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Mini lathe speed and tailstock question

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Jack Tapper13/10/2018 19:55:45
6 forum posts
1 photos

Evening everyone,

I've finally got my 'Warco new super mini lathe' up and running today and after taking some test cuts I have a few questions I'd like to ask.

First, my mini lathe has a brushless motor but still uses a High and low gear selector on the back of the headstock. When I have it in low gear the speed tops out at 600 rpm and in high about 1250 rpm. This seems to be half of what I expected? Maybe I'm missing something really obvious.

Secondly, the tailstock won't hold onto the dead centre unless it is extended about 15mm out. It seems the pin that should push the tool out when the quill is fully retracted is activating way to early.

Any help would be greatly appreciated.

Vic13/10/2018 19:59:17
1775 forum posts
10 photos

Can’t help with the speed but the tailstock issue is quite common. Luckily It’s ok on my metalwork lathe by I have to extend the quill to accept tooling on my WW Lathe.

John Rudd13/10/2018 20:56:36
1242 forum posts
57 photos

Bottom line here, if Warco supplied your machine complain to them about it!

They claim, 1100 for the lowspeed range as a max and 2500 for the highspeed...(figures from their website..)

As for the tailstock issue, if the dead centre is supplied with the machine, tell Warco you lose 15mm of travel...(  in fact with that amount of overhang you are not supporting a workpiece very well....)

Edited By John Rudd on 13/10/2018 21:01:34

Neil Wyatt13/10/2018 21:17:31
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14723 forum posts
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Hello Jack,

Make sure you aren't running the lathe in reverse (you wouldn't be the first...), reverse speeds are electronically limited to about half the forward speed.

You probably have a tailstock dead centre with a tang?

You should find the tailstock barrel is more or less at the zero graduation when the tooling ejects. Use the locking lever to keep it rigid. Bear in mind the tailstock might need adjustment to line up front to back.

This is the way mini-lathes are designed, they are all like it.

If your really want the 15mm you can saw off the tang or get tooling tapped for a drawbar and fit a suitable screw in the end.

Neil

 

Edited By Neil Wyatt on 13/10/2018 21:20:19

SillyOldDuffer13/10/2018 21:52:14
3414 forum posts
669 photos

Tailstock is a non-problem - just chop a bit of taper off. It's allowed when you take up metalwork! Don't take too much off because you want the centre to eject. Overhang is common on the mini-lathe

Not familiar with the brushless mini-lathe but it's odd it's running at exactly half speed. Just a suggestion but could it be the tachometer rather than the motor? Apologies if you know what 2400rpm looks like! However, if the tachometer counts by detecting two magnets rotating on the spindle and one is missing, the tacho will display half speed. Worth a look at the sensor - it may be an easy fix.

Otherwise, new lathe, talk to Warco. You have my sympathy - very frustrating to start by having to sort out a faulty tool. Pain in the rear - but worth it in the end.

Good luck,

Dave

John Rudd14/10/2018 15:49:37
1242 forum posts
57 photos
Posted by Neil Wyatt on 13/10/2018 21:17:31:

Hello Jack,

Make sure you aren't running the lathe in reverse (you wouldn't be the first...), reverse speeds are electronically limited to about half the forward speed.

Neil

My Sieg C3 brushless minilathe runs at the same speed in fwd or rev......

Jack Tapper14/10/2018 16:44:47
6 forum posts
1 photos

Thanks for the reply's everyone,

The dead centre doesn't actually have a tang but my drill chuck arbor does and the quill has to be extended about 30mm for the taper to grab so I'll definitely cut that tang off..

I'm still a bit lost on the speed as I have tried forward and reverse and both are running at the same speed as mention above. I do think Dave might be right about the speed readout.

I've uploaded a picture in my albums of the tachometer sensor. It looks like it is pointed at the 2 nuts on the back of the spindle when there is a dot on one of the nuts. Next time I have the gear cover off I'll check if there is another dot.

I should say I'm guessing the tachometer is optical and looking for the change of colour instead of looking for magnets.

Neil Wyatt14/10/2018 17:20:58
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Moderator
14723 forum posts
628 photos
72 articles

Try running it at minimum speed and counting the revs in one minute that will show how accurate it is.

Michael Gilligan14/10/2018 18:28:44
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11911 forum posts
518 photos

Jack,

I have taken the liberty of cropping and brightening your photo

... hope that's O.K.

img_2365.jpg

.

Sorry, I have no idea what sort of sensor that is.

MichaelG.

Ron Laden14/10/2018 18:50:06
575 forum posts
80 photos
Posted by John Rudd on 13/10/2018 20:56:36:

Bottom line here, if Warco supplied your machine complain to them about it!

They claim, 1100 for the lowspeed range as a max and 2500 for the highspeed...(figures from their website..)

As for the tailstock issue, if the dead centre is supplied with the machine, tell Warco you lose 15mm of travel...( in fact with that amount of overhang you are not supporting a workpiece very well....)

Edited By John Rudd on 13/10/2018 21:01:34

Jack, I agree with John, you should speak to Warco. Not suggesting you would but I wouldnt be tempted to go adjusting or changing anything until you have explained the problems to Warco, you could find the warranty void should the machine have to go back to them.

Michael Horner14/10/2018 19:31:05
188 forum posts
49 photos

Hi Jack

The white dot looks off white and the sensor bracket doesn't look like it is at 90 degrees to the dot. My RPM display is an extra and uses a reflective opto and if things aren't just right can give wacky readings.

Cheers Michael

Jack Tapper16/10/2018 17:56:57
6 forum posts
1 photos

Evening all,

I've found the missing RPM's!

The white dot in my picture is in fact a magnet. There are four in total around the spindle nut but in my case two where partially covered by a black substance.

After cleaning it up the readout is now showing the correct numbers.

Thanks for the help gents, I'm sure I'll be back soon with some more beginner questions

SillyOldDuffer16/10/2018 18:06:21
3414 forum posts
669 photos
Posted by Jack Tapper on 16/10/2018 17:56:57:

Evening all,

I've found the missing RPM's!

The white dot in my picture is in fact a magnet. There are four in total around the spindle nut but in my case two where partially covered by a black substance.

After cleaning it up the readout is now showing the correct numbers.

Thanks for the help gents, I'm sure I'll be back soon with some more beginner questions

Well done. Compared with the faff of sending the thing back that's an easy fix. Another bonus - you're now the forum's leading expert on fixing mini-lathe tachometers!

Have fun,

Dave

not done it yet16/10/2018 18:26:27
2241 forum posts
11 photos

I am wondering what the covering was, that deflected or absorbed the magnetc flux sufficiently. Jack is now a better judge of rpms, too! smiley

John Rudd16/10/2018 19:10:32
1242 forum posts
57 photos

So, was this a machine supplied recently by Warco?

Sort of begs the question about being 'out of the box ready to go'

Neil Wyatt16/10/2018 19:54:57
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Moderator
14723 forum posts
628 photos
72 articles

More likely the sensor had been knocked a bit out of position and you realigned it as part of the cleaning process.

andrew lyner22/10/2018 22:42:24
42 forum posts
Posted by Neil Wyatt on 16/10/2018 19:54:57:

More likely the sensor had been knocked a bit out of position and you realigned it as part of the cleaning process.

I think that's very credible. There aren't many 'substances' I can think of that will act as a screen to a magnetic field when applied as just a small piece at the front. If you wanted to screen the sensor coil from a passing magnet you would need a big clunky piece of mu metal. wink

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