I managed to bend my spindle- interested in any approaches to git 'er straight

Trboatworks · Feb 7, 2014

Any humor anyone can manage would be appreciated.

I don't have much as I crashed this nice little lathe I have and bent the spindle.

Lathe- that nice Hendey T&G I have.
What I did- Parting a 1.2" gummy steel rod and had the work climb up over the HSS blade and stall the lathe.
How I know it's bent- I had measured at the base of the taper on nose as I was setting up lathe and found 0 detectable runout using a Interrapid .0001 indicator.
Now I have ~.001 runout at same spot with is duplicated on same axis out on the various surfaces on the nose.

I plowed through the old posts here and found consensus that it is very unlikely that a seemingly minor crash bent the spindle.
"In 40 years of machine repair, I never saw a bent spindle even in some crashes which broke the bed right it two" etc.

On remediation- I found press work by someone who has a gift for the work seems like the way to go.
I also found the comment by Forrest that high grade lathes have the spindle ground in place.
I also had heard this before in regards to Hardinge lathes.

The only thing I can think of is sending out the spindle for grinding if it is possible to re-establish the various surfaces on the nose to the degree of accuracy require through this route..

The lathe has a 1-1/2" bore, D1-4 nose with M5 taper inside.

If there is a PM firing squad going to be assembled for such trespasses- tell me when to show up and I will bring the donuts.
I suppose I prefer hood on..

Thanks all

SAG 180 · Feb 7, 2014

Can you remove the top cover and measure the spindle between the bearings for distortion?. Regrinding the spindle nose is risky as you then have to remove much more from the face of the spindle (where the camlock holes are) to preserve the D1-4 geometry.

moonlight machine · Feb 7, 2014

I don't believe you could bend a spindle with such a minor hit. How far from the chuck were you parting that a 1.2" was able to flex enough to "climb up over the parting tool"? I would never hand my spindle to anyone who "has a gift for Press work". How do you know till he gives you your spindle back in worse shape than it was in to start with. .001 out is not good but in reality your chuck is worse than that. If I was going to mess with it it would be done in place with a tool post grinder. I would leave it alone.

Trboatworks · Feb 7, 2014

Yes- can and will do.
I will get out to the shop today and see if I can determine where the spindle is tweaked.

The work was off a 1.25" hex held in a 6" three jaw.
Parting off a turned down section maybe 1" from jaws so the cut some 5"-6" from lathe nose.

Edit- no, I wouldn't turn the thing over to someone on a press- this is just what I found on PM as possible repair approach.

Thanks

Heavey Metal · Feb 7, 2014

You cant straiten a rotateing part with a press you only make it weaker.

I suspect your measurement is faulty rather than the spindle.

Trboatworks · Feb 7, 2014

That could be Heavy- I was smacking my head against the wall & seeing red.

:wall:

I will take a better look today.

hobbyman · Feb 7, 2014

I had a spindle bend on a Raglan lathe in a school shop many years ago. The carriage had ran into the chuck. I took the spindle out and left it with maintenance for straightening over the summer.
When I put it back together it ran true. I never put an indicator on it but for a school shop it was fine. Millwrights have been straightening shafts for eons.

Billtodd · Feb 7, 2014

could you have damaged the bearing ? if the front and back bearings are the same, swap might get things back to useable.

Bill

i_r_machinist · Feb 7, 2014

I won't argue with Heavey about straightening makes it weaker, But I have done this. I bought a war era Monarch that needed saving. The spindle had a little wobble to it. You need to run two indicators. One on an od and one on the face of the spindle. Close to each other. As stated, measure between the bearings to find the sweet spot. Take a "little giant" jack screw and tweek the shaft back while still in the bearings. You'll need the two indicators on the spindle nose and one directly above the jack to see how much you are deflecting the shaft. .001" is not much so don't don't get crazy with that jack.
Good Luck
i_r_

wippin' boy · Feb 7, 2014

if this is an old manual I would go to the back end and see if there is any slack in the nut holding the thrust
you may have just pulled out a little end play that was already there and now the thing is wobbling a bit

GregSY · Feb 7, 2014

.001? That would be a big improvement on my lathe! Don't worry, be happy....

browniesharp · Feb 7, 2014

Don't despair, if you have the cash (win the lottery) have a new one built! I have a fully dimensioned drawing of the spindle which I got from Hendeyman. The original started out as a BCIV (Hendey designation for some steel alloy) forging and was turned, heat treated, and ground to the final product.

RayG · Feb 7, 2014

Trboatworks said:
Any humor anyone can manage would be appreciated.

Easy fix, mount up the parting off tool on the other side.... a popular option in some cultures, run the lathe backwards and duplicate the crash in reverse. Thus reversing the damage.

I'd choose to have the hood off. So you know when to duck.

Ray

moonlight machine · Feb 7, 2014

Treat it like a sore dick....don't f&&k with it!

eKretz · Feb 7, 2014

I find it very hard to believe that you bent the spindle in such fashion. Perhaps check again while you are calmer and not extremely pissed off at yourself. I'm guessing you were just hasty and not careful when checking. Soft steel climbing over a parting tool should not be able to damage the spindle at all unless it was sticking out a mile and turning so fast it whipped out and repeatedly beat against the toolpost or lathe bed.

Aside from that, even if it IS running out .001" I'd leave it be as long as it still cuts round. With a 4-jaw you'll still be able to dial parts in to zero runout. With a collet you'll only be out .001" - not horrible. And with a 3-jaw you'll still probably be closer than the chuck.

shapeaholic · Feb 7, 2014

You need to call me and we can talk about the spare spindle and bearings I have in my garage!

Pete

Tyrone Shoelaces · Feb 7, 2014

I've been in the machine tool repair game a long while and in all that time I've dealt with two bent lathe spindles. One was caused by a combination of a careless lathe operator working in conjunction with a careless overhead crane driver ! The one good reason for not bolting your lathe down to the slab ! At least you just lift the lathe off the ground and the spindle doesn't get hurt. The other one was caused by an even more careless fool of an operator trying to stretch ( straighten in the US ) a pretty big shaft with an hydraulic jack. Bent the spindle and wrecked the spindle bearings ( Gamet, very expensive repair ).

I've never come across a lathe spindle being bent by turning alone. Any way it's a thou out ? What's a thou between friends ? You could take it out and easily make it a lot worse.

On the two spindles I did have to repair it was a combination of grind down, chrome plate, and grind back to size that did the job, again not a cheap repair but it was as good as new when it was finished.

Regards Tyrone.

S_W_Bausch · Feb 7, 2014

thermite said:
If/as/when more serious remediation IS required, it is an absolute wizard with heat, and not at very high temps even so, that is wanted. Not a jack-on or a benderman.

Bill

.001 isn't much, it could be simply be that a layer of varnish was disturbed.

I agree that a judicious application of heat is the answer, but the details aren't mine.

Tyrone Shoelaces · Feb 7, 2014

Most places I've worked parted off by mounting the parting off tool upside down in a rear tool holder. That way they didn't have to reverse spindle rotation. It also seemed to work really well. I used to work with a wacky Hungarian turner who had ideas all of his own. He used to turn long slender piston shafts ( say 3" dia by 8 ft long ) by putting the turning tool in the front tool post upside down and at a negative angle of about 10 degrees. He ran the spindle in reverse then. Sounds strange but you couldn't knock his results.

Regards Tyrone.

Trboatworks · Feb 7, 2014

OK- it looks like maybe I just scare easy..
I went over this a bit in the light of day.

This is the spindle with a .0001" indicator on the end of the nose:

Indicator on nose - YouTube

This is the indicator on the face:

Indicator on face - YouTube

This is a photo of the headstock guts:

The indicator on one part of the gear cluster:

Indicator on gear body - YouTube

And the indicator on another part of cluster:

Indicator on spindle tube - YouTube

I also ran on the part with the large holes and got .005"

As none of the spindle tube was exposed, I don't take much from these readings- note the bolt together means of assembly on those parts.
I don't think they represent how the actual spindle be running in the headstock.

Thinking back- my baseline measurement was done before the lathe was running.
I placed a .0005" indicator on the on the nose and saw I was measuring some surface defects so moved it off the contact area and got what I thought was 0 movement- a dead steady needle.
Doing this now the surface is not good enough for dead steady in spite of runout so I question what I saw that first time.

I am pulling .002" end float (along long axis) on the spindle by hand pressure.
It rests in the center and I can push or pull .001"

I am getting ~.001" of radial play by firm pressure.

So it looks like the spindle needs tightened up a bit?
I am thinking that even kinks in the old belts might be enough to throw it around as much as I am indicating on the nose.

Thank you all for the input.

I managed to bend my spindle- interested in any approaches to git 'er straight

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