Size of a Boxford metric Lead Screw

[Kim GarnettParticipant @kimgarnett94824]

Hi Could any one tell me the outside diameter the core diameter and angle of the Boxford Aud,Bud metric lead screw as i am looking to make one. As far as I know the the outside diameter is 0.750 thou and the form is ACME and the core shoud be around 0.612 thou but this is a guess

Thanks

[Kim GarnettParticipant @kimgarnett94824]

[Rex HanmanParticipant @rexhanman57403]

My metric BUD leadscrew is spot on 20mm diameter. Sorry, I can't help you with the core diameter or thread angle.

[Kim GarnettParticipant @kimgarnett94824]

Thanks Rex That put the cat amongst pigeons

[Thor 🇳🇴Participant @thor]

Hi Kim,

Have you tried asking the Boxford group?

Thor

[Kim GarnettParticipant @kimgarnett94824]

Hi Thor No but it might worth a try.

thanks

[HopperParticipant @hopper]

If it's Acme the thread depth is half the pitch. So core diameter is OD minus 1 pitch.

But being metric, could it be a 30 degree Trapezoidal thread instead?

No need to guess at core diameters. Specs for both threads are standard and widely available online down to the enth degree.

Edited By Hopper on 27/04/2022 10:05:13

[DC31kParticipant @dc31k]

Posted by Hopper on 27/04/2022 10:03:13:

But being metric, could it be a 30 degree Trapezoidal thread instead?

We have had discussions here before about metric leadscrews used on UK-manufacturered machines. Sadly, I cannot find one by searching, nor can I remember whether it was specific to Boxford or concerned another marque.

However, the consensus appeared to be that many of the manufacturers used imperial diameter stock and an ACME thread form for their leadscrews, just with a metric pitch.

It would be great if someone could find the thread just to refresh our memories.

[Kim GarnettParticipant @kimgarnett94824]

Hi Hopper I have a drawing for a denford viceroy half nuts which seems to suggest that a viceroy lathe lead screw

was 3/4" acme for both metric and Imperial lathes and just the pitch changed and as denford made both machines I was expecting it to be the same for the boxford but it seem not be the case. It would make the interchange between metric and imperial easy from a manufacturing point of view. The core depth would help determine the thread angle

Would this mean that they used a different worm in the saddle which the lead screw passes through on metric boxford lathes from the imperial lathe as i said in a reply to Rex that's put a cat amongst the pigeons

[HopperParticipant @hopper]

Indeed. I think as Thor suggests you would be best to quiz the Boxford groups on Facebook or groups.io etc. The aficionados can probably quote you chapter and verse on the topic.

Like DC31K I vaguely remember threads about metric Acme hybrids but no idea if it was Myford or Boxford or Raglan or another. Sounds like a typical cost saving piece of production engineering any of them could have indulged in.

[HopperParticipant @hopper]

Another possibility to consider is that if it turns out to be a standard metric Trapezoidal thread, you can buy lengths of readymade leadscrew for very reasonable prices but again I forget the name of the UK suppliers discussed in old threads here. One advantage is that the commercially rolled thread is work hardened so more durable than a screwcut thread. But of course you miss out on the fun of cutting your own very long and very thin trapezoidal thread which is only as accurate as the possibly worn leadscrew of the lathe you make it on!

If you are making your own half nuts then you might go one step further and make your own (or buy) worm gear to mesh with a trapezoidal leadscrew in the apron  . Just go fully standard metric trapezoidal thread. No need to copy Boxford's mass production cost saving hybrid deal if that is what it turns out they did.

Edited By Hopper on 27/04/2022 12:47:52

[Ex contributorParticipant @mgnbuk]

as denford made both machines

Maybe at one time, but they were two different companies with two different manufacturing sites for a very long time. I would be wary of assuming that the drawings for one manufacturer were interchangeable with products from the other.

Nigel B.

[Kim GarnettParticipant @kimgarnett94824]

Hi Nigel

My lathe was made by denford before they were sold off its over 60 years old but it may be a change they made when they started making the viceroy lathe as a cost saving and I am wary that's why I ask the question in the first place it appears that it not be as straight forward as I first thought

[Ex contributorParticipant @mgnbuk]

Hi Kim,

If lathes.co.uk are correct, Denford sold the Boxford side to Harrisons in 1952 & designed their replacement machines after the split. If your machine is early '60s, that would put it as being made after the two companies split up ?

The lathes.co.uk descriptions of the Denford machines produced after they moved to Brighouse suggest that their design was different to the Boxford product to address perceived shortcomings. The pictures of the various Viceroy models on the site look quite different to the Boxfords & I would be very suprised if Viceroy parts would drop straight in to a Boxford.

Boxford used a Jowett thread whirler to manufacture some (if not all) of their leadscrews – a rather noisy thing, it was at the end of the workshop near the loading bay door ( I did the last year of my apprenticeship at Boxfords Sept '80 – Sept '81).

Nigel B.

[bernard towersParticipant @bernardtowers37738]

the company I used last is Moore International, surprisingly cheap!!!

[Pete RimmerParticipant @peterimmer30576]

Denford certainly used imperial stock sizes for Metric pitch leadscews. Their metric cross slide screw drawing calls for a 0.750" diamter 5mm pitch LH ACME form thread. A friend of mine enquired with someone for a Boxford cross-slide screw and he was also told it was a metric pitch but ACME form screw, but I cannot verify that. I have an imperial drawing but not a metric one.

[Kim GarnettParticipant @kimgarnett94824]

Hi Nigel

The reason I think that my boxford was made by denford is because it has a denford plate on the bed.

[Kim GarnettParticipant @kimgarnett94824]

Hi All

Thanks for the help but appears that there are two sizes of lead screw on metric machines 19mm and 20mm I have just had a reply from boxford group where some has measured an Aud and has 19mm lead screw with acme thread 3mm pitch

And Thanks again for the help

Kim

[AJAXParticipant @ajax]

Posted by Hopper on 27/04/2022 12:44:31:

Another possibility to consider is that if it turns out to be a standard metric Trapezoidal thread, you can buy lengths of readymade leadscrew for very reasonable prices but again I forget the name of the UK suppliers discussed in old threads here. One advantage is that the commercially rolled thread is work hardened so more durable than a screwcut thread. But of course you miss out on the fun of cutting your own very long and very thin trapezoidal thread which is only as accurate as the possibly worn leadscrew of the lathe you make it on!

Edited By Hopper on 27/04/2022 12:47:52

I'd be very interested if anyone remembers the supplier name.

[Kim GarnettParticipant @kimgarnett94824]

is it ABSSAC

[Rex HanmanParticipant @rexhanman57403]

Oooops! Shoot the cat! I was in a rush this morning when I measured the leadscrew on my 1984 BUD. It is 0.750 thou. Specsavers appointment booked for tomorrow,

My apologies to Kim and everyone else for misleading you.

I hang my head in shame and hope that nobody at tonight's club meeting has seen this!

[HopperParticipant @hopper]

See Bernard's post above re Moore International for leadscrews.

[Author]

Posts