rack and pinion

snipped-for-privacy@nowhere.noose writes:


That seems like a simple enough test.

As a matter of fact, there seems to be, if I understand you correctly to mean on the same surface that the rack is mounted to. It is mostly near the rack but "slop" is a good description of it.

When you say "to one side", I think you mean either towards or away from the eyepiece. This is an interesting point. As I mentioned, all three flat pieces could simply sit on the 4 pedestals in the box, which would lead to a symmetric pressure on the pinion axis. You seem to be saying that is undesirable. On the other hand, when I opened the box, there was asymmetry in the placement of the flat pieces: the one furthest into the box was placed diagonally with one short edge at the "top" of the box and the other short edge at the "bottom", where top and bottom refer to distance from the drawtube/focuser body. The other two were placed as flat as possible, given the asymmetric placement of the first one. So, you seem to be saying that the way I found it was correct. Thanks!
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wrote:

Ok. On some of the focusers, I don't know if Meade ever used it, there are flat springs opposite the rack, and they furnish friction to keep it from moving unless driven by the rack/pinion. If these are properly set, they will hold the drawtube in a sort of balance with the pressure of the rack, but will seem to be allowing movement, which in use will not be the case. The old 6" Edmonds has two felt strips opposite the rack, some have other methods, even going so far as to having eliminated the rack for a friction drive, and having ball bearings instead of springs or felt. The main thing is that with the eyepiece installed, it should be centered and with the optical axis also centered and parallel to the optical axis of the objective lens. If it was a cheaper focuser, and has the felt, chances are that the felt has compressed and is no longer holding it firmly. Quicky repairs can be made by replacing the felt, but I prefer to use the flocking from the film slit of a 35mm cartridge instead of felt. It seems to not compress as quickly, and sometimes gives a little more "solid" feel to the focuser.

It should be holding it so the shaft can't move up or down or towards the drawtube easily. If it's too loose, it acts like backlash, or excess play when changing the directon you're moving the drawtube. There are as many variations in how it was accomplished as there are makers of telescopes, every one of them believing they have a "better idea." My own "better idea" would be a planetary drive fine focus knob, but due to the costs of making such an animal, maybe it wouldn't be worth it. I probably have ten or fifteen focusers in different stages of "maybe this will work" in the basement, but still have to come up with the "perfect" idea. It's pretty hard to improve on something that people have been working on for several hundred years.
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I've been trying to follow up on details of some suggestions.
Regarding the threads in lens holders in eyepieces, the use of collapsing taps seems to be prohibitively expensive, although in searching for them the collapsing taps I've found don't seem to be for that range of sizes. On the other hand, one doesn't have to make them exactly the way they are made in commercial products. One reason given for the odd sizes was so that other things don't get screwed in by mistake. For making my own, I probably don't need to worry about that. There might still be a reason one wants very fine threads. One thing that occurred to me was that maybe by making multiple threads, one could achieve the same fineness. Alternatively, by using CNC one might just be able to tell the lathe exactly how to cut the threads.
Hence, regarding CNC: it was mentioned that Nick Carter has some device called a Frog for upgrading a Taig lathe to CNC for about $200. I'm not sure what assumptions are made regarding the configuration about the Taig nor what assumptions are made regarding the computer to which the Frog is supposed to be able to be connected, if one wants to connect the Frog to a computer. To take an extreme example, suppose I find a vacuum cleaner discarded on the street and perform a motorectomy on it and order the K1019 deal at http://www.taigtools.com for $144.50 and one Taig Frog for $199 from Nick Carter. Then for a total of $344, more or less, I have a lathe and a Frog, but it's not clear to me whether there is enough Taig there to use the Frog with it. Obviously, one can't have the Frog tell the Taig to do stuff that requires a tailstock, but there are things one can do without a tailstock. (More on this below.) As regards the computer, will the Frog work with the computer if it is a PC running some version of RedHat Linux (as mine is)?
I haven't taken any courses on lathes. I happened to read Joe Martin's book, Tabletop Machining, and I read Gingery's book, The Metal Lathe, and I have version 55 of the South Bend Lathe Book, from around 1958. In particular, Gingery shows you the lathe in various stages of completion and how to use it to bootstrap the rest of the lathe. So, I compared the parts list at http://www.taigtools.com/mlathe.html with what I found in Gingery's book, not too meticulously, but enough to give me some idea. The part list of the Taig Micro Lathe II kit mentions a bed but doesn't mention anything about ways. I think I'm supposed to realize that the bed includes the ways. In the Gingery lathe, there is a lead screw. I'm not sure but I think the analogous part for the Taig is 100-09, which is the carriage rack (there is also a pinion gear, so I think I am still within bounds of the subject "rack and pinion"). On p.100, Gingery writes: "At this point, you have built a lathe that is as complete as some that are sold commercially. If you have been in the market for a lathe very long, you are not surprised to learn that some lathes are sold without a tail stock. I could hardly call a tail stock an accessory, as some do, but the partially finished lathe can do many jobs now." Gingery declines to say what the jobs are that the partially finished lathe can do, but How to Run a Lathe says: "Work that cannot readily be mounted between the lathe centers is usually held in a chuck, as shown above, for machining." I assume that is meant to include the case where there is no tailstock. It goes on to mention, specifically: (1) taper turning with a chuck and compound rest and (2) cutting screw threads with a chuck and compopund rest, using gears that connect the headstock spindle to the lead screw." Maybe there are other things and maybe more can be done using the Frog with it, but I don't see it clearly. For example, I'm not sure what, in the case of the Taig, would take the place of the gears that engage the screw thread to achieve (2).
Regarding the motorectomy, I'm reading the book, "Fractional horsepower motors: use, selection, operation, repair and maintenance", by Rex Miller and Mark Richard Miller. I'm about 100 pages into the book and a lot of just goes past me, but it has already discussed removing and repairing a vacuum cleaner motor. The book lists a lot of tools and parts one needs to get involved with motors, probably adding up to a significant investment, but I think the authors are assuming that anyone who reads the book is probably giving at least some thought to opening up a repair shop. What one actually needs just to scavenge one motor from a discarded vacuum cleaner for use with a lathe is probably not much.
Incidentally, the micro lathe parts diagram and parts list at the Taig site seems to have a small typographical error: there is a part in the parts diagram labeled 100-28 but there is no such part in the parts list.
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    [ ... ]

    O.K. The "frog" is not a part of Taig, or of Nick Carter. It was started by another person, who during the last year dropped the line and it was picked up by yet another. (I should remember the name of the latter -- from a mailing list in which I participate -- but I don't.)
    Have a look at this URL (which mentions Nick Carter, as he is the premier worker with the Taig.
    http://www.avatartools.com /
and this subpage shows one fitted to a Taig:
http://www.avatartools.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=Taig
    Note that you do not *need* a computer at all. The frog contains a keypad to allow you to enter commands to it. (A computer is probably easier to save programs and re-load them -- especially if it takes a lot of keystrokes to enter the program.
    I don't know whether there is anything locking it into Windows, and I somehow doubt it. Just a simple text transfer should be sufficient.
    [ ... ]

    Yes. The ways are a steel dovetail, which is mounted onto a aluminum bed filled with concrete to minimize vibration and chatter.

    Larger lathes have a rack-and-pinion to move the carriage under control of the handwheel, and the leadscrew is only used with the gearbox for threading and power feed (and on the better ones, power feed picks up rotation of the leadscrew through a keyway milled along its length, to drive a gear train connected either to the handwheel (for slow longitudinal feed), or the cross-feed crank (for facing). This reduces wear on the threads and half-nuts over the life of the lathe.
    Smaller machines may have a leadscrew which is only operated by a handwheel at the end of the bed, so it is very slow to go from one end to the other. The Unimat SL-1000 (and DB-200) were of this type. The Taig has only the rack and pinion, and the frog kit for the Taig is designed to work with this. According to the web page, if you want to use it with a Taig which has been retrofitted with a leadscrew, you want to order the Sherline kit, which suggests that the Sherline is similar to the earlier Unimat machines.

    Limited to the length of travel of the compound.

    Except that there is no leadscrew on the standard Taig. But, there are other ways to cut threads -- with the Frog driving the carriage.

    The Frog monitors a sensor on the headstock of the lathe, which produces a pulse once per revolution. It times the delay between pulses to calculate the RPM, and then drives the carriage at an appropriate speed to cut the thread, It always starts just after one of the pulses, so the successive (deeper) cuts are made along the same track.
    It is possible to fit a lathe with two Frogs, interconnected, so you can turn tapers using that.
    Note that when turning with a chuck, and no tailstock, you are limited in the length of the workpiece extending beyond the jaws of the chuck. This must be limited to something like no more than perhaps three times the diameter, or the flex of the workpiece material will introduce errors. A tailstock, with a live (or dead) center can allow much longer cuts, as the workpiece is supported at both ends, and the bending moment of the middle makes it able to work beyond twice the maximum length when using just the chuck.
    There is also available a stead rest, which can support a workpiece some distance beyond the chuck, without needing a tailstock.

    A Vacuum cleaner motor may not be a satisfactory one -- in part because it tends to be more of an open frame format than most others, and thus allows chips from the lathe to get into the motor, and possibly damage it. In the vacuum cleaner, it is protected by the bag or filter in the cleaner.

    I have not looked at that, so I don't know.
    I seem to remember you mentioning the lack of a dog and a faceplate (somewhere in the trimmed text, I suspect). Note that as long as you can mount a center in the spindle and access it through the chuck, you can use a jaw of the chuck to drive a lathe dog. (And, you can *make* a lathe dog, if you can't find one of the needed size -- especially in these smaller sizes.)
    But -- there is a faceplate available for the Taig. One with T-slots, so you can bolt a workpiece to it which can't be held in the chuck, among other things.
    And a (small) faceplate is not that difficult to make, if you also have milling capability.
    Enjoy,         DoN.
P.S.    I suspect that you would get more immediate positive feedback if     you bought the Taig with as many accessories as you can. Making     your own is best done for a later machine, if needed, when you     have the skills needed.
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Thanks very much for answering my questions about Frogs and Taigs and other details. I think I understand a lot better now.
snipped-for-privacy@d-and-d.com (DoN. Nichols) writes:

I just took a look at http://www.sourceforge.net and did a search for cnc and found a number of projects in progress aimed at using Linux for CNC. Apparently most of them haven't released any free software yet, but it is only a matter of time. One that has released some stuff is at http://sourceforge.net/projects/cnccodegen and is described as follows: "CNC code generator is a software to generate CNC codes (G & M codes) for maching operations like milling, drilling. At present CNC code generator is limited for end milling. we working on other machining operations like turning, drilling etc."
Two items that look especially interesting are the OpenCNC, which simulates what happens when you run a program on a lathe and does some error checking, and the Linux Multiple-Axis Control Project. Unfortunately, neither has released any files yet, according to sourceforge.
Meanwhile, maybe it's time I learned to read and write G code. I vaguely recall that there is something on this in Machinery's Handbook and it doesn't cost me anything to look at it in the bookstore.

I searched for "dog" and "faceplate" separately in this thread at http://www.dejanews.com and only found your article mentioning them. But the information about them is still welcome.

I agree. I'm not in any way in a position to make my own. For one thing, I can't cast molten aluminum in a crowded apartment. I should be able to find enough space to do some work on a lathe when I get one, though. I was only mentioning Gingery's book because it enabled me to do a comparative anatomy of lathes in various stages of completion.
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    [ ... ]

    That is good news. I look forward to it.
    But the G and M codes are probably meaningless to the Frog -- it is its own world. :-)

    Hmm ... there is a simulator built into the EMC project -- built around a modified linux kernel to add real-time capabilities.

    O.K. Though I suspect that without a context (a machine to try things on, or at least a description of a machine) you may find the _MH_ description not too clear.
    Hmm ... one posibility would be for you to download the programming manual for the Compact-5/CNC, which would give you an example of a real machine -- I know this, as I own and use one.
    Go to:
    http://www2.d-and-d.com/EMCO/index.html
One of the sub pages has the programming manual, broken up into a separate PDF file for each chapter. Most of the others show various features about my Compact-5/CNC which I have seen fit to document from time to time for discussions here and elsewhere.

    O.K. It must have been another thread -- and perhaps even in another forum.

    You've been paying too much attention to the Gingery books. You can simply start with a piece of aluminum, or cast iron, large enough, and remove everything which does not look like a faceplate. :-)
    For a dog -- start with a thick enough piece of metal, drill a hole, file one side of it to a V, and thread a hole for a setscrew opposite the V. Then, drill a hole parallel to the other, but out beyond the end of the V, tap it, and screw in a pin to engage the chuck jaw or the slots in the faceplate.
    One benefit to an aluminum one is that you are less likely to mar the finish on the workpiece when turning a workpiece between centers end for end. Just be sure to put another scrap of aluminum or copper between the setscrew and the workpiece.
    Where the casting helps is that it produces less waste material, and less required machining. This is more important as the size of the project scales up.

    O.K. A Taig is a nice sized desktop machine. The old Atlas or Atlas/Craftsman 6x18 probably should be bolted to a workbench in a more permanent setup. The Taig can be lifted clear and put away in a cabinet when the job is finished.
    And at least the one which I have has a couple of dummy spindle nose threads on the plate to which it is mounted -- useful for storing the faceplate and chuck not currently on the spindle.
    Enjoy,         DoN.
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snipped-for-privacy@d-and-d.com (DoN. Nichols) writes:

When a computer sends something to the Frog, what format is the information in? If it depends on software provided by the vendor of the Frog, that again raises the question of Linux compatibility.

I forgot about the EMC. I remember being led to it by looking at the Sherline web pages on the Sherline CNC capabilities. Apparently, the real time modifications to the linux kernel are not something the likes of me can add to the kernel, so one has to install an actual real-time Linux kernel such as RT-linux which, as I recall, is not free software. Sherline solves all these problems by selling you the computer with the right version of Linux and the necessary software installed on it as a necessary part of the deal. Another problem with the EMC was that some of the files one would need to download just to look at the software are about 75 MB, which is way to much for my system to download (I use a modem over a phone line and my ISP clocks me out after a certain number of hours). I don't know whether it is possible to just use the EMC simulator on an ordinary non-real-time Linux distribution.

I agree with you. I'm also trying to get some books on it.

Thanks, I'm getting it now.

I'm probably going to get a Unimat 1 for starters, since it gives me several capabilities, not just a lathe, even if it is basically just an overpriced toy (especially after one adds in the shipping and handling and manual and taxes). But since I know it is a very limited tool, I'm already trying to decide what my second lathe will be and that is why I've been looking so closely at the Taig.
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    Presumably, plain ASCII. But I don't have a Frog, so I can't do more than guess.

    Why not? I've done it, and I found the instructions pretty clear. (But you have to apply the patches to the right version of the linux kernel, so there is a better way for you.

    What? Of course it is free. (Or a minor fee for the CD-ROM copying.)
    Check out http://www.linuxcnc.org /
In particular, look for references to BDI (Brain Dead Install), a CD-ROM which can be booted and used to install the patched linux in a raw machine.
    You can download it -- but on a dialup, this would be a killer, as it is a CD-ROM image file which you would use to burn your own CD-ROM.
    Or -- there is a list of e-mail addresses (under "Where to get it") for those who will burn CD-ROMs for those whose download time is excessive. I don't know what they charge, but it should be something reasonable, for burning, time, blanks, and postage.

    Probably one of the BDI versions -- perhaps with standard drivers tuned for the Sherline hardware.

    Hence the contact addresses for the BDI CD-ROM. At least one of those is something like 500 MB, and at least one distribution is two full CD-ROMs.

    It should be, as there is no real-time interface involved. But why, when you would have to download the source and compile it anyway, and the BDI package makes it so much easier.

    Good. Enjoy.

    I'm not sure which recent Unimat is which -- but at least one of them is good for nothing more durable than plastics, from what I have read.
    Enjoy,         DoN.
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snipped-for-privacy@d-and-d.com (DoN. Nichols) writes:

I must have been thinking of another real-time Linux system. Thanks for pointing this out. I'll try to get one of their CD-ROMs.

I was thinking of getting it from Edmund Scientific. I have been operating on the assumption that it is ok for wood, plastics and at least some non-ferrous metals.
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I was so taken aback by the suggestion that all my plans were based on a false assumption that I took another look at the Edmund Scientific catalogue. Here is what it says about the lathe module of the Unimat 1: "Module #3 Metals and Plastics Lathe: Works with soft metal, non-ferrous metal, precious metal and plastics."
Regarding wood, Module #1 is a small woodturning attachment.
I wonder whether there is any chance that the Frog could be made to work with the Unimat 1.
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    Of course they would make the maximum claims that they could get away with. They are trying to *sell* the things. :-)
    Note that I expressed a doubt as to which recent Unimat was which. The Unimat which I have used was the SL-1000 -- back from the days when the bed was a pair of steel rods supported only at the ends. That could turn steel, but not very robustly. At least one of the recent Unimats is almost all plastic, and cannot be practically used for steel. This mention of "soft metal" suggests that this is what they are describing.
    The page for the Frog mentions that the Sherline version of the Frog should work with the Unimat-3 -- and says nothing about the Unimat-1.
    O.K. I'm looking at it now, on their web page. It is the modular plastic-bodied one which I feared. Note that the power supply is a wall-wart, good for all of 24 Watts. That means something like 1/30 of a horsepower. Quite anemic.
    Also -- the focus of the description for the jigsaw attachment suggests to me that this *is* a toy, not a serious tool.
    "Module #2 Jig Saw: Completely safe (short stroke only vibrates     the skin); max thickness: 7mm."
That short stroke means that it cannot practically be used with thicker materials, as there is insufficient stroke to allow the chips to clear the workpiece.
    I truly consider this to be a toy, intended to teach the *principles* of a lathe, without giving you enough power to hurt yourself.
    Doing a web search on "Unimat 3", I am led to the Blue Ridge web page, which says (when I click on "Unimat-3":
    "The Unimat Lathes are no longer being manufactured. However,     some parts and accessories are still available."
    Also, I see that the spindle nose for the Unimat-3 is a M14x1 thread, while that for the Unimat-1 is M12x1.
    The Unimat-3 I believe had the same bed as the Compact-5 -- one flat way and one inverted-V way. And that works well for me in my Compact-5/CNC -- especially after I reenforced the plastic gibs with an aluminum backup strip.

    I frankly doubt that it is repeatable enough for it to be worth the trouble.
    I would suggest just skipping over the Unimat-1 and getting either the Taig or the Sherline. Or -- you could get really lucky, and get a Compact-5 (not the CNC model) for not too much. O.K. No Compact-5 lathes on eBay at the moment. Even an antique Unimat SL-1000 would be much better than the Unimat-1.
    Good Luck,         DoN.
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Thanks for all the critical comments on the Unimat 1. I think ebay is out of my league, first of all from the standpoint of purchasing online, secondly from the standpoint of knowing what is worth buying and thirdly from the standpoint of being able to follow what is going on in an auction. There's no point in explaining to me how easy it really is to do it; I'm just not ready for it.

I wasn't too concerned about the saw, since I figured I can get an electric jig saw for about $20 or so at a hardware store if the need arises.
The Unimat 1 does at least offer some crummy capability of doing both some lathe work and some milling machine work. I don't want to do entirely without milling machine capability and just rely on a lathe for everything. Given what I'm prepared to spend (under $500), I don't see how I can do better than a Unimat 1, even if it is a piece of junk. Whatever its limitations are, there must be a way to work with them.

Thanks. Clearly, I'm going to need it.
I apologize in advance for all the questions I'm going to have to ask about how to get things done on the Unimat 1 after I get it and I promise to accept with good grace and without complaint all of the excellent advice I will get about how I should really be using some other machine. I agree with all of it in advance. It's ultimately a question of money and I have very little discretionary capital. That being the case, I have to find a way to make the cheap toy do the job, but where there is a will there is a way. Meanwhile, I don't think I'll be unhappy about using it. I have a lot of experience learning under the most unlikely conditions.
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    O.K. So be it.

    Certainly -- I was just using that as an indicator of the limited capabilities of the rest of the "machine".

    Note that the Taig at least *used* to be offered with an optional milling attachment. That was an object which bolted onto the cross slide, and which had T-slots to allow attaching of workpieces to the vertical face. And that vertical face can move vertically with a handwheel at the top. It had two bars of steel which would bolt with t-nuts to the vertical face, one of which had setscrews to clamp a workpiece between the two -- sort of a bodyless miling vise. It was not very good, but more capable than I expect this plastic-bodied device to be.

    Up to a certain point.
    When you are through with this, *you* will be the person who others are directed to when questions on the Unimat-1 are asked.

    Remember -- *you* are going to become the expert. I seem to remember that someone else got one a few years ago, wondering just how bad it can be. He discovered the answer to that.

    As I say -- you *will* become the expert.
    I once did a lot of things with a Unimat SL-1000. Not because it was truly capable, but because I only had room for that and a sensitive drill press (1/8" maximum chuck capacity) in my apartment. Whenever possible, I would use *real* machines at work, but there were weekends in which I spent hours setting up to mill a rectangular hole in 1/8" aluminum rack panel for mounting a meter, rather than waiting until I could take it in to work and find time to do it there.
    Enjoy,         DoN.
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snipped-for-privacy@d-and-d.com (DoN. Nichols) writes:

Oh, no, not that!!!! I had better rethink this....

I was hoping for something like that but the only thing I saw at the Taig site was a separate milling machine costing a lot more than the fully functioning lathe. On the other hand, it occurs to me that if some other company sells an inexpensive milling machine, say for around $300, that might be a possibility, together with the no-frills Taig lathe.
What do you think of the improvised milling machine shown at
http://members.rogers.com/lenwinn/mill_wlathe.html
He says it cost him about 300 Canadian dollars to modify the drill press for this purpose, presumably including the vise he attached to it. I think he means also including the cost of the drill press. I don't know what it would cost now or what equipment would be needed to carry out this project. It seems possible that he didn't need anything but the drill press to carry out the modifications. Well, maybe he needed to tap some threads by hand. It doesn't look to me as though he had to do any welding, not that I can really tell.
He also says he started off with a Taig lathe that he used for his lathe work and milling. I'm not sure whether he is talking about the attachment you mentioned or the milling machine he cooked up out of the drill or something else, for example something like what is described at:
http://easyweb.easynet.co.uk/~chrish/tmilling.htm
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Allan Adler < snipped-for-privacy@zurich.csail.mit.edu>
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    :-)
    Because it needs one more axis of feed as a starter, thus one more dovetail assembly, and more metal to give it all rigidity. Also, the cheap or found electric motor which can be easily adapted to the lathe is more difficult to use for the milling machine, because the motor must be supported by the column with the milling head.

    Hmm ... let's look at the cheap Harbour freight milling machines. I've seen them, and they are at least a major step up from the Unimat-1 configured for milling. let's see -- there is the "Micro Mill-Drill" for $279.99. Check out the URL:
    http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumberG158
It is not much of a machine, but it is *far* beyond what you were considering. It is also well beyond the capabilities of the Taig with the milling attachment which I mentioned before, which itself is beyond the capabilities of the Unimat-1.
    Normally, I would suggest something even bigger, but bearing in mind your stated limitations, this may be the best bet you have.
    Beware that any milling machine or lathe will sooner or later double your investment in accessories and supplies. Do you have any precision measuring equipment, such as micometers? Those, at least, can be time-shared between the mill and the lathe.

    Frankly -- it scares me. It is a combination of a cheap drill press (with all the rigidity issues that involves), and a small X-Y table with a vise mounted on it. Those tables are sort of reasonable for placing holes at reasonably accurate location, but the side thrusts involved in milling tends to rock the top of the workpiece on the rather wimpy ways.
    Second -- a drill press's quill is also not designed to take side loads. The bearings are designed for thrust loads only. The quill is usually rather sloppy in the head casting. (It looks as though he has attempted to work around that by tightening a bolt threaded through the side of the casting to press upon the side of the quill. (Look just in front of where the hub of the feed levers attaches.
    Third, a mill should be able to produce a fine feed of the quill, and to lock it at a certain extension. It looks as though the "locking" is accomplished by turning the stop assembly on the left partially upside down, to press down upon the quill, instead of stopping it at a preset depth. That bronze colored collar, with the white scale wrapped around it, should be above the black arm, and is adjusted according to the scale on the white sticker to the right of the threaded shaft.
    This lack of positive control of the quill position, let alone a lack of a way to *lock* it in position, means that if a cutter starts to dig in, as will happen on certain materials under certain conditions, it will pull the end mill deeper into the workpiece, probably spoiling the job.
    Forth (and this would have been first, had he not found a workaround) -- a drill chuck is *not* made for holding the hardened and ground sides of an endmill, so the endmill tends to pull out. And the chuck is normally attached to the spindle via a Jacobs taper, which is excellent on thrust loads, but which is known to let go under side loads, or loads which pull. Apparently, this one has a threaded spindle, instead of a standard Jacobs taper to fit the chuck (making it closer to a hand-held electric drill motor). And -- he has made an end-mill holder to screw onto the spindle, thus reducing that particular problem. This, he almost certainly made using the Taig you mention below.
    One final consideration is the diameter of the column. That is rather small to be handling the loads involved in milling, and is likely to flex and lead to serious chatter.
    If you want to study modification of a drill press to make a milling machine (sorta), go to google, and pull up a lot of dgoonz's postings in this newsgroup from a few years back.

    That one is talking about a milling attachment for a much more solid lathe -- a Myford, which is a top-quality (and far from affordable) lathe used by hobbists in the UK.
    And even with that, it is rather limited in capability, compared to a real milling machine. I would guess that the Myford with the milling attachment is probably about as capable as the Harbor Freight micro-mill indicated above.
    P.S. The person who got the Micro-Mill that I saw, got it to experiment with retrofitting it with CNC capability -- as he had already done on a slightly larger mill-drill from the same source.
    Good Luck,         DoN.
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On 13 Dec 2004 23:04:40 -0500, snipped-for-privacy@d-and-d.com (DoN. Nichols) wrote:

I've looked at that in the store, maybe it might work ok, but I don't like the Morse taper spindle. The next one up has the R-8 spindle and is a much heavier machine. Morse taper collets are hard to find and very pricey.
However, http://www.homier.com sells pretty much the same mill as the mini-mill, and for $100 less. Shipping is pretty high, they're not feather weights at over 100 pounds. Homier also has the 7 X 12 lathe for $300, but like any import machine, they will need work before they're working machines. Doesn't matter who you buy them from, about the only difference is that some of them have Morse taper spindles. MIcroMark has both, but the Morse taper in the spindle, the highest price available, and I find it hard to believe that their machines are anything except the same thing with a higher price. However, MicroMark offers a milling attachment that will fit any of the 7X lathes, and a tool post grinder that's reasonable, but somewhat restricted. Won't do internal grinds, external only, and not for something you'll want between centers, the pulley guard is bigger than the wheel. It works reasonably well, but only reasonably. Haven't looked at the milling attachment, did milling on both my Taig and the 6" Atlas, didn't like it on either one of them. Pretty shakey.
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They use something that they call "Overnight shipping". There are probably cheaper options, but maybe Homier doesn't use them. They show shipping costs as being about $100 for one zip code and it can easily be a lot more.
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Allan Adler < snipped-for-privacy@zurich.csail.mit.edu>
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snipped-for-privacy@d-and-d.com (DoN. Nichols) writes:

Thanks for pointing this out. I'll call them and ask about shipping charges on that and other items (more on other items below).

At the Harbor Freight site, the mill/drill is one of a number of items they say come from "Central Machinery". I clicked on "View more Central Machinery items" and a few things caught my eye, including: (1) Item 40102-3 VGA, "8 in 3 multipurpose mini machine" for $189. Just change 47158 in the URL above to 40102. This seems like a fancier version of the Unimat 1, but at about half the price. (2) Item 39743-1 VGA, "Mini multipurpose machine (mill/drill/lathe)", $399. I can't really tell but this seems a lot sturdier than the Unimat 1, and only costs a little more. I don't know about shipping.

No, I have no measuring instruments except for a ruler, a tape measure and a plastic protractor. I don't even have a bathroom scale. I have a level in the toolbox.
Thanks for the critique of:

Greybeard said something about needing to make modifications in imported machines before they will work properly. I may not be qualified to do that.
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    From other postings over time, I understand that they sometimes have free shipping for purchases over a certain amount -- if you have the magic code number for the month. I also understand that it does not exist for December. Keep your eyes open for the next posting of someone asking for it (next year) and someone replying.

    1/125th HP motors. If anything, perhaps weaker than the Unimat-1, though it appears to be made of a bit more metal. same restrictions -- "soft metals". I would skip this just as I would skip the Unimat 1.

    Something around 0.4 HP -- better than the above. And you *could* use it. But beware that while it is probably not too bad as a lathe, the milling function tends to be awkward. It is difficult to put things at the right height to allow the milling cutter proper access.
    The lathe size is a bit smaller than the Compact-5, but certain things are rather klugy. An example is found on page 28 of the manual (which you can download in PDF form). The compound of the lathe has the tool holder as a single piece with the moving part of the compound, resulting in a lack of ability to adjust the angle of the tool independent of the angle of the compound motion (something important for threading).
    Also -- it *can't* do left-hand threads. (I spent some time analyzing this a while back as a result of a question from someone else), and has no half-nuts so the threading is going to be a pain. There is only one leadscrew, and they don't say whether it is metric or inch, and very little in the way of choices of threads in either system. Also, the slowest spindle speed makes threading rather exciting, unless you do it without power, and fit a show-made crank to the spindle.
    I tend to dislike 3-in-1 machines, and this is a primary example of why. Far better to get separate machines for milling and turning, so you can upgrade each when you discover it is needed, without losing the other capability.

    Look at 47257-5 VGA on the same site for at least an inexpensive start in both inch and metric measuring capability. A micrometer can be more accurate, but this is quick to use, and covers a lot more range than a single micrometer, as well as having the ability to convert between inch and mm at the touch of a button.

    This mostly involves disassembling parts, cleaning out sand and grit, filing off burrs on the edges of dovetails and such, replacing cheap soft metal screws with higher quality ones (as needed), and reassembling, lubricating as you go.
    And this is not required by *all* import machines -- but those from Mainland China, India, and (to a lesser extent) Taiwan. Japanese equipment is excellent, these days. Austrian, German, Swiss, and UK equipment are all good to excellent. (And way out of reach, pricewise. :-) Finding stuff actually made in the USA is harder, and the Taig is one of the few examples in the reach of hobbists.
    Good Luck,         DoN.
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On 14 Dec 2004 17:40:30 -0500, snipped-for-privacy@d-and-d.com (DoN. Nichols) wrote:

The 0 - 3" micrometer set that seems to be on permanent sale for $19.95 at our local store isn't bad, couple that with the above caliper, (of which I have four, two of them at the $11.99(?) price of the one day sale) and it should handle most measuring requirements. It's not the equivalent of the Starrett Master Venier or their .0001" micrometers, but you aren't paying for the Starretts either. I've been "abusing" one of the chinese 1" mics for about ten years now, still seems pretty accurate but doesn't have a nice feel to it. Kinda clunky after my 436P set.

The Taig is probably the best bang for the buck available. Even with all the attachments, you're still in the $500 range and what you can do with it is limited only by your imagination. Just so I'm not steering anyone astray though, by the time you spend $250, you have a running machine. Basic means exactly that, the basics around which to build up a running lathe. But it's a good one.
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