The perfect ME Lathe

[Roderick JenkinsParticipant @roderickjenkins93242]

Interesting, Interesting…

 

Bearing in mind that this fantasy lathe is for Model Engineering:

 

I think you can go too big. A 100mm 3 jaw chuck seems about right to me, so probably not camlock. Definitely not bolt on – chuck changing has to be easy.

 

I need to be able to swing 9 or 10 inches for flywheels or loco wheels (3 1/2 or 5 inch gauge). Larger gauges or 1/4 scale traction engines are outside of my requirments.

 

I’m not too hung up on a large through bore, now that I can part anything off using a carbide tip I’m quite happy cutting down to a suitable length. 4 morse taper tooling is getting a bit clumsy (and expensive). Not much point in having large tapers if you are going to fill them up with adaptors to make them small again

 

Space is an issue, so for me a gap bed seems better than 5″ over the bed with the consequent beefing up everything to give good rigidity. A removable gap piece would seem to be ideal. A slotted cross slide with a rear toolholder is good. Gets a bit long if we need to cater for 10″ swing.

 

Weight – The lathe needs to be able to be carried through the house to the workshop (or even up-stairs) by 2 strapping lads (motor, topslide and tailstock removed)

 

Not too bothered about a gearbox for screw cutting but a selection of fine feeds would be nice.

 

Back gear. VFC is great but no substitute.

 

Provision to retro-fit DRO and/or CNC drives already built in with relevant mounting points.

 

I don’t need a set-over tailstock. Enough travel on the topslide to cut a 2MT.

 

So, basically, a Super 7+ tweaks. Would a roller headstock be cheaper to make and do we need to hand scrape slides with modern manufacturing? Can it be done for ~£4,000?

 

Interesting to see what Grizzly have done with Southbend – perhaps they could call them Boxfords over here.

http://www.grizzly.com/products/South-Bend-10K-28-Bench-Lathe/SB1002

happy fantasing,

 

Rod

Edited By Roderick Jenkins on 19/07/2011 13:52:38

Edited By Roderick Jenkins on 19/07/2011 13:57:42

[Speedy Builder5Participant @speedybuilder5]

Yep, some good ideas, but no one has mentioned coolant pumps and for me, a really fast speed so you could do a bit of wood turning as well. Thought for adding a bowl turning faceplate on the left hand side of the headstock. Often our workshops are small and have to be used for all sorts of things besides metal. I believe that Southbend did a dual speed range lathe for metal / wood.

 

I often use the vertical mill for routing and morticing, but have to have a second lathe just for wood turning.

[Steve WithnellParticipant @stevewithnell34426]

I guess the coolant brings out the grain quite nicely? I guess you would need to use soluble oil rather than Neatcut

 

Steve

[John McNamaraParticipant @johnmcnamara74883]

Hi All

Gee I tried to keep out of this discussion, but it was too tempting……..

I suspect electronic control is the way of the future. The catch being that the currently available low cost software Emc or Mach 3 for example, and there are others; while being perfectly capable of doing the job, are not particularly user friendly, particularly for those that are not well versed in PC computer usage. Whatever package is chosen it must have a large established user base and web support as the two programs mentioned above do.

Some of the more advanced commercial Machine manufacturers have a so called “conversational” interface, Haas for example. This type of system asks the user questions about the task selected. Say A thread, once that task is selected it will ask you the type the size the position and the material speed etc. That is a far cry from entering G codes. However I guess evolution will guide all developers towards that, even at the low cost end.

 

Mach 3 costs 175 USD “Non-commercial users (aka hobbyists) are permitted to use one license for as many machines as they want.” (Quote From their website) I have no connection with the company. Mach 3 does have wizards; conversational as above, that do simplify many tasks already. But there is a learning curve.

In a perfect world it would be nice to have conventional control via hand wheels as well. Or should I say that is mandatory. (It would not work for screw cutting there are no change gears) Screw cutting would be done automatically.

Re the motor drives themselves together with their controllers and a USB (Now more popular than Parallel) interface board to connect the servos, limits switches Etc to the PC.
I guess it is a matter of cost versus performance, prices are dropping all the time in this area. Steppers are less expensive overall compared to AC or brushless DC servos but the prices are dropping.

Accuracy I guess we would all like to think we can position the tool to .0001inches, actually quite difficult when you take the errors of whole machine into account.

For motors this is a good starting reference.

http://en.wikipedia.org/wiki/Stepper_motor

 

For Steppers and servos this is a good commercial site with prices in the US. (I have no connection)

http://www.anaheimautomation.com

 

Some Chinese manufacturers In this case a company called GSK are also making complete 2 and 3 axis Brushless DC servo CNC kits Motors Drives all ready to plug together with A commercial looking plasma screen and keyboard front panel (You do not need a PC) for under USD 2000. I saw one running at an exhibition a couple of weeks ago. I must admit their representative who had flown from China was very knowledgeable.

 

http://gsk.en.alibaba.com/

To me that is a lot of money and being a turnkey system you are locked into their spare parts. Not so if you buy the components separately as discussed above.

It would be a different story if there was local support.

 

There has been some mention of the bed.

A lot of new commercial quality CNC lathes now use linear ball rails (Profiled rail not round shaft) instead of prismatic ways. A number of these rail systems are now internationally standardized meaning you can substitute different brands (Prices vary a lot) the bolt holes and dimensions are the same. They have to be changed as a pair you cannot mix manufacturers rails and bearing blocks. The result is very likely to be a much stiffer connection, compared to a conventional V or Box bed particularly if it is a little worn. And linear Rail systems can simply be replaced the machine does not need to be sent out for a regrind when the rails wear.

The supporting structure for the rails can be cast Iron or Mineral casting. Or even a weldment if it is properly heat treated and stress relieved.

Bed length: what is the ideal distance between centres? The Boxford mentioned appears to be 22 inches is that enough?

I guess that is enough for one brain storm…….

 

Cheers

John

Edited By John McNamara on 19/07/2011 15:40:25

Edited By John McNamara on 19/07/2011 15:43:35

[Billy MillsParticipant @billymills]

Well everyone’s going to have a different spec! But there is a halfway point between a full CNC lathe and manual control, by simplifying the mechanics you can swap out gearwheels for a few lines of code, you can have a hand operated machine -like power steering on a car- but the work is done by motors.

 

Steppers are an obvious but not the only power source, a lot of volume manufactured machines use PM motors and encoder wheels- much better than a stepper, more torque, much greater acceleration, more holding torque and no missed steps worries as the system becomes closed loop not the normal open loop with most steppers. It’s also cheaper which is why most modern printers don’t use steppers.

 

Would agree that G code is a bit like hand coding machine code, but a powered lathe does not have to take G code, you can have a simple controller- perhaps like a DRO display which could be used to display tool position, to set up thread pitches and to spec taper angle and length or the diameter of a ball. If this appears a bit much then think about the modern automated sewing machine which now makes buttonholes and all other kinds of fancy stitching- Why should SWMBO’s have toys that we don’t?

 

Happy planning

Billy.

[Steve WithnellParticipant @stevewithnell34426]

Billy,

 

G code is not an issue, nor is it like handcoding machine code. G-code can be auto-generated from 2+3D CAD. It’s been that way for donkeys years, the only difference is that the old £250k CAD terminals are called PC’s and much of the software can be had for buttons or less.

 

Yep closed loop servo based systems are superior to open loop stepper based systems, but for machine tools, they are not yet close to being in the same price range. I wouldn’t like to guess how far the price of a KX1 or KX3 would soar if implemented on that basis. There are at least two gents in this thread able to call the number. Part of this is the cost of robust encoders of appropriate accuracy/precision.

 

Run the free download of Mach3 and play with the wizards for lathe or mill – that’s your fancy stitching right there and you do not need to write any g-code.

 

 

Regards

 

 

Steve

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[blowlampParticipant @blowlamp]

Billy.

The problem with a CNC lathe is that it’s almost too easy to make complex shapes, that would otherwise take forever to do on our size of manual machine.

You could turn out ball-handles and Morse tapers by the million without even breaking into a sweat.

 

CNC really comes into its own on a milling machine and is perhaps the better parallel to your wife’s automated sewing machine.

 

Not trying to hijack this thread, but here is a couple of videos of me going through the steps in CAD and CAM, of cutting a simple tyre with some writing ’embroidered’ onto its sidewall.

 

Martin.

 

http://www.screencast.com/users/Hammering/folders/Jing/media/f0f21c0b-52e4-42d4-8358-cdc2341bcb61

 

http://www.screencast.com/users/Hammering/folders/Jing/media/16232f3d-1c3d-459b-9a6b-b7c41fc6a415

 

 

 

[Billy MillsParticipant @billymills]

Well we are speculating about our personal lathe ideas and so our different views emerge.

 

Perhaps 99% of home CNC conversions use steppers rather than servo motors so we collectively tend to think of steppers as the way to drive an axis. However the “encoder” on the back of a PM motor can be a plastic injection moulded disk and a pair of slot sensors costing a couple of quid total and that can be much better than the 5% step angle accuracy of a Stepper motor – it does not need to be an absolute but a relative encoder- that would give you the potential to PID autotune the loop.

 

I don’t see it a problem to make complex shapes easily, that classifies as a very big selling point and a useful feature. What is needed is a simple range of options for people to unleash the power of the processes without having to spend a lot of time training how to do it. So if -for example- you could turn an item by hand control then replay the motion you could fuse manual skills with the repeat accuracy of the machine to knock out as many parts as needed.

 

So my version is a lathe that looks like a lathe with a DRO box with knobs on. You drive it the same way as of old, you still use your skills of control, still see and hear the cut but you can also do loads of what was very specialised stuff as almost a free extra. You do it by getting rid of the change gears and gearboxes, fitting two PM motors to drive the two leadscrews with great big long plastic nuts – in the style of Henry Maudsley. ( If you want ballscrews Squire that’l cost you a little more). By the way, most of the other Accessories on the Mills WonderFord Special do add up a bit more than you might think but you are buying a very versatile machine……and it is an absolute bargain!!!!.

 

Happy saving up!

Billy the Industrialist.

 

Edited By Billy Mills on 20/07/2011 01:37:15

[adyParticipant @ady]

Anything too electronic is going to be goosed in 10-15 years, if
not 10 days in some cases as the control board emits little puffs of
smoke.

There’s a load of manual stuff up to 100 years old
which can still being used to turn out nice work, what’s becoming
increasingly rare is the people with the skills to do it.

 

CNC
is great for repetition and production type work but the best ME type
lathe is a manual unit which trundles happily along for decades in the
hands of an ME enthusiast.

 

You can always mod
a manual lathe to do whatever you need or want, including bolting some
CNC gear onto it if that’s what floats your boat.

 

Most ME enthusiasts want to discover the skills and abilities which lurk within that man.

 

[John McNamaraParticipant @johnmcnamara74883]

Hi All

Steppers versus closed loop servos?

Early step motor control systems were “open loop” In simple English the controller sent a set of pulses to the motor to move it to a particular position, If it got there all was well however if it did not due to any reason, friction stopped it moving for example. The control system did not know it missed the move.

Steppers are also used in closed loop configuration, this is done by attaching an “encoder”; a device that feeds back to the controller the actual position of the motor shaft; thus closing the loop. Meaning it tells the controller if there is a positioning error and it can be corrected by the control system or the machine stopped and the operator advised. Non stepper servos already work that way. Now that both steppers and conventional servos can operate in the same closed loop, selection is simply a matter of price and performance trade off’s.

As noted above there is constant evolution of the components that make up a servo system. Also there are maintenance issues, and maybe by the time a component fails it may not be serviceable. However I do not believe that is an insurmountable hurdle. From time to time sub assemblies might need replacement. However it is unlikely that an entire system need be replaced. Competing manufacturers have standardized on interfacing to other components. The same evolution has taken place with the modern Personal computer. Parts can be replaced with parts made by different manufacturers. At this point in time CNC parts are not necessarily “plug and play”, other adjustments may need to be made to make the new component work, but we are heading in that direction.

While it is interesting to ponder the pros and cons of individual components, and having read the posts to this thread so far, I guess the biggest problem will be some sort of consensus. Some members have limited space; the overall size of the equipment is important to them. Some want a minimum centre height above the cross slide and others a larger height above the bed for turning larger wheels Etc.

I guess we will end up with more than one size.

MEWA. Small lathe for watchmakers and instrument makers
MEWB Myford size lathe
MEWC larger lathe

It would be interesting if we took a poll in this forum asking what the MEWA and MEWC sizes might be….. Would we get consensus?

The control systems can be similar apart from the motor/drive rating changing.

What is clear from reading the posts is that if the human interface to the lathe was more intuitive a number of MEW members may be more interested in an electronically driven machine. As mentioned the sewing machine manufacturers have addressed this problem, the modern domestic sewing machine is all CNC driven for special patterns, buttonholes Etc. all driven by a simple menu.

This is where innovation can shine we need to think outside the rectangle of convention and develop that interface. Once this is done the mechanicals can be finalised.
We should be able to walk up to the lathe
Set a piece of material

Set Zero (X and y) to the piece of material (by moving the tool to a known point)
As this can cause small errors because the point is hard to see there should be a means of dialing in a small change in the X and Y setting after a trial cut is made. (Already available on mach 3)

Then via a menu tell the system the cut we want
Giving a “start point” an “end point” and “depth” then the shape….Thread… Chamfer… Plain turn… face etc.

Some will want no access to the underlying code; for those that do, it can be a menu option.
Full manual control should still be available via the hand wheels, including infinitely variable speed feeds for the saddle and cross slide.

Cheers

John

Edited By John McNamara on 20/07/2011 06:47:31

[John Stevenson 1Participant @johnstevenson1]

Whilst this is an interesting conversation it will go nowhere for a multitude of reasons.

Some want electronics,

Some want different sizes, Some won’t accept the majority if their views have been ignored.

 

However the main reason is that no one will want to poppy up in the quantity needed to ensure ongoing production.

 

The Chinese have succeeded because it’s cheap, they have a world market and it can be improved or modified on, a bit like Myfords in the early days.

 

For a project to succeed you need on going sales. How may on this forum poppied up and bought a brand new Myford whilst they were still in business ?

Second hand sales don’t count, that adds nothing for the parent company in terms of continuing sales.

 

John S.

[Donald MitchellParticipant @donaldmitchell68891]

I bought a brand new S7BPXF direct from the factory, complete with all the usual accesories including 4 chucks (one was a Griptru) way back in 1977 or 78. it was one of the very first green ones – all for £1100.00 inc tax

 

Donald Mitchell

Castle Douglas

Bonnie Scotland

[Donald MitchellParticipant @donaldmitchell68891]

I bought a brand new S7BPXF directly from the factory back in 1977 or 78, complete with all the usual extras including four chucks, one was a Griptru; all for £1100.00 inc tax !

 

Donald Mitchell

Castle Douglas

Bonnie Scotland

[Andrew EvansParticipant @andrewevans67134]

John – what about the example of Tormach Cnc mills in the states? They seem to be successful at selling expensive new units to the individual (that’s my perception anyway). I think if the product is good value and good quality people will buy it. Yes people weren’t buying new Myfords recently at 8k but that’s because people decided that they were not value for money.

As a relative newcomer to ME I had the choice of buying a lower quality new Chinese lathe or a 2nd hand higher quality lathe – I didn’t have the choice of a new high quality lathe in my price band with the features I wanted. I think if there had been an innovative, quality, modern lathe available as described by various posters here I would have jumped at it if the price was right.

What Myford did in the 40’s and 50’s was innovate and come up with a quality product that, while expensive appealed to lots of people – they marketed the product well, gave great service backup and sold lots of units (at a time when people didn’t have much spare cash compared to now) I think there is a gap in the Market now for something similar.

Andy

[John McNamaraParticipant @johnmcnamara74883]

Hi All

This morning a young man and his Dad came to visit. I am helping the father with a database software problem….. Anyway once that was solved the conversation moved to engineering. Naturally in the meeting room at our place, the workshop!

The lad (about 19yo) was looking at the worden project as posted else ware in this forum.
We discussed the epoxy methodology, what it was for and so forth.
We also talked of the Lathe and mill and the merits of CNC, He is currently a technical student (Networking) , also he is rebuilding an off road car. It is people like him that are the future. He was genuinely interested, and spent some time moving the controls on the lathe and mill. You never know maybe a seed was planted that will grow into a life interest in engineering.

Hi Andrew Evens

I think you are right about the Tormach certainly not inexpensive but with enough features to beat the cheap competition and pique the interest of the buyer.

It will be interesting to read this thread after a day or two; hopefully we may refine our wish lists for various size machines.

Cheers
John

[Ian S CParticipant @iansc]

It’s similar to other industry, ie., aviation. In the US the manufacturers build an aircraft and sell to the airline, and seem to get things fairly OK, DC 3 etc. UK manufacturers ask the airlines what they would like. Airline a bit conservative, they order a few , but it does not suit the other airlines. Small production run high cost, thats where the aircraft COs are now. You’v got to as a manufacturer build a good range of machines that is affordable. Ian S C

[Billy MillsParticipant @billymills]

There are a lot of good examples of how traditional stuff was updated with modern production methods and electronics, often there is an outcry of “it’ll never be as reliable as the old hand fitted stuff” well tell that to people who drive modern cars, use digital cameras, washing machines, PC’s, printers/scanners. The general effect is to make products very much cheaper, easier to use and to vastly extend the range of things that can be done.

In 1946 expert opinion was that only one advanced computer in the UK could do all of the calculations needed. No one thought that we would have more than one machine per person. In 1960 a mobile phone was installed in the boot of your car if you were very rich. Now every kid has one in a pocket. The list is very long! The lesson is that traditional products can be made more popular by re-considering their function and construction and adding enabling features. It is a decision made by the buying public, they choose to have more tech gear at a fair price.

Manufacturers that don’t listen to the card machines close down eventually despite the sad grief of their loyal customers. But if you fail to adapt you get rubbed out by the people who do.

I am sure that there are good markets for CNC machine of all sorts, the Hobby market is perhaps the smallest, but there are a lot of small businesses that would love to have affordable basic CNC at an introductory level price so that they could prototype and do small scale production without massive costs. The KX1 & 3 and the Tormach are three examples, a man in a garage can make a living making stuff that bigger outfits can’t do. So If I was Rod’s imaginary new machine business person I would be thinking of making millions by following the exemplars of consumer manufacturing, design machines with new capabilities with the home and small business user in mind. But the plain vanilla version is too well done by the far east, it is now a commercial death trap.

 

Happy plotting

Billy.

 

PS Sir John’s “it is going nowhere” is absolutely true, it is just a pass time for us Meldrew’s but it is interesting to read the variety of different viewpoints and sometimes you learn something too!

 

[WALLACEParticipant @wallace]

All too true – I transfered a BBC documentry about the ‘Imperial Type Writer Company’ a few years ago – it must have been made in the late 70’s and it was all about how a once proud manufacturer was going under, people would be thown on the scrap heap and the governent was doing nothing about it – etc etc.

 

Lots of atmospheric shots of empty factories, busted typrewriters in a skip and interviews with people who had worked there all there lives – that sort of thing.

 

And the final bit was an interview with the man from the government whose last line was something along the lines of ‘ it’s all very sad but there are new electronic devices coming along that will make the mechanical typewriter obsolete’.

 

All too true.

 

 

W.

 

 

 

[Ian S CParticipant @iansc]

Another example of improoved production methods, and its effect. This goes back to WW2, and the difference between the RR Merlin engine, and the Packhard Merlin built in the USA using automotive production line manufacturing methods, even down to using proper oil seals instead of felt ones, The Packgard engine kept its oil in the engine, where as an aircraft with a RR engine tended to get covered in oil especially after aerobatics. Back then they were a bit stuck, they felt that it would upset production to update production, and I suppose the UK automotive industry was not as mechanised as the US one. Ian S C

[KWILParticipant @kwil]

Looking at a RK International machine tool list for 2008, they listed a Dalian CDS 320mm swing, large bore high speed gear head manual lathe, equal or better than the large bore Myford for £5490 + at the time. More like a Harrison M300 in style. This was I think cheaper than the Myford at the time.

Look at Dalian if you want to find out how many lathes they make (55000pa). Roberts sell them in the States. Dalian = http://www.dmtg.com/English/Products/CDS.asp

 

I wonder how much they would charge for an ME size decent lathe?

Edited By KWIL on 21/07/2011 14:55:23

[Ian S CParticipant @iansc]

The machinery for making the stcks for the Lee Enfield rifles were imported from the USA, bet that P****d off a few blokes that hand carved gun stocks. Ian S C

[Raymond AndersonParticipant @raymondanderson34407]

Sticking only to a lathe suited to model engineering, I would have my ideal one as a miniture DSG [same features as my grown up one, only in Harrison M300 size]

Regards,

Raymond.

[Steve WithnellParticipant @stevewithnell34426]

Turning this around then. For a Model Engineering manual lathe, what’s wrong with this?

 

WM280V-F Variable Speed Lathe with power cross feed

 

http://www.warco.co.uk/WM-280V-F-Variable-Speed-Lathe-5995194573.aspx#

 

At £1500 for this, why would you buy a secondhand Myford?

 

Regards

[JasonBModerator @jasonb]

Nothing wrong with the Warco at all, thats what I’ve been using for the last 3 years, If I can knock out stuff like this andthis on it who really needs more. Well I have added a 160mm Bison 4 jaw.

 

J

 

PS the speed ranges are actually 50-950 and 100-1900.

 

Edited By JasonB on 21/07/2011 20:16:44

[Peter G. ShawParticipant @peterg-shaw75338]

Re the Warco WM280 lathe.

 

On the face of it, it looks good, but I would comment on the following:

 

My lathe has a centre height of 110mm and a X-slide travel of 110mm. The WM280 has a centre height of 140mm and a X-slide travel of 140mm. In my albeit limited experience, the X-slide travel is not enough. In my case an additional 20mm would certainly be advantageous as if turning at maximum diameter, the X-slide is just about off it’s screw. I imagine the WM280 will be similar.

 

Distance between centres: 700mm. Longitudinal travel 550mm. ???

 

Metric & imperial threading is quoted as 0.4 3.5mm and 8-56tpi. My lathe, a smaller lathe, has 0.4 – 12mm, and 3-72tpi. Now I don’t know if these extreme figures are necessary, certainly I have never had to use them, but it just makes me wonder.

 

Finally, the speeds are quoted as 50-950 & 100-1900rpm. Now, there has been comments elsewhere about these electronic minimum speeds actually being down on power so I wonder just how useful they actually are. In addition, with a centre height of 140mm one could expect to be able to swing in excess of 250mm, eg a locomotive wheel. Now from what I can see in the Model Engineer’s Handbook, the lathe can only turn wheels made from soft or easily turned materials, eg aluminium, brass or free-cutting mildsteel. For anything such as cast iron, a much, much lower speed is required. Which, I suspect, is why the Myford Series 7’s could go down to 15rpm (I think).

There is another point – screwcutting. Personal experience is that my minimum speed of 125rpm is much too fast for a short thread which is why I have a mandrel handle and remove the belts when using it. Again, I wonder if 50rpm is too fast for short threads.

In short, I would like to see something, let’s call it a reduction gear, mounted, say at the rear which would enable the speeds to be really dropped. (Perhaps we could call it a “back” gear!)

On a more general theme, I am generally unhappy about the ever-increasing complexity of modern equipment due to the ever-increasing use of electronic control systems as all they seem to do is ensure that if a fault does develop, either the equipment then becomes an expensive door stop, or it becomes necessary to pay someone to diagnose and repair it. Let me give you an example. My car is a 4 year old Ford Focus. Shortly after I bought it at 2 years old, a fault developed such that hard acceleration in the lower gears, eg high engine revs, would cause the engine to start stuttering. My local garage attached a diagnostic unit which agreed there was a fault, but could not go any further. Accordingly the car was sent to a Ford Main Dealer for a full diagnostic at £70, only to find that the problem was the fuel filter at £30. In all probability, 20 years ago, my local garage would have simply changed the filter anyway as there wasn’t much else it could have been, but with electronic controls…..

So, as far as an ideal lathe is concerned, what I would like to see is one which has the choice of electronic and manual controls, electronic for the flexibility electronics offer, but has the option of being able to fall back onto pure manual control for those occasions where manual is thought to be better and for if the electronics fail.

As has been said, electronics are here and are not going to go away, but it does make the device, whatever that device is, more complex, and hence, in my opinion, more likely to fail.

Another idea would be to ensure that the elecronics are an add-on and that there is a publicly known specification for the lathe or whatever, such that any electronic controller could be used provided it’s output matched the specification. This would mean that any faulty electronics could be simply and easily changed for a new and possibly more up to date version.

 

Regards,

 

Peter G. Shaw

[Author]

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