The Shop > Tools

Making short precision tapers

(1/3) > >>

bogstandard:
I just didn't know where to post this, so I suppose here will have to do.

How many of you need to make a short taper and don't know how to do it, so you start trolling the web to buy what you need.
This post shows how I go about making a short taper.

Your topslide, if it has a degree scale, can be used very easily to do this job and the only limitation is the actual stroke you can get on it. Mine can give me nearly four inches, most of the smaller lathes should allow you to do around 2" in length. Plenty long enough for a chuck taper or a stub MT that I mentioned somewhere the other day. This is purely a manual turning job, no power feeds, as you will only be using the top and crosslide.


Look what fell into my hands the other day, a very kind donation from someone who knew I was looking for a very small key chuck.
This is a 5/32" (4mm) Jacobs chuck that has a 0 JT fitting. Getting hold of one of those will be rather difficult, so I decided it is quicker and easier to make my own.




So I chucked up a piece of 1/2" bar and faced the end off.




By searching the web, I found the correct dimensions for the taper. So a quickie calculation using the triangle feature of my desktop calculator (in the downloads section), it told me that I would need a 1.41++ degree angle to be cut.
So I set the topslide over to 1.5 degrees. Always go slightly high if possible, it makes the correction of the taper much easier.




Turn the taper, continually checking the chuck for fit, if it goes too far and you get a wobbly fit, just take 1/4" off the length and start coming down to size again. Once it seems to be almost there, go to the next pic.




This is the messy bit.
Using engineers marking blue (NOT layout blue), coat the inside of the chuck taper with a very thin coat. I use a cotton bud. DO NOT put too much on, you will get a false reading. Just a very thin film.
This blue will jump out and get you, it will get everywhere if you are not careful, and SWMBO will hit you with a big stick :wack: if it appears in the house.
I have had this tin a few years, it lasts forever, and will most probably be sitting, ready for use, in my great grandson's workshop, years after I am long gone. A very good investment.




So very carefully, put the chuck on your turned taper, then push it home and give it a twist around the taper.




Gently remove the chuck and see what impression is left on the taper. This pic isn't very clear, but you can see the ring of blue left behind. Because it is at the big end of the taper, it means that the angle is too large. If it is at the small end, you will need to cut a bit off the end and increase the angle slightly. This is why I said, make the angle a bit big in the beginning.
So what I do now, is slacken my topslide bolts off just a little bit, and using a plastic handled screwdriver, gently tap a tiny bit off the angle setting. One or two very small taps is usually enough, then tighten up again and take a very fine cut, just to clean up the taper. Try the chuck on again and see what you get. Repeat as necessary.




I got this after two 'tapping' sessions, and took me about ten minutes from start to finish.




End rounded off, cleaned up a bit and parted off. Job done. Now wasn't that easy?

But in my case not finished. I will show you the next bit of my project.




While the lathe had the correct setting on the topslide, I made another, just in case.




I cleaned off all the marking blue with some meths, put a dab of loctite hi-strength on the taper and assembled the two parts.




While the loctite was setting, a bit of metal was chucked up and a 5/32" spigot was turned on the end.




The chuck was tightened onto the spigot and the tapered bit I had just made was very carefully turned down to 1/8" diameter.
This part of the job was now finished.




Popped into the collet holder of a high speed mini die grinder, it ran absolutely spot on. No detectable run out.



This is the drill part of my high speed precision drill press project. This will now be put away until I have time to make all the other bits for it.

If you notice, I left a gap at the back of the chuck and a machined on shoulder on the taper. If I ever need to remove the chuck from the mandrel, I will use a wedge between the chuck and the shoulder.

I have shown this for use with a chuck, but this method can easily be used for any taper, as long as you have an original fitting you can use the blue with, to check for correct fit.


Bogs

sbwhart:
Nice one John

That chuck looks familiar  :lol:  :lol:  :lol:

Stew

bogstandard:
Thanks Stew,

It turned out just as I had hoped. If all goes well, I will be drilling very tiny holes in the near future.

I don't normally disclose benefactors names when it comes to hard to get items, just in case you get innundated with requests.

Now about my other die grinder and the spare taper I have made.  :lol:


John

Divided he ad:
Ah.... The birth of the precision drill.... Looking good so far John.

I like the mounting idea for eliminating the runout.... I'd have probably not thought of that.

Probably a good reason my peck drill attachment dosen't spin!!  :lol:


I'm certainly going to watch for the rest of this build  :dremel:



You getting rid of some old tooling Stew?  :scratch:    :lol:





Ralph.

sbwhart:
Left myselve open again

 :bang: :bang: :bang: :bang:

Navigation

[0] Message Index

[#] Next page