(Part 2) Best calibration products according to redditors
We found 384 Reddit comments discussing the best calibration products. We ranked the 29 resulting products by number of redditors who mentioned them. Here are the products ranked 21-40. You can also go back to the previous section.
Requirements for gauge block wringing: Average surface roughness of at least 25 nm and flatness of at least 130 nm. The blocks do not need to be metal. It works even with clean blocks or under a vacuum. There is no or virtually no pressure required to wring blocks together. The strength from wringing two blocks can be as high as dozens of atmospheres.
Things this is not:
Van Der Waals Force/Gecko feet: Technically london dispersion forces. Between two flat planes with 10nm separation in a vacuum, the van der Waals-induced pressure is around .05 atm. This is two or three orders of magnitude too low. Its an additional order of magnitude lower under atmosphere. Additionally, the force is repulsive before its attractive.
Cold Welding: Cold welding only works with metals. Wringing works with any flat, smooth, hard surface. It also requires pressure, zero contamination, and no atmosphere. Also, cold welding would result in galling.
Magnetism/dielectric/electrostatic: Works with ceramic blocks, is independent of resistivity or electronegativity.
Some other kind of metal attraction/molecular attraction: These bond lengths occur over hundreds of picometers, and would be blocked by a film of any thickness or composition in between the blocks. Also beyond half a nanometer the force will be repulsive. In fact the longer the bond length, the more repulsive it will be initially. These bonds drop off with the sixth power of distance. (edit: straight from the mouth of the wiki: bodies have to be conformal to 1 nm or less to exhibit this.)
Casimir effect: Operates on a longer distance than van der Waals, and can cause pressures of 1 atm. at 10 nm. Still a little low to be the culprit. Also, as someone who worked in a nanotechnology lab, making devices that can fit in the space between gauge blocks- the Casimir effect is witchcraft and not to be trusted. By most formulations it would not describe what we see in gauge blocks. Among other things it should work MUCH more strongly for metals.
Surface tension: Maybe. But it doesn't work in vacuum or with clean blocks, so no.
Trapping a vacuum: No. If anything this should push them apart because you'll tend to trap air underneath the thing rather than trap vacuum. Also, the maximum force would be 1 atm, which is 50x lower than reality.
Trapped liquids: The idea here is that any amount of trapped liquid would try to vaporize if you pull the blocks apart, and since it doesn't want to do that the blocks stay together. This wouldn't keep the blocks together, just resist pulling them apart momentarily.
Personally I don't think we can say nearly anything about wringing without actual data, which I haven't seen. I suspect that it is mostly surface tension that does the high force stuff, and the effect is way weaker with clean surfaces, and that it probably has something to do with the casamir effect, and nobody is totally sure on that shit because it has confounded nearly every nontrivial experiment done with it. Primarily though- I'm not sure anyone has ever done an experiment with TRULY clean gauge blocks, which is way harder than you'd think. Dropping a block in acetone isn't good enough.
http://www.amazon.com/gp/aw/d/B003U9W8BM/ref=mp_s_a_1_2/182-1573071-3110618?qid=1408820061&sr=1-2
TIL!
And not very expensive.
Good question, and it pains me a bit that I have a small box of unused tools that were purchased when I began. I'm sure I missed a few things, but here you go:
If links weren't provided then I already had the item.
You are doing everything right from what I can see, just needs more!
That handle part of the square is probably machined perfectly flat and can't flex right? I'd use that. It took me well over an hour to get the finish i wanted with 400 grit. Just keep rotating the cooler 90 degrees every 5 minutes or so so you are working it evenly. Sand in a figure 8 motion and if it starts catching too much to be smooth, add a little more water. I'd cut the sand paper in to small pieces just large enough to use comfortable around the block and change them every 5-10min depending on how it was feeling.
The amount of paste in the first one was a bit much, I recommend people over apply because its easy to smear off the paste during re-assembly or just not have enough to fill in a bad job and the HBM gaps. You can't hurt it, it just takes more clean up time, too little paste and its cooked. Now you have a feel for it the second application is looking good, I'd put a little excess over the HBM and go thin in the middle (when its flat!) now you have the hang of it.
Looking forward to your results! I see that SC mouse pad :)
If you are looking for a good block to sand with, I'd grab these: https://www.amazon.com/BL-123NH-Pair-Blocks-without-holes/dp/B000P496VU/ref=sr_1_8?ie=UTF8&qid=1550778570&sr=8-8&keywords=machinist+block
Judging by how the Shore scales overlap, you probably want to be using D anyway: http://www.imperialrubber.com/images/03-numerical-comparison-of-shore-scales-for-measuring-hardness.jpg You can always convert into another scale if you really want.
Here is the same meter that you found for less money and ships from Amazon: https://www.amazon.com/Digital-Durometer-Rubber-Hardness-Display/dp/B01ET0E2UA/
I would just buy that and try it out. The reviews you posted seemed mostly positive aside from one asshole who left one star because he's an idiot, one guy that got a defective unit, and another guy who said it isn't accurate (no idea what he was actually doing with it).
Buy it from Amazon and return it if it isn't working.
You aren't going to get exceedingly accurate readings with a device that isn't a piece of actual lab equipment. This is serious business. We're talking very precise tip geometries, forces/springs and measuring equipment (think micrometer or dial indicator). https://en.wikipedia.org/wiki/Shore_durometer
I would buy the cheap meter and then a calibration set: https://www.amazon.com/Mitutoyo-64AAA590-Calibration-Included-Mahogany/dp/B007FFTUGI
You can determine a correlation between your readings and known values. Plot the three points in excel to generate a best fit line and equation, plug the values from the cheap meter in and bingo. You will still be under $250 and you can buy a the right used shore tester when it pops up on ebay.
Are you calibrating the scale with 10grams? Then weighing something at 25mg? http://www.amazon.com/Calibration-Kit-Tweezers-Weights-10mg/dp/B0010TEPLA/ref=pd_sbs_k_3
is what you need to make sure it really is accurate...
A 12"x18"x4" one is north of $200, can't imagine what this is:
https://www.amazon.com/Starrett-Granite-Toolmakers-Thickness-Tolerance/dp/B003XU77XC
0.0001" or 0.00005" tolerance is par for the course for these.
they're typically used for metrology and the like as reference
No problem, what your basically doing is getting a cheap version of this