Tail Stock Taper Turning Attachment

[rossbotics]

Taper turning in the manual lathe is a pretty straight forward process; there are basically 3 ways to do it using the Lathes own features, #1- moving the tail stock off center, #2- with a taper turning attachment, #3- with the compound.

My lathe does not have a taper turning attachment and I don’t particularly care moving the tailstock off center due to the lengthy process of realigning, all the angles I machine are done with the compound, luckily enough the compound on my major Lathe has enough travel to cut a #3 Morse Taper without having to reposition the cutting tool.

With all that said it is still a process of setting the compound to cut a precise angle such as the Morse Taper, I usually do this by using a well known manufactured tool with a ground Morse Taper Shank, with the manufactured shank mounted between centers in the lathe and a dial indicator mounted on the compound I then run the compound back and forth on the taper until I zero it out.

I have used Milling Machine boring heads with a #3 MorseTaper shank mounted in the tailstock of the lathe with a dead center mounted where the boring bar would normally go, the Boring Head will give you a much finer off set adjustment especially when you’re trying to get acouple of thousands of an inch out of a taper.

So by using the same principle as the Boring Head I came up with this dedicated tool that I call the Tail Stock Taper Turning Attachment.

This tool consists of a Male and Female Dovetail Slide, It has a Live Center fixed to the Female Slide and a #3 Morse Taper Shank fixed to the Male Slide, I had a new #3 Morse Taper Shank with 1.500”-18 threads which was originally designed for a Milling Machine Boring Head that I modified and fixed to the Male Slide, the offset of the Live Center is adjustable by means of a left hand screw and a Graduated Dial that has one hundred .0005” increments engraved on the circumference for precise adjustments, the unit has an off center movement of 11/16” which will cover most any taper I desire.

This tool can be set to cut any angle, just indicate the live center in with the headstock of the lathe then set the graduated dial to zero, with some simple math you can then move the center over the amount require to cut the angle you want.

Everything pictured in this post was made from brass, aluminum and alloy steels, I have included multiple photos of the machining processes, a couple videos of the graduated dial being engraved and numerals being stamped, along with a video of the completed tool being used, I am not an actor nor a narrator so excuse my repeated words and or my fumbling for words in the videos.

Captainleeward made a tool similar to this one back inDecember; I made a comment in his post that I was in the process of making something similar to his at the same time.

Below are some photos of the machining processes and three videos of the tool being made and operated.

As always Thanks For Looking and Happy Machining

Doug


































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[hook86]

Great tool . Love the idea any chance you have plans so i could make this?

[rossbotics]

Thanks hook86

There will be some plans available soon as I go over them for errors

Thanks Doug

[DougVan]

Have you worked up any plans for this tool yet? I started making one from the pictures but could sure use some plans to save time on figuring out some of the pieces.

Thanks,
Doug

[rossbotics]

Hi Doug
The plans for this tool are being edited, should be done in about a week, they will be available soon

Doug Ross

[petertha]

You do really beautiful work Doug!

Coincidentally I was just setting myself up to do some taper turning in my 14x40 lathe which has no taper attachment. For better or worse I got an el-cheapo 2" boring head & MT3 arbor to fit my tailstock. Anyway, now I see so many good features & advantages of your design, I guess I'm going to have to put that on the Make-It list. I have a couple (ok, maybe more than a couple) questions related to this I would like to tap into your expertise.

When you set up the attachment into tail stock, I assume you position the block horizontally so its traverses across the bed correctly. I can roughly do the equivalent of that with the boring head as it has a flat milled on one side. But I was concerned about 2 things here: 1) the whole assembly turning on the MT3 arbor and 2) unscrewing the boring head from the 1.5x18 threaded arbor. I'm told that even though the arbor is tang-less, it should hold securely. Do you think this is dangerous in terms of cutting pressure direction wanting to 'unscrew' the assembly either way?

Because the boring head has 0.500" tool holes, my plan was to make a 60-deg dead center from tool steel because I cant think of a good way to adapt a commercial tapered shank live center into a straight shank. I assume commercial live centers are hardened & ground. Do you see any issue with this?

In terms of the center drill holes on either end of work, I can see the potential for a 60-deg center to only contact a small line of the typical 60-deg center drill depending on taper geometry. Hopefully my pics explain. Ball ended centers might be a good plan, but that's another thing again. For insurance I got some some type-R center drills. Any words of wisdom in that regard?

Lastly, I've been thinking about how to set up the head when a specific taper must be cut. Because the length of part will be different every time, I cant think of a good way to pre-set the offset. Here's what I mean. If I start with accurate cylindrical stock, hold a DTI in toolholder so it contacts on center & register zero. Now move carriage over fixed amount say 4", then back out set amount to achieve taper angle, then screw the taper attachment displacement until DTI reads zero. Only problem is, now the whole part has rotated about the headstock center so the original reading is no longer valid. So... do you iterate this procedure until it converges to the proper angle for that particular length? Hope my clumsy description hasn't confused you.

[petertha]

Sample 60-deg center at an angle within 60-deg countersink

[petertha]

Ball within 60-deg counter sink

[rossbotics]

Hi petertha and thank you for your comment
Answer to your questions, #1 yes you setup the block horizontally I done this with a 6" machinist level, if there is any play in the key of the barrel in your tailstock you should rotate the barrel away from you and lock the barrel in that direction before you install the block, that's the direction where the force is, #2 your arbor is threaded into the back of the boring head mine is bolted on so just put a few drops of blue Loctite on the threads and take small cuts say .050".

Making your dead point center is fine, that's what I did, look at photo 20 of my post, my center was made from 4140 pre hard steel, I then further hardened the just the point.

Use a bell type center drill they put 2 angles in the large end of the center hole, you can get those from most commercial tool suppliers.



Presetting the offset of the attachment is quiet simple, lets use a #3 Morse Taper for example, you need to know the taper per foot or taper per inch and the length of the taper to calculate the offset.

Taper per inch divided by 2 times length
0.05019" / 2 = 0.0251" * 3.250" = offset of 0.082"

Hope this helps

Doug

Just don't go and move over that amount at once work up to it, you will need a gage of some kind when working with machine tapers, you may have to adjust the offset a bit as well

[ChrisB257]

Very fine work as usual - nicely done. Thank you.