1267 forum posts
All, I suppose I can predict the response to this, but I've got some nice Mitutoyo digital verniers, and sometimes use the points to scribe lines on permanent marker on cast iron, steel, brass etc. Assuming the faces and points are hardened, and I'm only using very light pressure, does it really matter for occasional use on materials like these? I know it's kind of wrong, but...
I suppose I could use my old set of verniers for this, but then again it seems to partly defeat the object of getting the new ones. Transferring a reading to other calipers or dividers would seem to introduce an error, so...what's the best method of scribing accurate lines offset from a face for model engineering?
I'm looking at getting a digital height gauge (fairly cheap one), and I notice their pointers seem to be specifically for scribing - I think I saw some described as scribing pointers? Presumably they are similar material to verniers?
2423 forum posts
Yes they are carbide tipped. I have 2 mitutoyo versions. They both have a carbide tip. Here is a pic. That said i & plenty of others use the calipers to scratch with.
|Tony Pratt 1||31/08/2021 16:01:44|
|1936 forum posts|
Nothing wrong in using calipers as a light scribing aid if you are careful, I though mainly used the end of a steel rule held in a combination set square head, just set the rule to say 10mm butt the head against the work surface & scribe a line, not at all accurate but gives you a rough guide to start with, I never actually worked just to lines but setting out a job saves scrappage, well usually. Back in the day most height gauge scribers were hardened tool steel but invariably are now carbide.
22605 forum posts
If scratching with callipers it's best to use a dedicate one with modified ends, grind the fixed one shorter and flatter so the scale remains parallel to the surface as tilting them so one leg is resting against the edge reduces the length being scribed.
Or you can pay for someone to do it for you
Though I prefer the height gauge to odd legs or the occasional digital calliper.
Edited By JasonB on 31/08/2021 16:16:37
1267 forum posts
I've ordered a 12" digital height gauge just now (an M-Sure one) at about £130. I've thought too often that one would be useful, so I can use that for most of the scribing work I think.
|Andrew Johnston||31/08/2021 16:45:12|
6577 forum posts
Wow, scribing lines? That really is old school.
I very rarely mark out now; mainly for sheet metal that will be filed/drilled by hand, and for the odd reference point to aid setting up a casting. I use a secondhand mechanical vernier height gauge and surface plate and very rarely odd legs; never used my vernier calipers. But then again I rarely use my calipers as I prefer micrometers.
1267 forum posts
It’s mainly to mark out castings as a sanity check for where things are going to be machined to with the DROs, like hole centres offset from edges, or heights above a datum. Also for marking around the circumference for turning things to length, or parting off, at least non-critical lengths.
I don’t do it routinely to machine to, but it’s sometimes useful.
|Mike Poole||31/08/2021 19:50:22|
3308 forum posts
There are plenty of youtubers who are not shy about abusing their caliper, of course I would never dream of abusing a precision measuring tool for marking out but there is a bloke who looks remarkably like me who abuses my calipers. So far the points have not developed any obvious wear and I think it would be an easy job to stone any wear away, I am sure the frame and slide are not designed for this use either but if any problems do occur I shall drop this practice, buy a new one and put it down to experience. Many of our tools have useful alternative functions that often don’t do any real harm, scribers are excellent picks for some jobs and a quick touch up will soon restore the point. I would definitely not abuse someone else’s tools and I hope they won’t abuse mine.
|Mick B1||31/08/2021 20:39:17|
|2163 forum posts|
I don't scribe with digital or vernier caliper tips simply because I don't know how I can keep from tilting or angling them.
I use the ground flat front edge next to the moving inside nib as a register to get the shaft of the caliper square to whatever datum I'm working from, as per step measurement guidance in most instruction sheets, set the distance, then scribe as near as I can to the ground front of the fixed outside jaw.
Then I work out the theoretical position of the same feature from the opposite face of the workpiece, if there is one suitable, and scribe similarly - and then, because errors if any are likely to be similar, aim between the two lines.
So far, this method has generally worked well enough when I've needed to use it. But it's better to edge-find and dial off your dimensions if you can, or use DROs if you have 'em.
|Bob Stevenson||31/08/2021 20:48:48|
|579 forum posts|
........Ooh er!....I think I must be the only bloke still marking out 'properly'.....
What does get me started is members of my clock club who use the vernier on work in the lathe and don't see a need to turn the lathe off first!
I did once see a vernia sticking out of someones thigh, although not from this to be fair......
|Nigel McBurney 1||31/08/2021 20:54:55|
999 forum posts
I started in the 1950s and am definitely old school and I dont see anyting wrong with that ,and why not most of the models we build are based on engines ,machinery etc which may have been made donkeys years ago and the castings and materials are nearly all similar, I would for a start never never use a vernier with pointed jaws for marking out, a scribed line needs some depth so that it can be felt bythe point of a prick punch (smaller than a centre punch) where the punch touches the point where two lines meet thats when you hit the punch or if you doing a very precise job check the position of the punch point with an eye glass. marking out machined parts and surfaces can be carried out with a surface gauge ,a more precise method is to use a vernier height gauge with a wide chisel like edge more modern ones have carbide scribing edge, marking out castings to establish datum lines and machining allowances use a surface gauge, to set the height make sure the rule is held vertical or use the square and rule from a combination set..like Andrew I prefer to measure accurate dims with a micrometer rather than a vernier, and still prefer non digital vernier and height gauge ,more reliable in the long term than digital.
|not done it yet||31/08/2021 22:11:40|
|6749 forum posts|
I know it's kind of wrong, but...
Says it all, really. Do you use your micrometers as ‘G’ clamps? Cheap digi or vernier maybe, but not a proper Mitutoyo!
The scribed line can only be most precise with zero overlap on the casting edge, so might just as well use odd leg calipers to do the job (if a rough line) or a proper scribe.
2423 forum posts
I only have moore & wright micrometer, but you have given me a great idea.
796 forum posts
You can buy verniers designed for scribing, I own some, they are made of stainless steel, have a roller on the movable jaw, and a replaceable scribe point the fixed end, I'm not allowed to put a link, but you can buy them for under £7 delivered.
2423 forum posts
Why is there always a strange smell in the room. Of course it is ok to use the calipers to mark out. the only reason you get comments is because there are those that have nothing better to do. Buy a TV license & watch some telly. Or just take the meds the doc prescribed.
Great forum. Love it.
|Ron Laden||01/09/2021 06:45:17|
2297 forum posts
Ti's up to you if you choose to use your Mitutoyo for scribing lines but for me I would use your old caliper and save your Mitutoyo and keep it pristine as much as possible.
I have a Mitu and a cheapie caliper but I don't tend to scribe with them. For marking out to get a feel for general positioning etc I just use a quality steel rule a small square and a sharp scriber. Where I need accuracy I use a height gauge (non digital) and angle plate, I know some say they hardly ever use theirs but I use mine a lot.
22605 forum posts
Not really a bad smell just pointing out that it may not do what the Doc wants.
" Transferring a reading to other calipers or dividers would seem to introduce an error, so"
This would seem to suggest he wants a fair level of accuracy as even the cheap callipers compare quite well with name brand ones in the accuracy of their measurements. As a couple of members including myself have pointed out unless the calliper is modified to have the fixed leg shorter you won't get your scribed line positioned from the edge by the amount shown on the calliper so may as well use an oddleg or Jenny set from a rule.
Look at this sketch, 20mm wide bit of metal and wanting to mark a line down the middle, if you set the calliper to 10.000mm it won't mark down the middle, it needs to be set to 10.050 assuming moving leg 1mm lower than surface. It's basic schoolboy geometry.
Certainly more error than you are likely to get between two callipers so won't suit the Doc but often good enough for a bit or roughing out.
What you actually do with your tools is upto the individual but if you think you are getting a line the distance in that is shown on the screen then think again or modify a cheap Aldi/Lidl pair.
22605 forum posts
I suppose this is what can happen if you use them to scribe too much or take live measurements off rotating work, my Dad must have bought these 70 odd years ago but I don't know if they were new then or seconhand/surplus.
While on the subject of marking out I have had a dig into the back of a draw and this is how my equipment has evolved over the years, on the left a homemade scribing block from "unimat lathe projects" then an import one and finally an import height gauge.
And for marking along an edge this one again from the Unimat book which is similar to a carpenters marking gauge
I certainly used the Unimat items and even that old vernier calliper to build my 10V as schoolboy pocket money was limited and that will run simply by blowing into it. Most of the Stuart Beam would also have used them and I think they were superseeded during the Minnie build
|Mike Poole||01/09/2021 09:30:12|
3308 forum posts
Being guilty of abusing digital calipers I find the instant setup very useful compared to setting odd legs to a dimension. As I use a caliper for jobs where I would probably use odd legs the I would expect the accuracy to not be an issue. Although I don’t own a digital height gauge I think it would be very useful to be able to establish a datum at any height. My trusty old school height gauge is stuck with the surface plate being the zero datum so you need to set the job up to minimise awkward calculations.
8516 forum posts
There's a hint of bad fish whenever an expensive tool is misused without good reason! Adapting and overworking tools is OK after engaging brain for deliberate benefit, but spoiling tools due to laziness, ignorance or bad internet opinion is surely to be avoided.
Presumably people cough up serious money for Mitutoyo verniers because they need the tool's extra features. To me, it's odd to spend big dosh and then risk damaging an expensive tool when a decent digital vernier suitable for scribing and other rough work can be had for under a tenner. Unlike a Mitotoyo, inexpensive verniers are disposable - replace when damaged. It's what I do.
I mark out much less often than I used to. Getting more confident in myself, the DRO and the dials seems to have reduced the need for sanity check marking, though I still do it when accuracy is critical. I mostly use a scribe and spring calipers plus a cheapo vernier for marking out. I don't expect the same vernier to measure accurately and scratch steel.
Please login to post a reply.
Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!
You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.
Click THIS LINK for full contact details.
For subscription issues please see THIS LINK.