View Full Version : Taper attachment - buy or build?

04-20-2006, 02:24 PM
I've been considering a taper attachment for my South Bend 9. I've cut tapers by setting the tailstock over, but that's a PITA, especially when I need to true it back up.

Obviously, getting a genuine SB in decent condition and for a reasonable price is a long shot. Have any of you out there had experience with building one?

At first glance, a taper attachment seems like a pretty straightforward accessory that shouldn't be all that hard to make. But is it really? I consider myself a novice machinist, at best, but I know how to be careful and I can learn.

I have at my disposal the SB9 lathe (of course), a Bridgeport vertical mill, a small Atlas horizontal mill, an Atlas shaper, and the usual motley assortment of clamps, hand tools, grinding stuff, and a MIG machine. Now I'm wondering if I should buy a book or some plans, and I'm interested to hear from anyone who has gone down the same road. Thanks in advance, all.


04-20-2006, 03:03 PM
I had toyed with building one too, but found a tip in the 3rd? Machinist's bedside reader where someone made a tool with a center point on a cross slide arrangement that fits in the tailstock taper (on the end of an MT arbor). You leave the tailstock alone and adjust the widget. Then...I found another tip that suggested the use of a boring head in the same fashion. Now all I have to do is find a live center that can have the tail cropped and turned to .5" straight to fit into the boring head. I already had the boring head and happened to have an MT2 arbor that threads right into the rear. It is a cheapy import, but has something of a micrr-adjustable offset and should do nicely.

Yet another tip suggested taking the points off the centers on either end, center drilling that "flatted" tip, and then using ball bearings between that center drilled hole and another like it in the work. In effect, it deals with the intentional misalignment of the piece being turned relative to the center.

I think I can incorporate that into the design....and a whole lot cheaper than buying a taper attachment. The taper attachemt would still be handier, but this should allow for tapers almost the length of the bed if needed (not likely) and theoretically with as much offset as the boring head allows.


04-20-2006, 03:05 PM
John Foster wrote an excellent article in Home Shop Machinist Jan/Feb 2004 on building a telescopic taper attachment for the South Bend 9" lathe.

A back issue is probably available from Village Press.

J Harp
04-20-2006, 03:51 PM
The October/November Machinist"s Workshop has an interesting article by Thomas Morrison, on building a taper attachment, I'd like to try that one if I can ever get the other equipment necessary to do such work.

John Foster
04-20-2006, 04:08 PM
The article that JC mentioned about is for a telescope taper attachment but everything you need to know about a regular attachment is there also. The one critical part is the mounting bracket and I believe that all dimensions are given for that. John

Mike Burdick
04-20-2006, 04:35 PM
If you make one you might consider using linear slides in place of the dovetail.

04-20-2006, 05:42 PM
Just a short note.

I use a boring head as pcarpenter described and made my own live center for it. Works great and no readjusting the tail stock. Have thought of using balls as described, just to reduce stresses, thats another roundtuit that may happen someday.


Fred White
04-20-2006, 05:53 PM
I bought the main part of one on eBay ( lathe brand unknown) and modified it for my Clausing 5900.

I don't have the telescoping cross feed screw...I just remove it when I'm not using it.

I had a taper attachment on a 10 Rockwell and the telescoping screw made the cross feed sloppy. I really didn't care for it.

John Stevenson
04-20-2006, 06:09 PM
I made one a few years ago to fit a Myford ML7, two reasons, one was the genuine Myford one was too expensive for me in those days and secondly it was limited in travel.

Having previously built a small milling machine to the Dore Westbury design I followed their design of using standard off the shelf ground flat stock and screwed the whole lot together. This way saves a lot of machining and construction and can even be made on the lathe itself and a drill press.
Scraping the sole plate edges for running clearance isn't hard or you can cheat as I did and fit a 0.0015" thou shim between the spacers on the top carriage.

This design by also being a simple built up design can be adopted to fit virtually any machine.

I no longer have the lathe, a friend does still have it so photo's can be obtained but I sketched the layout up a while ago in answer to a similar query.


The boring head idea is also very simple and it means you can do long or short tapers with very little setup.
It can also go steeper than most other setups besides the compound which is often limited on travel.


This shows a variable cone pulley being driven between centres supported on 2 balls to prevent the centres galling because of the acute angle.


George Barnes
04-20-2006, 06:22 PM
Here is one that I made for my 12" Atlas and also have used on my 10" Clausing. Not too hard to make and it works fine for me. You do have to unhook the cross slide nut to use it.


It just clamps to the back of the bed and I drilled and tapped a couple of holes to attach the link to the cross slide.

Hope this helps! :)

John Stevenson
04-20-2006, 06:41 PM
That's so nice and elegant it's painful ;)


04-20-2006, 07:45 PM
Here's a simple one that I'm going to make for my little 8x16 when I get some time. http://www.gadgetbuilder.com/Taper.html

I love this fellows website, it's full of easy to make goodies with clear instructions for noobs....like me! :)

04-20-2006, 08:26 PM
Thanks for all the replies! Once again, the collective knowledge of this group comes through in fine fashion.

Sir John - I like the boring head idea somewhat, but I'm not sure about the use of the balls. I recall the galling problem when turning a taper with the tailstock set over, so I'm on track with that. Do the balls go in the center-drilled holes?

George - That's a thing of beauty, all right. Is that a "bought for purpose" material or is it simply what you had? Also, do you ever wish the sliding part was dovetailed? Is there some unseen "keeper" on the underside of the bit that attaches to the cross-slide (which keeps the slider on the guide rail)? Is that your design, or from a plan?

Also, what's this business about a telescoping cross slide lead screw? My understanding of the workings of a taper attachment such as George's is that the CS lead screw has to be disconnected, or in my case, probably removed temporarily. Is that just a buzzword for a special "disconnectable" lead screw?

Again, many thanks for the replies!


John Stevenson
04-20-2006, 08:35 PM
Yes the balls go into centre drilled holes. The one in the boring head can be a pre done spigot but the one in the headstock/ chuck needs to be done just prior to setting up to ensure concentricity.

There are two type of fastening for the link bar on TT attachments, simple type bolts to the cross slide and you disconnecter the feed screw.
Cut is applied with the top slide swung around.

Better designed ones has the link bar fastened to the nut so it pulls the nut to apply feed.
This way you can still apply the cut in the normal manner.

George Barnes
04-20-2006, 11:11 PM
The bar material is just a piece of 1/2" x 1-1/2" 1018 cold rolled material that was probably something that I had laying around. I don't remember for sure. I built the slide block first and used it to check the fit on the guide bar. I did some draw filing to get a nice smooth sliding action. The pivot holes in the bar are 24" apart

The guide block has a gib for adjusting the tightness of the fit with the bar. There is a plate on the bottom of the slide block to keep it captive on the bar. I just didn't think that the extra hassle of cutting a dovetail and fitting it and a gib worth the effort. Just lazy I guess :)

I guess that I could say that the plan is mine...but it probably is more like "take some material and cut away everthing that doesn't look like a taper attachment" type of design. :)

Thanks to you and John for the kind words!

kap pullen
04-20-2006, 11:53 PM
Thanks for the sketch John,

I built a similar attachment for my Pratt and Whitney Lathe to do a taper bore job.


This lathe has the advantage of having a milled and "t" slotted surface machined the full length on the rear of the bed.

A variety of form relief, cam machining, and other accesories were at one time avalible for this machine to mount on this surface.


04-21-2006, 11:14 AM
George -
I am familiar with that type of plan. I believe it was once characterized here as:

1. Build
2. Design
3. Refine
4. Make a Drawing

...in that order. It's amazing how well this approach can work. There are a few here that are truly masters of this method.

On a related note: I've had most of the carriage of my South Bend 9 apart at one time or another. I have a decent grasp of how it all works, but I've never figured out how to take the compound slide apart. I even made a special tool for the fastener that retains the little crank handles. (It looks like a screwdriver with a notch in the middle - kind of like the bottom half of the letter "H") Anyway, can anyone enlighten me? What am I missing?

Thanks again, all.


04-21-2006, 12:16 PM
Wirecutter, the lead screw bushing has to come out. There is a hole on the underside of it. I use a pin punch to unscrew it. Then look for the screw in the bottom slide casting. This lets you remove the nut. It will then fall apart.

Thanks for the pictures and diagrams. This is a project that is on the top of my list for my lathe.

04-21-2006, 01:18 PM
I'm going to have a need for one of these for my Lathemaster. It doesn't appear there is a comercially available attachment for the lathemaster, so building one is going to be my only option. Keep this up, cause I'm going to need the info too



J Tiers
04-21-2006, 02:14 PM
One of the plan articles in the magazines had the slickest setup ever.

The main problem with a TA is the reproducibility, and the issue of set, cut, measure/try, reset, cut, measure/try, etc, etc.

A lot of TAs have a setting mechanism that means you adjust by loosening a nut and tapping the arm over. Not exactly a precise, reproducible setting method. (Anyone who has had the pleasure of working on an Amistar component insertion machine knows way too much about that)

Many/most of the factory ones for the machines we are likely to have are intended to be set up like that. Not really a problem for a "run" of parts, but a royal pain for a one-off.

The slickest one is the one that is 24" long and uses gage blocks to set, between a set block and a round setting surface. That way, if done right, you can set a taper and get it perfect first time.

Maybe not a problem for some stuff, but a real helper if you are making something with a Morse, Jarno, B&S, etc taper. If the attachment is made right, you know that if your taper doesn't fit, the SOCKET is wrong.

04-21-2006, 03:03 PM
why not make a 'lead screw' affair for the sliding end of the TA. Have a threaded block, 2 bearings, a screw, graduated indication plate and a lock down bolt/nut. I think when/if I get around to building one, that's how I'm going to make it. I'll prolly use a coarse thread for the screw, no sense in making adjusting the thing take forever...

I would think that idea would be better than tapping it into place.

J Tiers
04-21-2006, 05:44 PM
Some, including Logan, do that.......

But you still have to set it to a model, or estimate the setting from a scale.

Being able to set it directly with gage blocks, as if the TA guide bar were a sine bar, is slicker than....... well..... it's pretty slick.

04-21-2006, 05:55 PM
hummm...get Cofer in here to rig up a pot on the far end...get it calibrated to 0* in the middle of the slide and use a LCD display to show * of movement. Turn the screw till the LCD shows the number ya want...lock it down..all done...no guessing and no extra parts dug outta the toolbox.

04-21-2006, 06:31 PM
Wire... you could have had it built it by now.Now get busy and build it,take pics and show it off.
Hell, about a year ago you could have had one for nothing you would have had to come get it, and pay $400.00 for the SB lathe it went on. ;)