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WARCO Reversing Problem

Electronics

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Mike Smith 2005/10/2018 14:55:09
3 forum posts

Hi Guys, This is my first ever posting on a Forum, so if I don't get it right, please forgive me.

I am the proud owner of a Warco WM 240lathe. It has had very little use since I bought it new due to work commitments. Now that I have some time to spare I thought I would get down to some machining on my lathe. But when I turned it on it rotates up to the recommended 1000 rpm in forward but only goes up to about 300 in reverse. Any ideas or suggestions would be very welcome

Mike

JasonB05/10/2018 15:00:41
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Assuming it is a DC motored one they don't run as fast in reverse so nothing wrong with the board etc.

Mick B105/10/2018 15:08:47
1187 forum posts
66 photos

Jason's understanding matches mine. I think only the WM<n>V (where <n> = swing in mm) models have the AC motor and inverter to give full speed in reverse.

The blurb on the WM250V that I have appears to support this.

Jim Nic05/10/2018 16:04:39
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My 8 year old WM240 does an indicated 1200 forward and 600 in reverse. I agree that there's probably nowt wrong with yours.

Jim

Mike Smith 2005/10/2018 16:16:57
3 forum posts

Thank you for all the reply's, they have put my mind at rest knowing that it isn't going to suddenly give up the ghost. what a great forum, thanks again!!!

Mike

oldvelo06/10/2018 21:20:56
156 forum posts
43 photos

Hi

Reading through this posting it appears that the control has most probably got a speed reduction built in to it look for a Pot on the board that reduces speed in reverse.

Normally a DC motor will run at the same speed in either direction OR as my own setup with a KB controller with separate controls for forwards and reverse.

Eric

Mick B107/10/2018 09:12:11
1187 forum posts
66 photos
Posted by oldvelo on 06/10/2018 21:20:56:

Hi

Reading through this posting it appears that the control has most probably got a speed reduction built in to it look for a Pot on the board that reduces speed in reverse.

Normally a DC motor will run at the same speed in either direction OR as my own setup with a KB controller with separate controls for forwards and reverse.

Eric

 

If reverse RPM has been deliberately reduced, it makes sense to consider that there was probably a reason for doing so before making mods to defeat it.

Edited By Mick B1 on 07/10/2018 09:14:13

SillyOldDuffer07/10/2018 09:47:48
4708 forum posts
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Posted by Mick B1 on 07/10/2018 09:12:11:
Posted by oldvelo on 06/10/2018 21:20:56:

Hi

Reading through this posting it appears that the control has most probably got a speed reduction built in to it look for a Pot on the board that reduces speed in reverse.

Normally a DC motor will run at the same speed in either direction OR as my own setup with a KB controller with separate controls for forwards and reverse.

Eric

If reverse RPM has been deliberately reduced, it makes sense to consider that there was probably a reason for doing so before making mods to defeat it.

Edited By Mick B1 on 07/10/2018 09:14:13

I've failed to find the reference, but I think I remember that some DC motors are de-rated in reverse because the brushes are mounted offset to increase the contact area in forward. But an offset geometry means the brushes wear rapidly in reverse and the effect is reduced by dropping the speed. Seems reasonable - a motor optimised to deliver max power running forwards with the ability to reverse occasionally for odd jobs. Or did I dream it?

I think the lathe is fine.

Dave

Mick B107/10/2018 10:23:31
1187 forum posts
66 photos

Posted by SillyOldDuffer on 07/10/2018 09:47:48:

...

...but I think I remember that some DC motors are de-rated in reverse because the brushes are mounted offset to increase the contact area in forward. But an offset geometry means the brushes wear rapidly in reverse and the effect is reduced by dropping the speed.
...
I think the lathe is fine.
Dave

You mentioning that has blown the dust off a similar memory of mine. I think that's spot-on.

Or did I just make that up? laugh

John Haine07/10/2018 11:06:04
2607 forum posts
133 photos

How many people have actually done any machining in reverse? The only thing I use reverse for on my S7 is when using an old toothbrush to clean the spindle nose threads so the grot drops off the end rather than being screwed on to the register.

Mick B107/10/2018 11:52:16
1187 forum posts
66 photos
Posted by John Haine on 07/10/2018 11:06:04:

How many people have actually done any machining in reverse? The only thing I use reverse for on my S7 is when using an old toothbrush to clean the spindle nose threads so the grot drops off the end rather than being screwed on to the register.

I certainly make frequent use of it - mostly for chamfering on the far side, reversing taps out of deep holes and sanding wooden turned surfaces.

Oh, and screwcutting on continuous engagement.

Edited By Mick B1 on 07/10/2018 11:55:15

JasonB07/10/2018 13:30:40
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I do it quite a bit - upside down boring bar to reach around the edge of a flywheel. - Cutting matching tapers without moving the topslide where the bore can be done forwards and the make part at the back of the spindle in reverse. - Also can be easier to see what you are doing when boring say a valve seat down the end of a hole. Threading away from a shoulder - the list goes on, suppose it just depends how much you actually get upto in the workshop

Helps that I don't have a screw on chuck to worry about dropping offwink 2

Mick B107/10/2018 15:30:00
1187 forum posts
66 photos
Posted by JasonB on 07/10/2018 13:30:40:

...

Helps that I don't have a screw on chuck to worry about dropping offwink 2

I had a Myford Speed 10 for 15 years that ran (as far as I could tell) just as fast in reverse as forward, and I was of course aware of that as a theoretical risk, but nothing like that ever actually happened during the ops I did. Perhaps I was just pussyfootin'... smile

Neil Wyatt07/10/2018 15:54:56
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Screwcutting, so I never have to worry about dials or if it's imperial or metric.

Neil

Mike Smith 2007/10/2018 16:42:21
3 forum posts

Hi Guys, just wanted to say thank you for all your help regarding the reversing problem with my WM 240. I have to say you were more help than WARCO were, I sent them three e-mails over the last two months, with no reply to any of them. They took the money for the machine quick enough though.

Mike

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