New Proxxon lathe question #1

Background:
I have been messing with camera lenses and was talking about getting a lathe to make some adapters and maybe learn something and have fun.
(If I just wanted adapters it would be far less expensive to just pay someone to make them.)
My wife pre-empted my dithering about the "best" choice and got me a Proxxon 230 as a birthday present. So now I get to dither about accessories instead.
So, my first question is hopefully simple; should I get the Proxxon splash shield / chip catcher tray gadget? It looks like a sensible way to reduce mess, but I have no lathe experience.
Bob
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    What is its native threading system? For most lens adaptors, you will want metric threading capability.
    O.K. According to this:
    <http://www.proxxon.com/eng/html/24004.php
it is metric.
    You'll want the boring tool set -- since you need to bore the center out of your adaptors.
    No need for the die holder -- you'll be cutting non-standard threads for which you could not afford a tap or die. :-)
    The quick-change toolpost will be a big hell as you switch between turning and threading tools (internal and external). Get extra holders. I see four total to be a good choice for what you want to do.
    Both the 3-jaw chuck and the 4-jaw chuck will be good to have. But the lathe comes with the 3-jaw, so you don't need another until you start milling with a rotary table. And I don't see that as needed for what you are doing.
    Hmm ... if you are going to make bayonet mounts (which many cameras use for their lenses), you will want the milling capability, and the rotary table down from the milling section. I don't see a rotary table listed, so you would have to get one from the Sherline folks to have one of reasonable size.
    No need for the collet set for what you have specified you want to do --but as you get to doing other things, it will me nice to have.
    The fixed steady is probably not big enough for most adaptors or extension tubes.
    The three piece thread cutting set for sure. (And learn to grind your own tools from HSS lathe blanks.

    Where are you going to be setting up? I don't see you needing to use flood coolant, so the splash part you don't need. If you're going to be doing this in the dining room or other living part of the house, the assembly could help control where the chips go, so you can clean them up more easily.
    I see you likely to be using aluminum and brass, neither of which really need flood coolant, and the aluminum can benefit from a bit of WD-40 spritzed on as coolant, while the brass cuts dry very nicely. Brass makes nicer and smoother threads, but it costs more and weighs more.
    If you don't already have one, get a shop vac to clean up the chips.
    And in addition to the listed things on that site, you will also need:
0)    *Absolutely* -- safety glasses for yourself, and for whoever     comes to look over your shoulder. Spares for when the original     ones get too dirty to see through.
1)    Micrometers in mm (since the lathe is calibrated in mm). At     the least 0-25 mm and 25-50 mm. The maximum capacity of the     lathe barely goes over 50 mm, so probably not the 50-75 mm one.
2)    Thread pitch gauges for metric threads.
3)    Digital caliper will be convenient for quick measurements     and for converting between inch and metric dimensions. Typical     inexpensive ones go from 0-150 mm (0-6"). They will eat up     batteries quickly, so plan to use SR357 or SR44 in place of the     original LR357 or LR44 cells. They will last longer, at least.
    Beware that the "off" button does not really turn it all off,     just the LCD display. It still keeps running internally to keep     track of when it is moved, so it has the right reading when you     turn it back "on".
    You can't trust it to provide as much accuracy as the     micrometers, but it is quick to use and read.
4)    A scissors style knurling tool to allow knurling parts for grip.     A "bump" style knurling tool needs a much heavier and more rigid     lathe to drive it.
5)    A bench grinder for making your own threading tools and other     turning tools -- and for re-sharpening what you buy.
    Probably lots of other things, but these are what I can think of at the moment.
    Certainly others will think of other things. FWIW, I have made lens adaptors in the past, and expect to make more. I've even made some with a much less capable lathe.
    Good Luck,         DoN.
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Thank you for the very comprehensive suggestions!
Comments interspersed below:
On 4 Mar 2012 06:24:57 GMT, DoN. Nichols wrote:

I would probably take bayonet mounts from junk lenses and bodies. But I can see that milling and a rotary table might come in handy for many things. My father donated an old Unimat II (not threading, but it will convert to a mill), and amazingly I have a very small rotary table from a yard sale!

Yes, I only have an inch micrometer so far...
The 52mm specification is European style, giving the radius not the diameter of the swing over bed.

Great idea; I hadn't thought of that.

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    Best way to do it. Thanks!

    [ ... ]

    Great! I've never had my hands on a Unimat II, but the even older Unimat SL-1000 and DB-200 have problems with rigidity, since the bed is only steel rods supported only at the ends. If the Unimat II has a cast bed, then it should be significantly more rigid, like my Emco-Maier Compact-5/CNC. (Still not up to my 12x24" Clausing, of course. :-)
    [ ... ]

    [ ... ]

    That makes the range of sizes you can handle better. I was thinking that it might be a bit tight for some sizes of camera, even if you stick to 35mm ones. I'm used to "Centre height" being used for the European style, and "swing" for the US style of dimensioning of a lathe.
    Interstingly enough, the Compact-5/CNC is specified in Inches of swing over the bead (diameter) even though it came from Austria.
    Make that a four-micrometer set. :-) There are pretty good ones (except perhaps for long term wear and retaining the accuracy) made by the Chinese and sold at various places. The ones which I have seen (four mic sets and 6 mic sets) have been inch mode ones, but presumably they also make and import metric ones.
    For one micrometer, a digital is nice for the ability to switch back and forth between inch and metric. (But somewhat expensive.) I've got two 0-1" ones, and one 1-2" one (each of the 1" micrometers is kept near a different lathe, the 1-2" one near the Clausing. (The Compact-5/CNC is a 5" swing (diameter, not center height). For beyond that, I have a 0-6" set of Brown & Sharpe mics to cover to the max size of the old Atlas/Craftsman 6" lathe I started with, and a collection of Starrett ones of various sizes to fill things up to the 12" size. (Though to be honest, *most* of the time, the 0-12" digital caliper (Mitutoyo) is accurate enough. But if I did not have those micrometers, then is when a job would come up where the extra accuracy would be mandatory. :-)
    [ ... ]

    I got my first one to use with the Compact-5/CNC -- way too small for bump knurling -- and I really don't like it on any system. I found a really nice one by Aloris to fit my BXA sized quick-change toolpost . It has the two knurls on two arms which move in a vertical dovetailed slide, each moving in the opposite direction with a leadscrew with left-hand threads on one end and right-hand ones on the other. Once it is set to the proper center height, I can just drop it on to knurl any size within its range without having to re-adjust the height.
    Enjoy,         DoN.
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On 5 Mar 2012 05:17:22 GMT, DoN. Nichols wrote:

OK, I will do it again :-)

The Unimat II is from the 60's and has rods supported at the ends, so it will never be a great mill, but it may be good enough for some learning.

Yes, I suspect that for most lens threads and such I could survive with even 0.1mm accuracy, which should be easy even with a calipers. For many other things "make it fit" is probably the order of the day, and absolute measurements are not relevant. But I suppose that it is inevitable that something will come along requiring a real number...

I did a little casual looking on the web and it looks like casual looking is not going to do it.
There are many tools that will do up to about one inch, which is fine for knobs but not so good for an 82mm filter ring.
Tools with large capacity probably don't fit on the small lathe.
Maybe a hand knurling tool is what I need.
However, it may be that no knurling tool is going to work well as the last step on a filter ring because the ring is thin and will bend under the load. Maybe I need to knurl first and then bore out the center.
Bob

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On Mon, 05 Mar 2012 18:22:27 -0500, Bob S

It is an excellent little machine. Like all well-designed and well-made lathes, it has a lot of capability within its designed limits.
Bob Hatschek, a former Senior Editor of American Machinist and a world-class model glider builder (who has flown all over the world in competition), for decades made a little device known as the "Hatschek Hook," a tow-release hook for competition gliders, on his Unimat II of '60s vintage, sold them through the model magazines, and made plenty of hobby bux with it. He used it for making all kinds of model parts.
So don't diminish its value and capability. It was a clever machine, well-made, and it has a lot of capability.
If you're into this as a hobby, my suggestion is to focus on what you *can* do with the machine(s) you have, rather than always pining for another machine. You can get a lot of pleasure out of learning to get the most out of basic machines. I decided years ago that I would define my hobby interest in terms of learning old methods and doing what I could with them. CNC was my business. It was not my hobby.
I can have a lot of fun with my 1945 South Bend 10L, with rocker toolpost and all. I could have a lot of fun with a Unimat 2.
BTW, Hatschek uses music wire for a lot of his tools, including the "production" tools used to make the Hatschek Hook from aluminum and brass.
--
Ed Huntress


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If you can index and lock the spindle you could manually shave gripping grooves in the OD of a ring with an appropriately ground lathe bit in the tool holder. Don't expect to take more than a few thousandths off per pass.
The carriages on lathes I've tried it on had to be held down against the ways with one hand while I cranked them toward the headstock to shave off the chips.
jsw
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On Mon, 5 Mar 2012 20:00:49 -0500, Jim Wilkins wrote:

I suppose that another way to get grooves would be to take the part off the lathe, mount it on some expendable wooden rotating and sliding fixture, and make grooves with a Dremel grinder.
Or if I can get the Unimat II going as a mill I could cut grooves as though it was a gear-cutting exercise; that would probably be a lot neater than trying to control a Dremel...
Bob
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A triangular file would be neater and easier to control than a Dremel if your hands are steady enough. Wrap a strip of paper around the ring and mark where the end overlaps. Lay out lines evenly along it and transfer them to the ring with a prick punch.
To lay out the strip marks you could place it on gridded graph paper at an angle that gives a spacing you like, with the ends aligned on the grid.
jsw
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    Good!
    [ ... ]

    O.K. My Unimat SL-1000 is from the mid to late 1960s as well. Perhaps the same machine? Something like about a 3" diameter 3-jaw chuck as part of it (the lathe part, that is), and a spindle nose which is a M12x1 thread.
    [ ... micrometers ... ]

    In particular, if you need to make a part to fit something which someone else has at a distance.
    First off -- you need the right bore diameter for an internal thread, or the crests of the threads are likely to bind on the roots of the matching thread, and by the time that starts shrinking, you have way too small a thread pitch diameter for a good fit.
    The advice someone else gave for fitting a crank to the spindle (with the lathe unplugged) for making threads which end at a shoulder is very good -- and applies to many threads made for mounting lenses.
    Also -- for measuring outside threads, the best way (if they are at least three threads long) is thread measuring wires. You put two wires of the right diameter into adjacent threads on one side, and one wire of the same diameter into the thread groove on the opposite side between the first two, and measure over the top of the wires with a micrometer. There will be a chart, or a formula, with the set of thread measuring wires to tell you how much to add to the pitch diameter to get what the micrometer should read. (There are thread pitch micrometers, but these get expensive, especially with the sets of anvils for different thread pitches, when you need to get two or three of the same brand of different sizes so you can share the anvils between them.
    Check out eBay auction # 160636274261 for a 0-1" micrometer with some of the anvils you would need. (Maybe all.) But, you would need other micrometers of the same brand to use those anvils on the other sizes.
    Beware that some thread pitch micrometers do not have interchangeable anvils, but rather are made for a narrow range of thread pitches, such as: eBay auction # 310383570733 -- which is for 8-13 TPI, a bit coarse for most lens threads.
    This one is 1-2" (25-50mm) and has both inch and metric anvils: eBay # 330518405934 -- brand/seller is "Shars".
    This one is all three sizes in one set: eBay # 150765779502, and you could use the inch anvils for metric threads, but it would be more convenient to have metric micrometers for the purpose.
    This is one of the ones which I have, but still not metric: eBay # 260971726026. Note that the ones marked B&S and the ones marked TESA are made by the same people.
    I also have the 0-1" and the 1-2" ones of the same brand. And I *still* have the thread pitch wires.
    Here is an example of thread pitch wires: eBay # 380408293791. (Hmm ... chart not included. Buy new then. Or pick up a copy of _Machinery's Handbook_ which will have the formulas for calculating the measurement over the wires -- and many other things which you will need.
BTW     Did I earlier mention a metric thread pitch gauge? You should have     that for sure.

    Go to MSC and look there. The trick is to know how big your tool shank slot is in the quick-change toolpost. The one I got (by Eagle Rock) fits into a 1/2" slot, which works for the Compact-5/CNC.
    This one on eBay will handle up to 2" diameter:
    eBay # 300394065202
    Here is the AXA version of the knurling tool which I use on my Clausing in BXA size: eBay # 120748127351 -- also good up to 2" diameter.
    You can find articles for making your own scissors style knurling tools, and if you make the pivot point a greater distance from the knurls themselves, you can make them handle a larger diameter workpiece.
    Note that I've skipped over a lot of bump style knurling tools, as well as various ones designed for use on turret lathes which would be awkward on your lathe (but *very* quick for production of many parts if you *do* have a bed turret attachment.)

    Not unless you make an arbor to support the ID of the ring.
    But yes, knurling as the first step, then turning the OD to produce flat areas which end at the knurls is a better way to go.
    The best for working on thin material is the cut style knurling tools -- which are amazingly expensive, so forget it unless you luck onto one for perhaps $200.00 or so. :-)
    Good Luck         DoN.
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On 6 Mar 2012 05:45:05 GMT, DoN. Nichols wrote:

It is almost certainly the same machine. I actually has Unimat-SL on the motor box.
I actually have more than one of them at this point. Last year I got a box of Unimat spare parts flying in formation at a yard sale. It was stored in a basement, so there is a certain amount of rust. The base casting, ways, and lead screw on the base machine are badly corroded. However, there were spare way rods and lead screw included that are not bad. I would need to make a base. The pile also had a spare slide, the milling table, a circular saw and jig saw, and a few other gadgets.

Yes, getting thread wires and/or a thread micrometer would be good. Very few of the threads will be as small as 50mm though. It sounds like the thing to do would be to get a metric micrometer set going up to at least 100mm, plus some wires.

I guess that there is a good reason why almost none of the step adapter rings sold these days have knurled edges, despite the potential convenience advantages. I guess that I will emulate the professionals and not knurl thin rings, at least until I get some experience and a few projects done.
Thank you again
Bob

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I hadn't noticed that you've got more potential machining capabilities than just your new Proxxon. Congrats.. the small machines offer a multitude of possibilities, as Ed mentioned earlier.
As far as needing a lot od specialized measurement tools goes.. well maybe. Of course it's good to know how to measure parts and dimensions accurately, a lot can be accomplished with a couple of calipers. Also, understanding basic principles of how to attain accurate readings are of significant importance.. it will undoubtedly be very helpful for various other measuring purposes.
As long as one's not required to make parts to aerospace specs, there will always be certain limitations of measuring tools and machines.
A caliper isn't the ultimate measuring tool for measuring the minor diameter between threads, which is easily seen when using one on coarse threads, the caliper is no longer reading in a straight line due to the thread pitch.
The percentage of error is quite small when measuring the minor diameter of fine pitched threads on a part with a caliper.. if the user has an existing example of the threaded part they want to duplicate, then measuring becomes a matter of comparison of measurements, not to an exact size specification.
I realize that some folks know trig formulas better than I know my own phone number some days, so math calculations often cloud the issue of making a measurement, for me. For certain type of measurements, I know I'll need to do the math, chart comparisons etc.
Otherwise, wires are wires, and if one would care to do the comparisons and choose wire the same size for a particular thread size, a common micrometer or caliper can yield the same results. The benefit of a common micrometer in this instance is that the anvil faces are wide enough to span several threads.. although a claiper will yield the same measurement if the jaw faces are placed squarely across, or diagonally across the wires.
On short threaded sections such as 4 turns of a fine thread on an optical filter ring, there won't be much room for the measurement tool to make a measurement. Threading charts show how far the cutting tool is advanced into the properly sized workpiece, to achieve the proper cutting depth for the minor diameter. These standard recommended cutting depths for a number of popular threads are etched/engraved into the back side of a "fishtail" thread gage (~$10), which is a very inexpensive tool for setting up thread cutting tools.
In case it hasn't already been mentioned, Machinery's Handbook contains more information on metalworking standards and details, than most people are capable of learning. There are abbreviated (and not so overwhelming) versions and similar spin-off books such as the Shop Reference For Students And Apprentices.
So, if one has an example of a known good threaded part, then measurements can be considered as a comparative process. Eventually most HSMs encounter threads which are unfamiliar to them, and may not appear to match any commonly available published standards. Microphone stand connectors, optics, military/aircraft hardware standards may all have minor differences for no apparent reasons.
As long as the machine user has an existing part (not just low tolerance specs listed on a page), almost any matching part can be made depending of course, upon experience and the required number of tricks up one's sleeve. I'll not likely ever be an expert at cutting threads, so I usually always have a "known good" mating part sitting within reach when I'm threading on a lathe.. and carefully sneaking up on the final cuts works very well for me.
Chucking and threading thin hollow parts can require some additional methods that don't usually apply to solid stock workpieces.. but there are plenty of methods to minimalize problems.
Lastly.. threading dies may seem like a logical shortcut/substitute for the learning process of cutting threads on a lathe, but in general, they aren't.
And then there's that gratification thing, again.
--
WB
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    [ ... ]

    Except that you usually don't want the minor diameter, but rather the pitch diameter which is about half-way down the thread (depending on the shape of the root of the thread).
    [ ... ]

    Yes -- here is probably the place where thread wires of an appropriate size and a micrometer is the best bet -- unless you have a standard to test it in.
    [ ... ]

    FWIW -- the standard US microphone stand connector is 5/8-27, which is a problem for many because only some lathes with a quick-change gearbox include that pitch. My 12x24" Clausing does. I think that the typical South Bend does not.

    Weird threads for military connectors are usually because a finer thread does not cut as deeply into the wall of the connector shell. If you were to use a standard thread for say a 2" diameter, it would be *way* too deep in a connector shell, cutting deeply into the area where the pins are located. :-)

    Yes -- as long as you do have something to test it against. However, if you are making something to thread into another part which is across the continent from you -- there is where the ability to use the measuring tools wins.

    One thing which helps significantly with thin-walled parts is a 6-jaw chuck. Even better is one with two-piece jaws, for which you can make some pie-wedge soft jaws.

    They just lead to the "I can't do this because I don't have the right tap or die." excuse. Far better to be able to define your own thread at need.

    Indeed so.
    Enjoy,         DoN.
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Man overboard..
There is essentially no value of knowing a precise measurement of thread pitch to duplicate or match a threaded piece directly in front of me. Pitch diameter may be an important spec for hardware design engineering, or QC quality control compliance, but not really necessary for duplicating or matching a thread, IMO.
I Will xxxcan only state that I will neither confirm nor deny that I'm involved in sceret project contracting utilizing my Chinese home shop machines.
My machine dials don't indicate pitch diameter.. they indicate DOC depth of cut.
A 6-jaw chuck would be a great accessory for a variety of reasons, but pricing a small Bison or other precision brand will cause many/most HSMs to consider alternatives. When the company or university is paying for accessories and tooling, it's a great idea.. otherwise a chunk of hardwood may produce very good results.
I managed to set up my 1220XL Smithy (no QC gear box) for microphone 5/8-27 thread cutting, by receiving the generous help from a earlier RCM participant Ted Edwards. I was glad that there are sharp people who fully understand these things, so now I have maximum threading capabilities for both the 1220XL and the 9x20 models.
--
WB
.........



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    I *did* mention that it was important when making a thread to match another part well out of reach -- say across the continent from you, or perhaps embedded in a machine which *has* to be kept running. Yes, making to fit works well as long as you have that other part for reference.

    Of course -- but you can use them (and a known starting point such as zeroing when just barely touching the OD after turning it to the proper dimension.
    And -- with a compound set to the proper angle, you can zero both, use the cross-feed to back away prior to winding back to the starting end, return to zero, and set in the proper additional DOC using the compound (compensated for the angle of the compound). I typically have the compound set to 29.5 degrees as close as I can read the scale, and compute total needed infeed based on that using the trig functions in a calculator.
    But DOC set does not always translate to actual DOC produced. Backlash, rake, and give in the compound and cross-slide ways can affect this.

FWIW    I was at a combination tool auction and flea market earlier     today, and one of the things which I saw, was tempted by, but     resisted, was a Buck 6-jaw, with both the inside and the outside     jaws, new condition, with adjust-tru mounting. It was about 4"     diameter. If I were still using my old Atlas/Craftsman I would     have gladly paid the asked $250.00. But it is just too small     for my 12x24" Clausing, and I already have a 6-jaw Burnard     Pratt, though without the outside jaws.
    So -- not dirt cheap, but if you can use it, difficult to     resist.     

    Yes. Especially in combination with the 4-jaw chuck.

    Yes -- any basket-of-gears threading setup can be set for almost     any thread in the same system -- and with a pair of 127/100     tooth gears, even for Metric if made for inch or vise versa.
    But it does take some computation.
    But the real benefit, IMHO, to a quick-change gearbox is that you are not tempted to leave the feed in an inappropriate range when you are switching between turning and threading -- you tend to leave the gears set up for threading -- and on into the next project until you have to set up for a different thread. Been there with the little 6x18 Atlas/Craftsman. And with proper lube on the pot-metal gears, you hands take a *lot* of washing just to get to gray from black after working with those gears. :-)

    Indeed.
    Enjoy,         DoN.
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Yep, I definitely recommend an indoctrination period of becoming familiar with the differences in actual results compared to expected results such as DOC depth of cut relating to feed dial scale markings. I've gotten used to making notes and reference examples and hanging them in plain view of the machine controls, as a deterrent to ohshit! moments.
Especially in the huge numbers of imported models which are marketed to potential owners who may be interested in either metric or inch based features, whereas we're aware that one size does not fit all. When trying to remove metal in thousandths results in accumulative errors by counting metric dial ticks, it can fairly easily lead to confusion (for me, doesn't take much to do that these days).
Wow, $250 for a quality 4" 6-jaw.. and that's still considerably less than some new quality brand 3-jaw models that size.
I just picked up a used 4" Dunlap 4-jaw for the 7x mini lathe, since the only spindle accessory included with this new machine was a 3" 3-jaw. The Dunlap backplate is made to fit a 3/4" thread, so I'll be making an aluminum backplate to replace it which will match the spindle flange of the 7x mini. It would be easy enough to just cut the existing backplate to match, but there may be a future use for the original threaded version, so I'll preserve it. I wouldn't feel that a 7x mini from China is deserving of a good 6-jaw a far as a cost effective upgrade.. especially at new prices. I would've then felt compelled to find a lathe of equal quality to match the chuck, but that's just me.
--
WB
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    :-)
    And -- to add to the problems, I've seen machines with dials marked 0-0.125" -- but there was a slight gap between the 0" and the 0.125" points. Turns out to be something like 0.128" per turn (3.25mm/turn) so they could use the same leadscrew and nut on both Inch and Metric machines. Never mind what happens when someone is mentally counting the turns adding 0.125" per turn. :-)

    Indeed. I'm still sort of sorry that I skipped it. But it was a threaded backplate, so I would have had to make another backplate for the Compact-5/CNC (the most appropriate size lathe I have for it which is good enough to be worth it). And the Compact-5 needs access from the tailstock end of the spindle to access the three (or four for a 4-jaw chuck) screws which pass through the chuck body to mount it. Kind of awkward, in that I would have to dismantle the adjust-tru assembly to access the mounting screws. They go directly into the flat end of the spindle nose. (A total of six threaded holes, with one of them acting as a corner of both a triangular pattern and a square one.) The OD of the spindle nose is a precise 40mm, and the back of the chuck is turned with a matching recess for centering.

    This may have been a 3/4" (or perhaps a 1") thread. But since it is an adjust-tru, it is easy enough to make an alternative backing plate to fit to something else.

    Good!
    Same with the beat up old Atlas/Craftsman 6x18 lathe -- one prior to the Timken roller bearing spindles.

    I understand it totally. That is why I don't have that chuck now. :-)
    Enjoy,         DoN.
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