Imperial feed dials conversion

[ukjimoo]

Hi all

Does anyone know how easy it would be to obtain the nessesary parts and to convert a Metric Boxford BUD to English.

I suppose for the cross and topslide you would need new feedscrews, nuts and dials. But where could these be optained from and for how many arms and legs!

Also would the set of screwcutting change wheels be different for the 2 machines?

Any help would be appreciated. A friend of mine has one for sale but i dont think i could live with a metric machine

Before deciding whether to buy i need to get some rough idea of the cost of conversion.

[Chris Kelland]

Why bother to convert the machine?

I opted to buy a metric machine, in spite of being anti metric.

I find that I am quite happy now - working to fractional inch drawings with a few decimal inch measurements thrown in.

I made a few silly mistakes at first, but i am now quite happy.

Is there any special reason you want to convert the machine? am I missing something?

Regards

Chris.

[ridleyian]

fit a dro, and have it both ways!

[steam4ian]

G'day Jim.
It depends on the pitch of your feed screws. If the pitch is 1mm then just make a new dial with 40 divisions; it comes out to less than 1% difference.
My 7x12 had metric feed screws with 40 thou dials; it drove me nuts because I work in metric. I replaced the dials with 50 division dials, now each division equals 0.02mm (= 0.8thou).

Regarding thread cutting I have found a combination with 57/60 tooth gears works out well (better than 60/63) for all threads except 25 & 50 TPI. A 127 tooth gear will not fit my lathe without a lot of modification.

One good turn deserves another.
Regards,
Ian

[Jo]

On my Myford which I have converted to metric I couldn't get a metric leadscrew. My solution was to mount a 2" dia dial gauge on the back of the lathe and use that to read off the movement. Much easier to read than a DRO and does not need batteries.

Imperial guages seem to becoming two a penny....

Jo

[bradcan]

There is no satisfactory conversion from metric to imperial or the other way round for that matter. Of-course its possible to make hand wheel dials with approximations. The average metric machine has 0.025 mm divisions these are as near as makes no difference to 0.001 inch. BUT, as you will quickly discover 10 or 100 or 1000 times introduces a progressively larger and larger error.

The answer is to work in what ever units your m/cs' lead screw is made in. Use a micrometer of the same flavor as your machine. Actually a good digital mic is probably the best investment you could make if you must to work trans units.

Threads are a problem however. Most machines have change gears, but the dial cannot be used for the foreign flavor necessitating keeping the lead screw engaged and reversing the spindle, making it almost impossible to thread cut up to a shoulder. A Coventry die head is an alternative, but the chasers are expensive. There are gadgets called an Ainjest rapid threading attachment also a Metradial by the same company but these are beyond the pocket of the average modeler.

BradCan (founder member of the Rod Ton Fortnight Society) 'Measure length with your Rod our unit of length. A Ton(ne), our unit of mass, of material should always be purchased (good metric unit the ton - 10 wheelbarrows' full). And finaly it takes a Fortnight to do anything worthwhile so our unit of time is the Fortnight'

[Boadicea]

Brad - agree about working in the units of the machine and the value of the digital micrometer.

However,

BradCan (founder member of the Rod Ton Fortnight Society) 'Measure length with your Rod our unit of length.

I was not sure what you meant by the Rod. A friend came round and showed me what he thought you meant. We girls have a problem - I cannot ask him round every time I want to measure. I have looked in Boots and on eBay and find there are some substitute ones. I will have difficulties in working with the plastic ones since they are much larger than the natural ones and this will lead to errors. They also need batteries. Perhaps you can advise.

[stantheman]

if I have got the right end of the stick, an old saying my father used for many years, would these 'rods' not suffer from a high degree of error due to expansion and contraction

[Jo]

This reminds me of the fun I had when I took my 12" pattern makers ruler into work and explained to my French and Italian colleagues that we English call it a four seasons rule as it allows for measurements of a rod taking into account the natural changes due to the seasonal temperature.

I also took in a four and a three inch and explained that they were for measuring foreigners:

Jo

[stantheman]

My fellow club members would enjoy this, they always say that when I join in a conversation the whole thing de-generates, can't understand why!!
Stan

[houstonceng]

Don't bother with all these farmers' Rods, Poles and Perches. Piddling small foreign units like mm or everyday, nambie-pambie inches.

Use a sensible "Mansized"* system the FFF.
Firkins, Furlongs & Fortnights (Mass, Length and Time)

Firkin = 9 Imperial Gallons = 40.91366 kilogrammes
Furlong = 1/8th of a mile = 210.168 metres
Fortnight = 14 Days = 1,209,600 seconds

The speed of light is approx 1.8 Megafurlongs per microfortnight (Mega = 1,000,000 times, micro = 1/1,000,000 times) and a car travelling at 37MPH would be doing 100,214.7 F/F.

It is notable that One FURLONG per FORTNIGHT is a velocity of 0.0005456349 feet/s or 0.0001663095 m/s. In other words. So slow as to be barely detectable to the naked eye.

Besides having the meaning of “any obscure unit” - much in the same way that “Widget” is used for an obscure part - FURLONGS per FORTNIGHT (F/F) have also served in the classroom as an example on how to reduce units, like force, to their basic Mass, Length, Time constituants.

So, Force is Firkin Furlongs per Fortnight squared.

* By "Mansized" we also mean "Female Engineer Sized"

Sorry. Mea culpa, mea maxima culpa. I just couldn't resist it.