Chatter Problems - HELP!

[Dean Center]

deleted, superfluous.

 

[John Grace]

Question...once the chattering starts have you ever stopped mid-chatter so to speak and re-sharpened your tool? I don't turn spindles often but sometimes I forget when was the last time I sharpened a given tool, especially when turning ash or hickory, and a refresh on the blade clears things up.

 

[robo hippy]

Grayson, well, given the diameter of that spindle, maybe the skew is not the best tool for the job. I am mostly a bowl turner, but I can manage okay with a skew since the same general principals apply. One cause of the chatter could be too much bevel rub/tool pressure. That diameter is also getting to the point where I would use a peeling cut, or a spindle roughing gouge, then use the 80 grit gouge/abrasives to straighten things out. I don't think I have ever done an end grain spindle that size with a skew.

robo hippy

 

[Kent Reisdorph]

Thanks for the suggestions and the insight. I’ve made heavy cuts, light cuts, carbide tools, all of the above from both sides of the blank; It happens regardless. The tailstock is engaged as well. I’m truly at a loss.

Can you turn that one-handed with a bowl gouge? If not, your tools aren't sharp enough.

 

[Ed Sandle]

At this point I would try and clean up those spindle threads with a triangular file as previously mentioned, you really have nothing to loose. There is quite a bit of thread before that, so I feel there is plenty of strength left. I also need to say this next thing, and that is a file may not actually work for that as that spindle should be a hardened piece and will be very difficult to file for anything more than small burrs. You may have to actually grind that away with a Dremel and their thin wheels.
Regardless of how you fix it, the piece should screw on without resistance till it contacts the spindle face. If yours doesn't after attempting to fix, it either needs more fixing, or you have also damaged the threads on your accessories also.
As was mentioned, some lathes with their corresponding chuck thread inserts, oneway I think, will work with screwing the set screws down as the spindle has a groove for that. oneway does this because of their outboard attachment. If not turning on an outboard spindle, you should never need to use set screws.

 

[Terry Brown]

Threaded accessories for most lathes have part of the threads removed on their inboard end. This is to give clearance for them to bottom out against the spindle face, NOT the small shoulder where yours is hitting. Since your lathe has 1 1/4" x 8 threads. Your shoulder diameter probably should be 1 1/4" or less. If larger, the Laguna tech. representatives will need to be consulted. The inboard area of your faceplates. etc. have some threads removed. This space needs to be large enough in diameter and depth to encompass the shoulder without touching it. Please let us know what you find out.

 

[Bill Blasic]

On my very first good lathe (DVR3000) being in such a hurry to get it running I did not read the part about the grub screw holding the face plate on and after trying to take it off I had the same damage as in the pictured lathe. I filed it with a thread file and a square file so everything would seat properly. Well it has been over at least 22 years and that has posed no problem as all chucks have in that time registered properly with my desired runout of less than basically .002 runout with all my chucks. My advice is to file it and see if it works before thinking about changing spindles.

 

[Doug Freeman]

I agree that the chuck and faceplate NOT bottoming on the spindle shoulder is the problem, and the most likely root cause is the damaged thread on the spindle. The fact that @Grayson Truax did not have an issue with work mounted between centers pretty well confirms the thread damage as root cause.

Also agree that the thread damage appears caused by a set screw not being released and attempted removal of the chuck. As it is a new lathe I expect that you did the damage @Grayson Truax. Do you recall doing so?

I do not agree that the spindle needs replaced. Dressing away that small amount of thread is insignificant for its load holding capability. The threaded joint is grossly over designed for the loads generated. I base that on both my decades as an engineer and my own experience doing the same damage to the same threads on my lathe.

The chuck and faceplates must turn freely until their ends fit fully against the spindle shoulder. If they do not, find the root cause - either thread damage in the accessories or spindle, or the accessories are not deep enough to clear the spindle nose. Determining root cause will dictate required steps to fix the remaining problem.

 

[John K Jordan]

filed it with a thread file

One of the best tool set I ever bought is a collection of thread files, has both imperial and metric thread sizes. These are hardened square rods with different thread pitches files on each side - mine are also double-ended. Where practical, I usually like to use a die to restore external thread damage but those in large diameters would be expensive. I don’t need them often but they have saved the day on occasions over the years in the shop, on vehicles and equipment.

I have not checked to see where to get them in common sizes for lathe spindles, e.g., 8 tpi, but small areas of large threads are easily repaired with an appropriate file or two.

Thread files are also sometimes called thread chasers or restorers. A good set of thread pitch gauges also handy, but it’s easy enough to measure, count, and calculate.

One tip - you can often clean up minor thread damage by cutting a series slots in a bolt or nut with a dremel or file in a nut or the outside of a bolt. For hardened bolts I like the little abrasive Dremel cutoff wheels but they won’t fit inside hardened nuts. Diamond files will, though,

JKJ