Small Lathe T(r)ek - The Next Generation.

Forked from the "Worth It" thread.

Posted by Robert Atkinson 2 on 28/04/2023 15:57:42:

Jelly said:

"... For me there's a real gap in the market for Myford to undertake some meaningful product development to offer a lathe the size and quality of the Super-7, but refreshed with the features of the 254, and geared to offer speeds appropriate to modern tooling on the size of parts you'd expect to use a 3.5" centre height lathe for; that would actually differentiate them from the competition from abroad. "

I could not agree more. They have the name to charge a premium price. It would be so good if they re-engineered it keeping the style but integrating (not scabbing adding on) a 3 phase motor and VFD, deleting the clutch (not needed with VFD), camloc chuck (with adaptor for the old threaded kit), primatic bed etc. Options could be DRO (again properly engineered into the design), ELS (instead of gearbox) and powered cross-slide (possibly leading to CNC).
I recon they would make money on a bit of investment and possibly set the standard for the next generation of small lathes.

Robert.

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It's funny you should say that...

I currently have a stack of lathe beds in the workshop which were originally destined to become the ways for my Horizontal Boring Mill project... Having now filled both the space and niche it would have occupied with a very large turret mill, I've been mulling over what to do with them.

Attempting to develop something that fills the niche described would be an interesting project on a par with the HBM, although I doubt I'd be in a position to commercialise it past the stock of beds I have.

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I broadly agree with your list of requirements, but if I put a manufacturing hat on it potentially makes more sense for some of the options to be default features.

I suspect that for serial or volume production offering an ELS would actually be far cheaper than a proper screw-cutting gearbox these days, similarly electronically powered cross-feed is going to be cheaper than the machining time for feed-shafts and gearbox.

That would then allow the DRO to operate from the encoders on the servos (an idea I'm not mad about, but would save a lot of cost, separate linear encoders would be an easy add-on though) and enable an almost "plug-and-play" conversion to CNC with a dedicated kit of ball-screws and controller.

It also occurs to me that in a CNC scenario the quintessential Myford accessory, the vertical slide, would actually take on a whole new dimension in that sort of scenario, equipped with a servo-drive one need only add a 40mm standard powered spindle mount, it turns the lathe into a tiny Mill-Turn​.

The requirement I have in my head as most challenging would be to engineer a headstock which could truly provide a range of speeds allowing hobbyists to take full advantage of modern tooling, which would probably require a max speed of 10,000-15,000 rpm (assuming it's optimised for a minimum workpiece in the region of 1/4" to 10mm, and non-ferrous materials).

Assuming that for drilling, out-of-balance turning and the like, a more normal range of speeds would also be desired, that probably requires either a specially specified Inverter-Duty Motor suitable for very high frequencies, or a permanently tensioned flat-belt system, the former being perfectly reasonable for volume production, but rather pricy for the first prototypes, and the latter adding the kind of complexity more associated with Schaublin, Monarch, Holbrook, and Hardinge than with a Myford.

15,000 RPM also requires a lot more of the bearings, although if you're completely eliminating belt-changes there's more leaway to provide for that, it also pretty much demands a collet-chuck as a default option, and possibly an interlock to prevent using a 3/4 Jaw at full speed (it's scary enough swinging a 10" steel-body 4-jaw at 3,200 rpm, let alone a 6" one at 15,000!).

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Any opinions on the future development trajectory of the small lathe welcome.

In MEW300 I proposed a small adaptable lathe that could be easily changed in stages from a simple basic lathe through to a version with powered axes then finally onto a fully CNC lathe that could also be used manually or a mix of manual/ CNC as desired. The version show has a cast iron bed but this could be simplified with rectangular steel bars. I attach a screenshot. There are many more screenshots in my album.

Alan

Even if they did bring the S7 size machine upto date who would pay the money?

Current cost of a Connoisseur is just over £13,000 which has the decent bore, gearbox and VFD, by the time you have added a DRO, D1-3 spindle and the basic chucks and steadies that come with the far eastern machines you won't be far of £15,000 for a new "updated" machine. It is going to take a lot of sales to get the investment in developement costs back

Modern lathes aren't that much different to old ones, so there's little point in reinventing the wheel. I suggest that there could be reasonable market for some useful upgrades to a common machine, along with improved fit and finish. Even if that added 50% to the cost of current lathe, the price would still be affordable and reasonable.

So:

start with a 10x22 with a 1.5Kw motor and VFD for reliable variable speed. That takes a similar space to a Myford, but has a more useful range.

Ensure all the controls are properly installed, and work smoothly. I was amazed at how much better mine became after some basic, unskilled work with a scraper.

Paint it well, after adequate preparation.

add an electronic lead screw for all screw cutting and power feeds. This would need a sensible interface, not the four buttons and two-line screen beloved of DIY jobs...

Standard DI chuck fitting.

Branded bearings.

As big a spindle bore as practical.

DROs that don't get in the way of anything.

Increase the cross slide travel so the entire diameter can be turned without any clever setups.

Design some accessories that don't currently exist, like taper turning attachment, milling slide and an electronic headstock divider.

All that would make a good machine even better, and I suspect wouldn't add a huge amount to the manufacturing cost - they already get painted, and the electronic components ought to compare well with the existing mechanical gearing.

I can't disagree, fundamentally to complete with the range of far-eastern lathes (which are available in any level of quality you're willing to pay for) a "Modern Myford" would have to offer functionality that isn't available elsewhere to attract sales, which is what the original ML7 and super 7 did at the time...

And the price-point itself still needs to be reduced.

.

I do think that is do-able however, the Connoisseur whilst a lovely design, has a huge amount of mechanical complexity which can now be eliminated with (comparatively) cheap electronics to no loss of functionality.

When you dig into the design of the core components for the S7 range, it uses a significant number of individual thin-wall castings which would be time consuming to mould, demanding to pour, then require extensive fettling, and multi-operation machining on fixtures. Beautiful industrial design, but not great from a value-engineering standpoint.

.

The ubiquitous Mini-Lathe designs today themselves are well over 25 years old, and originate with further adaptation and simplification of value-engineered designs that are the best part of 40 years old, so there's definitely room for a refresh in that space.

The 10 x 22 or even a bit longer that Nick mentions would be the better size and avoid the need for a gap bed like the Myford has. 3.5 ctr height or mini-lathe swing is not ideal for model engineering as so many of the old designs are based on what could be swung in a Myford's gap, that's one reason I got rid of my Emcomat 8.6 as the 200mm swing limited the engines I could make. The American design need a bit more as 10" or so flywheels are quite common and just fit my 280

You could start with the bed casting of one of those, Neils has already shown us that a big bore spindle can be fitted, give the nose of the tailstock a bit more overhang and you are getting close with the main large components, just put them together to a high spec.

On cost, part of my train of thought was that the owners of the Myford name could leverage that to charge a higher price than say a new entrant into the market.

Robert.

Wouldn't a "teach in" CNC make more sense today? As in a CNC lathe with some sensible manual controls.

Absolutely, for a new market entrant the lack of a brand identity would be a major disadvantage.

I suspect that there's a price premium a new entrant could charge for a "British Made" or "Made in USA" brand claim if they can back it up, but they'd need a way of getting in front of prospective customers long enough for them to absorb that claim, to the point that buying a defunct brand and resurrecting it could be worthwhile.

Myford meanwhile has brand identity in spades.

That would be the next step for my suggestion, especially if you made the taper turning attachment a stepper motor on the cross slide. Then you would have most of the mechanical components for full CNC control, and would only need a viable controller. Which would make a good option.

Whilst we are fantasising how about integrating the motor and spindle. Make the spindle the shaft of the motor. Yes loads of issues etc... but...

It would at least eliminate the current motor-belt-pully noise-vibration-irritation complex.

Regards.

Frank C.

I think a modern polyvee belt would cure those problems, certainly my 5000rpm spindle on the CNC is smooth and quiet though a new set of matched bearings would set you back a few hundred quid.

The big advantage of separate motor is what most others seem to want here and that is a big bore through the spindle

Wouldn't making them both the same component be likely to increase the spindle vibration? And it would definitely mean an expensive custom motor instead of a simple, standard one.

I think that a woodworking lathe has been made this way.

Poolewood used to do wood lathes like that, think they have stopped doing them that way now

That is the one I had in mind; I wonder why the idea never caught on.

The lathe allowed a bowl to "embrace" the spindle nose end of the motor.

Motor integated into spindle has a couple of issues.
Not great for low speed power.
An induction motor would have a poorer magnetic performance.
A brushless DC would likely collect magnetic swarf in the bore.
Seperate motor (underdrive?) and pollyvee belt seem the best compromise to me.

Robert.

That would then allow the DRO to operate from the encoders on the servos (an idea I'm not mad about, but would save a lot of cost, separate linear encoders would be an easy add-on though)

Motor mounted encoders are the usual arrangement on most CNC lathes I have come across - all of the 7 CNC lathes at my last employment (ranging from 200 dia. x 500 BC to 700 dia.x 3500.BC) were motor encoder position feedback. Scales are rare on lathes - in 27 years working for a CNC rebuild / retrofit company before my last employment I can only recall a couple of vertical borer installations where the customer requested scales. Occasionally some machines used separately mounted encoders driven directly off the ballscrews (rather than measuring through timing belt reductions) but, in practice, motor mounted encoders work just fine. One advantage of encoders is the ability to use backlash compensation, which isn't available with scales (you can only compensate for the lost motion within the readhead mounting arrangement on the scale) which can give better contouring performance. If extreme accuracy is paramount with an encoder arrangement, most controls made over at least the last 25 years have non-linear axis compensation (pitch error comp) to "map out" ballscrew errors.

Question :

How do you make a small fortune manufacturing manual machine tools in the UK ?

Answer :

Start with a very large one !

Best I can make out at the moment there are only 2 manufacturers of small manual lathes remaining in the UK - Myford (Mytholmroyd) and Cowells (Essex). If you thought that the asking price for a current new Myford S7 was high, have a look at Cowells price list ! That all the others have either stopped making such machines, gone to the wall or sub-contracted manufacture to the Far East says it all, really. The cost of setting up to make such machines here, labour costs (if you could find a sufficiently skilled workforce) cost of raw materials (if you could find a UK foundry capable of making the required castings), plus product certification costs etc.mean it is not realistically possible to come up with a UK made product that could be priced within sight of imported machines.

Talk of going with ELS or CNC systems means going for at least partial (ELS) of full (CNC) interlocked guarding - yet more cost. Harrisons went this route with their Alpha range of machines based on the M series manual lathes. They "got away" with partial guarding on their basic ELS equivalent machines because they were not capable of automatic cycle operatation, but later - more capable - machines that could run programs had to be fully guarded. And they are not made here any more - UK manufacture ceased at least 10 years ago (probably a lot more - time flies ! ) in favour of making them in the Far East.

Integrated spindle motors for lathes are a thing from several manufacturers - they are sold in component form comprising a sleeve with permanent magnets attached to press over the spindle, a stator cartridge with windings fitted into a laminated core that presses into the headstock casting & an encoder to fit the spindle on the outside of the rear bearing cap for commutation and positional feedback to the drive & control system. They can be forced air or liquid cooled. You don't want to ask the price !

The UK machine tool industry is largely gone & is, I feel, unlikely to come back any time soon - if ever. The skills base has gone, the cost of rebuilding the industry is just too high & the returns are unlikly to keep the current crop of "instant gratification" investors happy. If Communist China gets to be too expensive as a mnaufaucturing base, then India is probably the next most likely candidate to take over at the lower price end of the market.

Nigel B.

So I actually did the design calculations for such an idea incorporating a decently large rigid spindle last night, and making space for the spindle and bore requires you to spread out iron core material around it to get acceptable (according to the guidelines I found) magnetic performance which in turn results in a very large motor for the rated power.

I think I agree that an underdrive system is most practical.

Low speed torque is definitely an issue, a gearing system of some sort is almost certainly required if you want decent performance, but it's difficult to come up with one that won't result in either mechanical complexity or vibration issues.

If I got given a bunch of money and told to make a British based small machine tool manufacturer, well first I'd have a nervous break down.

But once I'd recovered I'd probably go down the Sherline business plan of having highly modular machine tools but at a ML7 size. Gives a wide target market from hobbyist to commercial use. You're product is the perfect match for someone, assuming it has the right combination of parts. The accuracy required for interchangeable parts makes it somewhat difficult for SIEG to wrestle in on your product.

Considering where I've seen Myfords scattered about they must have gotten a steady income from garages and light workshops