Tapers

my bench top milling machine was so wobbly is the mandrel . The JT taper is all weird , too loose in the bottom of the hole . And since I like a
challenge (sometimes) I decided to fix it . BUT FIRST before I go screwing up a serviceable though shitty part , I figured I needed to make sure I can recut that taper . So out of the corner comes the home made taper attachment - which I used exactly once before today . After an entire afternoon of adjusting and cutting and adjusting ... I finally got it dialed in and made a successful taper on some scrap stock . I did try making very light cuts on the mandrel , but ran out of length before I got it quite right . Now I have 2 ways I can go , I can build up the taper with the TIG welder , or I can machine a bit off the bottom of the R8 section of the mandrel to get a little more length . I'm concerned about warpage if I weld it , but can chuck it in the 4 jaw and dial it in to relocate the center hole in the taper if it doesn't run true . If I machine some off , I have about a quarter inch at the bottom of the R8 taper that's cylindrical before the taper starts . I'm not sure that's going to give me enough length to get the taper right and I'll end up welding anyway - but without that cylindrical section to dial it in on the lathe . Or maybe I'll just order a new one on ebay and save this one for another project ... last time I looked I couldn't find any , this time there are several choices .
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Snag
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Terry - Enco/MSC has a variety of taper to taper tools. Cost wasn't bad if I remember correctly.
Hul

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On 2/5/2019 2:21 PM, Hul Tytus wrote:

revealed that when I cut from left to right the cut was convex , like a barrel . Just the opposite cutting from r to l , concave . That one did fit and hold , but it was just the ends that were in contact with the chuck taper . That's OK though I can use that R8 adapter for another project on down the line .
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On Tuesday, February 5, 2019 at 7:44:19 PM UTC-5, Terry Coombs wrote:

n

Just for grins I did a search on taper attachments and found a web site th at had instructions on hand fitting tapers. gadgetbuildir.com/taper
Dan
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I've had better luck with Enco/MSC than ebay. All of Asia's production rejects seem to go through Ebay.
Hul

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On 2/6/2019 4:26 PM, Hul Tytus wrote:

mid-price range , after checking the feedback scores and looking the item over . If the pics are fuzzy and weird I usually pass , got burned by fuzzy photos once and that was enough .
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I've seen that with electronic components from Amazon too. An order of "75V" gas discharge tubes tested either under 70V or over 80V and "50V" Schottky diodes began leaking beyond spec at 48-49V. They are still useable, just be careful if you don't have or know how to build the equipment to measure device parameters.
-jsw
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On Wed, 06 Feb 2019 18:07:51 -0500, Jim Wilkins wrote:

I've purchased many electronic parts on ebay and amazon, but prefer buying from Mouser (or other US companies) when I can. Buying ATMega328PA's or PB's on ebay, several lots came properly packaged and worked ok, but after I got a badly packaged lot or two (parts were stuck down with packing tape and none of them worked) I ordered from Mouser instead. Actually costs less (eg $1.15-$1.20 vs $1.20 up, like at <https://www.mouser.com/Search/Refine?Keyword=ATMEGA328PB-AU ), parts are in factory packaging and sealed with a moisture indicator, etc.
I don't know what form factor you need for 75V GDT's, but they carry some: <https://www.mouser.com/Circuit-Protection/Gas-Discharge-Tubes-GDTs-Gas- Plasma-Arrestors/_/N-5g3f?P=1yi1tty>
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    [ ... ]

    One thing to consider -- before your (now snipped) attempt to re-turn the taper -- you should have checked what the taper *really* was. Note that there are both the more common Jacobs tapers (JT?), and some for German tapers (B?? series), which are not necessarily interchangeable with Jacobs tapers. There may even be other tapers for chucks.
    Just to be sure -- get the chuck and the arbor at the same time, so you are sure that both are Jabobs tapers.
    Enjoy,         DoN.
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