What is a dot punch?

What's a dot punch?

Peter

Edited By JasonB on 17/11/2015 17:41:23

Hi Peter, a dot punch is essentially a centre punch, but is normally thinner and with a much more acute point. It is ideal for sheet metal work as you don't need to strike it very hard to form a small centre mark. They are often used before using a centre punch as you can see where you want your centre much clearer. Some people may call them a marking out punch. They are also good to highlight a faint line which you may want to bend or cut to, as the upset of the centre does not spread out sideways by very much. **LINK**

As the name suggests, it produces a dot.

Regards Nick.

Edited By Nicholas Farr on 15/11/2015 20:41:06

Edited By JasonB on 17/11/2015 17:42:15

Hmm,

Seems like my attempt at humour (What's a dot punch?) fell flat. Trouble is, I'm not into smileys etc

Oh well, must try harder, - a phrase that appeared on almost, if not all my school reports!

Peter G. Shaw

Edited By JasonB on 17/11/2015 17:44:11

Peter, I had to Google dot punch - I had nevr come across it before.

What, then, is the difference between a prick punch and a dot punch" Or is "dot" the PC gender-neutral modern term for "prick"?

Edited By JasonB on 17/11/2015 17:43:32

Peter G.Shaw:

If it's any consolation, I guessed you already knew the answer to your original question but I admit I still didn't get the joke!

A 1951 vintage English encyclopaedia lists dot but not prick but my Starrett catalog (sic) lists prick but not dot.

Edited By JasonB on 17/11/2015 17:44:35

PS another vintage English work has dot but not prick but also "dinking" which was new to me. The last-named is what I call a wad punch ie hollow punch for cutting circular slugs (or holes) in soft material.

Edited By JasonB on 17/11/2015 17:44:55

Perhaps English use dots and Americans use pricks for the same thing?

Edited By David Clark 1 on 17/11/2015 12:02:12

Edited By JasonB on 17/11/2015 17:45:31

It's my weird sense of humour.

Nick said this: and no one should be put off by asking the simplest and most basic questions e.g. what's a dot punch for? To which I, rather facetiously asked the question: What's a dot punch, whilst knowing full well what it was. It has to be said that I have been pulled up countless times at work for doing the same thing. Which to my detriment didn't go down well with some people, especially higher management (and I don't mean her indoors either). So really, I should not have asked the question.

Anyway, apart from my personal failings, it has proved usefull in that at least one other person genuinely did not know what one was. Further more, it has shown up the fact that there are apparently two names for the same item, eg dot or prick. I must admit that I've never thought anything about the difference, if any, and sort of understood that both were possibly names for the same item.

By the way, as far as I am concerned, it's nothing to do with gender. Just think, how do we describe a nut and bolt - one is the female part and the other the male part, and one goes inside the other. And this applies in all sorts of ways because it makes descriptions easier. Another term which made one of my sons look a bit askance at me was when I described one of my files as a big bastard - it was indeed a 12in long bastard double cut file.

But just going back to the dot/prick punch. I have three punches. One is what I would call a centre punch. It is relatively hefty and has a 90 degree point. At the other end of the scale is what I call a dot punch. This is altogether a much lighter device with a tiny, possibly 60 degree point. This is the one I use to either impress a tiny dimple by pressure alone, or by a quick belt with the palm of my hand. I would never use a hammer on this device. In between, I have a punch which still has about a 60 degree point but is halfway between the other two punches. This one is used after the light, shall we say marking punch, and before the true centre punch.

Now, in view of the correspondence above, I'm now wondering of strictly speaking, my lightweight punch is a prick punch, whilst the intermediate one is a dot punch as these descriptions would seem to more accurately describe their uses.

Over to you,

Peter G. Shaw

Edited By JasonB on 17/11/2015 17:46:07

I think they are all covered by, 'Center punch', whether it is sharp pointed or obtuse pointed. Used for many functions I have found where an engineer has decided to center punch along a line to tighten up a gap or make a shaft fit into a hole better. I have seen bearings retained by center punch marks, good or bad I dont know but worked for the person doing it.

Clive

Edited By JasonB on 17/11/2015 17:46:28

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... and a once-common way of 'recovering' worn pivot holes in Clock Plates

MichaelG.

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Edit: See image 3 on this page 

Edited By Michael Gilligan on 17/11/2015 16:40:10

Edited By JasonB on 17/11/2015 17:46:55

Peter G.Shaw:

Thanks for the interesting explanation. I also took the opportunity to read your public profile and trust you are not affected by the current flooding.

Dot or prick? I'm tempted to say what's in a name but can add the following:

The Starrett No 816 Prick Punch was made in 4 body diameters ranging from 9/32 to 3/8" with correspondingly graded point sizes but all the same 4" length; the point angle was not specified but from the catalog illustration seems to have been about 35 deg incl. I think one can deduce from this that a variety of work was envisaged; another illustration shows the finest of these being used with a 4 oz hammer "to locate hole centers."

My 1970 M&W catalogue surprised me by listing a Spring Dotting Punch "for use on small marking jobs where care and accuracy is essential"; they also list a Prick Punch similar to the finest Starrett item but, seemingly, with a blunter point.

Prick: this ancient word is apparently derived from the image of a sharp thorn - think early gramophones. Dot, however, means "to land a heavy and precise (on the 'dot' blow".

You will be aware that traditionally a scribed line was punched at intervals by the man responsible for marking out so that if the worker who had to cut to the line overcut the job it was apparent where the fault lay. In my view this would be done with a dot punch and this tool would, therefore, be unnecessary in the amateur workshop!

Edited By ega on 17/11/2015 17:36:16

Edited By JasonB on 17/11/2015 17:47:45

A finer, lighter, centre punch.

Not going along with the 'dinking' though it would seem to be the old term. Perhaps we should try resurrecting that usage by suggesting ME suppliers we know to list them by that name. It does come up on a search though. Is there a verb associated?

Edited By Bazyle on 17/11/2015 18:00:54

It was common practice when doing my 'time' as a hgv fitter back in th early 70s to tighten up the spring hanger bushes in the spring eyes for the mot - I dought you'd get away with it now - probably a good thing

Lionel

Edited By Limpet on 17/11/2015 18:44:08

In my KH Moltrecht book on engineering the hand prick punch is shown being used with a jewellers eye glass to track along scribed lines until it clicks into the intersection between two lines where a hole is required. The punch is then twirled between the fingers to create a small and highly accurate indentation for a prick punch to be used to enlarge this fine mark, and a centre punch being used to prepare the mark for a drill point. Quite a lot of steps for a simple hole but accuracy is paramount.

I use a Dankroy optical centre punch for any really accurate marking out on flat surfaces.

Mick

Tractor mans post is exactly how I was taught to use a M&w prick punch and follow up with a centre punch, I still use that same prick punch 55 years later. At my second job I worked with a lot older instrument maker who always followed up the centre punching with a twist drill,he believed a small drill was flexible and would centre on the punch mark rather than using a centre drill which is stiffer and can tend to make its own centre particularly if the work is held in a heavy vice, I was taught during apprenticeship to use a centre drill ,though I did find the use of a small drill to centralise on the punch mark was more reliable and have used a small drill drill ( 1.3 to 1.6 mm)ever since.

Even a set from the pound shop typically contains a prick punch, a centre punch and a flat-ended nail punch.

Neil

I was also taught that if the initial dot punch mark was not quite where you wanted it that the punch should be tilted and hit again to move the indent to where it should be, when happy follow up with a ctr punch if drilling or leave alone as the more pointed hole better locates the point of your dividers.

Also used to put a series of dots along a scribed line as they are a bit more permmanent than a scribed line, file or machine to split the dots.

J

Hi Peter, I did wonder if, when you asked the question, if it was a tongue-in-cheek one, but having known people that have not heard of some terms such as this one, despite being the same trade as myself and for a similar period of time as I have, gave you the benefit of doubt. I do understand your sense of humour though, as I do much the same thing and get some puzzled looks at times.

Regards Nick.

Hi Jason, I agree with you about tilting the dot punch over if you didn't get it right the first time and I believe that is the point about using the dot punch first, much easier to move at dot than a centre punch mark. (must be a pun in there somewhere)

Regards Nick.