Robert Porter's Micro Drilling Attachment?

Betzel

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Have any of you successfully made one of these using his plans? How satisfied were you with it? Would you do it again, or did you think of ways to improve on it, align it better, etc.? Many thanks.
 

wefalck

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I guess only finished products could be shown here, but I would be interested to see, what it looks like. Google turns up only covers of his book in low resolution.
 

Betzel

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Perhaps that's true. There was only one thread (2009) where someone made one, but they didn't post images or discuss it.

The Levin is out of reach even used, and it's WW. My W-J cross-slide (when tight and trammed-in fairly square) already has a Z axis lead screw, and I suspect it could be used with the vertical attachment to drill, if the centers align(?). But, the belt running under tension may flex things, as it's not so rigid. I could lock the spindle or support the bar on the end. [Just checked: No. Mine will not align spindle to spindle]

Alternatively, the slide could support a rigid platform holding stationary bits. This looks like part of what Porter had in mind, but I can't see it very well either. Jerry's usually right, but I wish I had a pump tailstock to test and might make one anyway. Maybe it's ok for larger jobs / pre-boring...
 
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wefalck

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I found the easiest and most reliable technique is to chuck a piece of carbide or precision-ground HSS rod into the lathe in a collet and then to adjust the milling attachment until the rod slides in and out of a suitably sized collet without touching or deflection. It's easier, when you can uncouple the feed-screws for the y- and z-movement. Then lock the head of the attachment in the horizontal postion.
 

Betzel

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Thank you, gentlemen.

Unfortunately, mine will not align on-center. It may just be the Wolf Jahn Geneva specific design, which was intended for grinding (and milling?) but not drilling. The vertical slide comes off one of the gibs, which is unacceptable. Even then, it's still too high, and milling the base would only make it less rigid. Just not worth it.

Since I have time to spend on silly (but skill-improving) projects, and another lockdown seems likely, I've found a spare, very accurately made 7mm OD tube for repivoting (with a pressed offset/clamp). With an ID of 5.5mm I think it came off an A&Z, as Lorch uses a 4mm inner runner and the Steiner uses a 5mm center. Since this was the one part I could not (?) easily make with what I have, I'll make a pump drill. I ordered a small chuck like one I got from RDG (not an Albrecht, but far better than China). This may be ok for large work, but I can use it. Besides, I'm curious to see if I can grind a JT0 taper onto hardened silver steel. Something to do, and skills improve as we make our own tools. Another runner will have the internal 25:1 taper, and a third will have a dead-hard center for pop-cheating the pipped centers I still make with a hand graver.

I do not have many J Malcolm Wild books, though they are excellent, and what I have is in storage. I remain curious to see what Porter used for support to (maybe) build a "stationary" holder to go into the slide rest if the pump proves too crude for fine work. Would be interesting to see just the front of his booklet close up. Billet aluminum? I had envisioned something like wefalck's alignment process, using an opposing tube and shaft; makes good sense. I suspect Porter made a better polisher than a micro drill, but we shall see?
 

measuretwice

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before I acquired more and fancier lathes with a lots of attachments, I found the tradition approach worked very well. Make a small centre mark with graver and then hold the drill with a pin vise. You keep watching the PV in two planes and the revolving work pushes the drill to the centre. Probably as or more accurate than anything else
 

Betzel

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Thanks. That's how I drill in wood, which works every time :)

"Catching the center" with the graver works when I have plenty of material to face and go again, but I always get a "pip" (the dreaded jet cone) when I have to get it right the first time. Someday, my hit/miss ratio will be closer to 100. Till then, I peck a dead center into the material (cheat) with the tailstock runner, then drill as described.

I made a pinwheel recently that came out fine, but it would be nice to be able to drill even smaller holes accurately. Maybe a few folks have made this Porter contraption for polishing, but likely none for micro-drilling...
 

dave-b

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Betzel, i've found an effective way to get rid of the "pip" is to push an engraving cutter (the tapered D shape with a point) hand held in a pin chuck into the hole. Being hand held let it float and cuts the pip away.
Dave.
 
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Betzel

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Thanks. Didn't know that.

I can't feel fine errors, so success depends on going slow and seeing good results before continuing, but I'm reluctant to stop and look :-(

I've recovered with just the graver if I catch it in time, but not always. Is the D shape you mean like NTG Round - GRS ? Do you plunge in at an angle to trim the pip? Does it leaves you a round center, and would you come back in with the standard graver, or drill into the dome?

Drills wander. And, I suspect the coned "V" is best to guide/prevent that, but don't know.
 

dave-b

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Thanks. Didn't know that.

I can't feel fine errors, so success depends on going slow and seeing good results before continuing, but I'm reluctant to stop and look :-(

I've recovered with just the graver if I catch it in time, but not always. Is the D shape you mean like NTG Round - GRS ? Do you plunge in at an angle to trim the pip? Does it leaves you a round center, and would you come back in with the standard graver, or drill into the dome?

Drills wander. And, I suspect the coned "V" is best to guide/prevent that, but don't know.
 

dave-b

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No, like these. Just push straight in. They guide themselves on the existing cone and cut the pip away. IMG_20210315_164050_2.jpg
 

Betzel

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OK, so a D-bit cutter like the bushing tools, but much smaller. Thanks!
 

Jerry Kieffer

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While a skilled person can certainly find center with a Graver, It is difficult and unlikely in most cases to produce a spot of proper shape and angle that avoids drill walking.
The following link gives a very brief explanation, but the first sentence accurately summarizes the issue.


Utilizing Equipment and or accessories designed for the use of spotting drills requires practically no skill, less time and assures success.

Jerry Kieffer
 
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measuretwice

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Betzel, i've found an effective way to get rid of the "pip" is to push an engraving cutter (the tapered D shape with a point)
I like that, will try it. I suspect its the sort of task that a pro would chuckle at us over, i.e. no pip is a no brainer with a bit of practice....but I'm not a pro so little tricks to hurry it along are good.
 
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Dr. Jon

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I have had good results with 1/8" spade drilss I make on my Universal grinder. I bought it to make pivot drills but found that the dialmond composisti wheels do not hold shape well enough to make fine dirlls.

I did find that the 1/8 spade drills I make with a 150 degree or more obtuse cutting angle will make a good enough center that carbide PC drills will center and cut. I test these with bits of music wire.

I alsl made a runner for 1/8" shank drills. The raw stock is 3D printer rod wichi si avaialbe in 6 7 and 8mm diameters. The are very hard and very precisely ground and readily available on eBay. I made a 1/8 spade a bit smaller to drill out this stock and got a fit tight enough that I hear a pop when I pull out a drill.

I get best results with my 6mm (5.978) runner going inside the universal runner on my F1
 

Betzel

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Old-school spade bits are great, and sphinx bits from Germany are interesting as well. I always wondered about those embedded wheels. Maybe a brass/cast iron lap and diamond paste works?

My center-catching with gravers is also coming along, but I'm just not there yet. As a kid, I found using a center punch (like my dad had said to) made drilling so much easier. Decades later, when I saw Steffen Pahlow pop a rotating face with a dead center in a video, then sort of wink to drive it home as a tip someone had taught him, I remembered and used it. Whether popping or spotting, then drilling, or all three --the key remains hitting those crosshairs, which is so much easier when the work is rotating. (If the lathe is aligned!)

Scribing a plate correctly and then punching a point "dead nuts on" in my own crosshairs? Another story. Working on that, too.
 

wefalck

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In spite of the risk of being stoned, but I am still wondering why in this age and day someone wants to centre a piece with a graver - other than for nostalgic purposes. There are, for instance, NC spotting drills down to 3 mm or ordinary centre-drills down to 0.5 mm that do that job very well. I am with Jerry on that.
 

Betzel

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No reason to throw stones I can see.

Can't say for others, but for me, it's just that, the lost craft of the forgotten Romantic Warrior who can casually catch a center without pipping every time. The distance learning courses I took reinforced the old ways, perhaps for the sake of tradition alone. A virtual mentor? Makes no sense at all, and my more modern and efficient side (the one that does the work) drives a dead center in and drills. But bits do wander, so I think spotting makes sense as a second step before drilling, when it really counts.

I use the center drills for their intended purpose, and once thought they would be good for spotting, but they are 60 degrees (included). For a 118 degree bit, even with oil, they run the risk of grabbing a flute and snapping it off. More swearing; I'm trying to cut down on that :)
 

wefalck

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Good point about the included angles. However, I tend to make a very small centre, just big enough to catch the centre of of twist-drill, with the cutting edges of the flutes hardly engaging.
 
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measuretwice

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In spite of the risk of being stoned, but I am still wondering why in this age and day someone wants to centre a piece with a graver - other than for nostalgic purposes.
I would suggest with a bit of practice, its quick and easy - that's one reason for using it. Secondly many tailstocks aren't going to have a way to hold a spot drill. I've got some watchmakers lathes that will take collets in the tailstock, which is great. They are rare (comparatively) as with most watchmakers lathes, sold to people who would centre and drill with graver and pin vise, the tailstock is about useless for drilling (lack of tooling, to small a quill?). Its more tooling to buy and like Betzel said with the slightest miss alignment of the tool, easy to have happen with accumulated error, and while it will get pulled into the centre, its not hard to break the ends off the extremely small ones. (btw, to use a centre drill to start hole, you really are just taking advantage of its stubby stiff nature - only make a divot with the conical end of it....that way the angle is right for the ensuing drill)

Depends on what equipment you have and what you're trying to do. repivoting the smallest watch part might take a different approach than the largest clock part.

I don't have much romance for self flagellation over the obsolete - e.g. little interest in say learning how to hammer out my own brass plate just because it was once done by skill practitioners.....but this imo is a basic watchmakers lathe skill that holds some advantages for the man trying develop and increase his watch repair skills
 
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DeweyC

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I would suggest with a bit of practice, its quick and easy - that's one reason for using it. Secondly many tailstocks aren't going to have a way to hold a spot drill. I've got some watchmakers lathes that will take collets in the tailstock, which is great. They are rare (comparatively) as with most watchmakers lathes, sold to people who would centre and drill with graver and pin vise, the tailstock is about useless for drilling (lack of tooling, to small a quill?). Its more tooling to buy and like Betzel said with the slightest miss alignment of the tool, easy to have happen with accumulated error, and while it will get pulled into the centre, its not hard to break the ends off the extremely small ones. (btw, to use a centre drill to start hole, you really are just taking advantage of its stubby stiff nature - only make a divot with the conical end of it....that way the angle is right for the ensuing drill)

Depends on what equipment you have and what you're trying to do. repivoting the smallest watch part might take a different approach than the largest clock part.

I don't have much romance for self flagellation over the obsolete - e.g. little interest in say learning how to hammer out my own brass plate just because it was once done by skill practitioners.....but this imo is a basic watchmakers lathe skill that holds some advantages for the man trying develop and increase his watch repair skills
Measuretwice,

I agree.

Any single skill taken in isolation may appear to be an anachronism. But the constellation of skills is what keeps someone like a watchmaker in good working order. They are mutually supporting and provide "practice" for the other skills.

Professional watchmakers do not employ approaches out of romance. They use techniques that are expedient, efficient, reproducible and precise.

When I use my 102, of course I use the slide rest and center drills. I have seen people use a graver to cut a small staff on a 102, but it scares me to death to have my nose so close to such a powerful lathe. I also use the slide rest on my WW to mark out lengths. But rather than grind a library of slide rest cutters I find it efficient to use the graver for my turning.

The use of the graver reinforces skills used in grinding/polishing operations and burnishing pivots on the Jacot. All of these require "touch" and "sight" so one skill reinforces the others.

How a job is accomplished is far less important than how the finished work speaks of the workman's standards.
 

Jerry Kieffer

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Have any of you successfully made one of these using his plans? How satisfied were you with it? Would you do it again, or did you think of ways to improve on it, align it better, etc.? Many thanks.
Betzel

Personally, I have never seen or used a Robert Porter micro drilling attachment. I have however scanned the publication and have the general idea of his procedures and equipment layout.

Here is what I can tell you.


In todays world, micro holes are often created by methods other than drilling. However, there are many where the finish, shape and accuracy required is more successfully done by drilling in industry. The most recognized company for micro drilling down to .0001" is national jet and their 7A current production drilling machine attached photo. The Photo is of my personal slightly older basic unit with non factory scope.

The second company is levin.
In levin`s case, they have designed their attachment to fit their lathe.

Both the National jet and levin offerings utilize basically the same procedures, drill control cautions and tooling. Again both have references of successful drilling on a daily basis without issues.

As mentioned, I have not seen the Robert Porter drilling attachment demonstrated, so I cannot comment if successful or not. Interestingly, his procedures, recommendations and tooling are completely the opposite of the above venders.

If researching this, it should be interesting.

Jerry Kieffer

DSCN3320.jpg
 

Betzel

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Nice machine, Jerry. I think I've seen it, but maybe not from this angle. Thank you for the picture and the Levin info. I don't know anything about Porter's setup, and was just curious if anyone had built one; seems not.

I was toying with making something to fit in my cross slide to drill "better" with, as a bench project. Since I only repair average to midgrade clocks, and am retired / not in any business, I don't need to machine as accurately or as efficiently as some here perhaps do. Still, I want to do the very best work I can with what I have (or can make with what I have) just for self-improvement, even if it takes more time. It's more an end in itself, rather than a means to something else. But, like measuretwice, I won't be hand-forging my own brass plates either!

For now, I think a bench-made sensitive drill for the tailstock will have to do, as I can make one in my price range, which is $0. Hopefully, I'll learn to turn between centers, use a boring bar, and grind accurate machine tapers with the milling attachment. I guess we'll see :)
 

Jerry Kieffer

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Nice machine, Jerry. I think I've seen it, but maybe not from this angle. Thank you for the picture and the Levin info. I don't know anything about Porter's setup, and was just curious if anyone had built one; seems not.

I was toying with making something to fit in my cross slide to drill "better" with, as a bench project. Since I only repair average to midgrade clocks, and am retired / not in any business, I don't need to machine as accurately or as efficiently as some here perhaps do. Still, I want to do the very best work I can with what I have (or can make with what I have) just for self-improvement, even if it takes more time. It's more an end in itself, rather than a means to something else. But, like measuretwice, I won't be hand-forging my own brass plates either!

For now, I think a bench-made sensitive drill for the tailstock will have to do, as I can make one in my price range, which is $0. Hopefully, I'll learn to turn between centers, use a boring bar, and grind accurate machine tapers with the milling attachment. I guess we'll see :)
Betzel
If I recall, you are attempting to use a watchmakers lathe for your needs.

While not my first choice, awhile back I did help someone out on your same budget who wished to do micro drilling for reasons and complications explained in the following thread utilizing a watchmakers lathe. Thought you may find it interesting.


Jerry Kieffer
 
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Betzel

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OMG, that was timely. Only "promoted products" came back in my searches, so, a thousand thank-you's!

Usually, better ideas come along after I've completed a project. Bed-parallel alignment while rotating, a precision feed / stop via threading in an existing tailstock? Much finer than a brass stop-collar on a pump shaft, and at the same price. Wow.

My heavy tools (cleaning machines, instrument lathe, microscopes, etc.) are stateside in storage, so I am making do here on a very tight budget. When I finally settle down, I'll have budget for specialized equipment (drilling, screw-cutting, milling, etc.) Until then, projects like this will keep me out of trouble, while developing better workshop skills for "someday."

Jerry, if you haven't done so already, you should really write a book. Better yet, develop a NAWCC affiliated multi-media distance learning course for horology, mechanical arts, and model engineering :) Thanks again.
 

Jerry Kieffer

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Jerry, if you haven't done so already, you should really write a book. Better yet, develop a NAWCC affiliated multi-media distance learning course for horology, mechanical arts, and model engineering :) Thanks again.
Betzel

Thank you for the very kind words.

While I have written a number of articles for various publications, at least for myself it is very time consuming.

In my experience, I have found that public display of work examples along with demonstrations has been a far more productive method for those interested to evaluate procedure effectiveness and value. In addition, I sometimes allow attendees and or onlookers to try their hand that in turn gives me insight on ways to communicate with beginners. I also sometimes demonstrate my failures for humor since my jokes are so bad.

Good Luck on your projects

Jerry Kieffer
 
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Betzel

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I have abandoned my idea of adapting a watchmaker's lathe cross-slide for (non-rotating) micro-drilling purposes, and will instead build a version of Jerry's threaded drilling wheel for the tailstock. But, I saw this today and though it an implementation easier to grok than what Porter my have designed. Since I have still not seen Porter's design, I don't know. But Levin's attachment, for all it's accuracy, is just not affordable, even used at around 2500 USD. For that, I can have maybe most of a Sherline, perhaps adapted for CNC wheel cutting, etc.

The guy makes these for your lathe and sells them on ebay. If you're curious, you can search for "Watchmakers Lathe Cross Slide Precision Drilling Attachment." It uses a threaded bolt for vertical alignment somehow, and has 3 "gib-like" holding screws to clamp the ER tube, but no idea how would be finely aligned, which is part of why I walked away. I know from experience to use better drill bits, and the ER-11's are probably cheap-o, but it is an interesting implementation (as I had imagined) and is sort of on-topic for this thread. A bridge too far...

Untitled.jpg
 

Dells

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Betzel
I have problems holding a pin vice due to gout in both hands so I had to find another way to drill small holes, I turned a JT0 taper on a length or silver steel using a graver ( because I could not work out how many deg to set cross slide ) and just replaced the tailstock shaft with it, my tailstock has a leaver but it could be done without just by putting something on the end to push on.
8489B72D-F53C-4320-ACAB-D33186537CE6.jpeg
Although I can find centre using a graver I also made a tool for finding centre that I found from J M Huckabee works every time.
4A148215-DFF9-433C-BD94-D3B190D85948.jpeg
 

Betzel

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Thanks, Dells (and George).

Gout is tough, but in the hands especially. I'm considering something similar to what you've done, a blend of this and another idea of Jerry's, essentially a threaded wheel that creates a lead-screw feed on the back of the shaft. The idea is to avoid over/under pressure for a speed @ feed rate (snapping the bit, or work hardening the material) and letting you eject swarf, then return to precisely where you were drilling before.

I don't have the room of a WW with 50mm on my Geneva (40mm) for a big wheel, so I will try a knurled nut and a shim to block the tailstock's clamp. I will also make a lever to pump, as once you have the right "feeling" if your chips are flowing well, you can keep going as you have the right feed rate by the feel. Hence the term "sensitive"?

Interesting center marking tool. The purist in me will keep going until I can catch a center every time, and it's coming along. Another idea I swiped from Steffen Pahlow is to tap in normal material with a dead center to make a "spot" and then take it from there. Hard material is another story.
 

Dells

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Betzel
As I said I can catch centre with a graver after a lot of practice but I still have a problem with silver steel but the little tool does every time so I use it most of the time now on all materials although sometimes use a graver just to prove to myself I can still do it.
 

Jerry Kieffer

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Betzel
As I said I can catch centre with a graver after a lot of practice but I still have a problem with silver steel but the little tool does every time so I use it most of the time now on all materials although sometimes use a graver just to prove to myself I can still do it.
Dells

I am sorry to hear that you have the Gout as mentioned and I am familiar with the issues it can cause.

However, In your post #31 first photo, shows you have installed a drill chuck on your lathe tailstock. As such, I am curious why you would not use a spotting drill to find center. The purpose of any spot no matter how it is produced, is to provide a matching pocket to a drill cutting tip that assures
the drill will drill to center of spindle rotation. Requires no skill and assures results.

Jerry kieffer
 

Betzel

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I think Jerry's right, again. Spotting drills are on my list as they cut a slightly wider angle than the (118 degree) drill bit. We just can't miss!

Anyway, 'tis far nobler for us to catch a center by hand with a graver I agree. But, if it's a business, we would need to be better than my 60% (on average). Lack of practice makes me even worse. And, though the tool you have seems useful, I have no trouble with my dead center "splotting" trick on silver steel as long as it's not hardened. No harm to the center if you tap progressively to make a workable spot in the steel --until those spot drills arrive. A dead center is only a paltry 60 degrees.

While looking at your lathe, though your belt might be thicker than I might use, I've found a "toenail cutter" will remove the mushroomed cap excess from fused belting pretty well. You have to gnaw at it, and spin it around, etc. but it works. I hated that sound each time the bump hit the pulley as it led me to think my work was not being held tightly, like a klunk in a bell-mouthed 3-jaw...nothing to lose?

Finally, cutting a taper is almost impossible to set numerically with any cross-slide. You're not alone. When I first ran into Jerry, he explained a working technique to copy any taper (pretty closely) with a dial gauge holding zero against the taper to be copied. He offsets his headstock, whereas we have to use a slide. Anyway, it looks like your JT0 worked out well so no matter. Hope your hands feel better...

All the best!
 

Dells

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Jerry
I do use a spotting drill on larger stock but never thought about using it on very small parts, I will give it a go.
Betzel
It would be nice to work out how many degrees to set cross slide for a given taper.
 

Betzel

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It would be nice to work out how many degrees to set cross slide for a given taper.
Totally agree.


But tapers are so very slight, that perfection (for me, anyway) only exists in reference books. In reality, all the cross slides I have used (that most of us can afford, anyway) will cut a slight --but identifiable-- taper even at "0" if you go out far enough and measure the diameter differences. I have a pop mark on mine, but I still touch off on each end of the top slide's range with a known straight bar between centers when cutting long parts. Try it and see?

The problem, I think, is that our ability to measure precisely lags our ability to make nice cuts. At least mine did. What a disappointment to find out, and what a relief to find you are off but within tolerances! :cool: I've used a permanent marker to "blue up" one side of a taper, then rub them against each other to see what shows. If I get "fair" contact across the mating taper, it will work for me. There may be other methods of chasing zero, but this has worked well enough so I can sleep ;-)
 
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wefalck

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I think we had the discussion of copying taper in another thread already ... apart from the dial-indictor method on a an existing taper, you can approach it quite closely by off-setting the top-slide and bringing a flat-faced tool close to the taper but not quite touching it. Run it along the taper and watch the gap. Adjust the off-set until the width of the gap does not change, when you run the tool along the taper. Put a piece of paper underneath, so that you get a good contrast. The final adjustment may need to be done by trial and error.

For cleaning up fused belts I first use some very fine curved scissors first and then a coarse grinding wheel in my hand-held drill. Seems to work well with the original Polycord belts and some Chinese stuff, but somehow some belting I bought a short while ago here in France was too rubbery for the latter treatment.
 
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karlmansson

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Totally agree.


But tapers are so very slight, that perfection (for me, anyway) only exists in reference books. In reality, all the cross slides I have used (that most of us can afford, anyway) will cut a slight --but identifiable-- taper even at "0" if you go out far enough and measure the diameter differences. I have a pop mark on mine, but I still touch off on each end of the top slide's range with a known straight bar between centers when cutting long parts. Try it and see?

The problem, I think, is that our ability to measure precisely lags our ability to make nice cuts. At least mine did. What a disappointment to find out, and what a relief to find you are off but within tolerances! :cool: I've used a permanent marker to "blue up" one side of a taper, then rub them against each other to see what shows. If I get "fair" contact across the mating taper, it will work for me. There may be other methods of chasing zero, but this has worked well enough so I can sleep ;-)
I've made som taper tooling for my mill recently and what really helps is the blueing up method combined with some abrasive papers in the lathe to get the final fractions off. It can also help to relieve the middle of the taper, if it is the alignment that is the most important and not transfer of torque. It gives you a much more forgiving situation, not having to match the entire lenght of the taper perfectly. I think my top slide is worn for instance so I'm getting a little convexity in my tapers. Turning the middle third of a taper down a few hundreths of a mm saves me a LOT of work with the emery cloth later.

Regards
Karl
 
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Dells

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The way I finished off my taper was I turned it almost to size with a graver and when I got close I would use a sharpie pen slide Chuck over and twist it to find high spots then I used a file rest and held a very fine file held at an angle on the file rest to keep it flat with a shim on one side then kept blueing it and testing and I am reasonably happy with the out come.
Dell
 
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dave-b

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Karl, {believe many taper problems stem from incorrecct tool centre height (think "conic sections " ) Have you considered this type of cutter for final finishing? It is just an old d-bit cutter. The end must be at 90 degrees to the body with about 7 degree back relief. This geometry ensures that the cutter only touches the work at dead centre, regardless of other orientations, so long as the tool body is horizontal. It must be sharp, and will only remove "hairs"- probably less than 0.001"

IMG_20210407_234335_1.jpg IMG_20210407_233812_4.jpg
 
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Betzel

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Another day to learn something new: a d-bit that cuts on its face.

Dave, is the orientation (rotation?) angle of the cutter face against the work (looks like maybe a 20 degree angle) important?
 

karlmansson

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Karl, {believe many taper problems stem from incorrecct tool centre height (think "conic sections " ) Have you considered this type of cutter for final finishing? It is just an old d-bit cutter. The end must be at 90 degrees to the body with about 7 degree back relief. This geometry ensures that the cutter only touches the work at dead centre, regardless of other orientations, so long as the tool body is horizontal. It must be sharp, and will only remove "hairs"- probably less than 0.001"

View attachment 648121 View attachment 648122
Looks to me like it would work like a "shear tool". I think I would prefer to mount it the other way around though, with the edge sloping away from the turning direction but still adjusted so that it contacts in the middle. I mean, if it works it works but in your setup it doesn't look like there really is any cutting edge.

That is a very good point about the center height. I had to mull that over for a little while but having the tool either above or below center height would result in a too steep taper. Thank you for that!

Regards
Karl
 

dave-b

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Yes, it is a shear tool, and does slope away from the direction of cut (sorry for poor photo) The angle is not important, just whatever works best for your material. You can also change the angle to get a new cutting edge. It produces a long curly swarf which is difficult to see until there's enough of it. The centre height problem is mainly that a straight surface is not being produced, rather a positve or negative parabola, with a curved surface.
Dave
 
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Betzel

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Besides a drill chuck arbor, I've yet to do many of the taper projects I've been thinking about because it seemed daunting, so this is interesting. The old (Wolf Jahn, etc.) stuff was very well made, but I don't know how they did it, or how to reproduce it with what I have today.

A very nice boxed set of W-J collets came to me a few years back with four (apparently quite rare) "extra" blank, tapered 4.5mm centers nicely radiused at the base of the ground tapers, faced flat on the ends. They were very hard on the tapered side, but soft on the blank side so you form them. I can't even find pictures of these things anymore. Hopefully you understand what I'm describing? I know the taper and dimensions, but not the process. How would you make a run of these tapered blanks? Harden and grind between centers, then draw out one side? Cut on a lathe (as above) then harden and then finish up with carbide?

I have a bunch of broken stakes that are good steel or could use silver steel. Once I had a bunch of these, I could make whatever I wanted on the soft ends and harden the tips after shaping as needed, polish up etc. Thoughts?
 

wefalck

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Perhaps a small induction coil would do for heating just one end ? Not sure when induction hardening/tempering came into being, certainly not in the early days of these lathes, but from the 1930s on.
 

dave-b

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Besides a drill chuck arbor, I've yet to do many of the taper projects I've been thinking about because it seemed daunting, so this is interesting. The old (Wolf Jahn, etc.) stuff was very well made, but I don't know how they did it, or how to reproduce it with what I have today.

A very nice boxed set of W-J collets came to me a few years back with four (apparently quite rare) "extra" blank, tapered 4.5mm centers nicely radiused at the base of the ground tapers, faced flat on the ends. They were very hard on the tapered side, but soft on the blank side so you form them. I can't even find pictures of these things anymore. Hopefully you understand what I'm describing? I know the taper and dimensions, but not the process. How would you make a run of these tapered blanks? Harden and grind between centers, then draw out one side? Cut on a lathe (as above) then harden and then finish up with carbide?

I have a bunch of broken stakes that are good steel or could use silver steel. Once I had a bunch of these, I could make whatever I wanted on the soft ends and harden the tips after shaping as needed, polish up etc. Thoughts?
Localised case hardening?
 

Betzel

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small induction coil
Localised case hardening
You guys are awesome :)

I guess I'm a cave-dweller thinking sticks and stones...which might be more complex. Cut a blank to rough, harden, draw to straw, grind the taper between centers, heat-sink the taper in something not too big, draw the other end to blue and finish in place in a center collet --kind of like a clock pivot? Somehow they did it at a fair scale (1920's?) very accurately, and without any fancy technology. Just some old Teutons playing with fire...

Nothing like a lockdown to keep you wondering.
 

karlmansson

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Yes, it is a shear tool, and does slope away from the direction of cut (sorry for poor photo) The angle is not important, just whatever works best for your material. You can also change the angle to get a new cutting edge. It produces a long curly swarf which is difficult to see until there's enough of it. The centre height problem is mainly that a straight surface is not being produced, rather a positve or negative parabola, with a curved surface.
Dave
Apparently I hadn't mulled long or hard enough. Now I get it, thanks again for explaining. It makes a lot of sense! And also applies to what I've been experiencing. I ground the spindle nose of a tool and cutter grinder that I'm rebuilding and although the grinding wheel has a larger radius than the point of a lathe tool, I try to keep the contact area as small as possible. Still got a little wonky results I'm afraid. Had to replace the bearings in the spindle though so I'll be regrinding it and keeping these aspects in mind!

Regards
Karl
 

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