Lathe Rebuild

[Oka]

I have a Delta Lathe, the model 46 525. I modified the unit with a 2 hp 3ph w/ VFD.

Anyway, the bearings were getting noisy (they were always noisy), so replacing them (6205zz and 5205zz).

Since I am there- I am thinking I might want to change the pulleys to double belt type. Any concerns with this?

The other question: anyone have any comments or experience changing the ratios on these?
I am thinking of changing the aspect from 2" motor to 5" spindle pulleys to - 3" to 4.25" . This would allow the motor @ 100% (3450 rpm) top spin the spindle roughly turn @ 2400. The original motor was 1 hp I figure there is enough torque with the bigger motor to accommodate.
I don't do pens, so I cannot think of any other instance where I would need a higher rpm.

Ideas, reflections and comments appreciated.

 

[Mike Davis]

If you go to a bigger motor pully won't that speed up the spindle?

 

[smallboat]

In isolation yes. But he is looking to change both. His drive ration will drop from 2.5:1 (5” spindle pulley and 2” motor pulley)to 1.41:1 (4.25” spindle pulley and 3” motor pulley). Fewer turns of the spindle for each turn of the motor.

That’s if I’m reading Oka’s note correctly. I might have got it wrong

 

[bob vaughan]

One of the big noise makers with that VS lathe can be the middle pulley when the moveable middle sleeve's bore begins to wear. (304 on the parts illustration)


Also, I thought that 1750 was the standard RPM for that lathe.

Were you thinking of deleting the variable speed middle pulley and replacing it with fixed diameter pulleys?

 

[Oka]

The variable center pulley I removed at the 1 conversion. The noise is because the bearings were shot. But yes the original set I had after changing to the vfd system was 5" spindle and 2 " drive.

Just wondering 1. if it would be beneficial to add double belt system and 2. what would I turn higher than 2400 rpm?

 

[Mike Davis]

Most of my turning is in the 400- 1200 rpm range.

I don't think there is enough torque to worry about double belting.
A link belt will run smoother.

 

[bob vaughan]

Engineering out that 2" motor pulley will go a long way to smoothing things out when using standard V-belts (A section, 4L section). A three inch pulley will be much smoother.

 

[John Jankowski]

Just want to make sure you realize that currently with 2:5 pulley you are running the spindle at only 1380 max rpm using a 3450 motor. You will be speeding the max spindle speed using 3:4.5 pulley ratio to as you said to approx 2607 rpm.

Larger motor pulley = faster spindle speed. Smaller spindle pulley = faster spindle speed. You have both and nearly double the speed.

Very rarely do I go above 2600 rpm on the lathe except for some spindle work. The faster speeds do give you a smoother cut if you know what you are doing.

 

[Oka]

Thanks all - I got what I need , appreciate it