HEMINGWAY MYFORD ML7 GEARBOX

Drawings and kit for sale here.

-- Regards,

John Stevenson Nottingham, England.

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I don't know offhand what ratios this box gives you, but having used the standard Myford object, the observation I would make is that their box is only really useful if what you are after is Imperial pitches. The Myford box gives you all of them at the touch of a lever, plus finefeeds by flipping over one of the gear clusters in the changewheel train.

However, as soon as you want to do anything exotic like Metric or (even worse) BA threads, then all bets are off. You lose the instant change to finefeed, and you are basically back in the nasty old world of fiddling with changewheels to get the right gear ratio. And of course, at this point, your threading dial is about as much use as a chocolate teapot too, so your only option is to keep your nuts engaged (always a good plan!) and wind back.

Hence my recent decision to perform the ultimate sacrilege and convert my ML7 to CNC. It is a cheaper option than buying a Myford box and Metric conversion set, even at used prices, and I will not have to fiddle with changewheels to get any pitch of thread that I might want to cut.

Regards, Tony

That should increase the sale of sackcloth and ashes in the Home Counties

-- Regards,

John Stevenson Nottingham, England.

Visit the new Model Engineering adverts page at:-

That's one of the nice things about the Machin design, the fine feeds are available from the levers on the box without a 'hands dirty' job.

In another brainwave, they've kept the standard quadrant so by setting to 8TPI you could do any pitch you were able to do before.

This completely takes the fun out of it ;-)

It certainly sounds like an interesting approach. How do you get the pickup for the spindle rotation and how do you deal with going backwards?

If I want that kind of fun I can find a brick wall to bash my head against

Spindle pickup is either a single pulse per rev from a Hall effect sensor, photoelectric sensor, or whatever (if you use Mach 3), or possibly a shaft encoder that will give me 2000 pulses per rev plus an index pulse - I am going to see if I can convert my "Divisionmaster" hardware into an electronic gearbox, and the shaft encoder looks like the right solution for that route.

It is early days, but the Z axis is already motorised, and I can use the Divisionmaster box for variable finefeeds in its standard form.

Regards, Tony

Which encoder are you thinking of using, Tony ? I sourced a Grayhill one from Digi-Key a while back at around the $30 mark but the highest resolution they do seems to be 256 ppr (I'd have preferred more).

An encoder also tells you what direction the spindle is going in which may save some scrap ;-)

Cheers,

I have sourced one from RS - part number 205-6881 - gives 500 counts/rev on 2 quadrature channels, which will translate to 2000 pulses once I've fed it through a quad to step&direction chip. £35 each.

Could have done it cheaper from US Digital, but I got burned last time I ordered stuff from them - bought a couple of potentiometer-style encoders for use as electronic handwheels & got stung $75 for postage and £32 for import duty and VAT. In future if I need stuff from them I will wait till my next US trip...

True! Although I seem to manage to create plenty of scrap regardless

Regards, Tony

That's a useful find, better than trying to source the things from the U= SA (I=20 don't know a disty for Grayhill in the UK). Also the rev counter is a go= od idea=20 as well - saves having to cobble something together externally.

Yes, it's a lottery importing things and ISTM the odds are worse now tha= n they=20 were a few years ago too.

--=20 Boo

Thats true. The carrier (UPS) said that everything with a value over £20 gets hit nowadays. There's also an ongoing tariff battle going on between UK and USA over some piece of US protectionism, so the UK customs are gradually hiking the duty on US imports in retalliation. Ho hum...

Regards, Tony

In article , Tony Jeffree writes

Customs duty tariff levels have for a long time been set exclusively by Brussels on an EU-wide basis. VAT is also charged at the standard rate; member states do still have some discretion over these, within limits set (again) by Brussels, but these are of course uniform for all imports from outside the EU.

David

I've been charged VAT plus a £10 "handling" charge on _every_ item sent by UPS over £18 in the last year or two - and I have _never_ been charged on items sent by USPS.

Ymmv, but I am told USPS and thus the UK Post Office don't charge a handling fee either.

I don't know for sure, but using a private name rather than a company name seems to help too.

Yep - that sounds familiar.

I got stung for a £4 "Royal Mail International Clearance Fee" as well as VAT on a recent USPS shipment, so maybe Royal Mail have decided to join the ripoff too.

All of my recent stuff has been in my own name, so I don't think that necessarily helps. However, country of origin does seem to make a difference - 3 imports from Hong Kong over the last year (a couple at around £30 and one at £55) all came through with no duty or handling charges whatsoever.

Regards, Tony

Haha I had the same with a couple of encoders for my 1st Hardinge retrofit many years ago.

They sent the encoders air courier. Which was great, but a. costs more and b. these guys are obliged to collect said duty. At least with normal postal services paying the duty is a bit of a lottery, which unlike the the national lottery you usually win!!

Wayne...

It's really annoying that you buy something overseas and pay fo

shipping,then when it arrives Parcel force stick another £8.00 on to plus the VAT.

Another post office rip off I think.

Alla

-- Allan Waterfal

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Looks downright affordable against the alternatives, though.

Cheers Trevor Jones

Are you sure that it isn't customs and excise?

--=20 Neil Reverse 'r' and 'a', delete 'l' for email.

PO can charge you for, in effect, acting as a Customs agent, so if the Revenue decide it's worthy of their attention you may get stung for import duty, VAT, and the PO fee.

Cheers Tim Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service