Machinist sort of question on a Powermatic morticing machine?

[Larry Edgerton]

My morticing machine has a chuck extension for use with smaller bits. It is a male and female morse taper on its respective ends and drops the chuck for use with shorter bit/chisels.

I can not get the machine to extension taper to stay. I have figured out that I can cut the longer bits and use the extension on all of the chisels but now that I have cut the long bits, the taper is not holding.

Before I drill and tap it to take a machine screw is there a remedy for this that I can try first? The extension has never been dropped or abused and I am having a hard time figuring out why it all of a sudden stopped doing its job. It's clean with no burs and as good as I can see there are no burrs up in the female end. There is no rust.

What about useing blue thread lock on it?

I can't really go back because all of my long bits are now set up to use the extension.

Lets hear it......

Larry

[Jerry Bruette]

I don't have an answer to your problem just some advice not to put any type of thread locker or sleeve retainer in the taper socket. If you do and it still falls out the locker or retainer is damn hard to clean out/off after it cures.


If your extension has a tang on it you could check that to make sure it's not twisted or bent. That would prevent full engagement of the taper.

[keith denbesten]

Have you cleaned it really good with a degreaser of some sort. Any oil or film could cause it to slip. Have you tried a block of wood under and a firm tap with a dead blow hammer. Also, you might check to be sure nothing like sawdust etc is trapped up inside the taper. That's all I have at the moment. It has been 30 years since I claimed to be a machinist. I still remember some of the tricks but they are starting to come back to me slower and slower.

[Carl Beckett]

I would look for any bump. Debris. Out of roundness

Maybe get some bluing and spray on it, then mate it up and see if you can find a high spot or such

Get a straight edge and lay it lengthwise along the length, and then rotate it all the way around to see if hits a high spot

My gut says something preventing it from mating all the way. ( the block of wood and dead blow smack is fine to try)

If true, it should hold quite well.

[Thomas Hotchkin]

As other have said look for dirt and oil. With a clean chuck extension, place it in your freezer, and slowly heat to no more then 100 degrees F your arbor. With extension removed from freezer wipe mating surface clean of any moisture and drive home, with a brass or dead blow hammer. you will get a couple thousand's tighter fit this way. Tom

[Ellery Becnel]

As Carl mentioned above look for high spots that might not let you get full contact. It is easy to remove them on the male
taper. If it is in the female end of the taper, you might have to use some very fine lapping compound to remove the high spot. The blueing will let you know. Do not get agressive, take your time, and keep it clean. No oils or anti-seize. You might never remove it with that stuff.

[Larry Edgerton]

Thank you gentlemen for your suggestions. I will try them till something works.;)

Larry

[Ronald Blue]

If I am reading correctly what the problem is it is only when you attempt to use the extension. That indicates to me the extension is the culprit. As mentioned by others, check the tang for damage or signs it is hitting. Look for and dimples/bumps that could be preventing correct engagement of the taper. Even a ding a couple thousandths tall can mess this engagement up. Rather then layout dye take a black permanent marker and color the shank so no bare metal shows. Try sliding it in and tapping it in place or put a block of wood under it and pull the handle to push it into place. When you pull it out if there is a high spot the marker will be wiped off showing it. There is never a need to use heat and cold on a properly fitting morse taper. This is what is called a locking taper and because of the low angle it stays put. I could go into more detail but not intending to be technical, just provide useable advice. Let us know what you find.

[Larry Edgerton]

Well, I am not sure what worked as I wrote down 4 of your suggestions in what seemed like a logical order and did them all. There was a small burr that showed up with dye, and ironically I did use a black Sharpie for that. Filed it, used some valve grinding compound to lap it in, cleaned it with a strong solvent, and gave it a gentle tap with a dead blow. No freezer at the shop so did not try that.

Worked like a charm. Job is done and there are 2-3 coats on the parts and ready for assembly.

Thank you kindly gentlemen, Larry

[Ronald Blue]

Glad it worked out and was a simple fix. In the end that's all that matters.

[Matt McColley]

as already noted, you have to get ALL the oil off of the taper.

Here's a tip that has worked for me... dip the taper into a pail of speedy dry or kitty litter just b4 inserting into the spindle. You will get a very fine coating of clay dust, which will help to further dry the surface and lock up the taper tightly into the spindle.

Try it .... you'll like it ;^)