# Emco V13 Taper attachment build



## Darren (Apr 22, 2021)

My V13 didn't come with a taper attachment, and they are impossible to find, so i'm building my own. Here's what they look like:










I'm going to loosely base mine on the Emco design. I found an old brake lathe at the dump a while back, and took it home knowing that someday i'd do something with it. Today is that day.

more in the next post.....


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## Darren (Apr 22, 2021)

That there is a taper attachment. 

To the bandsaw!


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## Darren (Apr 22, 2021)

So i wasn't real sure how it was going to look once cut apart, so i left plenty of meat, which meant i had some material to hog off.











I left a bit for the surface grinder








Since my lathe is an Emco, not an Ammco, this had to go







Couple hard spots there







Fits the cross slide good, both are 5.5" wide







The new rear toolpost slide. The tee slot will make mounting and positioning a tool pretty easy.

And thats where im at right now. More to come.


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## David_R8 (Apr 22, 2021)

Awesome work!
Just cut/mill away everything that isn't a taper attachment, I love it!


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## Darren (Apr 22, 2021)

David_R8 said:


> Awesome work!
> Just cut/mill away everything that isn't a taper attachment, I love it!



Thanks!

LOL thats pretty much the idea. I could have made that dovetail, but it saved me a bunch of time. I'll be making the other dovetail slide and the guidebar though. Theres also a bunch of nice 3/4ish thick cast iron in that old brake lathe that i'll be using. The bandsaw slices right through it like butter. Should be an interesting build. It may even get built twice.


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## PeterT (Apr 22, 2021)

Nice work, following along. Always nice to see a piece of unloved metal turn into something nice & useful.
When this Emco was sold with taper attachment, did they have a different, cross slide lead screw attachment that disengaged during taper turning mode or what is your game plan in that regard?


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## Darren (Apr 22, 2021)

PeterT said:


> Nice work, following along. Always nice to see a piece of unloved metal turn into something nice & useful.
> When this Emco was sold with taper attachment, did they have a different, cross slide lead screw attachment that disengaged during taper turning mode or what is your game plan in that regard?



Thanks Peter. The way Emco did it is fairly unique. The unit does not move the cross slide at all during taper cutting. It has its own toolpost on a slide block and is designed to cut from the rear, with the lathe in reverse. I'm doing it the same way. I will attach a few exploded view pics from the parts manual.
















part number 1 is what i started on tonight. I'm going to cut the excess dovetail length off and mount it to a plate, and the cutoffs, which will now be 2 pieces will be run perpendicular to form a dovetail slide for the guide bar


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## Darren (Apr 22, 2021)

I believe most taper attachments top out at 8-10 degrees, i'm hoping to do around 12 degrees, with a bit more than 12" of taper length.  I can't see needing much more. If i'm guessing correctly, i'll need a bit more than 3" of tool travel (x axis travel) over that 12". Anyone good with trig?


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## PeterT (Apr 22, 2021)

Veeeery interesting. That is unique. Cant wait to see this come to life.

Not quite sure I have a clear picture of where the slide action will be relative to the taper bar but 12" of base and 12 deg yields max 2.551" (of rise) displacement. If its acting at some other reduced position (just chose 9" for example) you get these kind of numbers


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## Darren (Apr 22, 2021)

Thank you for that. That make me feel a bit better. I can definitely get 3" of x travel, so i should be able to achieve 14-15 degrees. I'm good with that.  Without a dimensioned drawing of the original, it makes it harder to visualize the outcome for me.

Yes, i think you have it right, you can set an angle of 12 deg, but only travel a 1/2 of the 12" max travel distance and the tool is only going to move 1.25" relative to the work.


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## RobinHood (Apr 23, 2021)

Excellent work and for sure a unique concept.

Your taper angle is per side; so you will actually have double that as an included angle. In your case it will be up to 24*. That is a substantial amount on any lathe.

For example NPT taper is 1/16 (or 3/4” per foot) => 1.7899* per side, not a whole lot all, things considered. R8 is only around 7*/side. CAT 40/50 is 7/24 (just over 8* per side).

You’ll be able to make all the common taper tooling holders with your new TA.


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## Darren (Apr 23, 2021)

RobinHood said:


> Excellent work and for sure a unique concept.
> 
> Your taper angle is per side; so you will actually have double that as an included angle. In your case it will be up to 24*. That is a substantial amount on any lathe.
> 
> ...



Making my own tooling is the prime reason for building it. I know and have used all the other methods for tapers, but with this one, i'm adding a feature to pin it for specific tapers, then i just have to verify and tweak a small amount and i'm good to go. Turning NPT tapers is the other reason. Home Depot is 30 mins from my house, so i could make a fitting quicker...


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## Darren (Apr 23, 2021)

Didn't get a lot done today but here are some pics






Started grinding the sub plate for mounting everything












machining to 5.5" wide







Its coming along


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## Darren (Apr 25, 2021)

I managed to get a few hours in the shop tonight. A whole bunch of drilling and tapping and figuring. Here's some pics






I cut the tool slide piece down to a more reasonable size






I will have to cut the gib down and drill and tap for the adjuster screws






it'll have some sort of a tool holder like this spare that i have.







All the dovetails get mounted to this plate, and it is what mounts everything to the cross slide. Had to drill some holes for countersink screws.

















I put some extra bolts in to stiffen it up. These join the perpendicular dovetail pieces to each other.






These slotted holes allow adjustment of the rear dovetail like a gib. There will be a block behind the gib with adjustment screws to tighten the dovetail against the slide bar.












thats all for now


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## David_R8 (Apr 25, 2021)

Looking really good!


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## Darren (Apr 25, 2021)

Thanks. Its coming together but i could have carved it out of a solid block by now. But this is free and fun


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## PeterT (Apr 25, 2021)

Very nice. This is obviously not your first rodeo. Just wondering, with the inverted tool on the original. Can you still accommodate insert type tooling shanks or you need to stay with (what looks like) HSS blanks?


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## Darren (Apr 25, 2021)

PeterT said:


> Very nice. This is obviously not your first rodeo. Just wondering, with the inverted tool on the original. Can you still accommodate insert type tooling shanks or you need to stay with (what looks like) HSS blanks?



Thanks!  The dro on the mill makes it pretty easy. Edge find off of one corner and go from there.  All the holes lined up perfectly. I was surprised.

I'm going to make it pretty universal, and I don't plan to run the tool inverted. I want the force to be downward on the tool, although its not going to be taking heavy cuts.  Guess i'll figure that out once i get to the tool block part.


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## Darren (Apr 26, 2021)

Tonights progress






1x3" CRS for the sliding bar.  I never like machining CRS, it has so much stress in it that everytime you make a cut, it moves. It took a while to square it up and straighten it out, And thats only the beginning.






Looks purdy though.....






Starting on the first dovetail. 






About halfway through the first dovetail. I stopped for some measurements, and it was starting to move as the stresses changed. Some minor adjustments and kept on cutting.






went in 0.575" total on the y axis, 0.0650 LR, and 0.0350 RL (climb milling) per pass. 600ish rpms, but it tried 400 (too slow, lotsa vibes) to 900 (too much heat). Had to flip it around several times to chase some warp out of it.







It fits very good, but in the pic above it doesn't look like it because its slid all the way over and it was actually lifting at the end that the pic shows. The right side female dovetail is the adjustable "gib". No, I am not scraping anything in.






The bar on top is a 1.5x1 slice of the same CRS and will get machined down to become the adjustable angle bar that will make all the magic happen.


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## PeterT (Apr 26, 2021)

Coming along nicely. Do you happen to know the alloy? I haven't done many long-ish parts like that, but I have also experienced CRS wanting to stress relieve. Worse if the part is non-symmetrical. I've done a little bit with hot rolled (A36 maybe?) but not enough to know if it would be significantly better. Some people say 4140 is better but I thought it was also (usually) cold rolled but maybe comes in different flavors. Any thoughts? I wish there were bars of cast iron somewhere local but seems to be unobtanium. It isn't even horribly expensive with some suppliers but shipping is a killer.


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## Darren (Apr 26, 2021)

Its 1018.  Its typical for cold rolled to do that when machining. You deal with it similar to dealing with welding warpage/shrinkage.  It will be fine for what it is.  If i could have found a cast iron bar the correct size for less than a first born, i would have used that for sure. Hot rolled is usually pretty good as far as stress goes too. I didn't have the right size in stock and just wanted to keep moving on this project. The next one will be all cast iron.


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## Darren (May 4, 2021)

Some recent progress pics







Tee slots. 






Yup, I screwed up. Forgot to move over the radius of the 5/16" endmill on the second one. Dammit






Since I didn't radius cut the tee slots in the lower bar, I oblonged the slots in the upper bar. I don't think my 6" rotary table would have liked a radius cut of 6.9".  New 12" Yuasa rotary table is still a week away.












Pivot pin is a hardened 0.500" dowel pin. Drilled and reamed the lower bar for a half thou press, 0.000 fit into the upper bar.

Going to grind everything to size and make the guide shoe and linkage, and a tool holder and it'll be done.


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## Darren (May 5, 2021)

Bit more work today






Making the slider block.  Started off by slicing up some cast iron from a tractor weight.





























roughing out the bearing pockets.






I set the bearings about 5 thou tight on the bar and surface ground the bar to fit. The bar was ground with a paper shim to tilt it So the top of the bar is 3 thou wider than the bottom. This keeps the block seated on the bar all the time. It slides really nicely











I lubed it up to see the "in use" friction







More to come....


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## PeterT (May 6, 2021)

Are the bearing rotating on shoulder bolts or something like that? When you say you set them, how do you adjust the in/out play?


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## Darren (May 6, 2021)

They are not adjustable.  I adjusted the fit by purposely making them too tight then surface grinding the bar till it was a nice fit with no play.  I think it will be fine. If not, i can make another, or add cams or something.

I was going to use a linear rail and bearing block, but all the ones i have are matched pairs. Doing it over I might use linear rails and bearing blocks for both upper and lower bars, with a 1/2"x 3" plate sandwiched between, instead of cutting that long dovetail, but what fun would that be?


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