Trying to figure out my taper attachment and cross slide adjustment.

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TORQUIN

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I have 1947 12CK with taper attachment. I am trying to figure out some things about the cross slide and taper attachment. First, I have used the taper attachment before and created a tie rod end taper successfully. Now I am trying to make a female MT3 taper to use in my Monoset workhead. I was reminded of the instructions for the taper attachments and read them before attempting this taper.
If you are familiar with the Monarch taper attachment and cross slide you know that immediately behind the compound is the 7/8" bolt that is supposed to be tightened down when turning a taper. Behind that is a straight-blade screw, which is the cross slide adjustment, and then the 3/4" cross slide bolt, which the preceding screw acts on to tighten the cross slide adjustment. At the far end of the cross slide, on the other side of the taper attachment, is a special 7/8" 'bar rail clamp screw". The taper instructions say to tighten the 7/8" bolt immediately behind the compound and loosen the 'bar rail clamp screw', which also requires a 7/8" wrench.
On my lathe, the 7/8" bolt immediately behind the compound, when tightened, will not allow the cross slide to move when turning the handle, as it should. I have to leave it loose when using the taper attachment or I cannot adjust the cross slide. I do loosen the bar clamp screw on the back of the taper attachment. Yes, it still cuts a taper with the 7/8" bolt, immediately behind the compound, loose. I'm thinking it probably shouldn't, but it does.
I can clearly see, when I pull it apart, that the aforementioned 7/8" bolt screws into essentially a T-nut that floats on top of the cross feed screw that is supposed to clamp the cross slide to the taper "rail" which makes the taper attachment and the cross slide act as one piece and use the guidance of the taper shoe. What I don't understand is why , when tightened, it will not allow the cross slide to move.

Ideas appreciated.

Thanks,
Chris
 
Disconnect the cross slide lead nut from the cross slide?
 
If I disconnect the cross feed lead nut I don't know how I would adjust the cut I am making on my work piece.

Chris
 
The taper attachment adjusts the angle. The compound adjusts the depth. If you leave the nut connected it holds the cross slide to move parallel to the ways, and the taper attachment holds it to move at the angle of the control rod. It can't do both at once.
 
Have you seen these, Chris? Might help get your head around it. I haven't watched them fully since they were posted but I seem to recall then that even I could understand how it worked. As you say, the cross slide does not get disconnected. Might help.


-frank
 
That video is informative, and I guess I need to poke around inside to figure out why my cross feed binds when I tighten the taper draw bar clamp bolt.
I am working my way to the end goal, which is to figure out why I am getting a step in my taper. I have seen the compound lurch forward as it cuts the taper. I have not yet been able to see why, and it doesn't alway happen in the same spot. I am starting at the first possible problem I have and will work my way through the entire taper attachment and cross feed, if necessary.


Thanks,
Chris
 
Ah, I see. The lathe is designed around tapering. The taper attachment isn't an add-on like with other lathes. That's a cool setup.
 
Think I figured it out, and it's more like an omission in the instructions. Both my Monarchs have the same taper attachment, and they both act the same. Looks like you actually tighten the bar clamp bolt, the 7/8" bolt immediately behind the compound, after you adjust the cross slide to the depth you want, then take your cut. This keeps the backlash in the cross slide screw from factoring into the cut. We are not talking about the cross slide nut, but the other end, where the cross slide screw is carried forward and back by the taper attachment, which has a little bit of slack in it, and can be observed by moving the carriage back and forth with and indicator against the cross slide. When I locked down the bar clamp bolt that slack was gone.
Now, for practical use, this will be a huge pain to lock that bolt down for every cut then loosen, adjust cross slide, tighten, and take another cut, so I think locking it down will only be for finish cuts or if for some reason I feel I need more rigidity in a cut. I just have to remember to move the carriage far enough to take out the slack in the taper attachment before I begin a cut, if I don't lock the bar clamp nut down.

I put the lathe back together and took a few cuts with the bar clamp locked down and the step I was experiencing in the middle of my cut before didn't happen.

Thanks for the ideas,
Chris
 
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