Unbalanced 4 jaw on my 12x36

[terry_g]

I have a Craftex 12 x 36 lathe. When I first bought it the runout on the 3 and 4 jaw chucks
was about .012 if I remember correctly. The D1-4 adapters on both chucks were loose on the taper.
I machined a small amount off the face of the D1-4 adapters so the taper fit tight and no more runout.

 

[Proxule]

Test it at 800 rpm as well as 1000 rpm and at either top speed of the lathe or max speed of the chuck & report your findings.

My large lathe vibrates at around 500-600 rpm but is fine above and under that speed. It is simply the speed at which things get magnified.

You can check the chuck but I doubt it is the problem.

Vibration is there still at 800 100 and 1500, The frequency is different of course, Less at the higher range, more aggressive at the 600 area.
Thanks for your opinion

 

[Proxule]

That is a huge amount of runout. Check whatever it sits right in the taper -if it does not go all the way into the taper this could be the result - you can use feeler gages for this.

Exactly, I press the face-plate by hand and can easily move a .008 feeler in behind it. So yes that is partially my problem.
Contacted KMS, he wants an email with the issues so he can push it to his rep.

 

[Proxule]

ok, this could be a different issue, also which I experienced. I bought a faceplate that was not fitting the spindle nose quite right. Every time I locked the pins I got a different runout reading. What was happening was the taper angle was Ok but under diameter vs spindle nose. So it rides up & then basically gets stuck prematurely just depending on how its married & tightend. This was confirmed by blueing & examining the rub. There were no burr surface hang-ups and didnt appear oblonged which was good. It was just a bit tight everywhere. It has to match the taper and the vertical land backface simultaneously.

What I did was a bit ghetto but it worked. I made a partial lap from epoxy putty (basically Bondo but nil shrink) on my known good taper. Used a release wax intended for this purpose. Then I blued the surface with felt pen, trapped some wet-dry paper & carefully lapped it. Clean it, blue it, test again. Eventually it was a perfect fit. Only then its fair game to take a skim off the face & edge. Now its actually my best fitting accessory, takes a teeny mallet knock to come off. I could have made the Bondo tool the full spindle profile & used lapping compound. That was my initial thinking but I was initially suspicious it might be egged & so I figured a partial sector tool could work a certain area & not another area. If I had to guess probably took 0.001-0.002" off the wall but also made a much nicer surface.

Now in my case I trusted my spindle 100% & have no issues with my other chucks. It was just this oddball faceplate acquisition. Hopefully you don't have issues with the camlock studs or spindle itself. How much runout is on your spindle nose now with no accessory mounted? Also are your chucks mounted to a D1-4 adapter plate & maybe those are out radially?

Awesome method if kissing the taper. I will contact you privately to pick your brain a bit more. This might be a solution, Partially any way. As my 4 jaw and 3 jaw both mate up face to face prior to engaging the cam locks.
I was under the impression to want a couple of tenths gap before the cam-locks engage so it pulls it up on the taper. But not .008 like I currently have.

Thanks !!

 

[Proxule]

I have a Craftex 12 x 36 lathe. When I first bought it the runout on the 3 and 4 jaw chucks
was about .012 if I remember correctly. The D1-4 adapters on both chucks were loose on the taper.
I machined a small amount off the face of the D1-4 adapters so the taper fit tight and no more runout.

The run-out on my 3 jaw is .0002 on a half inch dowel 1 inch from the face of the jaws. So suffice to say I am happy and no runout exists.
But your issue of the loose tapers might apply here, What sort of gap did you settle on between the chuck and the nose of the spindle when doing your cutting ?

Thanks

 

[Proxule]

PeterT,

my spindle runout is amazing....Had to break out my metric dial test to read it correctly.
I am getting .00007 inch on both the face and taper of the spindle.

 

[PeterT]

As my 4 jaw and 3 jaw both mate up face to face prior to engaging the cam locks. I was under the impression to want a couple of tenths gap before the cam-locks engage so it pulls it up on the taper. But not .008 like I currently have.

That (couple of tenths) sounds about right but I cant recall where I read it.

You could confirm dimension C on your spindle just as sanity check & ensure the spindle nose face has no raised burr. I would expect if you have 0.008" gap between vertical faces you are in the territory where the chuck assembly could get cocked on non-axially & show up as bad runout (my exact issue mentioned). Even if you are careful & try & mount it exactly as square, just tightening the camlocks will suck it of axis I guess what might settle the score is a 'known good' D1-4 adapter plate. If it fits the spindle with same runout as donor machine you know for certain its adapter plate issues. How about felt pen bluing, have you tried that yet to see any egging of the backplate taper?

Longshot but any chance the D1-4 pins are out? The scallops are same distance & the key rotation tightening action is about the same amount?

 

[Proxule]

I have a Craftex 12 x 36 lathe. When I first bought it the runout on the 3 and 4 jaw chucks
was about .012 if I remember correctly. The D1-4 adapters on both chucks were loose on the taper.
I machined a small amount off the face of the D1-4 adapters so the taper fit tight and no more runout.

How did you measure .012 runout on the 4jaw ?
Im getting .0005 on the body of my 4jaw.

 

[YotaBota]

From your post in another thread is KING being more the jester or just being silent?

 

[Proxule]

From your post in another thread is KING being more the jester or just being silent?

I have contacted kms tools here in Edmonton, The sales guy was the middle man and stonewalled me from contacting king directly, KMS sales guy is going on a 2 week motorcycle ride so he finally gave in and allowed me to contact the king rep here. I will not be buying from KMS west edmonton again - A new location in South Edmonton just opened!

King rep is very friendly and said no worries on repalcement parts but he forwarded my video and pictures to the head guy in Quebec, He wasn't sure if the .008 feeler blade behind the face plate was with in specs...... LOL

So I wont get word back until Tuesday - 3 weeks from my initial request......
I assume they'll send out a new unbalanced 4 jaw and perhaps the same junk face plate.

I will keep you all informed - I need a static blancer and do my own balance work.

Thanks

 

[YotaBota]

I'm having a hard time believing all the chucks are unbalanced. When you change a bunch of parts but still have the problem this is pointing more to the machine than the accessory. Having said that it's not impossible, just seems improbable.
Is there someone close to you with the same chuck mount that would let you try the chuck on their machine? Or does KMS have a running floor model to try it on?
With the 4jaw you could try moving all the jaws to the center, then one at a time move them out and in to see if you can get it to stop dancing the machine around.

 

[Proxule]

I'm having a hard time believing all the chucks are unbalanced. When you change a bunch of parts but still have the problem this is pointing more to the machine than the accessory. Having said that it's not impossible, just seems improbable.
Is there someone close to you with the same chuck mount that would let you try the chuck on their machine? Or does KMS have a running floor model to try it on?
With the 4jaw you could try moving all the jaws to the center, then one at a time move them out and in to see if you can get it to stop dancing the machine around.

All chucks are unbalanced until they are checked at the factory, Is that not logical? Same difference as you would check with a surface grinder wheel, Static balance prior to mounting. Naturally the SG wheel being more critical then a 4 jaw.
With no chuck mounted I have no vibrations, Only a slight one at 600 with my 3 jaw, nothing to really chat about. With the 4 jaw body only it bounces it around like jello. So again logically is it not the 4 jaw? ( this procedure has the jaws removed to track down the culprit )

KMS does not have any 1236 lathes in stock, All their china orders are backlogged....

Yes that is a valid option to mode the jaws in and out, Or like another member suggested use the hose clamp method, Or static balance it like SG wheel, or have king send me another casting kit lol

I can assure you its not the belts or the motor, Just finished installing a 3ph motor and VFD.

Thanks for the comments.

 

[YotaBota]

I went back and reread your entries, I missed the part about the three jaw dialing okay. 600rpm seems to be your nemesis on this machine, the vfd will help you tweak to either side of that rpm. Hope King comes thru for you.
Our local KMS hasn't had a lathe guy for a long time, I rely mostly on this site and the net for the best way to do things.

 

[Proxule]

I went back and reread your entries, I missed the part about the three jaw dialing okay. 600rpm seems to be your nemesis on this machine, the vfd will help you tweak to either side of that rpm. Hope King comes thru for you.
Our local KMS hasn't had a lathe guy for a long time, I rely mostly on this site and the net for the best way to do things.

No worries, Glad you went back to dbl check. I think the vfd will help like you said. Its whisper quiet and with no belts on I can't tell if the motor is on or off, Other then the vfd whine.

I am grateful for this forum and the members here with in!
Thanks

 

[YotaBota]

How goes the battle?

 

[Proxule]

How goes the battle?

Thanks for asking,
The face plate arrived, Its siting at KMS tools because they failed to send a 4 jaw with it, And then they got wise and wanted to send it but noticed they had no stock, So they requested one from China.
I am pissed with my self for buying king canada, I swore I wouldn't do it again lol.
No sense in running to KMS now to grab the face plate, as I am told the 4 jaw is on its way. I hope?

Keep you guys updated.
Thanks

 

[Tom O]

Did they give you a timeline for arrival?

 

[Proxule]

Did they give you a timeline for arrival?

Yup winter 2027

 

[YotaBota]

That's rude,,,,,,, they could have at least made it spring! lol

 

[Susquatch]

Sorry, I'm a bit late to this thread but want to help.

I feel like it's really unlikely to be chucks since all three have similar vibration nodes. Usually different masses have different vibration nodes even if they are equally unbalanced. Since you changed the belt and motor and since they are silky smooth, I think that's unlikely too.

If you did find an unbalanced chuck, the wheel weight method (installed as close to the gear head as possible) would work well. I've used that for drive shafts and other rotating parts with excellent success - even better than the static balance method you originally asked about. Dynamic balance is always superior to static.

But I didn't read if you ran it without any chucks installed at all. I highly recommend that. You can do it without waiting for chucks. Although you probably don't want to hear it, I am suspicious of your headstock and especially the big gears in there. Of course, there is also the spindle itself.......