metric or inperial

[luke pennyParticipant @lukepenny99087]

how do i determin if my lathe is metric or inperial

[luke pennyParticipant @lukepenny99087]

[NobbyParticipant @nobby]

Is there a name on it ? or thread chart.? check the pitch on the leadscrew ? post a picture of the x slide micrometer dial.
Nobby

[John Stevenson 1Participant @johnstevenson1]

Does it speak english ?

[Ady1Participant @ady1]

Open up a cheap digital vernier a few inches

jam it between the saddle and the headstock, reset it to zero

 

Turn the leadscrew once and see what your reading is

On an imperial 8 turns would usually be exactly an inch (but not all)

Not sure about metric, 2mm a turn?

Or count the TPI on the leadscrew using a ruler

Line up one inch of the ruler with a crest, and count forwards(don't include the first lined-up crest)

Let us know what you get

 

Edited By Ady1 on 03/03/2013 02:50:57

[Sub MandrelParticipant @submandrel]

What make of lathe?

It's usually the carriage leadscrew pitch that you need to check, unless it has a screwcutting gearbox.

Neil

[luke pennyParticipant @lukepenny99087]

 

 

Edited By Wolfie on 09/03/2013 00:22:41

[JasonBModerator @jasonb]

Here you go, you will soon get used to teh quirks of ME forum

 

 

Edited By JasonB on 03/03/2013 18:16:22

[Speedy Builder5Participant @speedybuilder5]

Looks like a Colchester Bantam ?? As it has the screwcutting gearbox on it, and it looks like an older model, it is more than likely a Mk1 M/c.

From Lathes.co.uk:-

Mk. 1 Screwcutting and Power feeds
Although most Mk. 1 Bantams were fitted with a screwcutting gearbox, numbers of "Hawk" models were supplied to training workshops with cheaper imperial or metric changewheel screwcutting. On the changewheel models there was, unlike their contemporary Harrison competitors, no 3-speed leadscrew gearbox, instead a simple 2-speed gearbox was employed where a sliding double gear on the feed shaft could be moved by a lever into one of two positions to pick up a single gear on the leadscrew – and so select either a fast or a slow rate of feed (the leadscrew on Bantams is used only for cutting threads and should normally be left disengaged).
The "Eagle" screwcutting gearbox version offered 29 English pitches from 3.5 to 80 t.p.i. (and 15 metric with translation gears) and the Condor 27 metric pitches 0.2 to 6 mm (and 26 English with conversion gears). Sliding feed rates varied from 0.001" to 0.028" on the screwcutting model; from 0.001" to 0.032" on the Eagle and from 0.02 to 0.7 mm on the Condor. In every case the surfacing (cross-feed) rate was half that of the sliding. Both models were equipped as standard with a number of extra changewheels to extend the normal threading range beyond that commonly required; if these gears are missing from a used lathe, it's worthwhile asking if they have been stored separately and perhaps overlooked. Power cross and longitudinal feeds was fitted to all models with a push-pull knob to select sliding or surfacing and with the engagement and disengagement by a flick-in-and-out lever at the bottom of the apron. To protect the power-feed mechanism against overload damage all models were fitted with a shear-pin incorporated in the top gear of the drive to the screwcutting gearbox..

[luke pennyParticipant @lukepenny99087]

the bottom lever in the picure is thew only one and like you say it operates a sliding gear on the feed sharft

[Trevor WrightParticipant @trevorwright62541]

Luke,

Bantams from this period were imperial only.

Thanks for posting the picture…I have a Bantam mk1 identical to this but the plate that shows speeds per lever position for the spindle is completely worn away….

As for screw-cutting it would appear that the plate is showing the change-wheel settings for each thread with only the one lever. Mine has a 3 position lever and a 6-way circular handle for power feeds and screw-cutting, so yours is definitely not standard.

Perhaps a photo of just the lower plate? Should be able to figure out whether thread pitches are included in the chart.

Cheers

Trevor

[luke pennyParticipant @lukepenny99087]

i have mounted a mag base on the sadle with a inperial clock and then a metric clock touching the cross slide.

with the inprerial when i turn the crosslide 5 divisions on the dile it reeds 3.3/4 thows on the clock when i repeat it with the metrick clock 5 divisions on the dile reeds 5 on the clock.

so i think its a metric lathe.

the leed screw is inperial

im disapointed as i wanted a inperial bantam i would like to get a inperial crossslide and topslide for it

Edited By luke penny on 08/03/2013 21:53:18

[Les Jones 1Participant @lesjones1]

Hi Luke,
I think there is an error in your measuments as you say 5 divisions on an imperial guage read 3.75 thou which is 0.00375" x 25.4 = 0.09525 mm but you then say that a metric guage reads 5 divisions for the same movement which I assume is 0.05 mm. This means there is an error of almost 2:1 in your readings. Either one or both guages are wrong or your interpretation of the readings is wrong. I personaly only use a dial guage as an indication of runout. Not for actual measurments.

Les.

[Ady1Participant @ady1]

im disapointed as i wanted a inperial bantam

i would like to get a inperial crossslide and topslide for it

—

Just fit a DRO (digital read out) and it can be metric or imperial whenever you like

As far as threads are concerned all threads are TPI, be they metric, Imperial or from the planet Zog

Edited By Ady1 on 09/03/2013 00:24:59

[MadMikeParticipant @madmike]

Ady, not all threads are classified as TPI, only those using full size Imperial measure, as opposed to the over rated Napoleonic versions. the Latter are quoted as having a thread pitch of, for instance, 1.00 or 1.25 mm. Of course you can convert these to a TPI equivalent but you may get some rather strange values like 20.325 TPI.

[Ady1Participant @ady1]

Actually you've just reminded me of an old TPI project

I started and half finished… a bit like my life, lol

It does all the TPI calculations for a headstock->banjo->banjo-> leadscrew setup

plus you can specify any allowable error

**LINK**

So 20.325 plus or minus 0.001 is a doddle to calculate

[Author]

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