leadscrew pitch

[David Keil 1Participant @davidkeil1]

[David Keil 1Participant @davidkeil1]

as a newbie to a milling machine, I am trying to find out what this means in relation to a leadscrew pitch, 6.3 x 1mm.

[JasonBModerator @jasonb]

That's a bit of an odd one can you give us a few more details of the machine and the context of the text.

[Pete RimmerParticipant @peterimmer30576]

The pitch is 1mm David.

[David Keil 1Participant @davidkeil1]

The machine is (or will be) a Sherline milling machine. I am going to use mach3 so just trying to understand how to setup motor tuning in mach3.

[David Keil 1Participant @davidkeil1]

Pete

what does the 6.3 relate to?

[EmgeeParticipant @emgee]

6.3 (mm?) could be the 1 decimal place American conversion of 1/4" diameter feedscrew.

Emgee

Edited By Emgee on 09/02/2021 18:55:28

[Howard LewisParticipant @howardlewis46836]

6.3 mm sounds like a slightly inaccurate 1/4" (6.354 mm )

Don't know the Sherline, but imagine it as a fairly small machine, so could the leadscrew be 1/4 x 25 tpi?

Hard to imagine that a designer would specify a 1 mm pitch for an odd diameter such as 6.3 mm..

It could be hybrid with a 1 mm pitch on a 1/4" shaft.

Having been told that the by Pete Rimmer that the pitch is 1 mm, I would expect the diameter to be a Metric integer.,

The essential thing is that the OP KNOWS the pitch so that he write the program

Howard

[SillyOldDufferModerator @sillyoldduffer]

I guess this comes from Sherline's Specifications Page. 6.3mm is the diameter of their metric leadscrew.

Sherline's Inch leadscrew is given as ¼ – 20, which is USA speak for ¼" diameter rod threaded 20 turns per inch.

The metric leadscrew is given as 6.3mm x 1.0 pitch, which is similar in size to the inch version, but the dials measure in metric.

6.3mm x 1.0 is a non-standard metric size. I think for ease of manufacture Sherline have just put a metric 1.0 pitch thread on the same ¼" diameter rod they make ¼ – 20 from. Quarter of an inch is 6.28mm, close enough to 6.3mm.

For setting up CNC only the pitch matters – the 6.3 can be ignored.

Dave

Edited By SillyOldDuffer on 09/02/2021 19:04:06

[Michael GilliganParticipant @michaelgilligan61133]

Here it is, straight from the Sherline horse’s mouth: **LINK**

Standard Dimensions of Sherline Tools

I’ve never measured one [and there is no tolerance quoted] but can only assume that 6.3 is the diameter in millimetres

… either a truncated approximation for 6.35 mm, or because they actually skim down 1/4”

MichaelG.

.

Dave beat me to the post.

Edited By Michael Gilligan on 09/02/2021 19:05:06

[David Keil 1Participant @davidkeil1]

The 6.3 x 1mm is the sherline specification for the x and y leadscrew axis.

[David Keil 1Participant @davidkeil1]

OOps you both beat me to it.

[David Keil 1Participant @davidkeil1]

Thanks all for your help, so simple really….haha

[Anonymous]

Posted by SillyOldDuffer on 09/02/2021 19:02:04:

Quarter of an inch is 6.28mm, close enough to 6.3mm.

Last time I checked 1/4" = 6.35mm – exactly.

In case SoD thinks I'm getting at him again, he's not the only offender who doesn't know the equivalent of 1/4" in metric, just the simplest to quote.

Andrew

[DC31kParticipant @dc31k]

We have had long and interminable discussion in another thread about various definitions of the inch.

This here thread would seem to provide two more candidates:

the Howard inch, where 1/4 of it is equal to 6.354mm and the Duffer inch where 1/4 of it is 6.28mm.

[SteviegtrParticipant @steviegtr]

So i guess & Howard & Duffer inch is somewhere in between.()

Steve

[JasonBModerator @jasonb]

Would that be the "Howduff" inch?

Not to be confused with the typo inch.

Edited By JasonB on 09/02/2021 19:44:59

[Clive FosterParticipant @clivefoster55965]

Feedscrews of metric pitch but imperial diameter has been very common on metric versions of machines originally designed for markets using the imperial system.

Which can be a right pain.

Telling the difference between 5 tpi and 5 mm pitch on Bridgeport feedscrews or nuts is hard enough when everything is new and factory fresh. Throw in a quater of a century of wear and its time to invent new swear words. Screws aren't too bad when you know the cunning trick to make it easy but nuts …..

Many years a go I chose the best fit pair from several loose cross slide feedscrews and nuts when doing a "frankenlathe" Boxford saddle on southbend apron and bed job. I know some were metric, some imperial and all were worn. I'm pretty certain that best fit pair was one imperial and one metric but which was which I know not. Worked just fine for me over a decade or so and the guy who bought it was happy.

Clive

[Grindstone CowboyParticipant @grindstonecowboy]

Posted by JasonB on 09/02/2021 19:44:18:

Would that be the "Howduff" inch?

The "Duffard", I think.

Rob

[David Marks 2Participant @davidmarks2]

1/4 – 20 is a 1/4" UNC thread. A standard thread in the UNC/UNF series and the American equivalent to our BSW/BSF system of threads.

[Oily RagParticipant @oilyrag]

Some years ago I was passing through Hong Kong on my way home from China mainland, the connecting flight 'missed' so I had 48 hours in HK before I could get another flight. In this time I decided to have a made to measure suit which would be ready in just 36 hours!

When I was being measured up I was surprised to discover that I had miraculously lost weight – my waist size had dropped from 34" to 27", my chest from 42" to 34"! That was when I discovered the Chinese tailors inch where 1 CTI = 1.25 Imp inch!!

Martin

[Howard LewisParticipant @howardlewis46836]

My 1958 Zeus charts give 25 mm as being equal to 0,9843 inch. Dividing by 25 and multiplying by 25.4 gives 1.0000488. So The 25.4 mm to 1 inch figure that I have always used seems to be out by 488 millionths of an inch..

SOD's 6.28 mm for 1/4" gives 25.12 mm to his inch. I think that the low temperatures have made his measuring equipment contract!

My suspicion, in this case is that the Leadscrew is made from 1/4 inch bar with a 1 mm pitch thread cut on it.

Howard

[SillyOldDufferModerator @sillyoldduffer]

Posted by Howard Lewis on 10/02/2021 16:32:15:

…

SOD's 6.28 mm for 1/4" gives 25.12 mm to his inch. I think that the low temperatures have made his measuring equipment contract!

My suspicion, in this case is that the Leadscrew is made from 1/4 inch bar with a 1 mm pitch thread cut on it.

Howard

No, it was my brain that malfunctioned! No idea where 6.28 = 1/4" came from. 25.4 / 4 = 6.35

Perhaps a nap would help…

Dave

[duncan webster 1Participant @duncanwebster1]

Posted by Howard Lewis on 10/02/2021 16:32:15:

My 1958 Zeus charts give 25 mm as being equal to 0,9843 inch. Dividing by 25 and multiplying by 25.4 gives 1.0000488. So The 25.4 mm to 1 inch figure that I have always used seems to be out by 488 millionths of an inch..

SOD's 6.28 mm for 1/4" gives 25.12 mm to his inch. I think that the low temperatures have made his measuring equipment contract!

My suspicion, in this case is that the Leadscrew is made from 1/4 inch bar with a 1 mm pitch thread cut on it.

Howard

The Zeus figure is rounded. The real figure to 9 decimal places is 0.984251968", but the Zeus chaps probably reckoned that anything less than 1/10 of a thou was not for practical men. I my case anything less than a thou is a chimera

[Howard LewisParticipant @howardlewis46836]

So we got there in the end! Now I've forgotten what we were doing.

I know, we got (lead ) screwed up

Howard

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