Lathe start-up speed best practice.

Folks - I've recently been fortunate enough to buy a used Warco WM180 in very nice condition for my first lathe.

And I'm wondering -

What is best practice with a variable speed lathe such as this -

Turn the speed down to mimimum before stopping, and start at minumum when starting up again, or just stop and start at whatever speed you are working at?

Which is best for least stress and longest life for the control board, motor, etc?

Martin.

Martin, you ought to follow the manufacturer/supplier's recommendations to ensure longevity of the control board/motor......

Hi Martin,

On my milling machine with a brushed DC motor I turn the speed down before turning off, and start at low speed and turn the speed up to what I need for the job.

Thor

Hi Martin

​I have a WM250V-F I always do an initial start up from lowest speed available, then ramp up to speed needed for material, then I can stop /start as req'd, & when finished finally ramp down to lowest speed before switching off... similar to Thor I guess.

George.

If it's a machine that 'remembers' the previous speed it should ramp gently up to running speed which will avoid any stress on the motor or electronics. My SC4-520 and the inverter on my mini-lathe both behave like this. They both require me to start from zero on a fresh startup or if the emergency stop has been pressed.

In contrast, my mill (and the mini lathe as supplied) forces a start from zero rpm at every start.

Non-variable speed lathes always start at flat out, and even if equipped with a clutch this does (strictly) limit how many starts they can do in an hour.

Variable speed machines which ramp up the speed can generally start and stop as often as needed as long as the ramp up is not too fast.

Neil

One would hope that the controller is designed for a soft start and stop - certainly my VFD is. That way you just hit the button and the electronics takes care of it. But if the lathe is cold, it may be worth starting it slow and letting the bearing lube warm up before increasing to cutting speed.

I just start my WM280 at whatever speed I want it in seems to have survived almost 10 years use that way same with the X3. Neither ramp upto speed though the newer brushless SX2.7 on test does.

Thanks folks all.

Looks like we're fifty/fifty on this, and no-one's said that they've blown up their pride and joy by starting at full speed, so I guess it's "do what you like".

The point about starting up a cold machine slowly to allow lube to circulate is a good one though and I think that swings it for me -

A slow down to stop and a speed up to start it will be.

Thanks again,

Martin.

The low risk option is to manually ramp up and down from the lowest speed setting. Doing so makes no assumptions about the electronics fitted to your particular machine. Early Chinese controllers were primitive. Later ones are much better. Unless the manual says otherwise it's safer to assume the electronics are delicate and treat the lathe with respect.

Dave

Thanks Dave - yes, that's my viewpoint too.

I've played with electronics all my life, been a licensed radio amateur for fiftytwo years, so I tend to treat any electronics with respect, knowing how easy it is to get them all upset!

So, taking the lube point together with yours, it seems wisest to ramp up and down, costs nothing and may be of benefit.

Martin.

Just like not tuning for minimum SWR on full power! Those transistors don't like it up em!

Dave

Here is one to throw into the mix.

The DC motored variable speed machines are generally accepted as lacking torque at lower revs so what is the best when starting up the machine when you have a large chuck or piece of work mounted - use a speed setting where it will have the torque to get things moving or start up at the slowest speed where it may lack the guts to get things moving quickly and draw excessive current

Answers on the back of a control board please

Hi I have been fiddling with variable speed DC drives for a number of years now and found that controllers that the ramp up to speed with variable adjustment will give the best service.

Read the manual for your machine and follow the instructions there are far to many speed controllers out there to be able to offer a universal answer covering all.

If you have deep pockets go for an industrial controller rated for higher power than the motor Horse Power.

Properly adjust the settings to suit the motor then you can expect a long and trouble free life from it.

I have a clutch on mine ,on start up motor just driving itself really, when up to speed ( which only takes a millisecond ) operate clutch and hey ho off we go, clutch means I can stop the motion without turning motor on and  off all the time. Mine is an older m/c not sure what more modern types have

Mick

The advice given in the operator handbook for mini lathes with brushed motors, is always to set the speed control to Minimum before starting. This has been my practice, and for the little use that the lathe has had, (and its previous owner) without damage.

From what I've read on this Forum, failure to do this is likely to result in damage to the control board. It seems to blow the output FETs, and result in a bill near to £100 for a replacement board.

Inverter VFDs are usually programmed to ramp up the speed from Zero to the selected level over a few seconds.

(Mine has survived fourteen years of casual abuse, without problems; so far!)

My advice? Err on the side of safety, and always set to minimum before shutting down, or starting up.

Howard

Good morning all.

There's no mention of the best way to start up my machine in the Warco WM180 Operator's Handbook unless I'm selectively blind, but it's clear that ramp up/ramp down is the method preferred by the majority and the one least likely to cause undue wear and stress, as well as giving lubrication a chance to spread around, so that's what I'm going to do.

Thanks all for your advice and opinions.

Martin.

The manual I found made for a dodgy startup in my mind so had kept quiet.

1 Switch on

2 Select forward or reverse

3 Adjust speed.

Would have preferred number 2 to have been first but......?

Brian

Edited By Brian Sweeting on 08/12/2017 14:39:09

I've looked at the manual for my Warco WM250V and can find no instructions suggesting any order of setting speed and switching on. There is no zero speed - minimum is about 180 rpm in the higher range, and that's just slow enough and torquey enough to screwcut 1" x 8 TPI BSW, which is the biggest I've done yet on that lathe. I've had no reason yet to change to the lower speed range.

Mostly I just switch on at whatever speed is set, and adjust if necessary.

The titchy Sieg C0 I also have enforces a zero start simply by having no separate on/off switch - you've no option but to start by turning up from zero.

The manual for my milling machine says :

"The (speed control) knob should be turned to zero each time the machine is stopped. Always start the machine with the knob set at zero."

So I have tried to follow the advice given by the manufacturer.

Thor

My mini-lathe wouldn't start unless you turned the speed to minimum.

It only soft starts now because I have an inverter on it.

Neil