TR2/3/3A the large Philips headed field screws

[sp53]

I am kinda stuck on these large Philips starter screws because the PO tack welded the screw to the case. I ground off what I could of the weld and then tried using an impact gun and a hammer impact deal, but no joy. I guess I could drill them out or drill the head off then take out the steel piece. Anyways any other ideas before I start drilling.

In addition, would anyone know how much off the teeth of the starter are actually needed on the pinion before there is no contact on the ring gear. It seems to me the starter drive hitting the ring gear would have room to extend as the drive teeth wore down without causing damage. Moreover, it looks like the messing of the gear is only about a half inch. I am saying all this because the pinions are N/A.

I have replaced ring gears before because they wear worn out, but I think it took some time for a defective starter hitting in the same spot before the gear wore down(wish full thinking) wore out. But again, I guess a ring gear could trash out quickly.

Thanks Steve

 

[CJD]

My big gun is always the hammer driver. That is a dirty trick welding them in! Do you have to remove the field coils? You might want to wait for the next rebuild...

 

[charleyf]

I found a picture a number of years ago showing the construction of the starter. It showed how they "screwed in" those large Phillip's screws . They were using a "machine" that had a circular handle about 10" in diameter above the Phillips driver that screwed in those screws. So it was done by hand but the torque created must have been great. No wonder we can't budge them .
Unless you see some damage, there is little to no need to remove the field coil.
Charley

 

[sp53]

I probably need a lesson in electronics because when I hook an ohm meter on the field coil at the main lug with 2000 K ohms, I get a reading of 5.8 ohms. At first I thought this meant a short, but now I am thinking the reading could be correct because of the coils of the field. Is that the case? I hope so because now I can use that field.

Thanks Steve

 

[sp53]

I could not any information on the starter field coils but I found something for the generator. There is resistance in the coils. I am glad you guys said what you did because it slowed me down and I did not try to remove the coils anymore from the starter with the welded screws. I am thinking now the coils are good. They were rewrapped also. the other picture is of one where the coils where burned and arch to the case.

Randall send me a sign


TESTING FIELD COILS. - To test the generator field, you must disconnect the grounded ends from the frame. Place one probe of the test lamp circuit on the field terminal end of the coils and the other probe on the grounded end. If the lamp lights, the field circuit is complete. However, because of the resistance in the field coil wire, it should not bum with normal brilliancy. Normal brilliancy of the test light bulb indicates a possible short circuit between the coils of the field. If the light does not burn, the field is open-circuited.



Figure 2-16. - Testing field coils for ground.

A grounded field coil is located by placing one test probe on the field terminal and the other on the generator frame (fig. 2-16). If the test lamp lights, the field is grounded. The ground may be caused by frayed wires at the coil ends. In most cases, grounds and open circuits in the field coils cannot be satisfactorily repaired. The defective field coil must then be replaced.

Test for grounds, shorts, and open circuits in the field coils can also be made with an ohmmeter. The ohmmeter has test probes similar to the test lamp circuit. When these test probes are connected to the field coil ends, the ohmmeter will measure the actual resistance of the coil. If the specified resistance of a field coil is given in the manufacturer's manual, also obtained by measuring a new coil, you can compare values obtained through tests. For example, a short-circuited field coil would have practically no resistance and the ohmmeter would register near zero; or the ohmmeter would register excessively high resistance in testing a coil having an open circuit. By

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[CJD]

5.8 ohms for the fields are good. They use large gage wire, so as long as you have more than 3 or so ohms you are good. In fact, it is best to put new batteries in your multimeter, as testing for such low resistance takes a lot of multimeter juice.

 

[CJD]

Oh, just remembered, if you test from the case to the wire on either side of the fields, you should get infinite.

These are the topics Randall always got mad at me. I look at electrics from a layman's perspective, and he was always much more precise, being a EE major!?!

 

[ed_h]

Sounds like you are past this now, but here is how I removed those screws in the hydraulic press.

Ed

 

[equiprx]

I recently bought some very fine Carbide dental drills for my Dremmels.
The bits are very aggressive, so I don't use them at high speed.
I was able to do some very fine metal removal in no time at all.
They are smaller diameter than normal Dremmel bits but I use a drill chuck.
Something like that would be very easy to work the weld away from the screws.

I am kinda stuck on these large Philips starter screws because the PO tack welded the screw to the case. I ground off what I could of the weld and then tried using an impact gun and a hammer impact deal, but no joy. I guess I could drill them out or drill the head off then take out the steel piece. Anyways any other ideas before I start drilling.

 

[sp53]

Thanks you guys for all the help. I appreciate the ideas and will use them in the future. Hopefully in this situation, I can leave the screws and fields in the case. When I tried to check the case for a short with an ohm meter, I found it confusing because I kept getting readings of continuity where there should be none. I googled around and found this starter field coil test where I hook up one battery lead to the case and then touch other lead to the field winding if it does not spark the field coils are good. The test seems very basic, and I can see how it would clearly show a problem. The ohm meter became confusing.

steve

 

[CJD]

I hear ya'. Most ohm meters suck when dealing with very low resistance.

 

[Sarastro]

They do. But you can get something called a four-wire ohmmeter, which is quite precise in measuring very low resistances. Two wires create a precise current, and the other two measure the voltage across the resistor. the resistance, then, is just voltage / current. You can measure low resistances to several decimal places this way. Unfortunately, I've never seen a low-cost meter with four-wire capability, but I have a couple laboratory instruments, which I bought used on eBay, which do it.

But, back to the subject, I've also been unable to remove those screws. I like Ed's technique, though; I may try it next time.

 

[The Eight]

Leave the field screws alone unless it's absolutely to remove them. I broke a quality screwdriver trying to undo them and ended up drilling most of them out.
The screws, from memory, are 3/8" UNC 60 degree countersink (not the normal 90 degree). I found searching for replacements is worse than finding hens teeth.