Are NMTB toolholders weldable

I am doing something that some people may consider to be weird. I want to take a NMTB 30 toolholder, and mount a small lathe chuck to it, to
do small CNC turning on the milling machine.
Anyway, what I wanted to do it to take a steel round (cold rolled), bore a hole in the middle, set it on the toolholder, and weld it to the toolholder on both sides. I would square off the result on the mill and mount the chuck to that.
! / \ --- <--- NMTb 30 toolholdes !!! =---= <--- circle ! ! ~~.~~ <-- Chuck
The question is, is the steel that is used to make those (cheap) toolholders weldable?
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On 11/14/2010 12:52 PM, Ignoramus25291 wrote:

Have you considered taking a face mill holder, and making a chuck adapter that fits the holder.
Jon
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I have not considered, but it seems to be a good idea.
i
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On 11/14/2010 1:32 PM, Ignoramus25291 wrote:

Ah, but I see you've already made your adapter. Can't speak to the weldability of that setup, but you could probably braze it.
Jon
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I frankly thought to just weld it with 7018, reasoning that I will be guaranteed fusion and penetration due to the nature of stick welding.
This is a fairly tight fit, I would say 0.002-0.003". Would you suggest brass?
Since these are thick, large pieces, heating them with O/A torch does not seem practical, but I have a heat treating furnace that goes up to 2400 degrees.
Originally I thought to stick weld it, and, after stick welding, to anneal this assembly.
i
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I've done virtually zero stick welding in the last 20 years. Would leave it to others to comment on how you want to approach it, since I really have no idea what alloy that holder is.
Jon
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On Sun, 14 Nov 2010 18:55:06 -0600, Ignoramus25291

How I'd do it.
Make a tool holder into a lathe back plate. Make a disk the size you need and an interference fit with the tool holder you'll use. Heat the disk in your oven. Drop it on the tool holder. When cool turn the disk while in your mill so its perfectly true.
Then mount your lathe chuck.
My 2 cents
Karl
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Karl, I did it by welding, using 7018 to weld the mounting plate to the toolholder. I made two welds on both sides of the disk. I looked very closely and did not find any cracks near the toes of the welds, and at this point I do believe that the toolholder is weldable.
Then I mounted the toolholder on the spindle and turned it to make sure that it is 100% perfectly true. I also turned the bottom side down to make a mounting hub, exactly the diameter that is needed to go into the hole on the chuck.
The holes for mounting bolts, I also made on the mill, with all diameters (major and minor) very close to the bolt dimensions, so it was a tight fit.
Everything seems to be true and fitting together and I just acquired myself a tailstock-less CNC lathe for small parts.
i
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Ignoramus3001 wrote:
(...)

Iggy, please keep us posted.
One of my 'roundtuits' is to mount say, 3 piston lathe tool holders on risers on the mill bed, crank the head over 90 and do a 'chucker' emulation.
I bought the R9 lathe chuck but got no further.
That sounds like *fun*!
--Winston
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I will try to write a G code subroutine to make ball ends and will try to shoot a video of that process.
i
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Ignoramus3001 wrote:
(...)

Cool!
--Winston
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    [ ... ]

    Hmm ... is it rigid or free turning? If the latter, it could be for supporting long hollow workpieces. I made something like that from an interchangeable tip live center to accept a chuck from an Emco-Maier Compact-5/CNC. I used this in my 12x24" Clausing when making some Wi-Fi circular waveguide antennas out of something more rigid than Pringles cans. :-)
    This included threading each end to accept screw-on caps.
    Enjoy,         DoN.
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