rack and pinion

On 30 Nov 2004 02:25:01 -0500, snipped-for-privacy@d-and-d.com (DoN. Nichols) wrote:


I have a spare Micro-Vu that Id let go really cheap. Screen is in excellent condition, but the light source was removed for some reason. Power transformer is fine as is the staging. Might be a good place to put on a nice bright LED light source. No dial indicators, clamp your own on.
Gunner
"I mean, when's the last time you heard of a college where the Young Republicans staged a "Sit In" to close down the Humanities building? On the flip side, how many sit in's were staged to close the ROTC building back in the '60's? Liberals stage protests, do civil disobedience, etc. Conservatives talk politely and try to work out a solution to problems through discourse until they believe that talking won't work... they they go home and open the gun cabinets. Pray things never get to the point where the conservatives decide that "civil disobedience" is the next step, because that's a very short route to "voting from the rooftops" Jeffrey Swartz, Misc.Survivalism
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    [ ... ]

    Or build one around one of the Quartz Halogen projection lamps with built-in reflector. Some of them (usually marked 82 V IIRC) are designed to run from the AC line fed by a single rectifier diode. No big transformer to deal with. But then again, the transformer in the back helps counterweight the optics, stage, and lens at the front.

    Of course -- but provisions for mounting them. I've put a 5" travel one on the X-axis on mine.
    Out of curiosity, do you know which lens yours has?
    Enjoy,         DoN.
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On 30 Nov 2004 20:31:52 -0500, snipped-for-privacy@d-and-d.com (DoN. Nichols) wrote:

Not at the moment. Ill have to dig it out and look. I believe the magnification is 10x IRRC but which lens..no idea. It has the standard MicroVu screen and grid pattern.
Frankly its in my way, and Id like to see someone get it.
Ive a minty 12" Dorsey OC in my back office that I use and I understand that Ive just been bequeathed a Sony (? its orange) floor model with DRO. ("Its in my way..come and get it..we just got new CMMS and Mitys"...click)
Gunner

"I mean, when's the last time you heard of a college where the Young Republicans staged a "Sit In" to close down the Humanities building? On the flip side, how many sit in's were staged to close the ROTC building back in the '60's? Liberals stage protests, do civil disobedience, etc. Conservatives talk politely and try to work out a solution to problems through discourse until they believe that talking won't work... they they go home and open the gun cabinets. Pray things never get to the point where the conservatives decide that "civil disobedience" is the next step, because that's a very short route to "voting from the rooftops" Jeffrey Swartz, Misc.Survivalism
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    [ ... Micro-Vu optical comparator ... ]

    O.K. That screen has markings for three magnification ratios, 10X, 20X, and 40K IIRC. Mine has the 20X lens. (No real markings on it, you need to measure something of known dimensions to tell what you have.

    Well ... you are a bit too far away to make this practical, or I would be very tempted. :-)
    Thanks,         DoN.
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detail how I could make a thorough check of the condition of the rack and pinion on the telescope. I just have a few questions:

Is there some kind of common coloring one can mix with with "any good grease" to simulate the stuff the professional gear guys use? For example, how about adding a tiny bit of alizarin crimson or emerald green oil paint to the grease?
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Allan Adler < snipped-for-privacy@zurich.csail.mit.edu>
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wrote:

Allan, as so often happens in this group, most of them have gone off the deep end again.
You do not have to do a pattern check on the rack and pinion, that is for precision gearing, and precision gearing is not found in focusers under the $250 range. THe pinion is probably cut from extruded pinion wire rather than being a cut gear. The rack, if it's a gray metal as you describe, is die cast zinc, and no degree of precision there either. It simply is not needed. The optical comparator is massive overkill, just looking at the teeth with a good hand lens will show the problem if it's bad enough to cause a real problem. The racks and pinions in my old Edmonds are now over thirty years old, were never the epitome of quality to begin with, and don't cause any problems in use. If I were using one of the remote focusing units, the backlash might be a problem, but as I focus "eyeball to the eyepiece", it is not.
Lube, I lube the drawtube, but grease and oil only attract dirt to cling in the rack, so mine runs dry except for the shaft and the drawtube itself.
My final advice, put it back together, take it out and use it. If nothing else, it will give you far better views than the telescopes of Galileo, Herschel, Newton and others. IF the drawtube moves when you turn the knob, it's doing what it's supposed to do. A lot of time can be taken with technicalities, without looking at practicality. And already has, the prime question is "can I get this thing in focus", and if the answer is yes, going deeper into it is only wasting time and money. Your time would be better spent in a dark place, with the scope, even just sweeping starfields to see what is there that you can resolve with the instrument.
Have fun.
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Off the deep end? Perhaps. But the original question was about how to check the rack and pinion, not whether it should be checked. I appreciate you pragmatisism, but it was still fun to describe how to do a pattern check. Whare's your sense of humor? :)
described very clearly and in

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On Tue, 30 Nov 2004 18:34:19 -0800, "Kelly Jones"

My sense of humor disappears very quickly when it goes from the realm of the ideal to the realm of the ridiculous. A patten check on the hypoid diff gears that I used to do by the dozens is one thing, on a rack and pinion, where the rack is die cast and the pinion extruded is senseless. I could have gone into the whole nine yards of a gear lab check, but to what end? In this particular application, if the spur gear has .0002" helix, and the involute error is .001", what's the difference? Even pitchline to pitchline makes no difference here, the pinion is crushed into the rack for full engagement by a spring, and the relation of the pitchlines really don't mean squat. DP of the rack and pinion is going to be probably 32 or finer, you're looking for errors that are going to be in ten thousandths, and even if they're found, they won't bother anything. Even my 35 year old Edmonds, the focusing isn't perfectly smooth, but it doesn't make one bit of difference, it still works just fine. There are some focusers out there that are perfectly smooth, or as near as is possible, but at $300 or so per copy. To what end? The mirror in my 10" f8 cost me $350 for figuring and coating, I don't think a $300 focuser is going to make it work any better. It has an off the shelf Boston rack, and the pinion cut from pinion wire. Works just fine, and a hell of a lot cheaper.
Why complicate things?
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In all fairness to Kelly Jones, I did ask for how one would go about taking a fanatical approach to the wear on the rack and pinion. And I did find his reply interesting and informative, just as I found yours to be. I'm not really in a position to carry out his suggestions at the moment, and you're probably right that it isn't necessary, but I like to know how to do things, even if they're not appropriate to the task at hand, as long as I'm not under extreme time pressure to get something done (and with the weather the way it's been, there's nothing to look at in the scope anyway for the time being). Similarly, I realized that I probably don't need to buy a comparator, but it was good to learn about it, since I'd never heard of it.
As long as there was one person who was telling me exactly how to handle the specific situation I was asking about, there was no real harm in getting supplementary information from others that was not immediately applicable. In the absence of that specific information, it would have been a different story, but I think I can tell the difference between what is immediately applicable and what isn't.
If you don't mind, I'd like to ask about of your other comments, namely about the Taig lathe. I had never considered it and didn't know anything about it. I just took a look at http://www.taigtools.com and I see that the basic Micro Lathe II only costs $173 (or only $144, if I can assemble it myself, which I'm not sure I can do), and I think I saw somewhere that shipping is free if I buy it online. That's pretty tempting, but I may not realize that there is something else I would obviously need that would raise the price by a lot. I see that their milling machines are a lot more expensive.
I learned about the Sherline by reading Joe Martin's book, Tabletop Machining. I see that the Taig website lists a book by Tony Jeffrey, entitled, "The TAIG Lathe". Would it be a good idea to purchase this book before committing to getting a Taig lathe?
They show it with optional 3-jaw chuck, boring bar, tailstock, drill chuck, 1/4 HP 1725 RPM motor, motor mounting bracket, mounting board and pulleys for $399, presumably with free shipping for online purchase, which is less than the Unimat 1 comes to after taxes and shipping are added. Hmm, the motor is optional, as in no motor with the $144 deal?
Of course, the Unimat 1 comes with the other stuff (notably the milling machine attachment), but one can't go too far wrong for $144, can one, as long as it works, and the other stuff can wait a little while.
It's also probably easier to learn something by taking the Taig apart than a Unimat 1...
I've decided on the first thing I will do when I finally get a lathe: I have a T-connector for my Minolta XG-1 camera (which, even with its apparently broken internal LEDs, is adequate for taking photographs through my microscope), and an adapter to connect it to my microscope. Now that I finally got my hands on a telescope, I tried to see if the adaptor would work with the telescope and, of course, it doesn't. But if I can machine a 1.25" O.D. tube to have a somewhat smaller O.D. near one end, I can use it as an adaptor adaptor, with the telescope eyepiece holder grabbing onto the 1.25" O.D. end and the camera-microscope adaptor grabbing onto the smaller end. This seems like the absolutely simplest first project one can do with a lathe, and I have an immediate use for it.
The following is probably a bad idea, but it would be instructive to try out. I have a few eyepieces for my microscope. They are intended to fit the microscope barrel, but again it wouldn't be hard to make an adaptor that would let me insert them into the telescope. That is another very simple lathe project. Whether these eyepieces would be any good with the telescope is something I could then try out. Probably they wouldn't be, but I'd see for myself. The next problem would be to learn why, from the standpoint of optics, I should never have expected it to work in the first place. But there is a kind of information mismatch. The microscope eyepieces are only marked with their magnifications, such as 5X, 10X, 15X, while those for the telescope are marked with their focal lengths, such as 15mm,25mm,30mm. Even if the viewing isn't good, maybe I could wind up using the telescope to measure the focal lengths of the microscope eyepieces. In the absence of any optical equipment for doing such measurements, the idea of using a telescope as an optical lab bench is rather tempting, even if somewhat ridiculous.
--
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Allan Adler < snipped-for-privacy@zurich.csail.mit.edu>
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wrote:

The basic Taig is just that, the headstock, bed and carriage. Everything else is an extra, But it's still possible to have a complete lathe, with all accessories for under $500. IN the micro lathes, between one and the other, everything is different. The chuck for the Taig comes with soft jaws, which means, you have to learn to bore them. Not really a negative, but on the flip side, getting concentricity to where it's almost to little to measure is relatively easy.

By all means. I haven't seen the book, but often a look at what someone else has done makes what you want to do much eaiser.
Maybe Nick Carter will jump in here, he sells them and is very knowledgeable on what people are doing with them.

Right. The package sounds very good, although I bought mine piecemeal, which probably cost me more in the end. The shortcomings of the machine show up, but by that time, you'll probably be far enough along to recognize them, and have an idea of what to do to clear them up. (There is no "perfect" machine for everythng.)
One thing they don't push very much, the collets for it, this is something I bought quite some time after I had the basic machine and enough of the extras to make it work. They are invaluable when you have smaller diameter work, 5/16" is the biggest collet they have. Mine ran dead true and held like a bulldog.

The instructions for assembling the kit sound somewhat simplistic, but that's really all that's involved, it only takes a few minutes, well, less than an hour.

THis would be a very good project, not too much involved, but enough to learn from it. One of my buddies put a University mirror cell in an Oddesy scope, which moved the mirror forward almost 1 1/2", and no focuser has the reach to make up for that. Making an extention tube to move the eyepieces out was a relatively simple job, the Taig did well.

I've always had that idea, but have never acted on it. THe eyepieces are of a much different design from telescope EP's, and probably something is going to have to be done to compensate. IIRC, the focal plane of the microscope EP is between the lenses, but that's looking at older units. I have quite a few 10X and 15X wide field AO eyepieces, but as they're in scopes, I'm somewhat reluctant to risk taking them into the field. I spent hours going through a drawer of hundreds of eyepieces trying to match pairs, losing one of them would mean I couldn't find another to match it. I don't know any reason that they wouldn't work, and probably pretty well.
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snipped-for-privacy@Nowhere.moose writes:

It makes sense that someone would purchase a complete lathe with all the accessories. If they already had accumulated some of those accessories from earlier acquisitions, it would make sense that they might forgo some of them when purchasing a Taig. It would then make sense that Taig might accomodate them by offering lathes without the accessories. But I'm not sure under what circumstances someone (other than a complete beginner like me, who doesn't know any better) might purchase a minimal $144 Taig that doesn't even have a motor. Is there a significant part of the market represented by people who already have a supply of motors?

I've been thinking about this statement and there are two things you might mean by it. (1) You sometimes take your eyepieces apart to scavenge the individual lenses to recombine them in ways you find more advantageous. I know from experience that they come apart, and I also found a website (e.g. http://www.astronomyboy.com/eyepieces ) that tells you how to make your own telescope eyepieces, so this isn't unthinkable. It's another thing I was considering playing with when I get some machines. I'm not sure but it sounds a lot cheaper than buying eyepieces. (2) You have a binocular microscope and you need identical eyepieces for each eye. In the latter case, it sounds like you have all the eyepieces loose in the drawer but not grouped in matching pairs. If you had enough little boxes, you could group together all the ones that have the same magnification and not have to spend hours looking for matching pairs.
Regarding the threads on the threaded metal shells that hold individual lenses in an eyepiece, are these threads that would be easy to duplicate with standard tap and die sets or is there something special about them?
--
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Allan Adler < snipped-for-privacy@zurich.csail.mit.edu>
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    [ ... ]

    [ ... ]

    The only taps which are likely to be usable for that sort of thing would be the collapsable taps (sort of inside-out Geometric die heads) used on turret lathes or automatic screw machines.
    Optical threads of this sort are *very* fine relative to the diameter. The reason for this is because they typically screw into thin-walled cylinders, and fine threads are not as deep as coarse threads.
    And you wind up with really weird bybrid threads. IIRC (and I could well be wrong) the standard thread for microscope objectives is 0.800" x 0.5mm (Inch diameter and metric thread pitch).
    For production, you would use a collapsing tap to cut the inside threads, and a Geometric die head with custom chasers to cut the outside threads.
    For onesy-twosy work, you would single-point it on a lahte, which means (if you get a Taig) that you need to investigate Nick Carter's mod which gives it threading capability.
    Normal taps and dies are difficult to start square without some kind of machine support helping you. You *could* have any special tap and die made for you by the companies which make them, but it would cost you quite a bit, and you still have the problem of getting them started straight. And if you don't get them started straight, you have lens elements tilted relative to the axis of the equipment, thus offering optical abberations.
    I think that if you are going to be doing much of this sort of thing, you want to look for a dual-system lathe, with threading setups for both Imperial and metric threads. (To do this properly means two leadscrews with matching threading dials, and two quick-change gearboxes to provide the proper ratios for the different systems.)
    It is possible (with a set of transposing gears) to cut metric threads on an Imperial machine or vise versa, but it will be a serious pain, as you can't disengage the half-nuts until the thread is complete, with however many passes it requires.
    So -- while I have the Metric transposing gears for my Clausing, as long as the size can be handled by my little Compact-5/CNC, I will use it for metric threads, as all I need is to flip a switch to change systems. (And even then, the 0.800" x 0.5mm thread would require setting it up for metric threading, and converting the 0.800" to mm before programming the machine.)
    Enjoy,         DoN.
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On 3 Dec 2004 00:37:40 -0500, snipped-for-privacy@d-and-d.com (DoN. Nichols) wrote: <snip>

If I recall correctly, there was something called a Frog which could control a Taig, and would do threads under program control. Yeah, here it is http://www.avatartools.com/Merchant2/merchant.mvc
I considered trying that, but wound up getting another lathe with threading capabilities before I ever pulled the trigger on purchasing a Frog.
I kept the Taig, and still use it for a lot of little fiddly projects. It is excellent for small work. But threading jobs go on one of the other lathes, or get handled by taps and dies.
Adding a Frog still looks like an attractive way to upgrade a Taig to 1 axis CNC. With 2 Frogs, you could do 2 axis CNC (the Frogs can talk to each other, so interpolated taper and radius turning would be possible in addition to fully automatic multipass threading). At $199 each, that's starting to cost real money, but it is still a lot cheaper than most CNC retrofits.
Gary
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On 3 Dec 2004 00:37:40 -0500, snipped-for-privacy@d-and-d.com (DoN. Nichols) wrote:

Don, the standard is .800"-36TPI, 55 degree Whitworth threads, has been for over 100 years. The same thread is used to hold the turrets on the tube, or can be replaced with an extender to use single objectives, and I have seen scopes built that way too. The only exceptions I know of are Nikon and Olympus, and I've made a whole bunch of adaptors for these scopes to use the Society standard objectives. (If anyone can explain where "Society" comes from, it might be interesting. What society?) Microscope eyepiece diameters are .913", keeps the confusion away from telescopes where the smaller standard is .965" for eyepieces. The sizes are not an inch or metric standard, but were chosen to be completely oddball, meaning there's no chance that the wrong thing will fit and work. (And again, some Nikon eyepieces are non standard sizes, more expensive and I don't believe too well accepted. Their "academics" have the standard eyepieces.) Camera mount threads tend to be metric, .75mm pitch.
When it comes to stereo scopes, all bets are off, seems like everyone had their own idea of what would be best and ran with it. My old AO "Gray Lady" uses .913 eyepieces, my 7X with the 9" working distance has non removable eyepieces. (I made Jerry a mount to hold another long working distance 7X over his jewellers lathe, works great, wish I'd made two of them.)
(Metalworking content: I think I know what I'm going to do today now. Another overhead mount coming up.)
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snipped-for-privacy@Nowhere.moose says...

The Royal Microscopical Society. How's that for an obscure and useless bit of information crowding out more useful stuff from memory? Wish I could remember my wedding anniversary.
Ned Simmons
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wrote:

Hmmm. Figures. MIght have to google that one and see if they're still around, but knowing the Brits, once it's established, it'll be forever before they let it go.
(Wish I could remember what day it is.)
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wrote:

Taig also sells the motors, but most people just use a scavenged motor from an old washer, dryer or whatever. 1/4 horse is plenty, I ran mine on 1/6 horse until I got tired of having to lift the whole thing, and the old motor was from 1937, HEAVY! Changed it over to a 1/12 horse scavenged from an old Bodine gear motor with the gear broken. If you can get a slower motor, maybe 1140 RPM, it would be better. Don't know if they're available on the surplus market or not.

Bingo. Actually 5 binocs, two trinocs and a whole bunch of monocs. I like old things. Maybe too much. Matching them for power isn't too bad, but making sure they have the same aperture is where it gets fun, you have to hold the pair to your eyes, then swing the fields until they come together, they should be the same. (But usually aren't.) I don't have a good supply anymore, but used to work with J&H microscope on mods and accessories. You can get into some really wierd stuff.

Most of them that were made in the US had an unwritten standard of 40 threads per inch. Sometimes an odd ball of 36 TPI, but usually 40. Metric, I don't know about, I've been out of the attachment making for about ten years now, They're usually not included in the normal tap and die sets, but most of the supply houses will have them. The objectives, with only a very few exceptions, are .800"-36 TPI, 55 degree Whitworth threads. Most of the supply houses also have taps and dies for this as well. Prices are pretty reasonable.
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I'm trying to follow up on Nobody's suggestion that I use RT-44 as a lubricant for the rack and pinion on the telescope. Searching for RT-44 with Google turns up endless hits for places on Route 44. At Ace Hardware's website, searching for lubricant turns up what looks like mostly motor oil but no RT-44 and searching for RT-44 turns up nothing. I also searched rec.crafts.metalworking for messages mentioning rt-44 and found two, one of which was Nobody's posting I'm following up on and the other was from someone who said he had gotten a tube from American Science and Surplus. Searching http://www.sciplus.com for rt-44 no longer turns up anything, nor does searching for lubricant.
So, where does one get rt-44?
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wrote:

Probably not much help, but I got mine from American Science and Surplus, but their supplies of it are sporadic at best. They don't list it as RT-44, don't think they have any idea of what they're selling there. I'll take a look and see if they have anything listed, the last time, all they said, "It's slippery". The tube I got from them appears to be about a 50 year supply, and cost a whole buck. I think that when it's sold under the trade name, they're not so generous, but only tiny amounts are needed. IF all else fails, try J&H Microscope Repair Service in Madison, Wisconsin. I know Jerry keeps a pretty good supply. Just tell him Richard from Burlington steered you there. Don't have his phone handy, every time I call him I end up with some damn work I don't really want anymore.
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On Tue, 07 Dec 2004 08:30:20 -0600, snipped-for-privacy@Nowhere.moose wrote:

One could use a couple dabs of Slick 50, which seems to work fairly well for this sort of thing, for me...shug.
Gunner
"To be civilized is to restrain the ability to commit mayhem. To be incapable of committing mayhem is not the mark of the civilized, merely the domesticated." - Trefor Thomas
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