Record variable speed
- Thread starter themackay
- Start date
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After a post Chas made (I paraphrase here) about single phase power supply not sitting too well with variable speed control, I was a bit puzzled so I had a chat with the folk at Record.
For my lathe (dml320) they confirmed it obviously was single phase with variable control and a brushless motor. The advice they gave was twofold :
1. Start at low speed and only move up slowly ... the speed control doesmt like the loading of having to power up fast (obviously, again, I'm paraphrasing with my interpretation...but I got the sense of ..just be a bit careful when you turn the speed up ..dont whack it up from off straight to max etc)
2. Give the motor a chance to cool down for say 20mins or so every hour or two. (at low speed obviously there are going to need to be energy losses in the form, mostly, of heat. given how we can all, I guess, quite happily turn for a few hours, that might risk a heat build up etc)
All my interpretation...but kinda makes sense to me.
Not sure it helps resolve any particular problem you may have right now ...but probably worth knowing for any folk who didnt already.
hope you get a practical solution from someone!
For my lathe (dml320) they confirmed it obviously was single phase with variable control and a brushless motor. The advice they gave was twofold :
1. Start at low speed and only move up slowly ... the speed control doesmt like the loading of having to power up fast (obviously, again, I'm paraphrasing with my interpretation...but I got the sense of ..just be a bit careful when you turn the speed up ..dont whack it up from off straight to max etc)
2. Give the motor a chance to cool down for say 20mins or so every hour or two. (at low speed obviously there are going to need to be energy losses in the form, mostly, of heat. given how we can all, I guess, quite happily turn for a few hours, that might risk a heat build up etc)
All my interpretation...but kinda makes sense to me.
Not sure it helps resolve any particular problem you may have right now ...but probably worth knowing for any folk who didnt already.
hope you get a practical solution from someone!
Morning
Does it have this type of speed controller ?
http://www.recordpower.co.uk/category/l ... r-products
If so, it'll be like my CL4.
The chuck started 'jerking' about twice a second. I rang Record Power who couriered it back for repair. They changed the pot. They replaced the faulty one with a wire wound job.
Cheers
Dave
Does it have this type of speed controller ?
http://www.recordpower.co.uk/category/l ... r-products
If so, it'll be like my CL4.
The chuck started 'jerking' about twice a second. I rang Record Power who couriered it back for repair. They changed the pot. They replaced the faulty one with a wire wound job.
Cheers
Dave
Paul Hannaby
Established Member
Keithie":2ryswi49 said:
1. Sounds like they are talking out of their tailstock
The speed controller should be set up to limit the acceleration / deceleration rate to what it can cope with.2. As hobby machines, the lathes are not rated for continuous use so they tell you not to use them continuously!
Neither of the above advice has anything to do with the problem with the erratic speed, which does sound very likely to be a faulty potentiometer. Try cleaning it out with a vacuum cleaner / airline and if that doesn't work, replace it with a better quality sealed version.
CHJ
Established Member
themackay":2wj1at7w said:
As a temporary 'fix' assuming the pot is of a sensible design where you can access the innards, (might not be knowing modern manufacturing methods) try rubbing over the carbon track with a soft 2B carbon pencil. Won't last long but might prove the diagnosis.
Note of Caution:- Did you say this was in your club, not a personal machine ? you might need to be conscious of the liability factors if you 'repair' it.
selectortone
Still waking up not dead in the morning
Do you have a picture of the pot?
In my job as a guitar technician before I retired I dealt with noisy potentiometers on a daily basis. If the pot is an open type, ie there's acess to the innards via a gap where the solder lugs exit the body, you can fix it, albeit temporarily, by spraying contact cleaner in there and then rotating the pot through its whole travel ten times or so. In fact rotating the pot vigorously will often clean it even without the cleaner spray.
Having said that, I'd expect an industrial machine to have a sealed pot which, unless you can disassemble it, will need replacing. If it has a carbon track you might consider replacing it with a sealed pot with a wirewound track (from Bourns for example) - a much more robust solution for this type of application.
You can buy an aerosol can of contact cleaner from places like Maplins.
In my job as a guitar technician before I retired I dealt with noisy potentiometers on a daily basis. If the pot is an open type, ie there's acess to the innards via a gap where the solder lugs exit the body, you can fix it, albeit temporarily, by spraying contact cleaner in there and then rotating the pot through its whole travel ten times or so. In fact rotating the pot vigorously will often clean it even without the cleaner spray.
Having said that, I'd expect an industrial machine to have a sealed pot which, unless you can disassemble it, will need replacing. If it has a carbon track you might consider replacing it with a sealed pot with a wirewound track (from Bourns for example) - a much more robust solution for this type of application.
You can buy an aerosol can of contact cleaner from places like Maplins.
Morning all
Paul
As hobby machines, the lathes are not rated for continuous use so they tell you not to use them continuously!
RP may not have been referring to the CL3/4 machine. The spec. for the variable speed kit says
Cont. rating 380 / 415v 3 phase 50 Hz.
The manual for the CL4 recommends using a fan to force cooling air through the motor if it's running at low speed , (below number 3) for more than 30 minutes.
Selectortone's idea of turning it up and down a few times is worth a try. cPC sell Servisol track cleaner ...
http://cpc.farnell.com/servisol/1000013 ... nsku=false
I've just had a look inside my unit and the pot RP fitted as a replacement is marked
CITEC
TW 1W
10k +/- 10 %
CPC have this one ...
http://cpc.farnell.com/ab-elektronik/ab ... dp/RE04644
and Farnell have ...
http://uk.farnell.com/te-connectivity-c ... nsku=false
They both have linear tracks.
Cheers
Dave
Paul
As hobby machines, the lathes are not rated for continuous use so they tell you not to use them continuously!
RP may not have been referring to the CL3/4 machine. The spec. for the variable speed kit says
Cont. rating 380 / 415v 3 phase 50 Hz.
The manual for the CL4 recommends using a fan to force cooling air through the motor if it's running at low speed , (below number 3) for more than 30 minutes.
Selectortone's idea of turning it up and down a few times is worth a try. cPC sell Servisol track cleaner ...
http://cpc.farnell.com/servisol/1000013 ... nsku=false
I've just had a look inside my unit and the pot RP fitted as a replacement is marked
CITEC
TW 1W
10k +/- 10 %
CPC have this one ...
http://cpc.farnell.com/ab-elektronik/ab ... dp/RE04644
and Farnell have ...
http://uk.farnell.com/te-connectivity-c ... nsku=false
They both have linear tracks.
Cheers
Dave
selectortone
Still waking up not dead in the morning
Deejay":xpjbyeim said:
Important point that - if you get a log/audio taper pot it will work but most of the speed control will be up one end!
Those pots Deejay linked to look just the job.
selectortone
Still waking up not dead in the morning
That is an unsealed pot which will respond to some contact cleaner spray. I'm surprised it's fitted to something in as dusty an environment as a lathe. It is almost bound to fail eventually - even in an IP65 enclosure IMHO. If it was mine I'd replace it with a sealed wirewound pot.
B10K = 10k ohm linear potentiometer.
selectortone
Still waking up not dead in the morning
andygc":2676idpl said:
Yes, I appreciate that, that's why I mentioned the IP65 rating of the enclosure.
However, if you ever open that enclosure in situ that's it - the dust is in there. Very fine dust will also find its way down the shaft of an unsealed pot and thence onto the wiper and track.
Before I became a guitar repairman I worked for several years in the test department of a company manufacturing control systems for aerospace and the military. I understand why the manufacturer uses that type of pot - they are spending pennies instead of pounds. But, in my opinion, that pot is not really 100% fit for purpose in an industrial machine, whether in a sealed enclosure or not. It's just too flimsy. There are reports on this board and elsewhere of them failing.
Treat it gently, regularly brush away the buildup of dust behind the knob, and it will probably be OK if you resist the temptation to open the box and have a look at what is in there. (Who can resist that temptation? :wink: ) But for the few quid it would take to replace it with an industrial grade component, I know what I would do.
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