Help with lathe and Morse Taper 4 1/2

You can get sleeve adapters that convert your 4-1/2 MT into 3 MT. They're sold new by Clausing for their 5914 series of lathes but you might be in for some sticker shock. If you're patient you could probably find one on ebay.
I would forget about reaming out your current spindle to a larger taper, that would be hard to do accurately, would weaken the spindle and overall wouldn't be a good idea. If you want to do it yourself, I'd recommend making your own 4-1/2 to 3 MT adapter. If you can't find a 4-1/2 to 3 adapter at a reasonable price I beleive you can buy straight cylindrical tooling adapters that have an internal MT 3 taper pretty cheaply. You would just need to turn the 4-1/2 taper on the outside of one of these adapters. Check and to find these tooling adapters.
Good luck-
Paul T.

wow that's really weird
did you get an adapter to put in it when you got the lathe
can you check the actual measurements against the machinery handbook to see if maybe it is another taper than morse

Just so you have both opinions, I disagree. I reamed out a drill press to the next larger morse taper, no problems.
For the machining, I hope you have a taper attachment for your lathe. Do one for practice to make sure you have the cut set just right. I'd also hold the part in a four jaw or adjust true three jaw so you can indicate in the part just right. This calls for careful accurate work.
If you have a morse five reamer, use it only after removing most of the metal. Or, cut the tang off a couple morse 5 drill bits, slather with lapping compound, and use them to lap the morse five taper in perfect.
Karl

I'm glad that worked out for you Karl, but on a lathe I would still recommend against cutting the inside of the spindle to an oversize. You want that spindle to be as stiff as possible since on a lathe it takes a lot of side load when making cuts. If there was room to put in a 5 MT taper in it at the factory without making the spindle too weak they probably would have done so.
On a drill press you have a better chance of having this work out since the drill press spindle doesn't see as much side load as a lathe spindle. But just to be hard headed, I still don't like the idea of cutting the inside of any machine spindle oversize, you're just asking for trouble.
Paul T.

You can find the 4-1/2 Morse taper in the list of ASA tapers in Machinery's handbook. The ASA tapers took tapers from three series to make the full set. The smallest ones are B&S taper, IIRC. The middle range is the Morse series (with the addition of the MT 4-1/2, which appears not to be in the other listings of Morse tapers), and then (IIRC) Jarno tapers as the big end of the ASA series.
MT 4-1/2 is a common taper in spindles with L-00 noses, and sufficient through diameter to handle a drawbar for 5C collets. One example which I have is my Clausing 12x24.
You could buy one pre-made from Clausing -- but they are hardly inexpensive. (Back when I got my lathe (about six years ago, for a lathe made in 1957), the parts list showed the price as about $68.00, and I doubt that they have come down since then. :-)
I've made my own adaptors (two -- one to MT-3 and one to MT-2), once I got the taper attachment from eBay and figured out what parts were missing and made replacements.
Set the taper attachment by running a long-stemmed indicator along the ID of the spindle -- or by setting up a dial indicator on the cross-slide and measuring the offset over a known distance.
Then turn the OD to the proper taper and size, and test-fit it in the spindle -- ideally with bluing to assure that it is contacting the full length.
Once that is right, then remove the chuck, install it in the spindle, part off to a reasonable projection from the spindle nose, center drill, drill through at slightly under the minor diameter, then set the taper attachment to close to the proper setting for MT-3 (or MT-2, as appropriate), and using a boring bar, turn the ID to close to size, Finish up with an appropriate Morse taper finish reamer, held in a large tap wrench, and pressed by a dead center in the tailstock (which has been previously checked for being on center -- before you started this project). Use a male Morse taper gauge *frequently* to verify the depth. It is easy to take off too much.
I would suggest that you bevel both ends of the taper socket, to reduce the chance of burs being formed from it knocking into other things in your tool drawer) which would push the taper off center. Also, bevel both ends of the OD as well, for the same reasons.
Good Luck, DoN.

There was a lot of talk about boring the taper out to MT5.
If you did manage to enlarge it without ruining the spindle you can no longer use standard accessories such as a collet adapters that use the factor taper.

Thanks for all the info. I do have the specs on the MT 4 1/2 taper, but have no taper attachment for the lathe. The MT 5 is a real close fit into the taper. I am going to try to see where it is hitting. I would even consider cutting the back off of the taper if that is where it it hitting. The ground nose of the spindle only looks like it goes back about 2 inches. The rest is very rough, and not machined. This is why I thought about just reaming it out with a MT5 reamer. I am not worried about loosing the 4 1/2 taper as I do not have any MT 4 1/2 taper stuff, but do have some MT5 stuff that I picked up. I guess it comes down to how I want to spend the money. An adapter for about 100.00 or a reamer for about 100.00
By the way the newer model CZ-300A lathes have a 5mt taper in them, so I would guess there is enough room to ream it out to MT5. I wrote the factory in china, but have not heard anything back about getting an adapter, or a replacement spindle with a MT5 already there.
Dale

Dale, I have a Lantaine lathe which sounds identical to yours with the 4.1/2 MT spindle. I bought it from the local High School and it came with an adapter which is to 4 MT. The adapter is exactly 2" long, ground to size for about 1/2" at the front and back and, obviously, oversize in-between. Good luck, mine seems like a sturdy lathe, certainly built heavily enough. Mike in BC

that will help.
Martin