The one I tried was about 0.2" wide at 10 feet. The spot wasn't too far from circular and its intensity fell off sharply at the edges, so I was able to align both edges with marks on the scale the same distance from the 1" line, in this case the lines at 0.920" and
1.080". The alignment only has to be repeatable, not absolutely accurate.
I've done the experiment, and observed a significant shrinkage of the projected point on the wall. Granted, it is most likely a loss in brightness so the *visible* part of the Airy disk resulting is significantly smaller. But it *does* make the visible spot smaller. After all -- the more distant from the center, the less energy concentration.
But it will make the visible (to the naked eye) portion smaller.
Of course. Even with a HeNe laser we get significant beam spread, actually more than with a solid-state laser level of similar brilliance.
Note that if you mount a mirror on the mill head, and bounce the laser pointer off that so you get double the angular deflection from a given motion of the head as well as doubling the distance. Then select a pinhole based on the tradeoff between perceived spot size and brightness (you need sufficient brightness so you don't lose the spot. :-)
Add a second mirror as the target of the first but if it has a cylindrical surface (with the axis properly vertical, of course), you get more angular magnification for a given beam length. (You find this sort of setup in the old projection galvanometers.)
It at least will get you closer than just eyeballing the end mill itself. Better is a machine which doesn't have a round column, but rather proper dovetailed ways -- and even better with the table on the vertical dovetails instead of the head.
So, has anyone put a good scope-with-reticle onto a suitable mount point on their mill? Artillery aiming is routinely done this way, you dial in a deflection angle and move the big tube until your crosshair is on the reference stake. There's some realignment called for, each time the big tube ... shakes.
I do the same thing - my small level - 18" - has a laser and either a point or a cross. I use the cross and have a tape line edge that I can shoot. Tape is sharp edge vs. a pencil or pen.
Making a pinhole shadow of a big blob doesn't make the blob any more accurate. The blob moves around and the pinhole stays illuminated.
The whole approach just defies elementary principles. You can't improve on the beam divergence angle, and that is many thousandths of an inch at the spindle distance scale.
It makes the blob (Airy disk) dimmer, and thus makes the part
*visible* to the user smaller. If the disk is full brightness, you see the peak, and several rings of minor peaks surrounding it. If you make it dimmer, you limit what you can *see* to the central peak only.
And -- if the pinhole is mounted rigidly to the front of the laser, you are selecting the same portion of the blob as the laser and pinhole move as a unit.
The beam, through a pinhole, is producing an Airy disk -- a central peak surrounded by rings of diminishing brightnesses. Make the pinhole small enough, and you can see only the central peak.
Have you *tried* the experiment, or are you working purely from your own understanding of the underlying optics laws? Remember -- those laws are not taking into account what is visible to a human eye, just the overall distribution of light.
I tried it with a series of pinholes mounted in a turret (designed for adjusting the energy content of IR from a black body source while retaining the same color temperature). Granted, these were quality pinholes, made in very thin metal, blackened, and with absolute minimum reflection through the bore (because of the thin construction). The pinhole was mounted about an inch in front of the laser pointer, and was projected on a wall about five feet away.
Down to a certain size, the visible dot got smaller, then the diffraction started making things worse and spreading it out. FWIW, this was a red laser pointer. A green one would probably behave somewhat differently.
Both. As an optical engineer, I approach this problem all the time in many different forms.
Photons travel in straight lines. The childish gee-whiz notion about a laser is that its photons are also traveling in *parallel* from a nearly point source, because that is the casual impression when you wave the spot from a pointer around. The beam divergence is less than the angular resolution of your eye, so the beam *looks* perfect. That is the essence of the mistake that a laser is some magic mojo for this goniometry.
While laser light looks well-collimated compared to ordinary sources, and indeed looks indistinguishably like a perfect source to the naked eye, in reality it is not collimated to the kind of angular precision required for resolving 0.001" spindle travel on a radius of 12 inches on a mill-drill, or 17 seconds of arc, which is to say 0.08 milliradians. Compare this precision to a typical far-field beam divergence of about a milliradian for the best laboratory lasers, and you see why this hasn't a chance of working.
In fact, using a laser has nothing to do with this purported optical alignment gimmick. One could just as well use a flashlight with a pinhole, or just an alignment scope viewing ambient light. The laser is just a red herring. Which is what makes this laser-solves-all attitude even sillier.
Your pinhole notion is just wrong from the start. Study the basic laser principles like beam divergence and diffraction limits. Stopping a beam makes it diverge more, not less.
When you perfect your 0.08 mrad beam, please call me. We'll be rich.
100 Bayview Dr Suite 1029 Sunny Isles Beach FL 33160
800-526-4956 ext. 107
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------------------------------------- Michael Koblic wrote:
Hello users and people interested in the RF-30 Rong Fu Milling Machine. I have a free pdf operators manual I would be happy to share is you contact me at the address below. Not looking to violate rules of site, just offering some free info I think is usefull. thank you, snipped-for-privacy@lighttoolsupply.com
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: Hello I have a manual for the RF-30 Milling machine I can send you in pdf form if you like. Please email me for free copy
snipped-for-privacy@lighttoolsupply.com
Michael Elson President Light Tool Supply
100 Bayview Dr Suite 1029 Sunny Isles Beach FL 33160
800-526-4956 ext. 107
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------------------------------------- Charles U Farley wrote:
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I have just found a RF31 and am searching for an operators manual. Anyone have one they can share. A RF30 manual would be a help.
Mike Mitchell Parsons, WV ======================================================================
I know Harbor Freight sold some Rong Fu mill-drills but I don't know the model number crossovers. Is this the right one:
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Maybe the manual will be at least some help. Oh, also found this page with links to both the HF manual and the Grizzly version which the author says has a much better manual:
I suggest you find a pro or hobby machinist to show you milling and drilling operations in person, to teach you the feel of how fast and deep you can cut and how securely the work must be clamped. I've learned things by watching experts that I never saw in print.
Hmm ... one item in the instructions for wiring -- "make sure the spindle runs clockwise -- if not -- reverse the wiring" suggests that this has a three phase motor. Do all RF-31 mill drills have three phase motors? In the specs page, several motors are listed, and RPM at 50 Hz vs 60 Hz, but nothing about the number of phases needed. (However, reversing the wiring for a single phase will not reverse the spindle, though reversing *part* of the wiring (start cap and winding) can reverse the spindle.
Anyway -- if the motor is single phase, part of the information in that manual will not be correct.
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