harbor freight micrometer

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JohnFP

harbor freight micrometer

Post by JohnFP » Fri Sep 17, 2010 10:52 am

That's why I stated plastics are going to be hard to do as they have easy compression. Metal is going to be much more acurate.

Colin Kaminski

harbor freight micrometer

Post by Colin Kaminski » Fri Sep 17, 2010 2:23 pm

Joe Farina wrote:Thanks a lot John. I didn't realize shims went down that far, but I just checked http://www.mcmaster.com and they have plastic (polyester) shims at .0005" (12.7u), .00075' (19u) and brass, stainless, and plastic at .001' (25.4u).

This harbor freight micrometer is looking pretty good. The digital readout can be switched to millimeters and the scale reads 0.000 so it has a millimeter resolution of .001mm (1 micron) at least according to the readout.

I measured some saran wrap, and it came out at 0.010mm or 10 microns.
Even the cheap ones are pretty accurate. I use them to +-.0002" when lathing fits. If you really want to test yours get a feeler blade set at any auto repair store.

Joe Farina

harbor freight micrometer

Post by Joe Farina » Fri Sep 17, 2010 3:27 pm

Colin Kaminski wrote:If you really want to test yours get a feeler blade set at any auto repair store.
I forgot that I have some feeler blades, so I measured the thinnest one (marked 0.0015 inch) and the micrometer reading came out double that, 0.003. Quite a difference. Surprising that the saran wrap measurement came out approximately OK, but not this one. Then I remembered I have some 0.001 stainless from McMaster-Carr, and the reading on the micrometer came out exactly 0.001. It seems that my cheap feeler blade was way off it's specification.

By the way, this micrometer has a very useful feature, I'm not sure if this is standard on all micrometers. Once the main screw-handle is turned until it touches the surface to be measured, you stop, and then turn a secondary screw which applies only a specified amount of torque, until it clicks and doesn't move any further when it's turned. So a precise amount of pressure is applied to get the final measurement. So to calibrate the micormeter intially, I turn the main screw until the anvils touch, then turn the secondary screw until it keeps clicking. Then I zero the meter. Then I open the anvils, insert the material to be measured, and repeat exactly the same process to take the actual measurement. So the amount of torque or force on the anvils should be exactly repeated.

By the way, harbor freight also has an essential item for the holographer which only costs $1.49, which is "rubber dust blower" (item 66454). This is a common "photographic dust blower bulb." But it has a very nice, small metal nozzle, which I prefer to the plastic ones. The good thing about these bulbs is that there's no chance any propellant can get sprayed on the surface to be cleaned, and it's a very controlled and predictable amount of pressure, and quite gentle. I prefer it to any other kind of compressed air. I especially use it to clean glass fragments off of gelatin layers on glass. (I use a tile cutter to cut a large, coated plate into a number of smaller ones.)

dave battin

harbor freight micrometer

Post by dave battin » Fri Sep 17, 2010 3:34 pm

Colin Kaminski wrote: Even the cheap ones are pretty accurate. I use them to +-.0002" when lathing fits. If you really want to test yours get a feeler blade set at any auto repair store.
Yes yes Colin, when i worked in a machine shop, years back we would regularly lap parts to fit a micron or two opining.

buy clamping your film with a good 1" micrometer (fixed anvil towards the emulsion), record you thickness, remove emulsion and measure again.

Or do as i do and remove a strip and take a few side by side measurements, record them and average there sum for you film's thickness :doh:

Jeffrey Weil

harbor freight micrometer

Post by Jeffrey Weil » Fri Sep 17, 2010 6:08 pm

Hello Everyone,

I've used the bulbs for air, not enough for real work in my opinion. I have the expensive Newport lab compressor. It is silent with no vibes but it does spit oil every now and then. Even the slightest bit of oil ruins my embossed holograms. Unlike Silver or DCG it's not a closed ended process. After the hologram is made it still has to be metalized and electroformed. A bit of oil the size of this period "." would ruin the complete piece. It would fail in the tank and I would be left with nothing at all. Not a holo with a spot, nothing.

I've used nitrogen and it's great but you have to have it delivered and all that. I'm under great deadline pressure. I don't want to wait for a delivery if I run out or have a leak and find out as I'm working I have no gas.

So here's what I do now and it's perfect. I use a scuba tank hooked up to an air nozzle. Its the cleanest gas you will ever find at a good price and here in Miami Beach I can get it almost 24 hours a day within 2 miles of me from a few different places. So I'll never run out.

Some first stage regulators, that's the part thats hooked up to the tank not the part in your mouth, have an adjustment with a hex screw in the back. If you get one of those types you won't need anything else to lower the pressure in the tank to something usable. . Next get an attachment for your BC(the inflatable vest you wear) to fill car tires. That part splits in two and the non air chuck part will attach to your regulator hose and mate to standard NPT threads on your non scuba air hose and or your air nozzle.

Jeff Weil
NorthBeach Holography Inc.

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