Help with my spydermag

[wjr]

I did a flipped noid mod on a spyder clone frame and Im faced with a problem. I've heard that the solonoids plunger should have some pre travel before it hits the sear. To allow for pre travel I will have to shave a little off of the plunger. Will this in any way be bad for the solonoid? Am I even right that allowing pre travel is best?

[RapidTransit]

I'm not sure but it maybe good or bad these are the options:

Have a small gap for tolerance issues, metal will expand and contract as you know this would give it some room for any of that the noid will probably get hot itself and guarentees trouble free operation.

The strength of a solenoid is not the same i'm takin a shot in the dark but I think it might be inversley proportional to the distance traveled squared. It would also slow down the speed just a little bit but not by much. You wouldn't notice. A DMag has a gap and those rip

The ideal situation would be to clevis mount the noid ram to the sear.

[Arstron]

I am not sure what way is better, but I have built a few reverse solenoid frames and I have always had the plunger touching the sear. I will have to try setting my plunger so there is a small gap between it and the sear and see how that goes. Luckily with the solenoids I use I can adjust the length of the plunger without grinding.

[the electrician]

the reason you would want pre-travel of the solenoid plunger is solely about momentum. it has a chance to gain momentum and use the wieght of the plunger to help with the force generated to move the sear. does it helpwith some designs? yes it does. this application? probably so.

what is the disadvantge? wear.
the sear is much harder than the solenoid plunger. pretravel will cause the end of the solenoid plunger to start deforming. a possible solution to this?a small hard washer secured to the end of the solenoid plunger.

[wjr]

How would you suggest securing it?

[the electrician]

well it's just one idea. you could just super glue it on there. the washer will wear a lot slower than the plunger, and it could be cut off with a razor and replaced if need be.

the other option is drilling and tapping the end of the plunger for a setscrew. loctite the set screw where you want it. this would also be replaceable. not as much surface area to absorb wear, and more work, but adjustable.

there's probably other simple methods too.

[wjr]

I think Ill just leave it the way it is for now. If it gets worn down alot then Ill explore differant ways of reinforcing it.

[benzy2]

In some applications the extra plunger distance hurts it. Look at spyders. If you have the problem that the gun doesnt fire consistantly then you shim the noid closer so it has less distance to travel. The real problem I see with leaving extra distance is that any board that doesnt allow for dwell adjustment you will want a short travel distance on the plunger. As true as the momentum claim may be if you dont have enough on time the plunger wont make it far enough to activate the gun. The difference in gap here though is minimal and prob wouldnt show any difference in not being able to consistantly fire. And any board with dwell adjustments will solve the problem as well.

[flyingpootang]

I grinded some off the bottom of the sear to allow space. I wouldn't touch the pin.

[RapidTransit]

the reason you would want pre-travel of the solenoid plunger is solely about momentum. it has a chance to gain momentum and use the wieght of the plunger to help with the force generated to move the sear. does it helpwith some designs? yes it does. this application? probably so.

Are you sure on that? the force of the plunger is less as it moves away from its coil, but then again momentum does = velocity (or speed not sure so dont get technical) x mass its all an iffy subjct. One that I may investegate when I get a replacement noid for my Dmag eventually.

[the electrician]

yes. I'm sure. I'm not guessing.

I've designed few solenoid actuated things in my time. a few of them would not work at all without pretravel. yes the force of the plunger is less as it moves farther out. but your not asking it to do any "work". it only has to move the plunger during the pretavel. this makes the inrush current lower also. this combination of momentum and lower inrush current is what gives more shots per charge when using pretravel.

I designed an electro cocker with a direct solenoid actuated sear that used pretravel long before racegun or the eblade started doing the same thing. the came up with the same results I did.

as far as time goes, yes it can add some time, but that can be offset by the fact that it does not have a load on it when it starts moving. sometimes, incertain applications that makes a difference.

[wjr]

The solenoid that I was using is now broken. I havent even done anything to it. I just turned it on today, and it no longer works.

Is there anywhere I can buy a replacement solenoid? I would try to get one through kingman but I bought it used. Therefore I have no warranty card.

[RapidTransit]

www.solenoidcity.com <-Thats where the E/X Mag Noids came from, also Scenario sells them too