Scribing lines - caliper abuse

Well, you have this flat stock that needs some holes drilled. How do you lay them out without spending too much time? If it needs to be really accurate, you probably want a good height gauge or surface gauge and a surface plate, not to mention an equally precise way to make the holes...

A fast and reasonably accurate way for less exacting work is to set and lock your calipers, scribe away, whack a dimple in there and drill. The downside is that the caliper tips wear away. If they´re your Mitutoyo ones, and your measuring tools arent free of charge, it sure isnt a wise way to scribe lines. You can sharpen the tips only so many times before they are ruined. Even if your tools where free, you´d upset the balance in the universe if you abused your tools like that. Dangerous...


Solution? Buy, steal (no, I don´t mean that!) or borrow a pair of these:

Vernier scribe - Nikon D200, 18-200 VR AF-S, built in flash

They are pretty accurate with a verier scale and all. Carbide scribing pin, with plenty of stock for resharpenings. The roller is a bit cheap but it works with a drop of oil every now and then.

They actually cut a fine groove in the workpiece, so you can "click" down a prick punch where lines intersect. Then its easy to whack down an accurate center punch mark.

The scribers are really handy for laying out lines parallell to edges, to mark weld lines, to find centers of round or square stock, to mark keyway lengths, all those things you might be tempted to abuse your calipers for. Just the fact that the carbide tip holds up so well makes them worth having. If you make knife blades they are perfect for laying out the blade grind.

Since the distance is set between the inside edge of the pin and the roller, you can use them for outside measurements too. Its takes just seconds to measure, mentally divide, set and scribe center lines with the same tool.
What they don´t do very well is to replace odd leg (hermaphrodite) dividers for those times when you need them, mostly inside work.

They are quite useful for scribing wood, the sharp tip leaves a nicely cut line to guide your chisels.


Caliper abuser? Oh yes sir I certainly am, but I don´t use them for scribing lines. I have a proper tool for that!

Now where is my bottle opener? Never mind, I´ll just use my cal….

I like this… Fun!

This is the most fun kind of job you can bring to me:

Unused and abused driveshaft - iPhone 4s

This is fun because I get to play engineer - I measure things up, figure out how it was supposed to look when new, decide what material use and then make it. Fun!

There was both turning and milling on this one. Fun!

Sometimes its a challenge because whatever parts are left are torn, worn or twisted out of shape. Then its some head scratching and humming and some guesstimates. Fun!

These jobs also get me the opportunity to make a difference. Sometimes production is down or animals are hungry until the repair is done. So, I get to both have fun (while being paid for it) and help someone. Thats something I enjoy!

Cheap maintenance

The cheapest form of maintenance is none at all. In the short run! Its also the most expensive form of maintenance in the long run.


The cheapest form of effective maintenance is cleaning. Yes, simple soap and water can save your hard earned money. Keeping equipment clean helps you catch problems early on. A small leak here, a little rust there, a nut loosening up a bit - its all easier to see when its not hidden under dirt and grime.


Dirt itself can be the problem. Take a look at this lawn mower:

Neglected mower - iPhone 4s

The problem with it was that it had stopped self-propelling. Guess what? The pulley was full of old grass and the belt had jumped off. No surprise, as you can see. Had the customer spent five minutes with the garden hose after mowing the lawn this would never have happened, and they would never have had to pay me to fix it. Mind you, this is an expensive mower. I get if if you don´t care much for a cheap, rusty, smoking worn out mower that is barely hanging on. But a new, expensive one?

Grass traps moisture, is a bit acidic, and promotes corrosion. Old caked grass also disturbs the mulch and collecting functions, and can throw random clumps all over the lawn. I have found bugs and maggots in old grass. No, it did not smell nice scraping that deck clean. I´m sure they mowed more than grass with that one, by the smell of it...

Your mower deck will be corrosion-free much longer if you clean it. If its a ride mower, the bearing housings and the bearings themselves will last longer. All linkages, wires and joints will be happier too! 

Don´t go crazy with a pressure washer however, as you may push water into bearings or other places you´re not supposed to water. Use common sense.

So. Spend some time cleaning your equipment, be it your tools, your lawn mower, trimmer, car or concrete mixer. They will work better, last longer, save you unnecessary repair bills - and look nicer, too!

It´s the camera you bring that matters! iPhone, anyone?

It seems than whenever I bring my DSLR along, somebody always asks which model it is or how many megapixels it has. Like that matters. Don´t get me wrong, it really CAN matter, but you can have the most advanced camera ever made, with a zillion megapixels, and still take crappy photos. Sorry, but most people do. Flash in bright daylight? Colored gel over the flash? Huh? Hmmm, why are those eyes black blobs in this picture...?

The camera that matters is the one you actually have in your hands when something interesting happens. If you shoot for a living (who does, really?) you´ll most likely have "the best" already, with you at all times, and this post isn´t about you anyway.  But many people nowadays have a smartphone with a built in camera. And thats what they have in their hands when stuff happens, and thats what took the pictures and video footage you see in the news and on TV. Or that lovely picture of your children, or that vacation picture, or that funny thing you saw while driving, or... well you get it.


I used to haul my DSLR along wherever I went, but that is a heavy lump to carry along and it is attractive for thief's. I always felt a little nervous leaving it in the car. My iPhone 4S (UPDATE January 2015: now its an iPhone 5s) fits in my pocket, does 8MP pictures and does videos too and actually quite nice ones at that. I do miss my VR DX 18-200 sometimes for the zooming ability, but shooting people and my family the iPhone wins thanks to the greater angle of view. I always bring my iPhone along at work, wrapped in a clear plastic bag.


That´s a tip for you guys with real jobs with dust, sparks and metal filings flying everywhere. Put the iPhone in a 2 or 3 litre plastic bag, wrap in around the phone making a little "roll" and change it every week or so and you won´t have to pick metal and dust from the speaker vents again. That magnet sure attracts stuff, doesn´t it?


Back to cameras. In good light the iPhone takes better pictures anyway than the compact digital camera I bought before I went iPhone. This picture would never be if I didn´t have the iPhone in my pocket:

Gecko Lizard, iPhone 4S, built in flash

It would not be the end of the world if I missed that picture, but it´s a nice memory to have. This little guy climbed up a wall as I walked by, so I took it in my hands, walked over to my wife and had her take the picture. Imaging holding the lizard in my hands, handing over the DSLR, trying to avoid being strangled in the camera strap, then worrying about the settings, never mind explaining them, while still holding the lizard, and..... and now it was as simple as her pointing the iPhone and tapping the button.

Remember, the only camera that matters when it happens, is the camera you have in your hands! 

iPhone 4S + iOS7 = personal hotspot

One of the iPhones great features I use a lot is Personal Hotspot. It works so well that I settled for the Wifi-only version of the iPad mini, saving me a few bucks.

Tip: Use Personal Hotspot over USB for your computer, and over Bluetooth for your iPad. Using it over Wifi requires you to unlock the phone and go to settings/personal hotspot and have that page open while the other device searches for it. Using Bluetooth on the other hand lets you have the iPhone in your pocket or suitcase and connect to it without taking it out. Just keep Personal Hotspot and Bluetooth turned on and you´re good to go:

Bluetooth and Personal Hotspot ON - iPhone 4S
screenshot (home + on/off-button)

In fact, I think Personal Hotspot works so well that I´ve cancelled my regular Internet provider for my iMac. Again saving a few bucks. Now, this might be a little to radical for some if not most people, but given how well PH works and the fact that I´m not a heavy downloader makes this a perfect solution for me. I always have the iPhone within reach anyway, so plugging the cable is no big deal. This Blog is updated over Personal Hotspot when I´m on the iMac.

Don´t you just love clever solutions? I do. Or should that be "iDo"?

iOS 7 - disabling Game Center

So, having updated my iPhone 4S to iOS 7 I found it really annoying when the login for Game Center kept popping up. Turns out there is a simple fix for that, and it's also logical.

Go to settings/Game Center, tap on the field where you Apple ID is filled in, erase it, tap the password field, leave it blank and tap Go, then go back to settings with the blue arrow top left. Now you've basically told the iPhone that you don't want to use the Game Center. If your Apple ID is filled in the next logical step is to enter your password and login, don't you agree?



So, remove the Apple ID in this menu:

iPhone 4S - screenshot (home+on/off-button)

Note that the next time you open settings/Game Center your Apple ID will be automatically filled in again and you'll have to erase it once more, otherwise the pop ups will start again. A little annoying but then again, if you don´t want Game Center why would you open the menu?

Cylinder head resurfacing

My take on cylinder head resurfacing in the mill is to use a single point tool - a flycutter. Multitooth cutters can speed things up, but if one cutter edge gets chipped you´re in trouble. Flycutters take longer time to use since only one cutting edge is doing all the work, but if you have a mishap you only waste one insert. And swapping from cast iron inserts to aluminium inserts is quick, you change the one insert and go to town.

Now, I seldom do heads more than a few times a month. If all I did was cylinder heads you can be sure I had a big multitooth cutter or even a cylinder head resurfacer, but since I don´t I haven´t. Thats why I use what I already have - a vertical mill and a flycutter.

If the head is warped, which it probably is if you intend to resurface it, you have (at least) three options; pull it flat against the table, shim the blocks to fit the twisted head or straighten it before resurfacing. The easiest of course is to just tighten it down and start cutting. If there is only slight twist this may be the best approach. Shimming might be necessary if the head is too warped to pull flat. But if the head is so bowed or twisted that the cam bearings are out of line, maybe even causing the cam(s) to bind, it really should be straightened first. Or junked.

Straightening typically involves twisting or bowing the head the opposite way it's already warped, and then baking it in heat to let it "take a set" and end up straight. The bearing bores, that is.
While this sounds easy in theory it may be tricky in reality. After the head is straight 'nuff, the gasket surface can be resurfaced.

If the cam bearings are out of line, perhaps you could also resurface the head as is and then grind some off the bearing caps making the bore smaller and then hone them out again. Obviously this only works if there are removeable bearing caps. The end goal is to have the cam(s) sit straight and parallel to the gasket surface.

For a typical 4-6 cylinder head, I usually place the head on ground blocks, tighten it down just a little and feel if any blocks are loose - you want the head bearing on all corners. Watch out for burrs, dents, grit and gasket remains. After any needed shimming I continue to gradually tighten the hold downs until its firm and secure. I then touch off, snug the table locks (don´t lock the feed axis) and take a skim cut of 0,001" or so. This lets me see if any corner or side sits high or low. Add shims as necessary to average out the differences. Newsprint works well for small adjustments. When you are satisfied, dial in and take a cut. I typically run 269 rpm, 0,004" depth or so and 6-7 ipm while roughing. Adjust the cutting depth according to how unflat the head is. When it's almost flat I take another 0,0015" or so at 2 ipm to finish it off, hopefully cleaning up all areas.

Rover head starting to clean up - iPhone 4s

Note in the above picture how the o-ring grooves are starting to disappear at the ends, but are still there in the middle - this was a banana for sure, and the grooves seem to be cut crooked aswell.


Now, the above procedure assumes the previous gasket surface is factory original or at least resurfaced parallel with the valve cover surface. This is important as you are averaging the cut over all four corners. If the head is banana shaped you want to hit the ends equally. If it is twisted you want to hit diagonal corners equally. If it is both banana and corkscrew, well.... you get the idea. But if the head has been cut wedge shaped by the guy before you, and you also cut more on one end than the other, you´ll have a head that sits tilted when its done. Perhaps not by much, but still.

Of course you could touch off the skim cut, find the lowest point, dial in one roughing cut to remove all warp and then take one finishing cut. But fiddling around finding the low point may take just as long as just cutting away until things start to look flat. I tend to engage a cut and then do something else while the mill hums along.


How do you measure the removed amount? I like to touch off, set zero, cut until its clean and then see how much was removed from touch-off. You could also mark a spot that you measure with a micrometer before and after cutting and see how much you removed. If you measure the middle of a concave head you could end up with 0,001" although you removed say 0,01" at the ends. I feel this is misleading and thats why I prefer to measure from touch-off. That gets you the max that was removed.
If you don´t have readouts you could set up a dial indicator on a magnetic base as a poor man´s readout.

How close is close enough? / Digital calipers.

Just how tight tolerances do you really need? In a home shop environment making one-offs, with time spent not being a concern, you can fiddle as much as you want. When you are making parts for profit - not so. And in a jobber type shop where you are making repairs or replacement parts, you have to decide just how close you need to be.


Is the part for a tractor? Harvester? High end motorbike? Porsche 911? Granddads old something?


I have the feeling that people sometimes get carried away since its so easy to throw numbers around. The guy that asks for spot on probably doesn't know just how much, or little, a thousand of an inch is.

The hairs on my head typically measure just over two thousands.


Now that the price of digital calipers is so low, the same guy probably has them and thinks he is measuring to 0,0005". Oh yeah and the inside measurement must be what the calipers say, right?
Tell me, who pressed the "zero"-button the last time? Is zero really zero?


You can probably see how easy it is to misunderstand or miscommunicate. Your calipers and mine probably wont agree, and your way of measuring will probably differ from mine. Thats why we calibrate measuring equipment:

Checking micrometer calibration - Nikon D200, AF-s VR 18-200, on-camera flash, +something 

A quick check of the digital calipers is to measure some calibrating rods for outside micrometers. You might be surprised, not necessarily in a bad way. My Limit digitals are within +- 0,0005" with some care. Would I use them where +- 0,0005" matters? No way!


There are times when you really may want to be within a few tenths. Bearing seats can be such a time. The tolerance on high precision bearings can be just a few tenths of a thousand inch. But be aware that when we get down to these levels surface finish and temperature really matters. Shrink fits are an other example where thousands matters - miss with a few and your fit is gone. Thats why we have Loctite products heh heh.


There is no sense in trying to hit a diameter to a few tenths if you have a surface that's rough. You also have to know what you are measuring. Are you measuring just one peak, the average or the lows on the surface finish? Perhaps you have to grind the surface if the tolerance is going to be meaningful.
Roundness also comes into play, it it silly to try to hit a tenth if you aren´t truly round.


So how close is close enough? Most of the time the customer can provide you tolerances. If they seem fair, go for them. If he doesn't seem to have a clue, ask if "close as a hair is enough". Or look up a tolerance chart, and use the appropriate tolerance for the parts intended use.

Thats a hair, 0.05mm. Lines are 0.50mm apart - iPhone 5s, pocket loupe (10x) 

Chanses are you'll save some time and frustration, and spend a more reasonable amount of your customers hard earned cash, by working close only where it's needed. And you'll probably see more of him when he understands you're not trying to rip him off but instead provide quality work.

Atentech Perfectly Clear - iPhone 4s

So I bought the "Perfectly Clear"-app for iPhone and have found it really nice. You've seen this already in iPhone 4s camera:

Thistle - iPhone 4s, some cropping

And this is what it looks like after automatic correction in Perfectly Clear, on the iPhone:
(Yeah, its not the same size. Might fix that sometime.)

Thistle - iPhone 4s, not the same cropping, Perfectly Clear

So, which one is better? Im not sure, the "corrected" one is perhaps too much corrected. But the original sure does look grey in comparison.

Another example:

Huseby Bruk - iPhone 4s, HDR to keep detail in clouds

After some Atentech Perfectly Clear automatic correction:

Huseby Bruk - iPhone 4s, HDR to keep detail, Perfectly Clear

This time I´m sure I like the corrected one better. It simply has more oomph. Perhaps the grass is too bright green? This was the automatic correction, I suspect some fiddling around with the settings could improve the result... but then again, if you are after serious image processing perhaps you should use a better camera to take the picture, and your computer to edit and adjust it. 

You have to experiment, sometimes this app does make things worse, but often it enhances photos - right there on your iPhone. Let it do its thing automatically or control the settings yourself, and when you like it simply save the photo to the camera roll. Its that easy.

iPhone 4s camera

I am surprised how good the back camera is on the iPhone 4s. When you have enough light available you can take some really good pictures. This was snapped while out walking:

Thistle - iPhone 4s, some cropping.

Now, it wasn´t exactly windstill, the thistle something like three inches away from the iPhone. Shooting a moving target is what it is, I´m still surprised how sharp the image is. I had to crop a little to balance the image.

If I took the same picture with my Nikon D200 and some macro lens there would be very shallow depth of field, and that rig wouldn´t fit in my pocket. And I could not hold the dog in one hand either while taking pictures.  In this case, iPhone wins!

Telescoping gauges

Telescoping gauges, sometimes called telescopic gages, are really useful for "measuring" holes in the 0,313 - 6" range. They don't actually measure anything on their own, but they transfer measurements to something that can measure - a regular micrometer for example.


How do you accurately measure a critical bore? An internal bearing seat? How do you get that last "thou" just right? Forget vernier or dial/digital calipers, unless you really know the relation between what the hole actually is and what they say it is. And you better find the true maximum diameter!

Spring calipers work well, they use the same principle as the t-gauges but with more "feel" and skill required. Go/no-go gauges also work, but have to be purchased or made. Internal (stick) micrometers work on bigger bores, but they are slower and you really cant use one in say a 25mm / 1" bore. Oh, the three-legged affairs do work, comes in a wide range of sizes but are really expensive. Really. As far as fast, fuzz-free measuring goes, telescoping gauges are the way to go in my opinion. They transformed precise boring work from frustrating to actually quite enjoyable, and the same set works for all measurements within the range, provided you also have the outside micrometers.

Mitutoyo telescoping gauge - Nikon D200, AF-S DX VR 18-200 @ 200, +1,7, built in flash

But the gauges must be used properly. You first set the telescoping ends a bit bigger than the bore, either by letting them snap open on an angle in the bore and lock them there (fastest way) or some other way outside the bore. The next step is to hold them, with the lock snugged tight enough, in the bore at an angle so the ends clear the bore, then swing or move the tips through the bore by levering the handle so the bore forces the ends to the true diameter. They will in effect get stuck, and as you force them through the bore they will find the centreline and biggest diameter "automagically", and as soon as you pass the centreline of the bore they will "pop" free.

It sounds complicated, but in practice its really simple. Snap open a little bigger than the bore, tighten lock, swing handle to force the ends through the bore, remove from bore when they pop free. Then comes the next part, measuring them to find out what the bore is:

Measuring over ends - Nikon D200, AF-S DX VR 18-200 @ 200, +1,7, built in flash

You simply rest one end on the fixed anvil of the micrometer, and rock or swing the other end while slowly closing the mic. As soon as it drags against the closing anvil thats your measurement. Its easier if you have something white or light behind the mic, then you can see the gap close and next comes the drag. DON'T look at the thimble while closing the mic. Keep looking at the anvil and swinging end, and when you feel a light drag - stop and see what your measurement is.

Be sure not to force the tips through the micrometer, because you could in effect mash the gage smaller. What you want is to recreate the drag felt in the bore when you set the gage in the first place.

Repeat the measurement at least once to make sure you didn´t bump or somehow affect the gages - you don´t want that bearing to rattle around when you (think) you are done! :-)

Advice: don´t buy cheap gages. I started cheap thinking I´d avoid spending a lot, but had to sell the cheap ones since they didn´t work properly. The plunger ends on those had a turned finish. Then I bought more expensive ones, still off-brand. They also went back, the plunger ends were smoother but the lock and action had a terrible feel. So I bit the bullet and ordered real Mitutoyo gages - and the light came on! Smooth action and feel, really well made, smooth, hardened plungers. Save yourself the frustration and get the good ones right away.

Ignore the quality of the next picture. Having said that, this job went smooth thanks to the gauges:

Repaired stud - iPhone 4s, shaky hands

This was a cast iron sheave with six equally spaced studs around the perimeter used as spring seats, all very worn. I turned the worn studs in the mill with a boring head until they cleaned up somewhat and then measured them. Bored the sleeves next, aimed for half a thou larger as measured with the t-gauge and the same micrometer, coated them with green loctite and tapped them home with a small hammer. Six different studs, six different measurements as the customer wanted minimum metal removal. They all fitted nicely. I aimed for a little clearance, toolmarks tend to smooth out as you tap things home and the loctite takes care of the rest. The harvester this sheave came from won't get that hot in service, so I felt confident using loctite. Had temperature been an issue, thermal shrink-fit would have been the solution.

So, telescopic gauges are really handy to have in the toolbox. You can easily measure work still in the lathe or mill, and using the correct technique and good quality gauges should enable you to work to really close tolerances. If you are like me you will measure bearing fits with ease. There are machinists who can hit less than a quarter thou, but that does take some skill, care and experience.

To be fair, you don't even have to use a calibrated micrometer to do bearing fits or fits in general. As long as you have the actual part that is to be fitted, what you care about is the difference in size between the parts, not their actual size. As long as you use the same mic for both internal and external measurements you'll be fine. 

Once set you can use them as a go/no-go gauge to check if you heated that shrink-fit part enough, or you can use them to...  well, thats for you to find out!

This is the start of it all!

Ok, so this is the first post. What can You expect to read here?

Anything and all things technical. Simple, right?

Wether it be about depth of field, taking pictures with your DSLR or iPhone, telescoping gauges, boring on the lathe  -  you will find it here! And if you ask for it, it just might end up here as well! Go ahead and try me! Who knows just how much you can stretch "technical".....


In this picture, note how using the longest setting (200mm) gives that shallow depth of field:

Greece - Nikon D200, AF-S DX VR 18-200 @ 200. Some cropping.