MadModder
The Shop => Tools => Topic started by: BillTodd on April 16, 2014, 12:43:33 PM
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This is my experimental skiving tool in action making a tear drop handle.
Any expert skivers out there may suggest some improvements. ATM I think my rake angles are all too shallow and there appears to be a bit of rubbing, so my clearance angles are wrong somewhere.
Bill
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I've never skived (well not in this sense of the word!) but those seem to have come out pretty well I reckon :thumbup:
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I've never skived (well not in this sense of the word!) but those seem to have come out pretty well I reckon :thumbup:
My sentiments exactly. I even had to look up skiving. I thought it ment cutting leather, and it does. Just never heard or saw it applied to metal. Nicely done, Bill. I need to make some of those in wood for a casting pattern.
Chuck
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Skiving is something used a lot with mass production of components especially with the old cam operated multi spindle automatics its usually used as a finishing operation. (it takes me back a bit)
Stew
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I've never heard about skiving but it looks quite interesting Im just wondering about chatter on mine.
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Well here in OZ skiving meant (when I was a lad anyway) Goofing off, dodging work, bludging. Now I just need to remeber nuther meaning. Interesting video tho,
Thanks for posting.
John B
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Looks good to me I really expected the job to climb over the tool, not the case.
Right I am off to do some skiving, got my day in.
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Hi there, Bill,
That's very interesting and, please, I'd like to know more, much more. :mmr: :mmr: :mmr:
How do you go about designing and making the cutting tool? :scratch: :scratch: :scratch:
Is your lathe one of the larger, more massive models? Could I use this technique on a Myford ML7?
My computer doesn't cope well with your video - the strobing effect makes it difficult to be clear which way the lathe mandrel is rotating. It looks as though your cross-slide (or top-slide ???) is set at an angle, is this so? How do you decide the angle?
The slide movement looks fairly slow - was it operating on 'auto' or on manual traverse? You seemed to have at least one hand free to apply cutting fluid.
Have you employed this approach to make any other shaped work-pieces?
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How do you go about designing and making the cutting tool? :scratch: :scratch: :scratch:
The cutter was designed in a 3d CAD package. Essentially, the desired profile is projected on to the cutting tool . A picture of the tool is printed, transfered (with a felt-tip pen) to the HSS blade and then the blade is ground by hand to the profile.
Is your lathe one of the larger, more massive models? Could I use this technique on a Myford ML7?
The Hardinge is about as massive as a 6 x 18 comes. However, the skiving technique is a forming process that is engineered to reduce the forces on the work, so I don't see why a Myford would struggle.
My computer doesn't cope well with your video - the strobing effect makes it difficult to be clear which way the lathe mandrel is rotating. It looks as though your cross-slide (or top-slide ???) is set at an angle, is this so?
The lathe turns in the conventional direction (forwards) .
The Top-slide is at an angle. I simply used it to set the correct angle for the blade.
How do you decide the angle?
All the angles are currently 'under review' for the MkII version. It should be more of a knife tool than it is ATM.
(There are a few bit on the web about skiving but very little practical guidance so I'm learning as I go)
The slide movement looks fairly slow - was it operating on 'auto' or on manual traverse? You seemed to have at least one hand free to apply cutting fluid.
The powered cross feed in the video is too slow , it actually works better at about twice that speed :)
Have you employed this approach to make any other shaped work-pieces?
Not yet, the MkII's first blade will be the tri-ball handle parts for my Haighton Cadet renovation project (http://wktodd.webspace.virginmedia.com/cadet/page12.htm)
Regards,
Bill
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Hi there, Bill,
Thank you for your very full (and prompt) reply to my queries.
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Hi Bill thanks for posting , I have found it very interesting and it looks like ahandy method for making matching parts without all the trial and error etc.
Cheers Mick
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Thanks very much Bill! That makes for an intersting thread!
Do I understand the process correctly if I interpret your tool as 'progressive shear tool'? The angle of the tool mounting makes it look like it starts at one end and finishes at the other. Is that right? The tool shape is the projection of half the finished workpiece contour at the angle the tool is mounted?
What puzzles me as well is the clearance angles of the 'flange' part of the handles - the radial (mounting) cut.
Still trying to get my head around why it loads the lathe so little as you say...
Must give it a try :)
Cheers,
Joe
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Do I understand the process correctly if I interpret your tool as 'progressive shear tool?
yes pretty much:)
The angle of the tool mounting makes it look like it starts at one end and finishes at the other. Is that right?
startst the piece farthest from the jaws so there's as much support in the work piece as possible.
The tool shape is the projection of half the finished workpiece contour at the angle the tool is mounted?
yes
What puzzles me as well is the clearance angles of the 'flange' part of the handles - the radial (mounting) cut.
not quite sure what you mean? the tool clears the od of the flange completely simply because it didn't need to be cut
the mounting spigot is cut by the same shearing procss
Still trying to get my head around why it loads the lathe so little as you say...
the cutting force is smaller because it is only cutting over a small area at a time , unlike a typical form tool .
bill
Cheers,
Joe
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I'm impressed Bill. Thanks for posting this very interesting technique! :thumbup:
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Here's the latest experiment : a tri-ball handle.
still some way to go, unlike the avant-garde shape of a tear drop, if a ball isn't round, it looks odd.
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And the final part in stainless steel:
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:bow: :thumbup: Excellent :thumbup: :bow:
A very nice result for your hard work. That seems a very creamy coolant you are using, is it normal soluble oil or something else?
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:bow: :thumbup: Excellent :thumbup: :bow:
A very nice result for your hard work
. That seems a very creamy coolant you are using, is it normal soluble oil or something else?
Thanks :)
The mayonnaise is the result of water in my coolant tank (i thiught i'd emptied it properly!) when i added a gallon of oil
just one more problem to solve :(
bill
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When cleaning coolant tanks of nasty gunge, I put in sawdust, stir it around and vac it out with the Wet & Dry vac. Two or three sessions result in a nice clean tank. I'm amazed that yours emulsified like that if it wasn't soluble oil.
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It'll be water plus soluble coolant that was trapped in the pump.
I'm kicking myself for not checking but ...oh well it'll clean up.
bill
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Nice handles are you going to put a square hole in them?
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Nice handles are you going to put a square hole in them?
No. Thehaighton cadet uses a ¼ inch round shafts with the handle pinned in place.
bill
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Hi there, Bill,
I've watched both your videos now, more than once, and I'm very impressed by what you've demonstrated. However, I still have some questions:
The tool looks like quite a substantial lump of material to start with and the grinding to profile looks like a long job. Do you consider it's cost effective for a one-off work-piece?
Please could you give us some more details of marking out the tool-blank and grinding it to profile and relief?
Please could you also give us some more information concerning the tool-holder and the angle of the top-slide relative to the lathe axis?
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Pete,
the tool is just a blade from an old paper shear. I thought about using a parting blade. the blade holder is just a block of ally that ihad kicking about.
the shape is producd on a cad system by projecting the desired profile on to a plane at the angle of the blade.
the profile is printed at full scale and its outline tranfered to the blade for grinding (i cut out the shape and used a felttip pen to trace it for roughing out, then compared the blade to another print to fine tune the grind.
to assist getting the clearances right, i set up a grinding rest at the appropriate angles.
most of the clearances were just ground by eye and fine tuned after test cuts.
the angles used on the tri-ball were 25° rake, about 5° clearance and 40° skive (the top slide was angled to match the skive but is not used while cutting)
the skiving technique is only really suited to multiple parts production (unlesscyou have a complex part and are very good at tool grinding!)
bill
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You know when you've had enough for the day when....
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Looks good thanks for showing.
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Looks good thanks for showing.
:) you might want to look again ;-)
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Someone we all know and love is going to be along soon and say :
CLUMSY BASTARD
....now if those balls had screwed on you could rotate them ... :lol:
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Someone we all know and love is going to be along soon and say :
CLUMSY BASTARD
....now if those balls had screwed on you could rotate them ... :lol:
nothing clumsy about it ! you wouldn't believe the care I used getting it exactly 90° wrong:D
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Bill
Bummer! I think I have to agree with you on this one. I'll have :beer: one with you while we talk about it. :D
Cheers :beer:
Don
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You know when you've had enough for the day when....
Something like that happens quite offten.... :beer:
Can you make a pretty fork to attach that one :wave: Make it a "feature" like they call it it in SW-industry.
But this is very interesting topic....now where did I hide all those big HSS-blanks I tought I never need? I have a one ton capstan lathe (sans capstan....) consuming precious real estate and I'm wondering wh to do with it. That should be just right for this kind of work and maybe I should make something quorn like decoration for the mantelpiece before retiring.
Pekka
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got it right this time...
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Well I didn't notice that!! Well you could always machine it down and slip another ball on.
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Or drill another hole (in the right place), fill the old one with brass or the like and make a feature out of it :))
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As above and if asked about it then it is ready to fit the other model :clap:
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Or just put another handle on and use the first one to hang your apron on!
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Hi Guys, I seem to recall an article on skiving in MEW on making a Morse taper on a Myford lathe, but I could be wrong(not for the first or last time I suspect)
Ned
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while it would be possible to skive a morse taper, my mind boggles at the thought of setting up the knife to cut a five decimal point part! 8-)
skiving is best suited to slender and/or complex parts especially if it not possible to support the part.
bill