40 replies to this topic

[Bill from NH]

Dan, metric rules are in powers of ten. The easy way to convert metric to imperial & vice versa is use a web browser, such as Edge, Bing or Google,  And for example type in "Convert mm to in." Select one of the choices & type in the known value you want to convert. Some of the choices will automatically convert what value you put in to the units you asked it to convert to. This works with distances, weights, liquid measures, volumes, & probably a few measurements I forget right now. Others web browser choices will provide a conversion factor which you'll have to apply manually (use a calculator) to the value you want to convert. There are some special calculators that do conversion work for you, but you'll have to search out for what you want.

[Alan Dodson]

Is metric flatness different from Imperial flatness?

[swodem]

Is metric flatness different from Imperial flatness?

I think there must be a difference between flat-earthers and those that believe the planet is spherical ;-)

Which makes me wonder what flat is.... :-)


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[Bill from NH]

Is metric flatness different from Imperial flatness?

 

Alan, what have you seen whose  flatness is  measured in some metric tolerances. I can't recall seeing anything. A local cabinetmaker friend ran his shop all metric with Swiss power tools & Japanese hand tools. His large surface plate  had an Imperial tolerance.

[SpeedyNH]

I thought that a metric rule meant that everything had to be metered!

 

Bill, remember the guy who's son raced, he had a shop and made custom bicycles? he taught me that a mm is close to .040, so conversion was easy after that.

[Bill from NH]

Speedy, I don't recall the bike guy, but I don't remember a lot these days. That's a good conversion factor to remember. I use .078 arm shafts are 2mm & 3mm is approxiately 1/8".

[SpeedyNH]

LOL nor do I!

well, 2mm is a little less than .080, 3mm the same at .120, 1/8" is of course 0.125, and .078 is 5/64 (.0875), which is vaguely near 2mm but larger.

 

now that we're Totally off topic... wasn't this about flatness? I too use a granite block, a piece of glass or a good metal or ceramic block, sometimes transfer medium and/or a straight rule. whatever gives me the accuracy I think I need. 

I was surprised to see how bad those metal block were- heck, you could see it with the naked eye! I've also been known to use my big belt sander to clean things up if I'm not Too particular!  (no aluminum on that one, though- it totally Fods the belt.)

 

that guy's email was meltmtl because he was so proud of his welding.

[Bill from NH]

If he had been around, 40-45 years ago, I might remember who he was.     Do you have any idea what town or city he lived in, or his kid's name? those might jog me. I bought my surface plate for checking the sole flatness of woodworking planes. I've found other uses for it too. Previously, i had used a piece of white marble I got somewhere.

[swodem]

Here is another one I had a look at on the weekend




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[slotbaker]

Just curious, what thickness feeler gauge goes under there?

[swodem]

Just curious, what thickness feeler gauge goes under there?

I haven’t tried. I tried this on someone else’s block at a race on Saturday

I’ll try and remember to carry some gauges next time

Or maybe some guide washers would do

I’m guessing may be as much as .002” or .003”


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[Kevan]

The problem with milling soft material fairly thin is it's dead flat all the while it's in the vice but as soon as it's taken out the material flexes...and why would you machine a fairly large surface flat with an end mill/slot drill?  Get the job done with a fly cutter in one swoop.

[MSwiss]

[Bill from NH]

That person has very good hand-grinding skills! I've ground tool steel bits in the past, but not freehand.

[Kevan]

That video takes me back, I still have a couple or three fly cutters I made years ago very similar to the one in that vid...I used to hand grind everything, even 1mm drills (not with these old eyes though  )

[mark1]

Nice tip about getting the jig flat. I've sanded mine a few times over the years. I've also "fixed" a couple of squares that were way off.