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

 

[roydm]

Suggestion No 1 - make bobbin from layers of Armature paper or that red insulating fiber supported by a temporary steel insert to stop it swelling while you re-wind. Once rewound impregnate the coil and bobbin with epoxy to make it solid then remove the steel insert.
No idea how you are going to fix that steel housing however.
Suggestion No 2 - take it to your motor rewinder, let them deal with it.
Have fun
Roy

 

[Skogsgurra]

Yes - that's important - have fun!

Agree in all other respects, too.

Gunnar Englund

http://www.gke.org

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

 

[Skogsgurra]

Hey!

Do you know the manufacturer? I can speak to Belgium if you don't want to. UPS/FED/DHL, whatever can get the thing to your place in 24 hours.

Gunnar Englund

http://www.gke.org

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

 

[waross]

The number of turns is more important on AC than on DC. Not to say that the number of turns is not important on DC. On DC the Amp Turns is mostly determined by the wire gage. However, the more turns you can cram on, the higher the resistance and the less the I[sup]2[/sup]R losses.
AC is more fun. The induction and the inductive reactance are proportional to the square of the number of turns. Now more turns means less Amp Turns.
BUT, I would not count the turns, but find some way to estimate them.
On the other hand, I would step back and see if another method may be found to operate the valve, which is the primary task.
I always try to remember to step back and look at the whole picture. Often there is nothing to be gained, but sometimes plan B saves a lot of time and money.

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

 

[LaffeyDD724]

Save all of the coil wire, get it together and weigh it. You know the wire size, therefore the weight will give the correct turns ( or very close) if you use the correct size form and correct wire size you have it. Weigh the new wire and put the same weight of the same size wire on the repaired form. Tom

 

[BobM3]

-less the weight of any epoxy or varnish on the removed wires.

 

[LaffeyDD724]

Take the bobbin to a machine shop and have them turn a new one from something like nylon stock or other suitable material. Tom

 

[waross]

I like LaffeyDD724's weight suggestion, Keith. I have had good luck measuring wire by weight on a good scale.

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

 

[roydm]

With all that scrap copper, you might just about afford a beer.

 

[itsmoked]

Great suggestions.

We have a pretty good motor shop here. Problem is they are a motor shop not a solenoid shop! They don't have any bobbins. Once the bobbin is squared away it then just becomes a coil winding exercise.

I haven't thrown the wire away. But I would need to sweep up piles of drillings. I was VERY careful to leave one side of the coil relatively undamaged so I could saw it in half and count the ends in one face. (oh boy!)

Roy; Thanks for the coil form idea. Now I need to find the armature paper. ??

The alternative is to machine it out of Nylon. (Thank you Laffey)

Keith Cress
kcress -

http://www.flaminsystems.com

 

[bklauba]

Keith,

Your motor shop will have the armature paper, most EASA shops stock 3-4 thicknesses.

BK

 

[LaffeyDD724]

If you get a bobbin made from nylon or other suitable material it would be rigid enough to chuck in a lathe and you could wind the solenoid yourself. Tom

 

[LaffeyDD724]

Keith, Please let us know how the repairs went with the solenoid. Tom

 

[itsmoked]

Update:
Motor shop nixed the armature paper as a major PITA with high failure likelihood. This, while standing in-between bins of armature paper.

I think it could be done but the ends to hub connection do actually pose a real pain.

I decided to go with a form.
The form needs to be;
OD: 3.925"
ID: 2.220"
Long:2.65"

A 26" piece of Nylon 6 tube with a 4+inch OD and a 2-inch ID has been ordered. +$100

A purely dimensional calculation came up with 1,017 feet of wire. A 900ft and a 500ft spool of wire have been ordered.

I'll use my flat work plate and bolt the material to it.

I'll lathe the ID up to that required and lathe down the OD. Then I'll carve out the Wirespace. At that point I'll wind on the new wire.

Once done I'll use a cut off tool to cut the work off the flat plate the correct length.

I'm awaiting the material.

Tomorrow I'll count the actual turns of the ruins.

Standby.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[flexoprinting]

Hi Keith

Some really great ideas here, I learn and always enjoy reading these. But need to ask.

What kind of press is this? possibly someone out here would recognize it and get you a part number. Also I was wondering why you could not consider the load and upgraded the cluster stuff solenoid.

 

[itsmoked]

Hi flexoprinting.
It's a press-brake. You know, a wide Guillotine looking thing. It is used and I don't remember the make. I could ask, or drive over and look but..

Gunnar has offered to talk to the Belgium factory but buying Euro based custom made parts and then next day airing it,(60 pounds), from Belgium to California so I actually have it in 5 or 6 days doesn't compute,(at all). It would be likely cheaper to replace it with OTS items. (see below)

I dialed up my hydraulics pro and ran an upgrade past him. Besides it being a plumbing nightmare to shift to a conventional valve he estimated 40~60gpm and said it was going to be in the $800~900 realm.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[BobM3]

So, what is armature paper?

 

[itsmoked]

Think "gasket material". There are different varieties but it is just thick brown porous paper around 0.010-0.030" thick

Keith Cress
kcress -

http://www.flaminsystems.com

 

[LaffeyDD724]

Armature paper or motor stator slot paper is refered to in the industry as FISH PAPER. I think that is what is being talked about here. Tom