Solenoid issue.. 5

[itsmoked]

Why me?

I get called out to a job.
"I got a new machine,(used 1980), and it doesn't work, can you take a look at it?"

I get there and it's another press...

I start trying to understand it. Very strange. Belgium made.

It has two giant solenoids mounted up top. One clicks appropriately and the other is dead silent. It also smells as I get near it. Bad. No, Very Bad.

It has a name plate that sez STROKE: 8x2. Whereas its neighbor which is shorter sez STROKE: 8

This one has 4 wires the other has two. So I guess it has two coils in it.

We dismount it which is a lot of fun (NOT!) as it is integral with a huge solid steel spool valve that resides below the surface of the oil tank. But we get it pulled.

We get the case apart which requires grinding as some inconsiderate engineer had the ends swaged.



Here's the result (thumbnail):

Non thumbnail:

http://files.engineering.com/getfil...c-451d-8e43-819b11671f49&file=Sol_rebuild.JPG

It's not pretty. One coil appears to be OK. It measures 5.5 OHMs.

The other measured 0.1 OHMs.

My autopsy shows that the machine got rained on. This solenoid trapped the water that funneled into it. The slug rusted to the bore. The solenoid was activated and couldn't move. Death followed shortly thereafter. The plastic bobbin totally slumped. The wire lost all its enamel. This resulted in a one turn coil with very big wire.

I had to drill hunks out of the coil to get it loose enough to pry out.

Now I need to repair this. "Hurry, hurry, chop, chop."

The magnet wire measures about 0.033" diameter with the enamel burnt off. I guess this means it's 20AWG

My biggest issues are:

What do you suggest I use to replace the plastic bobbin or where can I get them?

Do I have to somehow count the turns of this mess or can I just wrap as much 20AWG as I can around the bobbin replacement?

Any other pointers will be eagerly snatched at.



Keith Cress
kcress -

http://www.flaminsystems.com

 

[OperaHouse]

I would make the spool out of thin brass tube and sheet stock and then insulate with varnished fish paper if I was in that situation. That would give the rigidity. Dealing with thin plastic is problematic.

 

[LaffeyDD724]

Here is one of many URL's for FISH PAPER.

http://www.electricalinsulationmate...rp=fishpaper&gclid=CKOp6Kvm1pQCFQVxFQodKWbtlQ

Electric motor rewind shops should have it. Tom

 

[ScottyUK]

Tufnol or the GRP equivalent that we call 'glassnol' at work - and no, that's not the proper name - should be easier to turn than nylon. It will definitely have better dimensional stability. Use carbide tooling though - HSS doesn't last five minutes on it.


----------------------------------

If we learn from our mistakes I'm getting a great education!

 

[Skogsgurra]

Good o'l Delrin is also much easier to work.

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[itsmoked]

Delrin didn't appear to take the temperature I looked at. The "Oiled Nylon" I picked is probably similar though.

Scotty the stuff I believe you are referring too is blatantly over priced. I would guess gold plated unobtanium would be less expensive.

OperaHouse; If you'd only suggested brass sooner I would've used it. I could've soldered the whole thing together then wrapped it. Dang.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[LaffeyDD724]

Keith, you are proceeding in the right direction.

Tom

None of us are as smart as all of us.

 

[LaffeyDD724]

I think that with all of the magnetic stress and shifting forces on the coil in the solenoid application that your effort will last longer with the non conductive spool. Grounding should not present a problem in the long run with the non conductive spool, the only concern would be turn to turn shorts and if wound properly that should not be a concern. Check the new magnet wire and be sure that the insulating coating is consistant, no bare spots. It may be a good idea to dip the completed coil in and insulating liquid that will dry rapidly this will tend to lock the turns so that they don't flex under the magnetic stress and help to insure that the magnet wire insulation does not fail turn to turn.
Tom

Tom

None of us is as smart as all of us.

 

[MikeHalloran]

Loctite 290 (thin, green) will wick into a solenoid coil nicely. A spritz of the appropriate Loctite catalyst will then set it up hard. Call your local Loctite rep; they love problems like this.







Mike Halloran
Pembroke Pines, FL, USA

 

[itsmoked]

Thanks guys.

I await the boring bar kit and holder for my mini lathe. Having to cut the inside 2-3/4" deep presented an issue for my lathe. I only have 1/4" cutting tools and they sure aren't up to reaching 3 inches down a bore.

My tool holder is a 5/16" (odd size) and long boring tools rapidly get larger in diameter to be stiff enough. Turns out I could get an adapter that will hold 1/2" tools so for $25 I have a set of boring tools and the adapter on the way.

Of course UPS doesn't get the material up here in one day,(ground), like stated..

I'll lob in some pictures as I proceed. Eudmacation like.



Keith Cress
kcress -

http://www.flaminsystems.com

 

[edison123]

Keith

I am sure you love getting your hands dirty. But wouldn't it be cheaper to buy a replacement coil from the OEM ?

 

[flexoprinting]

Hi edison123

I think Keith enjoys the challenge, his answer to my similar question was cost and time. We had a comparable situation and because it was a "Hot job" our company had to pay dearly for a rewind like Keith is doing. Otherwise the OEM could not get us a part for eight days.

 

[itsmoked]

I finished the coil. Here's some pictures that you may find interesting.

This shows the wire, a set of boring bars, a boring bar holder, and a 26" piece of Nylon 6 Oiled. It's green!!

This is the plate I'm going to bolt the chunk of stock to.

Like so:

This is a chunk of it. I gave myself very little to spare. It was nasty to cut. I used a hack saw till I was bored. Then switched to a wood band saw that would cut 1/32" before stalling. I essentially hacked it off using the band saw like and axe. That's what it seemed like anyway.

Oh ooh.. This is not good. I am so screwed! Look how little material is available to screw into. No way!

Turned out I had some inside jaws I didn't realize in a second three inch chuck I have. Wow total luck. It saved the day. Other problems were that the tool rest on these little lathes don't back up farther than the chuck radius! Why?? They think all people want to do is turn little rods??

Anyway after disassembling the entire tool holder and compound slides I was able to reassemble them with one bolt holding everything together allowing me to back the tool holder back enough to clear the work.

Here we go! What's it like turning this stuff? Different. Instead of the lead breaking off constantly like steel or auminum it never breaks. Ever! It then catches on the work and wraps around it. I had to stop about two times a pass and cut it all away with a box cutter.

Note the pileup in the chuck. What a pain.

Never EVER take a thin cut to clean up your Nylon!! This was a 3 mil pass. The lead came off and melted right back on. That's the light stuff. I had to scratch it all off. Every mm.

Now that I have the cylinder actually a cylinder it's time to start the figuring. I use a cut off tool to dive into the work piece to delineate the various areas. Notice the groves? Those represent the ends and the cut off from the stock. I had only about 1/8" of an inch available after all the material I had to remove from the ragged sawn end.

Here I am tediously making passes as I remove material. I had to remove 3/4", 0.030" at a pass. Each pass took about 4 minutes. Stopping to cut off the lead.

In desperation after hours, I tried to just plunge the cut-off tool in as it really seems to cut the material off. Turned out to be less than effective.

Still slogging along.

And slogging.. (AM)

Finally done with the outside figure. Time for the inside. I must remove 0.300" and the boring bar is only allowing me to remove 0.005" a pass. ARGH!!

Since the lead now can't wrap around the work piece it decides to just shove ahead of the tool. At the very bottom it pops off the walls to make a delightful snarl around the tool. Oh joy! Eventually I was able to stop this.

Here's the rusted up mess of a slug for the inside.
I tore this apart, having to dremel all the burrs and mangling off that the guys caused trying to get the solenoid apart.

Then I chucked it in the lathe to turn the rust off of it. It was looking bent all to heck! I had to just use emery cloth and a hand file. Then when I went to assemble the unit it jammed up horrendously. Turns out the long end was badly bent; out of coax 0.070" I ended up using a straight edge, a heavy vice, and a 2lb ball peen hammer to whack it with, to get it all true again.

Back to boring. Final pass. 0.300 / 0.005 x 5 minutes = 300 minutes <groan>

Yes! Time for the cutoff!! Note the distance from the face to the chuck jaws. Man that was close.

Bobbins R us.

Here is 32gallons of Nylon thread I made. Most of it passed directly thru my hands as I tried to keep the lead fed into the can rather than wrapping the work.

Fully loaded. Next to the worst calculator HP ever coughed up. (like a hair ball) To wrap it I chucked it into the lathe again and ran with it. I could never get more than four layers nested before it would go random on me...

Screw it: Random it shall be. Random it became.

I counted the turns in the ruined mess. It took about an hour. Turns out it was either 1033 turns or 933. I wasn't sure if I did 700 twice or not. My intention was to wrap 1033 then measure the resistance and peel some back off if required. This whole plan crashed and burned.

I could not slow my lathe down enough to humanly be able to count the turns. It was just on the edge of possibility but coupled with everything else and having the wire in my hands it was too much to handle. I decided that 82 turns per neat wrap layer was how to count them. Then that all went to hell.(random) So I ran my whole 900ft reel onto the bobbin.

Here's a close up. I decided that if a change was needed I sure didn't want epoxy in the picture so I just wrapped it with tape tightly.

I then decided to compare the original and mine. Turned out I bought 20AWG and the original was 18AWG!! Ah man! After mike-ing it umpteen times too. It was never a solid number seemed between the two sizes but afterwords the burnt stuff all seemed to measure 40mil <18AWG> when before it measured 37mil 20AWG is 35mil. Oh well. Probably over designed anyway.

I hooked a 100W bulb in series with each coil and turned them on. Mine was a little dimmer. Not too bad. Less wraps but smaller wire. Then I stuck the slug into the cores. The light dropped to about 60%; mine 50%.

Current <no slug> 0.6A; mine 0.4A hmmm.

Lets proceed.
I assemble the unit - lots of hassles there. Bent shaft etc.

I hold the whole 40 pound solenoid together with a clamp.

Hit a coil with with 120VAC straight. The shaft creeps out anemically. What!! This is totally, massively underwhelming! I can overcome the shaft with my fingers. With either coil.

I call the client and tell him.. "This looks bogus." Can you look at the machine? Maybe they feed these 240V?

"The transformer feeding them sez 24V."

That would be even less pull than now. Unless it's DC!

I drag the unit over to my 1kW DC lab supply and set it to 12V. POW! Scary. I can't even begin to budge the shaft. I'm afraid the clamp couldn't even hold the thing together at 24V.

I TIG weld the ends on. So nice. You can TIG weld things so fast you don't have to worry about the innards being torched.

I took it over today(Mon) and assembled the spool valve to it, and reinstalled it into the machine. We got the machine running to the client's massive satisfaction. He told me he just got a quote from the factory for a replacement for just the solenoid (62kilogram force) from Belgium.

$7,000.00

He's a happy camper.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Skogsgurra]

I told you - good old Delrin is easier.

Great job, though. And a very entertaining read, too!!

Smoked, the guy that makes it happen - or smoke!

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[LaffeyDD724]

Bravo, superb and magnificent, great job. Looks like a factory made item and performs like one also.
Keith, I salute you, you are true to the electrical arts and definitely have the go getter sprit. You have sucessfully climbed this mountain and now await another daunting challenge. A+
Tom

None of us is as smart as all of us.

 

[waross]

Nice job Keith.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[roydm]

Great story and pictures Kieth, your medals in the mail.
Roy

 

[cswilson]

So when are you going into mass production on these?

Curt

 

[flexoprinting]

Hi Keith

Thanks for the great read, You know with the addition of the lathe to your tool box your getting more like Norm Abram every day!, although I've never seen an oscilloscope in the New Yankee workshop.

 

[itsmoked]

LOL,
Thanks guys.

Curt. When the marketing is in place. I'll sell them for only $6k! I'll make a killing. Hopefully the market is greater than I perceive by the large metal tab spot welded to the side of the machine with the number "009" stamped on it.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[ozmosis]

Great story Keith. I hope you made a spare!
not sure about operating a lathe and a camera at the same time..