# Logan Taper Attachment



## mwestcott (Jan 9, 2017)

I've been slowly climbing the learning curve with my Logan 816.  I finally cleaned up and mounted the pile of parts I believe is a combination factory/homemade taper attachment. I've never used nor seen one, other than photos, but it appears all I need to complete it is a grooved block with a bolt to attach it to the cross slide, that will slide along the machined bar?  The back of the female sliding dovetailed part has several set screws, and the male part is a very loose fit, so I assume this needs a gib and then it can be locked down?  I posted some photos - I'm new so I don't know how many I can attach.  Thanks for any advice!


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## eeler1 (Jan 9, 2017)

Cool, but doesn't look like a Logan TA.  Logan didn't use a dovetail to mate the cross slide to the TA, as far as I know.  Yes, is you need the block to attach the cross slide to the TA bar.  Normally, the TA bar is precision hardened  steel.  Is yours?  yes, if dovetail, you need a gib.


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## mwestcott (Jan 10, 2017)

eeler1 said:


> Cool, but doesn't look like a Logan TA.  Logan didn't use a dovetail to mate the cross slide to the TA, as far as I know.  Yes, is you need the block to attach the cross slide to the TA bar.  Normally, the TA bar is precision hardened  steel.  Is yours?  yes, if dovetail, you need a gib.



I don't know if it's hardened - I'd guess not.   It does look well made, but I haven't taken any measurements.  I think the part with the long groove attached to the cross slide and the clamp that bolts to the way at the end of the bar may be Logan parts.  The other parts appear more to be shop made.  There are no indexing marks on the angle adjustment, and the female dovetailed part is welded onto a plate that is welded onto a piece of angle that is bolted to the cross slide.  All that  work appears to be well done, but a bit "cruder" than what I'd expect from a factory part. 

If I have someone machine me a block, what should I specify it be made of?  And for a gib, is that a special piece of steel, or any thin piece that will fit the slot?  Yes I don't know a lot about this stuff.....


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## Terrywerm (Jan 10, 2017)

mwestcott said:


> I think the part with the long groove attached to the cross slide and the clamp that bolts to the way at the end of the bar may be Logan parts. The other parts appear more to be shop made.


Your thoughts are correct as to which parts are factory and which ones are not. Your taper attachment is part original, part shop made, nothing wrong with that.


mwestcott said:


> If I have someone machine me a block, what should I specify it be made of? And for a gib, is that a special piece of steel, or any thin piece that will fit the slot?


A new block could be cast iron or steel, your choice, it is not critical. A gib can be steel or brass, I would probably just go with steel, 1018 or 4140 should be fine. No need for it to be hardened. You will need to keep it lightly lubricated with some good oil when in use.


mwestcott said:


> Yes I don't know a lot about this stuff.....


That is okay. You've come to a great place to learn as you go.


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## mwestcott (Jan 10, 2017)

Thanks for the help!  I've already learned a lot from browsing the forums, and I'm sure I'll have more questions as I go.


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## eeler1 (Jan 10, 2017)

On your 816, you would normally have a TA that looks like the plain TA (pl-taper), in the photo below.  The 12"+ Logans had a telescoping TA that looks like the other photo (tel-taper).  I hope these help in visualizing what you have there.  My only experience is with the plain TA version.  Anyway, I think you are correct that yours is a modified version of somebody's TA, with many of the parts being shop-made.  And they look pretty nicely made too.

What I'm not getting is the dovetail that sits underneath the TA bar, on top of that tray that sticks out rearward from the cross slide.  Does the bottom of the TA bar have a mating dovetail?   Maybe a picture of the underside would help me.


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## mwestcott (Jan 10, 2017)

eeler1 said:


> On your 816, you would normally have a TA that looks like the plain TA (pl-taper), in the photo below.  The 12"+ Logans had a telescoping TA that looks like the other photo (tel-taper).  I hope these help in visualizing what you have there.  My only experience is with the plain TA version.  Anyway, I think you are correct that yours is a modified version of somebody's TA, with many of the parts being shop-made.  And they look pretty nicely made too.
> 
> What I'm not getting is the dovetail that sits underneath the TA bar, on top of that tray that sticks out rearward from the cross slide.  Does the bottom of the TA bar have a mating dovetail?   Maybe a picture of the underside would help me.




Yes, the bottom of the TA bar has a mating sliding dovetail.  It appears that dovetail gets locked down to the part that sticks out from the cross slide with the three setscrews on the back of the unit - the ones I need the gib for.  (Shown in my third photo in my original post).  That would serve to lock the unit to the lathe.   The whole thing is also stabilized by the rear clamp on the ways.   The other TA attachments I've seen photos of seem to be attached to the lathe bed by  a fore and aft way clamp; the dovetail clamp would appear to take the place of one of those clamps.   I can sure take some more photos tonight if that's all clear as mud.


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