Morse Taper Kicked Me

[ddickey]

bum.
I decided I was going to make one of those tailstock die holders. My tailstock is a #3 so started by looking up the dimensions. This may have been my first mistake as I have several MT3 pieces laying about which I could have just measured up. .9380 large end and .7780 small end. 3.19" long. On a side note I did measure my centers and stub arbors not having .778 small end, they were more like .798. Anyway, I set up a stub arbor I use to align my tailstock between centers and ran a dial indicator using my compound slide, made small adjustments until I had pret' near zero movement. So I was all set up and was going to turn my piece some to get it close to the diameter (in the 3 jaw now) and realized the angle of the compound would not let me turn from the end of the piece. I had support from my tailstock, I guess I could of turned it without but it was 7" out of the chuck so loosened compound figuring I'll have to align it again. I then realized I would not be able to turn the taper from the rear-forward as the problem now was starting my cut from the rotating dead center the handle of my compound would run into the tailstock. So my next brilliant idea was to turn from front to back using a lefty tool. I reset the whole shebang from the headstock. I actually turned the taper between centers without a lathe dog taking small cuts. When I got the .7825 of the small end I also checked the large end and got .9170. Huh? By this time my feet are frozen on that cold concrete floor and I was about to put my lathe on CL. According to my measurement I really wasn't far off my other MT centers. I had .1345" taper and the others were about .140". According to the chart though it is .160" So my question is there a better easier more accurate way to do this?

 

[rgray]

On a cylindrical grinder. Makes beautiful ones.
Figuring the angle and setting the compound with a sine bar will get you closer.
Off setting the tailstock is nice for cutting a taper between centers. Or an offsetable tool for the tailstock is nicer so you don't have to reset the tailstock. Being able to cut the taper with out using the compound is the way to go. No hand cramping from trying to turn that little compound handle smoothly over and over back and forth.

My tailstock die holder I made uses a 9/16 shaft with the end reduced to 1/2 so it is chuckable in the tailstock drill chuck or ER collet.
That is quicker for me because the drill chuck is usually already in the tailstock, so I don't need to remove it and install one for the die holder, just chuck it in the drill chuck.

 

[MozamPete]

I have always set the crossslide using an existing taper.
- Make sure your tailstock is on centre
- Find an existing taper that also has a centre hole in the end (I have some infrequently use taper drill bit I tend tend to use).
- Dial the taper in in the 4 jaw chuck
- Adjust the top slide and run a dial indicator along the taper, adjust and repeat until the dual indicator doesn't move along the entire length of the taper.
- insert your work piece and cut

I find my biggest problem is getting a good surface finish turning the top slide by hand. So I made a fitting which allowed me to use an air ratchet to give a consistent drive to the top slide. Works much better.
An alternative I haven't tried yet is using a tool post grinder to give a nice finish. Setup of the top slide angle would be the same.

 

[T Bredehoft]

Be aware, once you have established a method of turning the correct angle, if your tool is not on center, the taper won't be straight. The cutter must be EXACTLY on center or the taper will be fat in the middle. Or thin in the middle.

 

[Bob Korves]

I have always set the crossslide using an existing taper.
- Make sure your tailstock is on centre
- Find an existing taper that also has a centre hole in the end (I have some infrequently use taper drill bit I tend tend to use).
- Dial the taper in in the 4 jaw chuck
- Adjust the top slide and run a dial indicator along the taper, adjust and repeat until the dual indicator doesn't move along the entire length of the taper.
- insert your work piece and cut

I find my biggest problem is getting a good surface finish turning the top slide by hand. So I made a fitting which allowed me to use an air ratchet to give a consistent drive to the top slide. Works much better.
An alternative I haven't tried yet is using a tool post grinder to give a nice finish. Setup of the top slide angle would be the same.

That is the way I have done it, Pete. All good advice. Using an existing taper it is so much easier to get the work set up accurately than measuring an existing taper or using a sine bar. I also do not think an existing taper can be measured with any real accuracy by just using a mic or calipers. A sine bar works great if you understand and address the limitations of that method due to lathe geometry inaccuracies. A cordless (or corded) hand drill with a repeatable slow speed works great for turning the compound, either driving the nut or making an adapter to fit the handles. The handle nut will often back off when reversing the feed.

+1 on using a tool post grinder instead of a cutting tool. It gives much better results, but costs a good amount more. I happened into a nice, slightly used Dumore at a bargain price...

Edit: The final result must be tested for fit in a good quality, new condition socket taper. You can use a very thin coating of high spot blue (Dykem) or equivalent to test the fit. If you are not getting a large percentage of contact between the male and female tapers, the tool is pretty much worthless. Making a Morse taper is a fairly fussy job if you are not an experienced machinist with the correct tooling and skills -- but it is also a great challenge!

 

[Tozguy]

Turning from the TS towards chuck with compound should work;
*can you turn the taper from fat to thin (smallest diameter towards chuck)?
*TS quill fully extended?
*with tool sticking out from holder more than usual?

 

[ddickey]

Turning from the TS towards chuck with compound should work;
*can you turn the taper from fat to thin (smallest diameter towards chuck)?
*TS quill fully extended?
*with tool sticking out from holder more than usual?

1) No. I still could not get full movement.
2) Yes
3) Hmm, Oops. Perhaps. I will check. If not I'll try againtonight by TS offset.

 

[4GSR]

If your compound does not have enough travel to cut the taper, here's what I will do. Just turn the first so many inches with the compound on the larger end. When you think you have it, reposition your compound and try to pick up your taper. And always turn the last amount of length on the smaller end slightly undersize. Doing this you will be mating the taper on the larger end. The smaller end of the taper will not be touching. And this is fine. The smaller end is not that important. There's nothing in the rule book that says the taper has to be constant fit from end to end and perfectly match from end to end. I used to do this to Brown & Sharpe tapered shanks we used on Gorton Mills. We make the taper match for the first 2 to 3 inches and left the rest undersize. Be amaze how it helped on chatter on them old mills. Ken

 

[MozamPete]

Also, once you have the top slide set up to the correct angle turn a couple of spare tapers on some suitable stock and put them away for future projects. Save having to go through all the setup again.

 

[Christian Poulsen]

For common tapers using a manual lathe I'm pretty lazy... sometimes I finish the major OD and minor OD (with the length (with a step to cut the taper too then face off):
...or sometmes just ruffing the work pc. (if needed) to the "front" (major OD) taper diameter (maybe leaving stock for final cuts;

Anyway, I just indicate and knock around (brass, rubber, plastic) one of my known tapers (OD or ID) in a "bucking" 3 jaw or a 4 jaw (Say whatever the taper is; like on a collet or match a short drill chuck taper ID or drill chuck or center adapter etc. taper OD (even if the chuck or whatever is still on it)...(with "pads" of course to keep the existing nice)...

...then I just throw the indicator (usually a test indicator (mag. base) on the compound with the tip on center (Z) on (or in) of whatever it is and crank the compound back and fourth (or back...or fourth, or "step it" lol (depending on the travel of the compound) ("X"), while adj. the compound (usually snug the compound and tappy tap tap too at the end) until it reads 0 (You can do this with the compound turned 180 to cut away from the chuck towards the minor diameter of the taper or towards the chuck towards the major dia. (depending, of course, on the lengths, where the taper is gonna' be, how far away from the chuck, yada, yada)...

...then take the "test taper" out and do your thing on the actual part because the compound is now set dead on angle (if you indicated it dead on)...

...I even do this on "weird" long tapers (well, say, just a foot or 2) on mold shafts and then using the carriage movement I "step and blend" because for me; I've gotten better results and faster this way compared to using even a nice manual Toolroom lathes graduated taper attachment...
Note: If you have a sloppy compound; Good luck! (Fixing it will help everything including chasing threads)

But yes, if the part is between centers or a center is in the end (from the tail stock) you usually have to have a "longer" tool and holder and play with the set up (sticking out) to clear...
...and yes, depending on your machine, finishes, tool and skill at finish cuts, (like blending "steps" yada), just like anything, you may need to leave .001 or more stock or so for hand (sand) work
...and I usually use bluing to check final (if a mate or gauges are available) with maybe some lapping to seat a taper perfectly...(well, nothing is perfect but if mating for a fit; Around 70% minimum with the front and end seated nice....