Mark I was going to offer my NCE up for grabs too, until I tried it on the diesel so I'll keep it now, but wont try more.More on motor mods and replacements
In this post I successfully try out a different motor, attempt a skewed rewind and search for worms. 1.5mm bored Worms
Mashimas are thin on the ground now. Hollywood Foundry’s out, the ebayer I got mine from are out but there’s still 1020s and 1024s. If you have got a Mashima you’ve still got the issue of accurately boring or reaming out the OEM worm to 1.5mm otherwise they are ideal replacements performance wise. I thought if only I could find a suitable worm I wouldn’t have to try rebore anything. I went on a search and found the world of gear cutting is more complex than I thought even on small scales. Basically, if I can use that term, the defining measurements of the Wombat’s worm are as follows:
Module = 0.4mm
Outside Diameter = 5.3mm
Pitch Diameter = 4.5
Helix Angle = 5.08deg
Bore = 1.0mm
Length = 9.0mm
The only commercially off the shelf worm I could find to nearly match the above and fit a Mashima shaft was from Northwest Short Line who sells a steel worm with the following measurements:
Module = 0.4mm
Outside Diameter = 6.0mm
Pitch Diameter = 5.2
Helix Angle = 4.40deg
Bore = 1.5mm
Length = 9.5mm
Unfortunately it’s not going to work. Despite the larger diameter and different helix angle the worm meshed ok with the worm gear when not fitted but sat proud. The housing is too small and the entrance blocked by a bulkhead that limits motor movement, similar to the one I cut away at the other end to fit a longer motor. I could cut that away and cut the gear housing in half but that’s all a bit extreme. Furthermore, the larger diameter and the mesh not being perfect means the motor has to sit higher which means the cage can’t be used and the body might not fit.
So if you’re using a Mashima and don’t want to or can’t rebore accurately, search for the top measurements but with 1.5mm bore and please let us know if you find any, I couldn’t.
This is just a pic showing a 30 nearly stripped right back so I could determine above measurements plus close up of worm and spur gears. You may notice the suspension springs I mentioned previously in the middle drive wheels hornblocks/bearing housing. Note the gearing is 50:1
Skewed RewindSumida Crossing
is a great read that I’ve referred back to a number of times over the past year or so and in particular the DC motor page linked shows examples of N scale motors, skewed 3 pole and 5 pole motors plus straight winds. Haven't found specs available on any to see if any of those motors could be a drop in replacement but I got the idea to maybe try and skew one of our OEM motors.
They are surprisingly easy to skew. I removed the windings on one older motor, trying to count the number of winds when after about 150 the rotor dropped and it was like a cotton spool unwinding. The remaining two attempts of counting winds were unsuccessful through breakages and loss of concentration. I used a thin screwdriver’s shaft and twisted between the slot’s gap and got instant skew.
I’ve no idea about which way to skew or wind and what sort of wire, thin or thick. A bit of misinformation was available claiming thick was better but then it’s all about resistance and long thin winds which means more resistance and less current. Some 0.2mm enamelled copper I had which I thought would be thin enough is grossly oversize. The OEM winding is I think 0.06mm to 0.10mm. Big variance but dodgy callipers and no micrometer led to a bit of guess work. Regardless I used the 0.2mm as it was all I had and got about 40-50 turns, I forget.
My first attempt caused a bit of humming and finally some rotation but then it quit. After repeated attempts I realised the Gaugemaster was cutting out. I waited some time then ramped it up and before full speed was reached I heard a little crackle and then it stalled. On disassembly I noted the brushes/contacts on one pole had vaporised. Windings were ok though. I tried another cap end with new brushes but this time connected to analogue volt and amp meters. To my shock during a quick turn of the controller the ammeter shot to near two amps. No wonder the fine brushes cooked at near full speed. So disassemble and wait for some thinner wire to arrive
Note the missing/shorter brushes closer to camera
The new enamelled wire arrived in 0.112 and 0.085mm from “physicalsciences
” on ebay in Canberra. I removed the wire from that rewind and skewed as far as I could.
I got about 170-180 winds with about 150 winds on the last pole/slot owing to space constraint. It’s a shame cos I was getting good at it with good tension and tight wind but the first winding in particular was loose. It was obvious it was going to be out of balance but I had to try it. It started turning at a lower indication on the gaugemaster, between 10 and 20%. Amps rose to approx 300mA before dropping as the motor turned. It vibrated ridiculously as I sped up and as I hit max power a couple of times the amps maxed out at 300-400mA and voltage near 15v before failure. Just a dead stop. On disassembly I noted the brushes were fine but some loose winding clearly was thrown outwards due to centripetal force then broke, lost continuity and jammed between the magnets. I was pretty chuffed regardless. It took 3 hours to rewind and 10 seconds to fail but meh, fun stuff.
But rather than rewind again I had a different spare OEM motor (I bought a few from Casula Hobbies
to experiment on) with bent shafts after being a bit rough when removing worm and flywheel. I inserted the shaft of the thin screwdriver between the outer edges of the slots then twisted and got 3 pole skew with factory wind. I reassembled and tested and got movement. The bent shafts prevented me from testing this further other than observing it on the bench.
So I grabbed another spare which is the one above, skewed the laminations and tested in the stripped loco. Results were pretty good. Windings weren’t damaged and in the video below you’ll see a comparison of OEM first with forward and reverse on manual control then with simulation followed by the same test for the OEM skewed motor. NB there is a slight bind in the mechanism of the stripped back test loco which I didn’t investigate when I had the loco apart but it’s there in some older vids too so it's not the motor causing those little stalls. The motor to final drive ratio is 50:1 so for at least three quarters of wheel rotation you’re seeing the motor rotate evenly a number of times displaying reduced cogging. The end result sees the skew modded factory wound motor starting off sooner and smoother than the unaltered motor and generally operating slower though at mid to full speed both locos were travelling at the same speed. The skewed motor stopped before the OEM motor on simulation. Not as good as the Mashimas but it’s a possible mod to see better performance on DC. I had the idea of adding 53grams of lead folded on top (equals the weight of the body shell), to make things fair. No real change in results.https://youtu.be/l6LX_dcVMVM A No Mod Needed Drop in Replacement Motor, that does works better.
There’s three potential candidates and all are 3 pole straight wound.
1015 from the UK available on ebay gets good reviews on RMWeb,
- High Level Kits
have got a 1015 and 1020 size
- NorthWest Short Line
have the 1215 which is 10mm on the flat. So same size as the 1015.
All have 1.0mm shafts.
High Level Kits and NWSL have been good to converse with via email. All three candidates say in one way or another that they’re worthy Mashima replacements. Owing to an earlier communication with NWSL and months ago promising here I’d buy their motor next pay day, plus wanting to buy those worms mentioned above, I decided to buy a 1215.
NWSL were really good, items arrived in 12 days and about $18USD shipping. I have to say I was a bit sceptical when I looked at the 1215. It’s so similar to the OEM replacements. I put on a flywheel and turned the 1215 by hand and compared with other OEM motors. Amazingly, very little to no cogging as was suggested to me. I had to open this sucker and see what was inside. Again, so similar. Here compared with one of the OEM rotors I skewed.
I think the magnets may be different, I’ve a dim thought of noticing that but never took a photo. The windings may be different, I'm not sure. Regardless, it really is better. There’s a short 1min video comparing older vids of the Mashima 1015, OEM, this NWSL motor and remembering how awsome the Mashima 1024 motors are on DC and using a Gaugemaster controller. I’m impressed with the NWSL alternative. When all is said and done I may just convert all three of my locos to this motor. It’s better than OEM on DC and I’m sure will be better on DCC too.https://youtu.be/XAgD8dwZdL0