Harrison M390 Spindle Taper
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  1. #1
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    Default Harrison M390 Spindle Taper

    Asking this question specific to this model lathe. The topic of non-MT Harrison lathe spindle tapers has been well covered in this forum, but was hoping for a definitive answer to this lathe model specifically. Knowing the taper specs straight away will help if I end up making one.

    1. What is the taper of the spindle of the Harrison M390 (1994 vintage)? I’ve seen references to a Jarno or Reed taper; if someone has definitively established please share.

    2. The lathe apparently came with, from the factory that is, a spindle bushing that external taper matched the non-MT spindle taper, internal to a 4MT. The manual refers to the spindle taper as 4MT in bush. Generally in bush is a good thing , but not so much here. Is there any commercially available bushings available? I have a call into the Harrison support for the part number and availability (I’m preparing myself to make / grind one).

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    A Harrison lathe that new is still supported so why not just call the support people at Colchester USA and order one? Of coarse you might want to be sitting down when they tell you the price but it will be sent to your door and done.
    I guess it's possible for a 1994 Harrison lathe to have a Reed or Jarno taper in the spindle nose but neither of those tapers or a Brown & Sharpe taper have been a lathe standard for decades. If you think it is something that special then how can anyone here give the dimensions for a bushing that special?
    Dan

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    American Standard (a 3/4" per foot on dia. series) has been used in lathes. These are like Am Std 250, which is 2.500 at big end

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    I do not know what a 390 is. A Harrison m300 has mt-5 in the headstock. MT3 in tailstock, D1-4 spindle nose.
    Bill D

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    I think I am right in saying that the Harrison 390 is actually a re badged Colchester Triumph. It will be abigger taper than an M300 ,2.125 bore I think so MT6 maybe.

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    They way I read the spec sheet it's supposed to be a 4MT.

    https://www.harrisonlathes.com/pdfs/m390.pdf

    My Leblond book says the same thing but I don't know how it could be that with a 2+" spindle hole. When I researched this I think what I deducted is that with the standard spindle taper it would be a 4MT. But I have a D1-6 so my machine is a American #250 taper.

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    My M300 only has a 1.5" spindle bore, actually 38mm which is slightly larger. It is mt5 bore it is supposed to have a factory supplied mt5/mt3 sleeve. So the OP has to be bigger then MT5.
    I think the linked specs are saying it comes with a factory supplied sleeve that is mt4 on the inside and some unknown bigger size on the outside.
    Bill D.

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    Bumping this old thread up. I am searching for the same answer. Has anyone discovered the information on the adapter bushing? I have a Clausing Colchester model V390 with a D1-6 mount and over 2" spindle bore diameter. The manual and spec sheet both say MT4 with a bushing. A MT5 disappears up the spindle bore, as does the adapter bushing from my old Clausing Metosa which also has aD1-6 mount and a 2"+ bore


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