Potentiometers

[ScruffyB]

Hi.

Hope someone can help. I have a Bridgeport series 1 J head 3 phase milling machine and the table power feed is giving problems. I assume the potentiometer as the table will only travel in fast mode, it will not creep along slowly. The pot fitted is a Colvern 1106/9S. 50KK. I am not sure if this is the original pot but it has worked successfully for several years. I have been unable to find a like replacement. Can anyone suggest an alternative.

Thanks in anticipation.

ScruffyB

 

[JimB]

At a quick guess, one of these:
https://uk.rs-online.com/web/c/pass...s=4294465799,4294466032,4294867345,4294882107
will do the job.

However, are you sure it is the potentiometer? Have you tested the potentiometer in any way?

JimB

 

[ScruffyB]

Hi Jim.
There is only the pot and a rapid switch in the control panel. Turn the pot spindle from zero and it starts to work half way round but comes in fast, there is no gradual increase.

My big boys toy is a half size traction engine. If I knew how I would post a photo.

ScruffyB

 

[Les Jones]

Hi Jim,
I also wondered if it was a 50K pot when the question was asked on the "Model engineers workshop forum" last night. I could not find any data on that particular pot and I could not find any information on how to interpret the Colvern coding.

Les.

 

[Colin]

Spray the pot with and oil-based cleaner and twist the pot 15 times.

 

[ScruffyB]

Hi.

Thanks for that, will try. I am a model engineer, my electrical prowess is very limited. I have searched the internet and emailed companies without reply. I have phoned companies and got a who cares attitude. I only got one email reply and that was from China saying the part was no longer made which I had gathered. As you rightly say nobody seems to interpret the Colvern coding. I contacted Bridgeport who were waiting for stock and because I live in France they would not supply to me, they say I should contact the suppliers in France. I asked who they were and I was told they did not know. Now how bizarre is that.
My machine is not working properly so I cannot continue with what I am doing so I am in a desperate situation. It is just daft enough that a squirt of WD 40 may cure the problem. Now why didn't I think of that.

Thanks all, please excuse my humour.

ScruffyB

 

[Colin]

I have fixed dirty pots for 50 years. I have never had to replace one. Only when the switch goes.

 

[Les Jones]

From the symptoms described in post #3 I think the track is open circuit near the half way point. If I am right switch cleaner will not fix the fault. Can you measure the voltage between the ends of the track on the potentiometer so we know what wattage rating is reqired ?

Les.

 

[JimB]

If I knew how I would post a photo.

Look at the bottom right hand side of the page, you should see a button "Upload a File", click on that and select the picture file on your computer and upload it to the forum.

JimB

 

[ScruffyB]

 

[ScruffyB]

 

[kinarfi]

google "Colvern 1106/9S. 50KK" and "Bridgeport series 1 J head 3 phase milling machine"
when I googled Colvern 1106/9S. 50KK and what i saw looks like a sealed pot. google Bridgeport series 1 J head 3 phase milling machine and then images and and choose the one that looks like yours, copy the address at the top and post that if you can't get a photo
I guess is that you have a speed control only for the table, probably ac voltage to the drive motor, so you may get by with a dimmer switch feed the motor until you find the right pot to do the job right.

 

[JimB]

Nice traction engine.
JimB

 

[ScruffyB]

Hi P.J.
If I pick something up it is sure to end up on the floor within minutes. The problem now is that everything is on the floor and it makes walking difficult. I will remember what you say.

I have googled the product number for the past 5 days and got nowhere except the threads I have posted. I just need a product number to replace the one I have posted and a company who will send a component to France although I can provide a UK address. The pot is sealed.

Roger

 

[Les Jones]

Googling using the test suggested by kinarfi suggested found the 25K version of the pot on the Farnell website. One of the pots suggested by Clive Foster on the MEW forum looks to be an almost identical replacement.
**broken link removed**

Les.

 

[ScruffyB]

That's brilliant. Ordered and paid for, thanks very much everyone