bent spindle?

Signed-In Members Don't See This Ad

sorcerertd

Member
Joined
Sep 30, 2019
Messages
2,655
Location
North Carolina, USA
I have posted and commented a few times about problems drilling. There is a lot of wobble when I do so and it seems to have gotten even worse lately. I'm pretty convinced the spindle is bent. I bought a used Jet 1014 and wonder if maybe it got dropped in the past. How that would get worse without some other recent impact, I have no clue. I noticed the off-center behavior on the outside of the chuck as it slows down enough to actually see the wobble. I've checked with a couple different chucks and faceplates and this is definitely the lathe and not the chuck. I wish I had some precise way to check that it is true.

There was no noise from the bearings, but they are cheap so I replaced them and the problem remains. The spindle is expensive, so I want to be sure I am correct on this before I drop that much. The spindle is still much cheaper than a new lathe. There aren't many things that would cause this, but before I order one, is there anything else I am possibly overlooking?


 
Signed-In Members Don't See This Ad

egnald

Member
Joined
Jun 9, 2017
Messages
3,061
Location
Columbus, Nebraska, USA
To confirm that the spindle is wobbling I would take off the faceplates and chucks, etc. and try a drive center or dead center in the headstock using a Morse taper. If the point of the drive center wobbles, then it is likely that you have a problem with the spindle or the bearings. If it doesn't, then the spindle is probably running true, but the threads on the spindle may have too much slop in them. The solution would still be to replace the spindle, but at least you would know for sure.

Dave
 

rherrell

Member
Joined
Aug 22, 2006
Messages
6,333
Location
Pilot Mountain, NC
Put a dial indicator on it, first inside the morse taper and then on the flat part the chuck seats on. Turn it by hand to check the runout.

I'm a little skeptical of the spindle being bent because you say it only happens when drilling, if the spindle was bent you'd notice it when turning.

It's awful hard to bend a spindle, there would be obvious damage to the headstock if it was dropped or hit hard enough to bend it. More than likely it's a bearing problem or the spindle was bent when installed at the factory.
 

Mortalis

Member
Joined
Aug 19, 2013
Messages
658
Location
Bardstown, Ky
I actually get that phenomenon when drilling a lot. It doesn't seem to have an appreciable affect to turning the blank and I attribute it to the drill bit sticking out so far, the grind on the flute points not being exactly centered and the hardness of the blank I am drilling and the imprecise grip of the long chuck jaws along with the precision of the cut of the blank itself. It would take quite a force to bend the spindle with how short they are.
 

Charlie_W

Member
Joined
Nov 16, 2011
Messages
5,918
Location
Sterling, VA USA
Several other things to check or that can attribute to your problem is to check the Morse tapers for any debris stuck inside or galling of the metal inside the Morse taper or on your centers.
Additionally, unfortunately on lesser quality/price range wood lathes, the parts are simply not machined to as tight tolerances than others. Notably, the rotational play between the tail stock and the bed, and play between the quill and the mating bore in the tail stock. These are magnified by the length of the drill chuck and bit extending from the tail stock.

Take in consideration of perhaps a dull or poorly ground drill bit and there is more chance for not drilling straight and true.
Then, the wood can be a factor as the bit could be following the path of least resistance….softer areas that lead a bit off.

Do you use a center bit to start your center and then switch to a drill bit?…or use the point of a skew to create a center pocket for your bit? Do you face off the end of the spinning blank before drilling?

The type of bit can come into play here too. I've had brad point bits where one flute cuts ahead of the other and brad point bits where the center point is off center.

Some long pen drilling bits have a lot of flex and can let the bit drift off center.

And finally, is the head stock and tail stock in alignment with each other?

So, there are many factors in play when drilling.
Hope some of these thoughts help!
 

montmill

Member
Joined
Jan 26, 2008
Messages
635
Location
13528 Old Hwy. G Montfort, Wisconsin
Good points Charlie. I would support starting with a center bit and even drilling first with a smaller bit and working your way up. I have wobble too esp. if I try and do it quick without locking down the tail stock or having the quill out too far rather than retreating it back as close to the tail stock as possible. Slow and easy wins the game. Lot's of torque out on the end of that bit.
 

Curly

Member
Joined
Nov 20, 2010
Messages
4,828
Location
Saskatoon SK., Canada.
I had trouble drilling a blank last week. Did the same thing as in your video. It is because the lathe bed was twisted, likely because the stand or bench the lathe is on is not dead flat or the bed of the lathe was made that way. By using a dead centre in the headstock and live in the tailstock. you shim under the Cornes of the lathe until the points line up perfectly. The way to see that is to put a steel rule or box cutter blade between the tips. When correct the rule/blade will be perpendicular to the axis of rotation. Square to the bed in all directions in other words. If you have the right measuring tools, dial test indicator etc, you can do better with them but the points will get you very close.
 

NJturner

Member
Joined
Dec 4, 2006
Messages
155
Location
New Jersey, USA.
After having just torn down and cleaned my lathe because of similar issues, I will add one comment - remove your tailstock from the lathe and clean the underside of the bed and the tailstock locking bar. I found a lot of accumulated junk (sawdust, drips from finish, etc) under the lathe bed (where the tailstock locks into) and on the tailstock lock (a bar in my case). I always keep the top of the bed spotless, cleaning and polishing it regularly, but never really looked at the bottoms of the rails - which is where the tailstock locks onto. Looking at my lathe from normal view spots, it looked really clean. I was somewhat surprised when I saw how much I had missed underneath (its hidden by the rail supports). And if you think of it, anything under there will affect the tailstock alignment when you clamp it down, as bumps and crud then come into play enough to possibly add some misalignment.
 

woodcutter199

Member
Joined
May 1, 2005
Messages
17
Location
Biloxi, Ms, USA.
I actually get that phenomenon when drilling a lot. It doesn't seem to have an appreciable affect to turning the blank and I attribute it to the drill bit sticking out so far, the grind on the flute points not being exactly centered and the hardness of the blank I am drilling and the imprecise grip of the long chuck jaws along with the precision of the cut of the blank itself. It would take quite a force to bend the spindle with how short they are.
I bought a school powermatic 45 several years ago and someone threw the holding pin while it was in motion and bent the shaft almost 1/8". a machinst friend of mine used a torch and heated it on her lathe while hitting it with a ball peen hammer after about 45 mins it was out of round 1000th of an inch. I smiled.
 

sorcerertd

Member
Joined
Sep 30, 2019
Messages
2,655
Location
North Carolina, USA
Thanks for all the replies!

It did seem odd to me that it could be bent. It's a pretty solid chunk of steel, but I wasn't sure what else to do after changing the bearings. I do TBC and have not had any really noticeable issues with that. It can be off a little bit if I take it off the centers and remount it, but generally just enough to scrape through the finish on one side and not the other. There is no noticeable wobble there. Still, I try to not move the barrel on the centers at all until it is completely turned and finished.

It's really bad when drilling and using the sanding disc to square the blanks. Actually, it's the same with the small screw chuck I use for stuff like finials, light pulls and fridge magnets. Pretty much anything that screws on the headstock. Checking my terminology, I should be saying runout. The thing about it is that I can see the runout on the sides of the chuck while it is slowing down. I do not notice that with a dead or spur center. Dave might be onto something with the threads. I'm not sure how loose it should feel screwing on, but nothing moves once the chuck or faceplate is seated snugly against the spindle.

I tested it and the dead/live centers meet up properly. It's a solid chunk of metal so I don't see how it's even possible for the rails to be twisted. There is a tiny bit of play in the tailstock, but it hasn't caused this much trouble in the past. I know that any tiny bit of play in the tailstock will be magnified significantly at the end of a long drill bit.

For what it's worth, here's my drilling routine.
  1. obvious, but... chuck the blank very securely
  2. lock the tailstock quill to eliminate any play in that
  3. using a center bit, slide the tailstock up slowly to the blank
  4. very gently let it put a dimple in the end
  5. lock down the tailstock
  6. loosen the quill just enough to be able to advance the quill
  7. advance slowly, pausing a few times to make sure it can "self center" (for lack of a better way to say it?)
  8. switch to a regular jobber bit <-- I start to notice the wobble right away at this step, no matter what bit I am using. I doubt the machining is that far off on all of my bits

But again, I can see the runout even without the tailstock touching anything.

I always keep the top of the bed spotless, cleaning and polishing it regularly, but never really looked at the bottoms of the rails
This would also be me. The tailstock does lock down very securely, but can't possibly hurt anything to look and clean under there.
 

Gary Beasley

Member
Joined
Sep 18, 2009
Messages
1,326
Location
Marietta, Ga. USA
Another place to look is the adaptor the chuck has screwed into it. A cheap one will cause the problems you outline and its not all that unusual to see.
 

egnald

Member
Joined
Jun 9, 2017
Messages
3,061
Location
Columbus, Nebraska, USA
I agree with Gary, I recall someone posting on a different platform that they had wobble in the headstock and it wound up being somehow connected to a nut on the spindle that the chuck was screwed up against. Evidently the face of the nut was not perfectly square with the axis of the spindle and there was just enough slop in the headstock threads that it introduced wobble whenever a chuck was screwed up tight against it. - Dave
 

howsitwork

Member
Joined
Jul 9, 2016
Messages
2,299
Location
Thirsk
Maybe consider using a Stub drill to drill initially then switch to jobber bits to finish? It sound like it's the extension of the bits magnifying the wobble as they cut
 

dogcatcher

Member
Joined
Jul 4, 2007
Messages
2,359
Location
TX, NM or on the road
I do not think this is a bent spindle. What is happening is when you start to drill the bit goes to the softest spot in the wood. It may be off only a 1/64 or 1/128 of an inch. But it causes the bit to work as a boring bar, fighting to get back to center.
Get a set of center bits, start your hole with the largest that is still smaller than the drill you will use.
 

KenB259

Member
Joined
Dec 24, 2017
Messages
3,537
Location
Michigan
I do not think this is a bent spindle. What is happening is when you start to drill the bit goes to the softest spot in the wood. It may be off only a 1/64 or 1/128 of an inch. But it causes the bit to work as a boring bar, fighting to get back to center.
Get a set of center bits, start your hole with the largest that is still smaller than the drill you will use.
I second this. Center bits are a game changer and I use them on every pen I make.
 

Curly

Member
Joined
Nov 20, 2010
Messages
4,828
Location
Saskatoon SK., Canada.
Another bit to consider is a Spotting Drill Bit. They are short and stiff and the tip angle is very close to a regular drill bit so it centres the longer bit better than a centre drill bit, which is made to drill the cone in the end of a shaft for a metal lathe centre. I prefer them. They vary in price depending on where they are made, the materials they are made of and who is selling them.
 

PatrickR

Member
Joined
Apr 8, 2017
Messages
1,423
Location
Rural America
Yes, spotting bit followed by a screw length bit and then a jobber. A hole will only be as good as it starts. The only time I use extra long bits is when they are necessary to finish the length of the hole.
 

egnald

Member
Joined
Jun 9, 2017
Messages
3,061
Location
Columbus, Nebraska, USA
I concur completely with Peter (Curly) and Patrick, short-length drill bits can make a world of difference. I only have a couple sizes right now, those that match up with the drills I use when I'm going to tap something.

They are usually referred to as screw-machine or stub-length and I can attest that they provide significantly better rigidity for drilling straighter holes than jobbers and maintenance-length bits. Most have a split point which also helps keep them centered when used without a pilot hole.

They are not terribly expensive (less than $10) for anything 1/2-inch or smaller, but the price seems to increase exponentially between 1/2 and 1-inch. McMaster-Carr is a good and reliable source for these and all other kinds of drills, like those that are made especially for drilling acrylics.

Regards,
Dave
 

sorcerertd

Member
Joined
Sep 30, 2019
Messages
2,655
Location
North Carolina, USA
It was the spindle after all. Well, kind of. Gary mentioned washers and, though I knew there was nothing like that, it got me to thinking about this differently. Ultimately, there was some CA on one side of the mating surface of the spindle. It took some pretty darned close inspection to see it. Dang, that simple!? I feel pretty dumb. I'm surprised that it made the big of a difference. Look at it now, though.

Shoot, I could not get the video to upload. The GIF doesn't quite cut it, but I guess you can take my word for it.

20211206_133128_1_1.gif
 
Top Bottom