Carbide tangentials for small lathes

Discussion in 'Tools' started by Niels Abildgaard, Aug 19, 2016.

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  1. Sep 16, 2016 #21

    goldstar31

    goldstar31

    goldstar31

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    I am still sitting in ranks of unbelievers. Firstly, the question of cutting material needs answering because cutting materials are actually in favour of carbon steel as it has a finer grain structure than high speed steel which has a finer grain structure than carbide. In other words, it should take a worse edge. Of course, carbide is tougher than both and is able to hold its edge longer prior to regrinding.
    The only bonus in using carbide is that the manufacturers of the bits do almost all the work of producing a polish and the 'top' is the only facet which needs attention by the user.

    Am I right? Well most long involved machinists can achieve near mirror finishes in steel using hss or plain carbon steel even with the lack of rigidity and lack of power of small home lathes. I'm not running a factory, I am running a wooden shed with a couple of small lathes near the scrapheap with wear and age. Like me, I suppose.

    I recently said that I can take a dusting of steel or cast iron by the simple use of either diamond bonded or in paste form( the modern way) or with a fine hone, probably a Wichita or Arkansas stone. Neither of the stones will touch carbides.

    With the mention of sword making, I confess to a revival of interest. I was born of a family of blacksmiths who lived where the German émigrés lived.

    With a sense of humour, I remain intrigued by the claim that a Damascus blade- of carbon steel can slice a feather floating in air.

    Perhaps somebody will clarify my doubts

    Norman
     
  2. Oct 9, 2016 #22

    Nick Hulme

    Nick Hulme

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    Same here, if only because my RDG Tools Dickson QCTP copy with a generic eBay holder on top of a completely standard Myford top slide is clearly capable of this-

    [ame]https://www.youtube.com/watch?v=pUI2GIGTz_c[/ame]

    What rigidity problems? If you have issues doing this on a Myford or similar "Light" lathe then you have not adjusted or set up your lathe correctly or should use a feed and speed calculator until experience catches up with reality ;-)

    - Nick

    P.S. I forgot to mention that that's 100mm of 30mm 304 Stainless bar sticking out there.
     
    Last edited: Oct 9, 2016
  3. Nov 11, 2016 #23

    Niels Abildgaard

    Niels Abildgaard

    Niels Abildgaard

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    On 28 of august I showed a differential closing mechanism:

    http://cdn.homemodelenginemachinist.com/attachment.php?attachmentid=83941&stc=1&d=1472363704

    My next will be strong enough and of smaller diameter



    The two jaw holess are threaded with a tap UN3/8 after squeze forming of carbide channel.
    The pink screw is a standard M6 Unbrako where head is threaded on my Imperial Boxford lathe UN3/8
    The dark red bush is M6 inside and UN3/8 outside.
    Overall diameter is less than 10 mm and can be placed 5.5 mm from underside of holder.
    This way it is possible to make a durable Myford holder of material from my favourite scrap steel container.
    The bush material is from a 12.9 Unbrako M10 bolt.
    Pitch of UN3/8 is 0.907mm and M6 is 1.0 mm.
    One turn of screw gives 0.093mm relative movement

    diff screw.jpg
     
  4. Nov 12, 2016 #24

    platypus20

    platypus20

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    I've been reading this thread with great interest, I bought on of the tangential tools, from Australia, through the US rep, Village Press. After seeing rave reviews, in a few magazines and on some of the forums, it now sets unused in the bottom of the lathe tool drawer.

    I tried it with HSS and carbide inserts and the finish I got on all 3 of the lathes, the finish quality was very poor. We used the grinding jig that came with the tool, the replacement jig from the supplier sent and by hand, nothing improved the finish quality. I could get a better finish with the cheap carbide inserts (TT-321 and TCMT 321) on the bargain basement tools, sold by the tool whores.

    I pulled the tool out about a week or so ago, and retried it, same results. I just find it amazing that other people get good results and rave about the tool. With my reading, I'm trying to figure out why it doesn't want to work for me.

    Its an interesting read.
     
  5. Nov 12, 2016 #25

    Dalee

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    Hi,

    I too have been reading this thread with some interest. Though I've yet to be tempted to make a tangential tool holder. I have always found it interesting that most people enjoy good success with the tool, there are those like you who just can't make them work. Through no fault of your own.

    And I've never been able to figure out a common thread as to why some people have difficulty with the tangential holders. It doesn't seem tied to machine type or condition or speeds and feeds. I wish I was close enough to see your machine in person to help figure it out Platypus20. I'm really intrigued.

    To Goldstar about carbide vs HSS or even plain high carbon. Much has changed over the last 5 years of so in the manufacture of cutting tools. I'm no Carbide Charlie or HSS Harry, use what is best for the job at hand. But I do get to decide on purchasing of said tools, so I get to talk to a fair number of sales reps.

    Carbide geometry was changed greatly. You no longer see as many blunt edges as we used to have. Cutting edges are now far sharper than the old days. There are finishing inserts that can take as fine a cut as your best HSS and even improve the finish. And there is HSS that can come within a hair's breath of matching carbide performance for wear and removal rates.

    Much of the increase in performance has come because of powdered metal technology. The material is made, and then ground into a super-fine powder and then remade. This refines the carbide size to amazingly fine grain size. Couple with new coatings and bonding agents for carbide to increase toughness allowing for sharper edge geometry and wider tolerances to speeds and feeds, and it's a wondrous new world. Did I mention the most incredible thing? It's cheap!

    So cheap that even I ordered a 3/8"(10mm) tool holder with a pack of 10 TiN coated inserts with free shipping for under $10US. A 2mm cutoff tool on the same shank size did cost me $4US more. And they work extremely well. Well enough that I'm not sure I can afford to grind good old HSS for regular turning anymore. I for sure won't be buying any HSS cutoff blades anymore.

    I do really believe and know that in any shop, commercial or home hobby, you need to be able to use HSS and carbide. And even plain high carbon tool steels have a place. You can no longer afford to stick to just one, you need to use a mix.

    Dale
     
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  6. Nov 12, 2016 #26

    Niels Abildgaard

    Niels Abildgaard

    Niels Abildgaard

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    Can we have pictures of the good and the bad?Not surfaces, but tools set up on lathe?
     
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  7. Nov 12, 2016 #27

    Niels Abildgaard

    Niels Abildgaard

    Niels Abildgaard

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    Hello Dale

    It is shoking news for an old man that my superduper toolholders are maybe not worth all the effort spent.
    On another forum a gentleman from Isle of Wigth has reported a seven holder set fo 45£.
    It is not that my holders are useless but the available commercial ones are maybe as good and cheaper.
    Can You post a link to Your recent buys please ?I will try one myself.
     
  8. Nov 13, 2016 #28

    Dalee

    Dalee

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    Hi,

    You made some good working tools, that ain't no waste!

    I got my holders and inserts from here. http://www.banggood.com/Wholesale-Turning-Tool--c-4289.html You can look through them to see what you may like. Unfortunately, the sale price I paid is over with now. Still, 12.10 English pounds for the holder(SCLR1010H06), 10 inserts(CCMT21.51), and wrench with free shipping is still dirt cheap.

    I bought them because I was curious too. I was expecting to be disappointed in the inserts. But they have proven much better than I thought.

    Dalee
     
  9. Nov 13, 2016 #29

    Niels Abildgaard

    Niels Abildgaard

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    It is incredible.
    I will take up a usefull hobby like breeding turtles .
    The differential clamping works great.
     
  10. Nov 13, 2016 #30

    Nick Hulme

    Nick Hulme

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  11. Nov 13, 2016 #31

    platypus20

    platypus20

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    I've bought boring bars, parting tools and numerous 1/2" shanked turning/facing tool sets from Banggood, the quality has been surprising good and the inserts are more than compressed dirt. The only downside to some people, is the delivery time, I've gotten packages in 6 days and others in 3-4 weeks, when ordering its not uncommon to get a delivery date about a month from the order date.
     
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  12. Nov 13, 2016 #32

    Dalee

    Dalee

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    Hi,

    Well, the the turtles might be all for that, but don't stop designing tools. There is nothing wrong with tangential holders. And if you want one, you almost need to make them yourself. And your latest bit holding setup is perhaps the best design I've seen so far.

    I like to make face mills. Some insert style, some flycutter style. Never seem to find exactly what I want commercially.

    Dale
     

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