Scribing with verniers

[SillyOldDufferModerator @sillyoldduffer]

Posted by Dr_GMJN on 01/09/2021 13:11:49:

Posted by Martin Kyte on 01/09/2021 11:33:55:…

 

That's really the question: does it harm them?

…

 

Asking 'does it harm them' implies a simple black and white answer, when it might damage them. The question is better put in risk management terms:

Given tool A, costing £B, is it worth the risk of damaging it by action C? The correct answer depends on your particular circumstances: what is the risk; how likely is it to happen; how severe are the consequences; and how happy are you to pay for any consequences?

As the answer varies, it pays to think about internet advice on the subject. No particular reason why Jeff Bezos shouldn't use certificated digital calipers to open cans of paint but in my experience Model Engineers are notoriously careful with their money!!! For that reason, although I'm content to pay the price of damaging my Lidl caliper by using it as a scribe, I choose not to risk my Absolute zero Dasqua.

Photo is of my inexpensive scribe, a tool specifically made for scratching lines in steel.

No doubt here, but even a scribe isn't expected to last forever. And unlike a Mitutoyo this one came with a spare carbide tip…

More dubious advice. As Digital Calipers are made of stainless steel, I confirm its OK to stir Sulphuric Acid pickle with them. Not having to find a plastic spoon will save loads of time, but who wants to take the risk…

Dave

Edited By SillyOldDuffer on 01/09/2021 15:46:55

[Roger BestParticipant @rogerbest89007]

Nice "discussion" here.

May I suggest the compromise it to have the ambition to improve one's equipment, perhaps even to budget and plan, and to (ab)use the current equipment for the time being, that way risk of damage is minimised.

I like marking out, I get that wrong often enough, the thought of making mistakes, even when using the DRO, horrifies me, I like to see what I am aiming for.

R

Edited By Roger Best on 09/11/2021 14:36:43

[Mick B1Participant @mickb1]

I'm struggling to see how you'd use the points of a caliper to mark out. Whether or not it harms them (and I'd guess it would, if you kept doing it), it's hard to see how you keep the line between the points square to the datum reliably.

I usually use the 'step' function on the caliper, register the sliding element against the datum and and scribe to the 'fixed' edge. If I have an opposing edge I'll work out the opposite dimension and scribe that one too, and aim between the lines to take out error. Can't see how that would harm the instrument.

[Jon LawesParticipant @jonlawes51698]

My "expensive" calipers I don't use for this purpose, but I would.

I don't know how some of you mark out, but I'm only removing a layer of Dykem blue, not scoring a channel. I reckon even cheap calipers will outlast me.

[Nick WheelerParticipant @nickwheeler]

Posted by Jon Lawes on 09/11/2021 15:47:25:

My "expensive" calipers I don't use for this purpose, but I would.

I don't know how some of you mark out, but I'm only removing a layer of Dykem blue, not scoring a channel. I reckon even cheap calipers will outlast me.

I agree completely.

[noel shelleyParticipant @noelshelley55608]

As an apprentice over 50 years ago – when calipers, good ones, were very expensive I would have been greased and feartherd, you can guess where – for such use ! Digital measurement was new, Now I can buy a digital caliper for almost the same price as a good scriber. If it is a cost effective use of the tool but shortens it's useful life in it's designed use is that wrong ? I say NO ! Discuss ! Noel.

[Tony Pratt 1Participant @tonypratt1]

I only use calipers digital or vernier for rough measurements

Tony

[BufferParticipant @buffer]

I do it every time i go in the workshop.

Oh and I also do this, all ready for soldering.

 

Edited By Buffer on 09/11/2021 18:01:22

[Michael GilliganParticipant @michaelgilligan61133]

Posted by noel shelley on 09/11/2021 17:32:13:

As an apprentice over 50 years ago – when calipers, good ones, were very expensive I would have been greased and feartherd, you can guess where – for such use ! Digital measurement was new, Now I can buy a digital caliper for almost the same price as a good scriber. If it is a cost effective use of the tool but shortens it's useful life in it's designed use is that wrong ? I say NO ! Discuss ! Noel.

.

I agree completely, except for one detail … The tip of a typical digital calliper [English spelling] isn’t sharp enough to serve as a good scriber.

Instead of arguing the toss over whether it is reprehensible to abuse ten quid’s worth of ‘consumable’ … Let’s have some ideas about how to add decent scriber points to said items.

MichaelG.

[noel shelleyParticipant @noelshelley55608]

WELL DONE buffer, some one had to do it ! Noel

[Martin CargillParticipant @martincargill50290]

A friend of mine tells of the time when they caught a labourer using a pillar drill with four micrometers as G clamps. Might have got away with it but he had used mole grips to tighten them.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Nicholas Wheeler 1 on 09/11/2021 16:19:59:

Posted by Jon Lawes on 09/11/2021 15:47:25:

My "expensive" calipers I don't use for this purpose, but I would.

I don't know how some of you mark out, but I'm only removing a layer of Dykem blue, not scoring a channel. I reckon even cheap calipers will outlast me.

I agree completely.

I feel an experiment coming on! Maybe Jon has a steady enough hand to remove Dykem without metal to metal contact maybe not. No need to exchange opinions, this can be tested. Easy enough for me to microphotograph the points of an old caliper before and after scribing along, say, 10 metres of mild-steel. I think it will show that scribing damages the points.

As I don't have have any gauge blocks I can't do a good test of any loss of accuracy caused by the caliper arms and/or frame being twisted by scribing. Anyone willing to record how accurate their expensive caliper is before scribing 10 metres and how accurate it is after? The difference would establish how bad, or not, scribing is.

I don't think anyone should expect a caliper to remain accurate after being used to scratch lines. But it may not matter unless the caliper is also expectedto take trustworthy measurements. Maybe most hobby calipers aren't required to be accurate? It's true I do a lot of approximate work with mine.

Dave

[BazParticipant @baz89810]

It’s your tool so you can do as you want with it but like Noel I would have been greased and feathered if caught abusing equipment when I was an apprentice and old habits die hard. I don’t say it’s right or wrong but I wouldn’t use a vernier that way.

[Michael HornerParticipant @michaelhorner54327]

Didn't John Stevenson modify a digital calliper as per Jason's link? I've looked through a hundred of his posts but not able to find it before boredom set in! Best I could find is the picture below just to show his sense of humour.

Cheers Michael

[noel shelleyParticipant @noelshelley55608]

I love it ! Can we form a comedy act ! Martin, Buffer, Michael, It's all priceless ! It's good to be here, Thanks Gentlemen. Noel

[BufferParticipant @buffer]

My caliper cost 7 quid from Aldi and I have checked it against gauge blocks and it's fine. They are so cheap I have even hacked the ends off and used them as a dro on my super 7. I think the tip of a caliper is perfectly sharp enough for scribing, after all I'm not making satellites in my shed I'm making steam train parts. If I need better accuracy I either don't scribe anything or use a surface plate and height gauge. Also as for wear, I don't measure with the pointed ends I nearly always measure with the thick bits because when they are squeezed up tight on a bar they hold the caliper nice and perpendicular. I probably wouldn't do it with a Mitutoyo if I had one.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Michael Horner, second post down John's El cheapo digital is the one your thinking of I believe.

Regards Nick.

[Anonymous]

Posted by Jon Lawes on 09/11/2021 15:47:25:

I don't know how some of you mark out…..

I rarely mark out, it's been superceded by using reference edges/circles and a DRO. Marking out is mainly used for sheet metalwork, done by hand, and the occasional reference mark for assemblies.

Andrew

[SillyOldDufferModerator @sillyoldduffer]

Posted by Andrew Johnston on 09/11/2021 22:28:05:

Posted by Jon Lawes on 09/11/2021 15:47:25:

I don't know how some of you mark out…..

I rarely mark out, it's been superceded by using reference edges/circles and a DRO. Marking out is mainly used for sheet metalwork, done by hand, and the occasional reference mark for assemblies.

Andrew

I'm pretty much in Andrew's camp except I often mark out a few key points as a sanity check. As the tool is moved into position the markings confirm I haven't confused myself whilst switching references, or bungled the simple mental arithmetic my cheapo DRO requires.

I normally start with a drawing(s), which can be anything from a quick sketch to hours of CAD, and use them to decide the suitable reference points and cut sequences needed to get the required shape from the starting lumps of metal, ideally a nearby stock size. Cuts are done in terms of x,y,z coordinates relative to fixed references rather than scribe lines and centre-pops. The closest I get to old-school marking-out is on sheet-metal, making front-panels for electronics.

Dave

[Howard LewisParticipant @howardlewis46836]

The risk with using Callipers, free hand, is that they will not remain "square" to the workpiece at all times, and so render a less that accurate or straight line.

Ideally, the "tool" to use is a Height Gauge, which will have attachments specifically for scribing.

This will ensure that the scribe is always the same distance from the edge of the workpiece (Assuming that it is clamped to an angle plate or something akin to it, on a known flat surface. Recently, to scribe some 6 mm x 6 mm x 23 gauge sheet steel angle, it was clamped to a 1/2" square HSS toolbit. )

As an Apprentice in the Toolroom, I was encouraged to make a base into which my Rabone Vernier Calliper could be mounted, a clamp, and and fittings so that it could be used for scribing or to carry a light DTI.

Effectively, this converted it into a small Height Gauge.

From time time to time articles appear on in the Model Engineering press on how to make such things.

For those lacking a Surface Plate, for the occasional small job, the bed of a machine or a thick piece of glass could be used.

It would be possible to use the marble cutting plates that are sold in Supermarkets, as cheap source, as long as they are correctly supported to be stress free.

I made a surface plate from a piece of marble, obtained from a stonemason, as an off cut from a grave headstone. It was about 40 mm thick and 500 x 600 mm, and cost £30.

It was bedded onto quite wet plaster, to ensure that it was not stressed, on ply, on an angle iron base, with cross reinforcements, and leveling feet at the corners.

Howard

[Roy MParticipant @roym]

I made a 150mm 'height gauge' and got good results.

Purchase a £7.50 digital calliper, remove the non moveable jaw and clamp into a slot machined in an appropriate sized base.Set height to zero on a standard block.
It worked for me!

Roy.

[Massimo DalmonteParticipant @massimodalmonte45801]

Hi,

I bought one of these a few years ago, was very cheap then, about 10 euros, complete with sheath and spare scriber:

it has a couple of advantages versus modified regular verniers, the roller and adjustable scriber "height".

Massimo

[James AlfordParticipant @jamesalford67616]

Posted by Massimo Dalmonte on 29/12/2021 09:01:30:

Hi,

I bought one of these a few years ago, was very cheap then, about 10 euros, complete with sheath and spare scriber:

it has a couple of advantages versus modified regular verniers, the roller and adjustable scriber "height".

Massimo

A small world: I bought one as well a week or so before Christmas. About £13.00 on Amazon.

[martin haysomParticipant @martinhaysom48469]

Posted by Roy M on 28/12/2021 23:20:32:

I made a 150mm 'height gauge' and got good results.

Purchase a £7.50 digital calliper, remove the non moveable jaw and clamp into a slot machined in an appropriate sized base.Set height to zero on a standard block.
It worked for me!

Roy.

i did this too. except i had too spend a little more on the calliper

[GmanParticipant @thomasgman46877]

You could always purchasing one of these: https://www.banggood.com/0-200mm-Measure-Scale-Ruler-0_05mm-Accurate-Parallel-Line-Digital-Vernier-Caliper-W-or-Case-Woodworking-p-1425961.html I have one and have used it a ton. Works great and comes with an extra carbide tip, I repurposed into a handheld scriber.

Edited: I just noticed the one I purchased is discontinued, but there are plenty of others that sell the same thing.

Edited By Thomas Gman on 03/01/2022 17:53:49

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