How To find a Canary in a 206RB-3

[banjo48]

My good mate has a Consew 206RB-3 in pretty good condition but was in storage for a couple of years by previous owner, It's in excellent condition and well oiled but since fitting a new servo motor, he's being driven mad by a canary squeak at very low speed. He asked me to have a look as he was stumped.

Dead easy to sort I thought, but after spending nearly half a day I'm no further finding it.

As a clue I've managed to isolate it by pushing up on the foot lift pressure bar (the bar that can be adjusted to give more pressure on the lift foot, under the head arm) when I apply upwards pressure to this bar the squeak stops, but after taking it off, oiling everything in near sight it still squeaks. I've removed the foot pressure screw and it's not that.

Any ideas ?

Edited August 12, 2016 by banjo48

[gottaknow]

A lot of chirps come from feed dog to throat plate contact. Not a place that gets lubed for obvious reasons. Way to tell is to loosen the throat plate a bit (both screws) and then sew. If it gets quiet, there's your chirp. You can usually fix this by tweaking your feed dogs side to side a bit.

Regards, Eric

[Art]

If what Eric says doesn't fix it, maybe the smallest drop of 50-100 cSt Silicone oil can help some. I never have gotten off that easy so I pull out the dog and dress it up a bit on a 9µ or 3µ stone (DMT extra or extra extra fine or Shapton 5000 or 8000).  It might be easier to go lightly at the needle plate where the dogs stick through with a ceramic slip stone like you get from CS Osborne or Brownell's.  With repairs, you do the easiest, less time consuming thing first, then work your way along.  Somewhere along the line, things get fixed, or you get used to it.

Art

[Constabulary]

I there a binding when the machine chirps? Maybe a slightly bent slide bar on the thread take up lever? Try some oil on that spot. if there is a binding you have to replace it. May sound stupid but try a shorter stitch length and adjust the foot lift hight. I once had something similar at a friends Duerkopp 239 - just an idea nothing proven.

[Uwe]

I had a similar thing happen to my Adler 205-370 about a month ago, just a few octaves lower. Two days before I was to deliver a custom binding workstation I had built around the Adler, it developed a low-pitched groan when I turned it over by hand very slowly. Something was rubbing that shouldn't be rubbing and it was unacceptable. After oiling everything I could think of and a dozen more places with no improvement, I started disassembling things to see if the groan would stop at some point - it didn't. The machine was in pieces and so was I. The following day, in a last-ditch effort, I took the hand-wheel off and, by golly, the groan was gone! It was so well oiled that I could easily turn it over by grabbing the shaft itself. It turns out the needle position sensor mount was the root cause. I had added a washer because the screw that came with the adapter was a tiny bit too long. Alas, the washer pushed against the hand wheel instead of the shaft. The groan started days later when I went over all the screws one more time to make sure everything was nice and tight before delivery. This last tightening pushed the handwheel towards the housing and started to rub and groan. I changed the screw for the adapter, got rid of the washer and all's been well ever since.

So the basic approach recommended above - to oil everything and then start removing things - is a good, methodical approach. 

Edited August 13, 2016 by Uwe

[banjo48]

Thanks guys for the suggestions, will be visiting again tomorrow so will give your suggestions a go, never thought of the feed dogs and throat  plate, not checked that, will report back.

[banjo48]

Had another play today, it's not the feed dogs and throat plate, and no binding at all, everything is swimming in oil and still the squeak is there !

Even sprayed some aerosol gun lube in hard to see places but it still persists, so mate is carrying on and hopefully it will either clear or become obvious what is running dry, but with the amount of lube we have thrown at it, well I'm just stumped.

 

 

[mikesc]

Try the car mechanic's trick for locating the precise origin ( or diagnostics ) of engine noises ..get a longish straight blade screwdriver put the tip against various places on the bed or machine casing that you think it might be coming from, put the handle end of the screwdriver against your ear ( so that your ear "cups" it nicely )..the screwdriver shaft will amplify the noises ( like a doctors stethoscope ) ..makes them easier to identify and easier to pinpoint where they are coming from..

It is how a mechanic tracks down which bearing is "knocking" etc..

If you live near a medical supply place, you can actually buy a stethoscope ( I have one ) , you don't have to be a doctor or a vet, they are not expensive ( some are , but the cheap ones work just as well )..they are even better for listening to machinery and diagnostics of "what is that noise" and "where is that noise coming from".

Worth checking that any nuts around bushings and bearings are tight..even the slightest play can cause a "squeak" as surfaces that should be "moving as one", instead rub a little..I recently built a speed reducer, mounted it had a "squeak"..turned out I needed to tighten a locking nut just another 1/100 of a turn.."squeak" gone :)

[Constabulary]

is it probably coming from the motor? I´d take of the V-belt and hand crank the machine....

[banjo48]

Constabulary

I did wonder about the motor, it is a fairly new Chinese origin cheapy servo, so could be a dry bearing, will give that a whirl next time.

I'm half an hour away so only visit him a couple of times a week.

Thanks again for the input.

[Northmount]

A piece of garden hose or similar used like a stethoscope works well too.  Helps determine direction nose is coming from.  

Tom