Thread: lathe vibrate at lower speed

If you have a faceplate for it , it might be worthwhile fitting it and positioning weights on the faceplate until the vibrations cease . This might prove if the problem is internal or external

Mike

Originally Posted by thorens

Hi Aaron.
yes it run much smoother when no chuck on .
Peter

OK, so the next step is to refit the back-plate to the chuck in each of the possible positions and see if any of them eliminates the vibration.
Check the runout of the chuck body in each position and the runout of a piece of drill rod at the same time.
If the lathe is new you could ask the supplier to swap chucks.

So have you used the lathe prior to the vibration surfacing,if so was the surface finish better before the vibration surfaced or the same?

Is the surface finish just rough or does it seem to have a spiraled effect?

If it has a spiral effect does the spacing between the spirals change with RPM?

If this effect is present is it uniform along a length of stock at a fixed RPM?

Originally Posted by Gavin Newman

OK, so the next step is to refit the back-plate to the chuck in each of the possible positions and see if any of them eliminates the vibration.
Check the runout of the chuck body in each position and the runout of a piece of drill rod at the same time.
If the lathe is new you could ask the supplier to swap chucks.

well.
i just chuck in two different round stock know to e grounded precision .adjusted the back plate so the stock have almost zero run out .seem to help the vibration a little .
i remember when i facing the back plate to have it run true i didn't tune the outer diameter of the back plate therefore I can see some run out on the back plate outer dia. is this effect the balancing of the whole chuck a little ? which cause the vibration to get worse ?
also i think the chuck body does have some runout as it is a cheap chinese chuck so i don't think i can do anything's about that.
Peter

Is this lathe new or second hand?

Originally Posted by pipeclay

Is this lathe new or second hand?

it is second hand .
brought from Sydney
Peter

Are there spirals on the od of turned stock?

How old is the lathe?

If it has the spiral effect on the machined surface I would be tempted to say either the bearings in the headstock need replacing or at least the spindle bearings need adjusting.

If you adjust the spindle bearings and the same problem still exists then I would suggest changing all of the bearings in the headstock.

One other thing that you could try if this problem has been there since you have been using the lathe would be to put some rubber between the motor and where it mounts against the lathe.

Another thing you could try to eliminate vibration is to remove one of the drive belts if it has 2 or if only 1 take a little tension off the belt.Don't take too much off otherwise the lathe will not have enough torque.

Originally Posted by pipeclay

Are there spirals on the od of turned stock?

How old is the lathe?

If it has the spiral effect on the machined surface I would be tempted to say either the bearings in the headstock need replacing or at least the spindle bearings need adjusting.

If you adjust the spindle bearings and the same problem still exists then I would suggest changing all of the bearings in the headstock.

One other thing that you could try if this problem has been there since you have been using the lathe would be to put some rubber between the motor and where it mounts against the lathe.

Another thing you could try to eliminate vibration is to remove one of the drive belts if it has 2 or if only 1 take a little tension off the belt.Don't take too much off otherwise the lathe will not have enough torque.

good question.
I don't know how old it is. i guess it is around late 80's early 90's. it doesn't have any date printed anywhere.
no it don't have spiral effect when tuning it just not as smooth .
i will play with it a it more and see what it is that cause this problem.
i have a feeling that the mounting arrangement might not be stable enough . may be cross bracing the two cabinets help reduce the vibrations some what.
Peter

peter hi again. I don't think that's the problem.
if you measure the distance between both ends
of the cabinet are they the same top and bottom?
Didn't you say before that the problem went away
with the chuck removed?
did you have a look at the link that cba posted before?

Originally Posted by azzrock

peter hi again. I don't think that's the problem.
if you measure the distance between both ends
of the cabinet are they the same top and bottom?
Didn't you say before that the problem went away
with the chuck removed?
did you have a look at the link that cba posted before?

HI Aaron.
ah yes , but i still feel the foundation is some what not rigid
yes I did read the link Chris pinked and still do .
Peter

fair enough it wouldst take to much to brace the cabinet.
then you will know either way.
aaron

Originally Posted by thorens

well.
i just chuck in two different round stock know to e grounded precision .adjusted the back plate so the stock have almost zero run out .seem to help the vibration a little .
i remember when i facing the back plate to have it run true i didn't tune the outer diameter of the back plate therefore I can see some run out on the back plate outer dia. is this effect the balancing of the whole chuck a little ? which cause the vibration to get worse ?
also i think the chuck body does have some runout as it is a cheap chinese chuck so i don't think i can do anything's about that.
Peter

You've already said that the lathe runs smoothly with the chuck off so the chuck should be your first point of investigation.
If you have runout in the OD of the back plate then that will affect the balance of the chuck as an assembly. Can you re-do the backplate to remove this runout on the OD?
Is there a chance that when you machined the register on the backplate that it's not a snug fit in the chuck body and so the chuck is not mounted concentric to the backplate (in other words, if you loosen the mounting bolts and tap the chuck body, does it move relative to the backplate)?

Originally Posted by Gavin Newman

You've already said that the lathe runs smoothly with the chuck off so the chuck should be your first point of investigation.
If you have runout in the OD of the back plate then that will affect the balance of the chuck as an assembly. Can you re-do the backplate to remove this runout on the OD?
Is there a chance that when you machined the register on the backplate that it's not a snug fit in the chuck body and so the chuck is not mounted concentric to the backplate (in other words, if you loosen the mounting bolts and tap the chuck body, does it move relative to the backplate)?

yes when the chuck unmounted then it is have minimal vibration . i was machine the backplate week ago to get it run true and have the register a little off so i can truing the chuck , it was snug fit before i machine it but the chuck have too much runout hence the operation . i can machine the OD of the back plate to have it run true since it have about 8mm or so bigger than the chuck body .
so to answer your last question is yes i can loosen the 3 bolt and tap the chuck body to move slightly from the back plate
Peter

Not knowing how much runout there is in the OD of the backplate I would take a guess and say it would have to be around 1mm or more to give any significant chance of vibration.

If as you say the backplate is 8mm larger than the chuck machine the backplate OD with the chuck attached,I wouldnt be removing or loosening the chuck seeing you have already set the chuck to be running .04mm.

I would turn the OD at around 150RPM with a tipped tool or your lowest RPM with HSS,feed slow.