rack and pinion

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

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.)

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

So, where does one get rt-44?

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.

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

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

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

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.

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.

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.

I just took a look at

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

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.

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:

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.

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.

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

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.

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.

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.

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

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

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.

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.

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

Enjoy, DoN.

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

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:

:-)

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:

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.

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,