. Buying EN1A was a revelation – it's a mild-steel specifically formulated for machining. Plenty of suppliers other than Metal Supermarkets, but their description is worth repeating:

EN1A is a low carbon-manganese free cutting steel suitable for machining using both automatic and CNC machines. EN1A is used for turned components, such as nuts, bolts, studs and hydraulic fittings.

EN1A, also known as 230M07, can be case hardened to produce components with enhanced wear resistance.

EN1A can also be supplied in a leaded grade, EN1A Pb, 230M07pb.

The leaded grade is particularly good for turning, it's about twice as machinable as ordinary mild steel.

Same advice when buying other metals especially Stainless Steel, Aluminium and Bronze: look for 'free-cutting' or 'suitable for machining' in the specification. Brasses are also somewhat variable, but they all seem to turn OK in a lathe. Plastics too need research.

The ground steel rods from old printers and scanners mostly turn well, but I have one that's incredibly hard. Tricky for beginners to identify if problems are down to the lathe, tool, material, or the operator. In the absence of a tutor, this forum, books, and YouTube all help, but be prepared to experiment.

Tools are another controversial subject. Personally I see little point in buying expensive high-end industrial cutters for occasional light use in my garage! Nor do I like the risk of buying from unknown web-sellers because there's more risk of factory rejects, 'too cheap' and counterfeit. (But people do get genuine bargains off ebay!)

I prefer established UK based sellers. Mostly ArcEuroTrade, Warco and Tracy Tools (for Drills, Taps & Dies), but I've also used RDG, MachineMart and several others without grief. While hobby vendors rarely sell the best possible tools they're OK for my purposes. (The reason the best possible tools aren't carried is probably economic. While Model Engineers are keen to own good tools they are rarely prepared to pay full price for them! Impossible, I think, to profit selling good tools to hobbyists because most of 'em have tiny budgets.)

I guess anyone starting with a second-hand MD65 isn't a serious professional machinist intending to make a living from it. Compromise is the order of the day. As a beginner my advice is avoid cheap and nasty, and don't get hung up on 'quality'.

There's debate about HSS vs Carbide. HSS is more general purpose, but it needs to be kept sharp. That means buying a grinder and learning how to use it! There are chaps who find grinding easy, others – like me – struggle. Carbide inserts avoid sharpening problems: tad expensive to buy but very easy to use. I mostly use Carbide for convenience (at least 80% of the time) but switch to HSS when carbide doesn't produce a good finish(rare), or when a specially shaped tool is needed for awkward corners or fine work. Depends on what you're doing. Owners of powerful fast lathes turning big lumps will likely prefer carbide, small lathes used for delicate work will probably do better with HSS, as will big slow lathes. I used carbide OK on a mini-lathe, which is similar size/speed to the MD65, but I wasn't making clocks!

Carbide inserts are available in a deeply confusing multitude of sizes and shapes. Hobby suppliers like ArcEuroTrade tend to stock the types useful to hobbyists, and you won't go far wrong buying them. Chaps who know what they're doing never recommend sets, but I recommend sets for beginners because beginners seldom know what they need or even exactly what they want a lathe for. Though I'm unlikely to buy a set now, I found sets invaluable for learning.

The December issue of Model Engineer's Workshop Magazine includes a printed ArcEuroTrade Catalogue. Buy one! Both magazine and catalogue give a good idea of what's available and who sells it.

Dave

Bother, beaten to it by SoD!

But I bet he can't compete in the kitchen, sorry assembly shop, stakes. I used to have a lathe on the kitchen table, as well as a number of other engineering items in the kitchen:

Now that I've had a new kitchen fitted the engineering stuff has migrated to the hall and sitting room.

Andrew

Out of the frying pan etc. You know bronze is one of the difficult ones, it snatches tools and also work hardens. Don't risk drilling it until you understand it and have worked out how you will remove the broken drill.

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

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.