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Post by nosubfor3 on Jun 14, 2009 5:06:17 GMT -7
How de all. How do you all air gap the arms in a chassis? What tools do you need? What is the procedure ?Can't seem to find any info on the net.  |
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Post by roark69camaro on Jun 14, 2009 7:01:43 GMT -7
hi, i use a diamond file and verners , i messager the in side of the magnet and the arm dia. and flat sand the magnets to come in on the chassis to get closer to the arm, i bring the gap down to .015 a side and put a little dab of supper glue to hold in place. hope this helps
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Post by johnbalich on Jun 14, 2009 8:09:00 GMT -7
Just a note here......Probably many guys are curious about the 'dark art' of airgapping.
Thank you to Roark for jumping on on this one.
There are two phases to the entire operation as I see it.
Many racers will want to sand or polish the edges of the comm plates to ensure a concentric (centered) shape. This assures a constant distance from the magnets, to theoretically equalize the magnetic motor action. It also helps to balance the armature in general. This is touchy work...... I have ruined a handful of armatures trying to get them 'just right.' (Btw this plate sanding is not forbidden by NTRA in Gas Class and is left untouched by the rules in SS class.....therefore a gray area for now.)
If you remove too much material from the arm plates, you can inadvertantly detach the wires that connect the windings to the comm plate. Instant motor death. So if you proceed, do so gingerly. I chuck the armature into a dremel tool ( a drill motor will do fine) and let a very fine grade of sandpaper (say 600-1000) skim the poles as the spin by. This is a 'blacksmith' approach to pole polishing. A lathe is perfect for this, but discouraged in classes below Pro Division, since most don't own a lathe. I'll see if I can find pictures of a 'finished' arm which has had the plates trued in this manner.
The second part of the operation is exactly as Roark has outline it. You are trying to get the magnets as close to the plates as is possible for obvious reasons.
For the geek heads: ( I stand accused as one) Magnetic force obeys the 'inverse square law". Meaning: if you HALVE the distance to the plates, the resulting force is QUADRUPLED.
(1/2 SQUARED = 1/4. 1/4 INVERTED becomes 4/1 or simply, 4.
INVERSE SQUARE law, get it?)
(Before you NTRA guys get greedy, tampering with the magnet mountings is verbotten in classes below Pro Division, i.e. not permitted in Gas or SS)
I hope this is helpful to all who are curious about this topic, and I welcome additions or comments that might shed more light on this.
I also hope I don't come across as a 'know it all.' After almost 40 years playing with these things, I just recently was introduced to the notion of modifying the magnet perches for horsepower gains, and tho I understand the concept, I have yet to experiment with it.
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Post by nosubfor3 on Jun 14, 2009 16:27:52 GMT -7
Roaker,what are verners??
So the basic idea is to get the arm as close to the magnets as possible. With in .015 or so.Lets see if I got this. I would put an arm and magnets in a chassis without a gear plate and measure the gap between the magnets and arm. Then either remove material of the arm or sand the magnets.Does this gain that much performance?
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wood
Pro Stock
Posts: 237
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Post by wood on Jun 14, 2009 18:50:10 GMT -7
I believe he referring to Vernier calipers, predecessor to dial and digital calipers. Either that or he pouring Ginger-ale over his chassis when he's done......... ;D
Really it's a good tip Roark, just yankin you chain a little
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