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GKman
03-22-2008, 01:18 PM
Need to know how to finish this drill press shaft straight. After about a grillion hours making cutters, jigs, chips and rejects, I have the new shaft (prehardened 1144 stressproof) splined. Think the following sequence will keep it straight.
1. Cut to length, center drill left end, mount between centers and turn the shaft including areas A and B for the bearings.
2. Install bearing B, poke splined end in headstock and center and chuck B. Support the right end with a tail stock center and grip bearing B in a steady rest.
3. Remove the tail stock center, drill, bore and ream Morse taper in right end.
4. Mill the slot.

As you can see, the shaft is so small the slot nearly cut it in two and it bent while trying to get a stubborn drill chuck out. Can't make it bigger or the right bearing won't go on. However after it is on I think I can add a tight fitting tube with the slot milled over it and Loctite/setscrew in place to stiffen the shaft in that area.

Am I on the right track?


http://img.photobucket.com/albums/v494/gkman/P1010001.jpg

Ian B
03-22-2008, 01:38 PM
Just a thought; does the slot for the tang need to be that wide? It looks to be almost the same width as the mouth of the taper. For a 2MT, the tangs should be just over 1/4" thick.

Ian

kendall
03-22-2008, 01:39 PM
depending on clearance in the housing, you could make the shaft between A and B thicker, then shrink or pin a collar over the end after installing the bearing.

I believe the existing 'collar' is just used as a stop and to possibly add a bit of extra strength at the taper.

Ken

ptjw7uk
03-22-2008, 01:52 PM
Surely the end with the slot has to go through the drive pulley so unless you make the holes in the drive system bigger you are stymied
Peter

MCS
03-22-2008, 03:53 PM
It looks all tiny, the inch scale is confusing for metric people.

I see a 6204 bearing measuring 20 * 47 * 14

In the same hole you can mount a 6005 bearing. It's 25 * 47 * 12

The basic load ratings differences are insignificant (source INA).
That can give a reasonable increase in diameter.

GKman
03-22-2008, 04:13 PM
Ian, I'll sure minimize the slot with, thanks.

Ken, Thanks, that makes more sense.

Peter, the splined end (left) installs up through the quill (heavy tube with bearings at each end. All of the splined part extends out the top end and through a splined hole in the drive pully which is fixed to the drill press housing with it's own bearing. Plenty of room in ID of quill for a larger shaft up to the A bearing.

These mods should take care of the weak shaft but will the method outlined keep it straight. The whole thing started when I replaced a worn out chuck with a precision keyless chuck. The old chuck was loose enough to let a drill find the centerpunch. New one is so rigid, the tip of a center drill just rotated in a circle around the punch.

JCHannum
03-22-2008, 08:01 PM
I would turn both bearing seats between centers, and rechuck the shaft in a four jaw and dial in the lower bearing seat to bore the Morse taper.

Definitely make the tang slot no wider than necessary.

You might reconsider the need for making a Morse taper at all and simply machine a Jacobs taper on the end of the spindle. How frequently do you intend to remove the MT and install something else?

GKman
03-22-2008, 08:18 PM
It looks all tiny, the inch scale is confusing for metric people.

I see a 6204 bearing measuring 20 * 47 * 14

In the same hole you can mount a 6005 bearing. It's 25 * 47 * 12

The basic load ratings differences are insignificant (source INA).
That can give a reasonable increase in diameter.

Metric people, please disregard inch scale and use 29.5 cm X 48.2 cm Manila file folder for ref. jeez.:o

Like the idea of a bigger shaft, thats almost 1/36 of a yard isn't it?

Seriously, good idea, will keep in mind for later since I already have bought the bearings for this project.

Carld
03-22-2008, 08:32 PM
You will or have already found that a center drill will not always drill to EXACTLY on center. It will most often wander off some. The way I would do the centers is to chuck up the end with the spline in a 4 jaw and dial it in with the end very close to the end of the jaws. Then drill it with the center drill. I then use a special ground cutter to reach into the center so I can single point cut it using the compound at 30 deg. Just take a very light cut. Doing it that way the center is now as near perfect as you can get it. Do both ends that way.

Then do the bearing journals. Using the larger bearing may be a good idea. If you do use a morse taper in it I would drop down to a #1 morse taper.

GKman
03-23-2008, 08:31 AM
You will or have already found that a center drill will not always drill to EXACTLY on center. It will most often wander off some. The way I would do the centers is to chuck up the end with the spline in a 4 jaw and dial it in with the end very close to the end of the jaws. Then drill it with the center drill. I then use a special ground cutter to reach into the center so I can single point cut it using the compound at 30 deg. Just take a very light cut. Doing it that way the center is now as near perfect as you can get it. Do both ends that way.

Then do the bearing journals. Using the larger bearing may be a good idea. If you do use a morse taper in it I would drop down to a #1 morse taper.

Carl,
I learned the hard way (about 6 times) to ALWAYS center drill stock on both ends before starting NO MATTER WHAT. I milled the splines with a spin indexer and tail stock center in the mill so I have that end covered. I'll sure make it a practice to cut the center instead of trying to drill it when centering in a finished OD. Thanks for the input.

JCHannun,
There's a big red handprint on my forehead left after my saying "WHY DIDN'T I THINK OF THAT?" Forget the @@&*** Morse taper socket and slot and just turn a JT on the end. THANK YOU, THANK YOU THANK YOU.

GKman
03-23-2008, 08:31 AM
You will or have already found that a center drill will not always drill to EXACTLY on center. It will most often wander off some. The way I would do the centers is to chuck up the end with the spline in a 4 jaw and dial it in with the end very close to the end of the jaws. Then drill it with the center drill. I then use a special ground cutter to reach into the center so I can single point cut it using the compound at 30 deg. Just take a very light cut. Doing it that way the center is now as near perfect as you can get it. Do both ends that way.

Then do the bearing journals. Using the larger bearing may be a good idea. If you do use a morse taper in it I would drop down to a #1 morse taper.

Carl,
I learned the hard way (about 6 times) to ALWAYS center drill stock on both ends before starting NO MATTER WHAT. I milled the splines with a spin indexer and tail stock center in the mill so I have that end covered. I'll sure make it a practice to cut the center instead of trying to drill it when centering in a finished OD. Thanks for the input.

JCHannun,
There's a big red handprint on my forehead left after my saying "WHY DIDN'T I THINK OF THAT?" Forget the @@&*** Morse taper socket and slot and just turn a JT on the end. THANK YOU, THANK YOU THANK YOU.