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Depthing tool anybody?

Talyinka

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Seems they're trying to push the individual inventor out unless he has very deep pockets.
Individuals are no longer allowed to make real money - only large corporations working for the ruling oligarchs are. That is one of the rules of crony capitalism.

I also have a few patents but for many years I've concentrated on getting first to market instead. Additionally I have tended to place important functionality in mask-programmed components, making it difficult and expensive to extract and understand the software.

I'm now in the process of making parts and should soon have something to show :).
 
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Tinker Dwight

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Individuals are no longer allowed to make real money - only large corporations working for the ruling oligarchs are. That is one of the rules of crony capitalism.

I also have a few patents but for many years I've concentrated on getting first to market instead. Additionally I have tended to place important functionality in mask-programmed components, making it difficult and expensive to extract and understand the software.

I'm now in the process of making parts and should soon have something to show :).
Even with security bits, software can be ripped. Often one can mix the order of
instructions. This allows one to encode signatures in the software. Then copyright
can be a more useful method of protection.
Such signatures are hard to detect and modify but easy to find by the person
that put them there.
Tinker Dwight
 

Talyinka

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Such signatures are hard to detect and modify but easy to find by the person
that put them there.
Indeed - depending on what I want to protect I tend to use somewhat more sophisticated methods. You could for example imagine a system which would function in China (raising no alarms in a development or QC situation) but if used for two months outside China would malfunction... ;)
 

John C. Losch

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Depthing tool.jpg
3/28/13

To the list:

Forty-five years ago I wrote a three part series on making a depthing tool that was published in the NAWCC Bulletin. It appeared in three issues: April, 1967 (issue127), October 1967 (issue 130), and February 1968 (issue 132). The series was extremely detailed; perhaps more than necessary, but it did deal with aspects of fabrication that would make the difference between just another depthing tool, and a very accurate one.

Much credit for those article go to the late Arthur Balthasar who did all of the illustrations for the series, and who reviewed the text supplying many helpful improvements.

For about five years I wrote a series called the "Clockmaker's Notebook" on shop and repair procedures. It was written when I was young, and knew everything except that I didn't know it all. As a result the style is embarrassingly pompous, but the content withstands the test of time. For the most part it is the conventional wisdom of the clockmaker's and machinist's trades as I had learned them starting in 1944.

I have attached a picture of the prototype depthing tool that is the subject of the series on making a depthing tool. It was made by Ernest Taylor in the 1920s, a Waltham, Mass. clockmaker, who was assisted by William "Precision" Nichols, whose name may be best associated with the Nichols milling machine. They were friends, and were both familiar with the depthing tool in Diderot's Encyclopedia. In my plan for making the tool I enlarged the capacity of the tool a little. The tool in the picture is the one I still use. It was given to me by Mr. Taylor around 1962, shortly before he died at the age of 96.

I added the sector that clamps the frames a few years later because I discovered that it was possible to spring the tool while using it. Be aware, however, that there should be a soft (brass or copper) washer between the clamping screw and the sector so that the frames are not shifted as the clamp is tightened

Several depthing tools that have been produced and marketed since that article was published presented the idea of an open vee groove to guide the runners, rather than a line-bored channel to guide the runners. All of those who produced the tool were smarter than the trio responsible for my article, and that includes me. They eliminated the complicated clamping method by making the vee groove on the side of the frame instead of on the top. That plan diminishes how close the runners can be put to each other, but it is of little consequence. Where that limitation would apply, it is probably time to use a watchmaker's depthing tool.

I had trouble searching the NAWCC resources to locate my articles. I wrote to the library research staff and got the following reply from Sara Butler Dockery
Library & Archives Supervisor, quoted in part: The Bulletin search can be a bit confusing. The best way to search is to use the Bulletin Search Index http://nawcc.org/BulletinIndex/search-bulletins-1.php, which can be found on the right side of the Publications web site. Once you figure out what volume, issue, and page you need the Past Issues http://nawcc.org/BulletinIndex/search-bulletins-1.php link is on the left hand side of the Publications page.

My thanks to Sarah Dockery. All of this information is perhaps a little too late, but if anyone is serious about making a depthing tool, it might be worth taking a look.

Jcl
 

Jay Fortner

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Indeed - depending on what I want to protect I tend to use somewhat more sophisticated methods. You could for example imagine a system which would function in China (raising no alarms in a development or QC situation) but if used for two months outside China would malfunction... ;)
Everything that that comes from and operates outside China malfunctions and you're lucky to get two months out of it.
 
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Talyinka

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I have attached a picture of the prototype depthing tool that is the subject of the series on making a depthing tool.
Thank you very much for posting this. I shall try to find the articles although, not being a member of the NAWCC, I am not sure I have access to them.

I like that you have installed your clamps so that they can be interchanged with other types. I am going in that direction by locking my centres into V-cuts, so that many things can be accommodated just by making different clamps. I think that by using a single cast and machining it accurately on a mill in one process without changing the position or clamping onto the mill's coordinate table you can attain very high accuracy so I expect extremely good parallelism. All the position-critical details will be cut with the same tool, probably on a horizontal mill. Also, I have used as much symmetry as possible in my design so that temperature changes shouldn't affect parallelism.

I have been considering adding a sector for locking the tool like you have and the fact you have found that necessary will weigh on my decision. Particularly a fairly large and heavy tool like mine would probably benefit from this addition. It might even make it possible to use a lighter spring.

I should be able to post the first photos of a prototype over the week-end with a bit of luck. When I have verified that my dimensions work I shall publish an updated first drawing as well as the second drawing, containing all the small parts, and the third drawing, showing the different types of turns, shortly afterwards.
 

Talyinka

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Unfortunately I don't have access to the articles mentioned by John :(.

Anyway, I didn't get quite as far as I had hoped over the week-end. Quite some time was spent on searching for M3 taps in all the usual and some unusual places. I found everything from M1 to M29 roughly, in metric, UNC and Witworth including some real exotics and M3 dies - but no M3 taps. Because it is a holiday I haven't been able to acquire any yet. That said, M3 taps are among the most used and abused tools here, particularly when designing enclosures for various electronic gadgets and systems so nobody ever buys them - we always have plenty in stock :).

Here is a photo of the current state of the project. The computer is a 17" laptop.

Please note that this cast is different from the one in my drawing - it is an early cast and the hinge system has an incorrect number of degrees of freedom - which is why that part of the frame has been changed as shown in my first drawing.
 

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shutterbug

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Nice! I'm anxious for you to get to the production phase :D
 

Jay Fortner

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Looking good! If I may offer a suggestion in regards to your hinge. Rather than having three pieces just have one,a rod with short shoulders to the outside or one shoulder between the fulcrums on the inside. I think you'll find yourself removing those chamfers on female end your points to allow for larger pivots.
 

Talyinka

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If I may offer a suggestion in regards to your hinge. Rather than having three pieces just have one,a rod with short shoulders to the outside or one shoulder between the fulcrums on the inside.
Thanks, Jay. That is a solution I haven't thought of. One piece would not be correct, though - still a superfluous degree of freedom - but two may do the job, one in each end, so that the whole thing is just tied together by the spring. That is actually not a bad idea at all. It would eliminate the need for two different frame moulds and several position-critical manufacturing steps. Thanks for that suggestion. I like it and will definitely give it a very close look, especially with regard to the direction of forces at work as the angle between the frame members change.
 

Talyinka

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As opposed to almost all projects this one took a little longer than anticipated but here are the first photos of an (almost) finished prototype. Disregard the finish - this is as machined and filed, and I couldn't find a knurling tool.

After the suggestions here I decided to take a closer look at the hinge mechanism and went through a couple of iterations based on the normal external leaf spring design. Then it struck me that a potentially more elegant solution would be to use torsion springs instead of the leaf spring. So, I redesigned the hinge (again) and had some torsion springs manufactured (that's where a couple of weeks went). I'm not used to specifying torsion springs, particularly not small ones, so I had to rework them to function as desired. All these things take time.

Anyway, comments invited. I haven't seen a depthing tool with torsion springs before and since the idea is pretty obvious I wonder if there is some specific reason I have overlooked which makes this a poor solution. If so please let me know. The tool seems to work very well, though, so I can't imagine what it might be.

The next step will be to consider exactly how best to make the design so that it can be manufactured on small machines without compromising accuracy. I now know where potential problem areas lie and have found solutions to most issues. I'm considering making a kit available containing only the two frame parts, fully machined, plus the torsion springs. Is that a good idea? All the rest is easy to make on a small lathe, or with a saw and a file. Machining a frame this large to the required precision requires a proper CNC mill, and you need to run a decent production run in order to keep the price within reach.

Please let me have your thoughts.

EDIT: I'm obviously thinking about crown wheels and such exotica. Any thoughts regarding requirements?
 

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shutterbug

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I think you should send them out with all the parts ready to assemble. Most folks won't want to fiddle to get things working :)
 

David S

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There could be two options for those without a lathe then the full kit, for those with lathe and other tools just main body as suggested.
 

leeinv66

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I nearly missed this update. It looks great to me! And yes, I would agree with David. Having the option to buy the basic tool or the whole kit would be the way to go.
 

Talyinka

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Thanks for the encouragement, guys. I really appreciate it. I didn't intend to make a business out of this, just to design a tool that people could make for themselves - and perhaps help by providing the casts and the difficult machining.

I attach the (hopefully) finished drawing for the frames - please let me know if you find errors. I have now reduced the critical parameters to three: the parallelism of the groves holding hinge parts and turns, the distance between these in the two frame halves (not critical per se but must match), and the diameters of the hinge parts (again not critical but must be identical, including the play in the hinges). I have kept a superfluous degree of freedom in the hinge design (parametric support in both the hinge pins and the external hinge surfaces). This is in principle an incorrect design method. The reason I have done it is that I am not sure of how well the torsion springs will hold the two frame parts together, and by choosing this solution it is possible to change to a leaf spring if this should be desirable. On the other hand, if everything works the way I think it will the diameter of the internal hinge pins can always be reduced by a tenth, allowing the rotation in the hinge to be fully and exclusively controlled by the surfaces touching the external part of the hinge (this is preferred to hinge pin control because of the difference in diameter between the inside and the outside of the hinge pins).

My prototype, which has been modified several times and manually machined throughout, with the turns fully extended away from the frame, giving a distance between the points of 30 cm, displays an error in distance between the points of max appr. 1/10 of a millimeter over the whole opening angle. This, for all practical purposes I can think of, is adequate, even good enough for some watch work if suitable points are manufactured.

Here is the drawing - the next one will come as soon as I have transferred the latest hinge design from envelopes to the computer:
 

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Talyinka

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Here is a drawing of all the small parts going into assembling the depthing tool itself. The drawing is largely based on notes I made while producing the prototype, so there may be errors - feedback highly appreciated - missing or incorrect dimensions, illogical details, etc.

I'll publish a drawing of various types of turns once I produce them. The ones in the photos are just simple ones of which I have so far made no drawing. Anybody can make some turns without the need of a drawing anyway so this is not urgent.

The next step is to manufacture a wooden pattern of the new frame design so I can make some casts and start to see what this thing will cost to produce. I must say that I am shocked at the current price of brass.
 

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Jay Fortner

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Not bad I still think you need to lose the pin and socket hinge. One, you're having to use shim washers that will wear and create eventual slop and the same problem with the pin and socket. The torsion spring is cool as hell but make the coils a little larger so if the frame is spread widely to accommodate a large wheel the coils won't constrict on the axis pin and get stretched and lose tension.
The nut on your adjusting screw only needs to be a piece of solid round with a threaded cross hole and should sit in a channel so it can't slip and change the setting.
Personally I think the ideal hinge pivot would be a point and socket with an adjustable point on one end.
All your red metal prices are almost off the charts with this poor global economy. Gold anodized aluminum would still have a nice appearance(I want mine blue anodized as I'm sick that way) and be cost effective. I'd keep the brass for the thumb screw and nuts. You've heard it several times on this thread already that the $500+ price for these things is out of most DIYers reach. Quality and quantity will make you more money than individual big sales.
 

Talyinka

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Many thanks for your comments, Jay - much appreciated.

Not bad I still think you need to lose the pin and socket hinge.
I have all the components to do so in case I can - because I developed a different system based on your suggestions (before I thought of using torsion springs) :).

One, you're having to use shim washers that will wear and create eventual slop and the same problem with the pin and socket.
This is not a rotating machine. Trust me, wear considerations are irrelevant in this application, whether you use steel against steel or steel against brass. If you lubricate lightly you are totally secure in that respect. I have only included the shims in order to compensate for small production variations - they do not influence the accuracy of the instrument. Furthermore, hinge wear doesn't have a great influence, only uneven wear that would influence the parallelism of the turns.

The torsion spring is cool as hell but make the coils a little larger so if the frame is spread widely to accommodate a large wheel the coils won't constrict on the axis pin and get stretched and lose tension.
That has been calculated. The problem doesn't arise with the selected diameter.

The nut on your adjusting screw only needs to be a piece of solid round with a threaded cross hole and should sit in a channel so it can't slip and change the setting.
I'm not sure I understand exactly what you mean - sketch? The adjusting screw needs to be able to either slip or pivot as far as I can see. In this case it rotates without slipping (on the adjusting nut). I do admit that I depend on friction to a degree in this detail and I can think of better solutions but not better and economical ones. Perhaps I should go to a bit of extra expense and make an embedded pin or pivot for the adjusting hinge to turn about (embedded in a track in the frame, parallel to the underside of it, replacing the small pin I use to arrest the turning of the adjusting nut). That would add three or four machining operations.

Personally I think the ideal hinge pivot would be a point and socket with an adjustable point on one end.
I think that would be more relevant on smaller models, for watches. It is easy enough to make, though, and might even cost less. Considering that you don't require the two frame parts to move symmetrically with respect to a vertical centre plane you could simply cut a thread through the outer blocks on one of the frame halves and run a threaded point through it, secured with a locknut on the outer end - and leave out the outer blocks on the opposing frame halves to prevent interference. Potentially, however, it could very easily become less accurate. My solution with the V-groves has the huge advantage that you can machine it with two cutting wheels or fly cutters on a single spindle in one pass, a very safe way to attain the required accuracy.

All your red metal prices are almost off the charts with this poor global economy. Gold anodized aluminum would still have a nice appearance(I want mine blue anodized as I'm sick that way) and be cost effective. I'd keep the brass for the thumb screw and nuts. You've heard it several times on this thread already that the $500+ price for these things is out of most DIYers reach. Quality and quantity will make you more money than individual big sales.
I must admit that making it out of $100 worth of brass would require it to be delivered in a $150 nice wooden box :excited:...
 

Jay Fortner

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OK!,I catch your drift now. Using two V cutters on a horizontal mill would allow you to machine the guides in a continuous operation then chop out the gullets and bore the holes. Good Idea,cost effective.
This is what I'm referring too with the adjuster screw pivot;
clock tech 257.jpg
 

Talyinka

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I only just discovered that the administrator of the forum system has failed to synchronise the old and the new system, meaning that posts made in the new system do not appear in the old system as well - very smart.

The status is that the first series of casts has been completed (see photo) - as soon as these have been machined and my drawings verified I shall publish a completed set of drawings.

RawCast.jpg
 

R. Croswell

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I am VERY interested.
Same here. Unfortunately, to be of any real usefulness such device has to be extremely precise and that usually means expensive. Is very hard to find this tool and the ones I have found cost nearly as much a Sherline mill that, using Jerry K's technique, can accomplish pretty much the same thing and do a lot more. So if one can actually produce a decent depthing tool at a reasonable cost there should be a market for them.

RC
 

Talyinka

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I could not find anybody willing to produce the small parts. Getting the sides cast and machined was not a problem but nobody around here seems to have the mid-sized lathes and mills you need for the small parts, nor do they want to undertake small jobs. My machines are clockmaker size, so I can produce prototypes but not even small production runs. Hence I spent a lot of time and money on it but unfortunately ran up against a wall.
 

Walesey

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What a shame! It was looking like a good project, with a lot of support from people on this BB.

I know that one suggestion was that you could offer it either as a complete kit so people without access to machinery, could just assemble it, or alternatively offer it as a basic kit, so that those with machinery and expertise could do lots of the work themselves. Obviously, from what you have said, the Complete Kit option is a "No-goer", but I imagine that most folks who are at a stage where they need a Depthing Tool, probably have a watchmakers lathe and a bench drill. How much of the "Small Parts" could be reasonably produced in a home work shop with a watchmakers lathe and bench drill?

I know that for me, I do not have a mill, and I do not have a way to mill out the "V's" to be perfectly parallel and of consistent depth, but I think I could have a reasonable stab at turning up some screws, and threading them with a tap and die set.

If you could supply the cast sides with the V's milled to exact tolerances and dimples cast where the drill holes were to go (and maybe some basic instructions), you might still find some folk who would be willing to give it a go, and help you re-coup some of your expenses

Just a thought!

Cheers
Walesey.
 

BigAl

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I don't know where about in England you are but checkout some of the local, or reasonably local, model engineering societies. Many model engineers will have access to milling machines and as clock making is one of the interests encompassed by the term, 'model engineering', some clubs might have members who might well be interested in doing the work for you. Incidentally, there is actually a series on clock making in recent editions of Model Engineer magazine.


Both the Northern Association of Model Engineers (http://www.normodeng.org.uk/) and the Southern Federation of Model Engineering Societies (http://www.sfmes.co.uk/public/) publish lists of their member clubs. Also, check out the forums at http://www.model-engineer.co.uk/. There will quite possibly be someone there that might help out.


All of that said, I do not think that there is anyone in my club, ( http://www.pembs-me.co.uk/) that would be interested so that is, regrettably, one small door closed. There are though, lots of other, much larger clubs.


BigAl
 
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tom427cid

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Hi all,
Great thread. With reference to small hardware items ie. thumb screws check some of the hardware suppliers or machine shop supplies,this might be an alternative by using existing pieces.
Just a thought.
tom
 
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