I noticed today that the chuck portion of my Jacobs chuck started slipping on the taper. This happened 1st while under load using a 1 3/4 forstner bit turning at about 300 rpm. I had previously drilled the hole with a 1" and 1 1/2" bits to remove a lot of the material. While the predrilled hole was 4" deep the slipping started with the larger bit just in about 1". I noticed that the taper has some wear marks just where it sits in the tail stock but the portion that mates with the chuck seems unscathed. Now the chuck spins even with small drill bits in use. Is the unit toast or can I fix it somehow?
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Jacob Chuck Slipping on #2 Morse Taper
- Thread starter Keith
- Start date
Check the interior of the tail-stock taper. Look for dirt or galling inside the taper. Also concentrate on the M-2 drill chuck taper. If the wear is concentrated on a particular area, this could indicate a poor fit of either component.
Also misalignment of the head-stock spindle and the tail-stock may place excessive directional pressure on the whole assembly. This is rare because the misalignment would need to be pretty substantial.
Also misalignment of the head-stock spindle and the tail-stock may place excessive directional pressure on the whole assembly. This is rare because the misalignment would need to be pretty substantial.
Keith,
Jake is correct. Your chuck's ability to function is in direct proportion to the fit of the two morse tapers. They operate on friction between the mating metal surfaces. Any kind of foreign material will rob them of friction.
First, carefully inspect the male taper on your chuck. Any bumps or nicks must be very carefully filed (NOT sanded) "level" with the surrounding area. In the case of nicks or gouges in the metal, this does not mean filing them away, but rather taking down the high parts of their edges.
Second, once you have the male section done, you'll need to "repair" the mating surface inside your quill. This is best done with a morse taper reamer ($30 at ENCO), but you can do it carefully with fine abrasive. Cut a piece of 600 wet/dry sandpaper that will wrap most (but not all) of the way around the male taper. The paper must not overlap at any point and there should be a gap between the edges. Stick the paper to the male taper with some double-face tape, and you now have a "reamer" with which to gently take off bumps and damage on the quill's female surface. Large gouges on the interior surface can be carefully taken down "level" with a fine round file. Once you have any "big" bumps removed, very gently insert the abrasive and twist it back and forth. Remove it and blow/wipe out any dust, and repeat this several times until the inside surface is clean and smooth.
Wet a paper towel with some mineral spirits and wipe out the inside surface. You must make sure that all abrasive grit is removed or it will start the galling process all over again.
I strongly recommend that you get a taper cleaner, sold by Packard as "Taper Mate" and use it to clean both of your morse tapers each time you're going to insert an accessory.
good luck
Jake is correct. Your chuck's ability to function is in direct proportion to the fit of the two morse tapers. They operate on friction between the mating metal surfaces. Any kind of foreign material will rob them of friction.
First, carefully inspect the male taper on your chuck. Any bumps or nicks must be very carefully filed (NOT sanded) "level" with the surrounding area. In the case of nicks or gouges in the metal, this does not mean filing them away, but rather taking down the high parts of their edges.
Second, once you have the male section done, you'll need to "repair" the mating surface inside your quill. This is best done with a morse taper reamer ($30 at ENCO), but you can do it carefully with fine abrasive. Cut a piece of 600 wet/dry sandpaper that will wrap most (but not all) of the way around the male taper. The paper must not overlap at any point and there should be a gap between the edges. Stick the paper to the male taper with some double-face tape, and you now have a "reamer" with which to gently take off bumps and damage on the quill's female surface. Large gouges on the interior surface can be carefully taken down "level" with a fine round file. Once you have any "big" bumps removed, very gently insert the abrasive and twist it back and forth. Remove it and blow/wipe out any dust, and repeat this several times until the inside surface is clean and smooth.
Wet a paper towel with some mineral spirits and wipe out the inside surface. You must make sure that all abrasive grit is removed or it will start the galling process all over again.
I strongly recommend that you get a taper cleaner, sold by Packard as "Taper Mate" and use it to clean both of your morse tapers each time you're going to insert an accessory.
good luck
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As Mark has indicated if any mechanical damage repair as necessary.
If the surface has burnished due to slipping rub chalk on the surface of the taper as this works as a type of grit and gives better purchase on the tapers.
If the surface has burnished due to slipping rub chalk on the surface of the taper as this works as a type of grit and gives better purchase on the tapers.
Jim's suggestion is also good because if you use colored chalk [have a pool table?] the rubs will remove the color from places on the tapers that is too high. Machinists use "indicator" fluid, but colored pool chalk will work well enough for your purpose.
Again, the best remedy is a Morse reamer that fits your quill and headstock tapers. They are very precise and all it takes to restore a damaged taper is a couple of light turns. If you have a turning club or a friendly machine shop close to you, you may be able to borrow a taper reamer.
Again, the best remedy is a Morse reamer that fits your quill and headstock tapers. They are very precise and all it takes to restore a damaged taper is a couple of light turns. If you have a turning club or a friendly machine shop close to you, you may be able to borrow a taper reamer.
I had the same problem and pretty much fixed it as was discussed. I also got some advise from Bob Rosand and he told me to hang onto the Jacobs chuck as it enters the wood to make sure it doesn't twist. He said he has always helped his in this way and has never had it twist on him.
Aside from the advice about cleaning, gently gripping the chuck as Bernie describes has always helped me too, for both the MT and the JT. For enhanced torque resistance, a knockout bar or round rod of the right size can engage one of the holes in the chuck body and rest on the lathe bed.
On my lathe, the MT is self-ejecting at about 10mm advancement, by design for ease of removal. It will definitely spin then.
I'm pretty sure the Jacobs taper into the chuck itself isn't the same as the MT into the tailstock, and there are more of them than for MT tapers. From an old computer magazine I once subscribed to, "The nice thing about standards is there are so many to choose from."
On my lathe, the MT is self-ejecting at about 10mm advancement, by design for ease of removal. It will definitely spin then.
I'm pretty sure the Jacobs taper into the chuck itself isn't the same as the MT into the tailstock, and there are more of them than for MT tapers. From an old computer magazine I once subscribed to, "The nice thing about standards is there are so many to choose from."
Good advice, especially when using larger diameter Forstner bits, etc. Also I have an inexpensive H.F. plastic and rubber strap wrench that I routinely use to hold the chuck when drilling with large bits. In my case, better quality, sharp longer, bits probably would be a big help too.
Nice idea! I've got a couple of those. [If I can find one.😉 ] Beats taking skin off on the check's knurling.