I'm almost caught up! A couple more posts and the backlog will be gone!
I posted the tentative design decisions in posting #29. If anyone has comments or wants to point out an error in my logic - I'm open to suggestions.
Now for the motor. Referring to the video linked in posting #27, at about the 4:15 mark I ran up the Netgain motor and was not happy with the noise that the motor was making. The sparks coming from the commutator (where the brushes contact the armature) and brushes were a bit unsettling as well.
Going through the EVTV index, (
EVTV Motor Verks | Electric Car Conversion Videos) I re-watched portions of the March 30, 2012 show where changing of the brushes is discussed for a netgain 11 inch and a netgain 9 inch motor. It appears that the noisy brushes are common when the brushes have not been 'seated' or worn into the curve of the commutator. I was also concerned that the brushes may not be installed in the same direction as the rotation. After watching the EVTV episode again, I realized that Jack Rickard has that concern. I likely learned that concern from him.
Another nugget of information - there is a CW, N, CCW stamp on one side of the stator that shows if the brushes are in the N for Neutral position, or advanced 12 degreees Clockwise or Counter Clockwise from the drive end. So I located the stamps on my motor and it is in the CCW position now. I think that it may be OK to move to Neutral position since what I've read is that there is no need to advance the brushes when you are below 96VDC. I have tentatively set up for 72 VDC but it may go down depending on how much room is left for the batteries in the Electric Motor Module frame when everything else has been mounted.
There ARE directions from Netgain on how to change the direction of rotation for the motor and that does not include removing the brush holders and re-installing them a different way. Jack Rickard specifically mentions that the Honda engines and transmissions rotate Clockwise from the drive end and that is different from most other manufacturers.
I started with the motor on a low cart. After coming up empty on ideas to lift the motor up onto my work bench without needing to use my back ... I picked it up and raised it to waist level on my Black & Decker workmate (NG9_lift). I could have worked on the motor at that level, but the lighting is not as good. I then lifted from waist level to the 40 inch benchtop (NG_lift1end).
With the motor rotated to give me access to the non-drive end, or commutator end, or auxilliary end, I first removed the shroud NG9_brush_end_shoud, NG9_brush_end_shroud_removed).
Then I removed the 4 allen head screws (1/4 inch) and set them aside (NG9_remove_brush_end1). The next challenge is to remove the end of the motor complete with brushes. First I needed to remove the cable terminated to A2 (NG9_field_cable_A2). Then I tried a simple pull and that did not work. So I did what I normally do while thinking - I did documentation. Use a jiffy marker to mark the end bell and the housing so that I can align them again. Draw an arrow to one of the bolt holes that is NOT used with an X and the one that IS used with a check mark. To get the end bell off the motor, the motor (or at least the end that I'm working on) needs to be off the bench. Find some scrap wood to elevate the one end. It is bevelled (45 degrees) so it also keeps the motor from rolling from side to side.
Inspiration was not to be found so I went onto the net and looked for instructions on how to remove the end. I found a video that showed a gear puller being used to push against the shaft while pulling on 3 points of the housing. It did not take more than 4 turns on the gear puller (after it was snugged up against the frame) to break the end free. After that the video showed pulling the end bell off by hand.
I don't have a gear puller. I don't know anyone who does. But if I can put something ... about 2 and 5/8 long into the vent holes between the end bell and the stator I should be able to put a bit of force into prying them apart. And if I pry on both sides at once, I should not damage the bearing.
A search for some tool that fits the bill yielded a 3/8 socket wrench with a shallow socket fitted. I looked around and sadly do not have a second 3/8 socket wrench (NG9_pry_with_socket). BUT I have a 1/4 socket wrench and a deeper socket that should work. Putting the wrenches in place on opposite sides of the motor and giving one quick push popped the left side but not the right side. Switch the wrenches around and try again. Now both sides have released - sorry, forgot to take a picture.
I should likely remove the brushes before I take the end off (NG9_brushes, NG9_brushes_bad_angle). The springs are clipped into the spring holders and it looks like it should release with some pressure on the spring toward the motor and a screwdriver pushing the clip side toward the brush. This does not work.
Back to Jack's video. It appears that the spring is forced out of the way and the brush can be pulled out ... but the brush holders are a Helwig design not the stock Warfield brush holders. Well, I'll try it. If it fails, it fails. Another search of the web give very little for results. Perhaps for most mechanically-minded people this is obvious. I am not very mechanical.
It turns out that the spring can be forced out of the way on the stock Warfield brush holders ... Jack used a tool that looked like a screwdriver bent into a hook. I don't have one of those. What to use? A screwdriver will get into the spring coil, but slips out. Something L shaped instead of hooked should work. The Allen set was on the bench - how about one of them? The 1/4 inch was too large to coil around the corner but a 1/8 worked OK .. success! The 8 brushes came out, but 2 of them are pretty tight. The wires go between supports and are tight. Now for the end bell. How to I keep the rest of the motor from sliding when I pull off instead of the end bell? I used a piece of scrap 2x6 between my chest and the motor shaft, then pulled by hand on each side of the housing (no picture of this for obvious reasons ... I'd need 4 hands!). It did not come easily. There is something resisting, but it came off.
The brushes and the brush holders (NG9_brush_holder) do not appear to have the brushes pointed at the shaft, but slightly to one side as Jack mentioned in the video. I don't see holes to re-install the brush holders in the opposite direction, so I won't be removing them. The brushes (NG9_brush_face, NG9_brush_face2) DO appear to be 'seated'. So what's with the sparks when the motor was turning? There is wear across the entire face of the brushes, making me think that there is good contact from the brushes to the commutator.
OK - what about the 'other' side of the brushes - the commutator. I lifted the armature a bit and it turns freely (NG9_commutator2_bad). A visual inspection shows a carbon film on most of the armature (NG9_commutator_smooth2). But there are 4 spots that appear somehow corroded?(NG9_commutator_rough2) Perhaps this is where the brushes were sitting against the commutator when the motor was in storage. The surface in these locations is rough to the touch and I could see this wearing the brushes quickly if it were allowed to continue. A few gentle (low pressure) swipes of my emery cloth (120 grit) block in the direction of rotation (to keep the slightly rounded profile of the contacts) makes things a bit better but does not resolve the issue. I'm hesitant to use too much pressure since copper is a soft metal. I only want the corrosion to be removed. So ... I use more repetitions at the same low pressure - about as much weight as letting my hand rest on the emery cloth block. NOTE - I SAID EMERY CLOTH NOT SANDPAPER! Emery cloth does not shed grit into the copper or into the spaces between the contacts. THIS IS IMPORTANT. Sandpaper grit is by definition - rough! - and it will wear your brushes if it is embedded in the copper contacts on your commutator.
After what seemed like a long time, but was probably an hour or so, the contacts are smooth to the touch all the way around (and my finger gets very black checking this). The carbon film and corrosion has been wiped off the contacts maybe 1/8 of the way around since I could not 'stop' perfectly at the edge of the corrosion where I was working, I overlapped with the adjacent contacts a little. There are no ridges, gouges or scratches. And there are no longer any bumps that stick out of the contacts (maybe that was brush material?). Hopefully that takes care of the sparking issue when the motor turns and most of the motor noise. I only have one picture, so you can't see all the way around (NG9_Commutator)
Next on the list is to remove the armature and do a visual inspection. I changed the motor from on it's side to on end so that I don't scrape the sides of the armature or the stator when the shaft clears the drive end bearing (NG9_vertical). I can't get the armature removed. It won't pull out. So I rested the drive end shaft on the work bench and pushed down on the stator. It still won't release. I'm sure it just needs a bit of a tap with a rubber hammer but I am hesitant since I am new to this. Back to the videos - can I find an armature removal? It does not appear so.
Perhaps it's obvious. I should put the motor back on it's side and remove the other end bell, which is where the bearing is and likely the part that does not want to release the shaft. I don't NEED the armature separate from the drive end bell ... I was just thinking that was how it would work.
So, remove the allen head screws after the motor is on it's side again. Again, I need to find something that will allow me to get some leverage. This side has a much smaller gap. Just under 3/4 inch so a couple pieces of half inch plywood scrap to start? I only have one (NG9_remove_drive_end_scrap). Use a piece of board that was cut out of a curve, tapered so I can break it off at about 1/2 inch thickness. Pry on both sides, but only one side popped (NG9_remove_drive_end_scrap2). Switch around the wood, left to right and right to left. Pry again and both sides are out. Now to get the armature out ... without scraping it on the stator (it is not supported on one end - putting the other end cap back on worked for about an inch of travel). Block up the armature on the commutator side with 2 x 4s and shims so that the armature turns freely. Use screwdrivers to pry on the drive end cap (the plywood is not a snug fit any more). It takes a bit of coaxing but it came out to about 5 inches. That's when the commutator side shaft ran out of blocks to sit on, so the armature stopped the travel by resting on the inside of the stator. I stuck my arm around to the commutator side and supported the shaft while pulling the armature out with my other hand. That got me a few more inches. The last of it was from the drive end with both hands supporting the armature and gently pulling it out of the stator and setting in on the bench. I was VERY CAREFUL to identify where the balancing putty is and keeping that away from contact with the stator. See pictures of the putty (NG9_armature_putty2).
The armature is heavier than I expected. According to the session that Tom Brunka from Helwig Carbon Products put on a EVCON, the color of the commutator should be a chocolate brown and you should NOT wipe off the commutator ... but I sanded it off ... He also mentioned that one should not remove the brushes of a motor to 'check' for wear, as removing and re-installing them will have them at a slightly different position and encourage wear instead. This motor has been in storage and I am looking for an issue, so removing the brushes is OK. What I was looking for was the source of the noise when the motor turns.
There are no abrasions on the metal surface (there is some minor surface rust as shown in the pictures) (NG9_stator_wide, NG9_stator_coil_rust, NG9_stator_close1, NG9_stator_binding) so it does not appear that the armature is rubbing anywhere despite the sound that the motor made while running. Further to the above discussion of taking corrosion off the commutator, there is no buildup between the commutator contacts. This is good. The shafts on either end show a bit of surface corrosion but nothing to worry about. This is good.
Now for the stator. No carbon dust at all? I was expecting some ... but there are no score marks or anything indicating abrasion. The insulation on the ends and the binding of the coils appears to be in very good shape. This is good. And there is some minor surface corrosion (rust) on the iron of the stator. There is no buildup of carbon. This is good.
Putting it all back together takes a lot less time than taking it apart. Lining things up with the arrows is pretty quick. I did't have lock-tite for the allen screws. I've read that the BLUE lock-tite is appropriate. That was a phone call, $10, and a short trip to pick it up ... since it would be very bad to have these screws loosen off in operation! (NG9_armature_backin, NG9_back_together)
So the motor is not in 'as new' shape, but it is in good shape. It needs to be run for a while at only 12V to ensure that the brushes are seated well in the slightly different position after re-installation. The brushes are in the Neutral position so it can turn either way, depending on wiring. The neutral versus advance CW is is easily changed if required ... not a big deal either way. I should look for the lubricant that is needed to dress the commutator. It never hurts to have good lubrication!
The Honda transmission on the WIKISPEED Electric Motor Module needs an electrically-controlled reverse, so the motor will turn backward in first gear (or second, or wherever we lock the manual transmission on installation) instead of keeping the motor turning forward and changing the transmission into reverse. So I guess I need to add a reversing contactor to my High Voltage Junction box ... and make sure that reversing the leads on the motor will reverse the rotation.
A very successful inspection!
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