Cooling Cans... a concern?

[LooseClu]

A few weeks ago I asked about the size of a can motor for a scratch built, vertical boiler, HO Climax.  The consensus was buy the largest that will fit.  The plan calls for the motor to be mounted vertically in the boiler.  My question now is do I use the larger motor, which fits into my mock-up boiler just a bit better than O.J. fit into his gloves, or use a smaller one that would require bracing inside the boiler.  The boiler can be either a cardboard tube wrapped in an embossed metal foil or a plastic tube- neither would like a lot of heat.  The smaller motor would allow some room for air circulation and therefore some cooling.  Is this a valid concern?  Neither of my two locos (Bachman Spectrum Climax and 3-trk-Shay) feels hot to me after a bit of running but they have some "breathing room".  Thanks in advance for your help  

  Roy

[fwright]

 The main reason for the advice to go with the largest motor that would fit was adequate torque at reasonable RPMs.  The larger motors contain more magnetic material to generate more intense magnetic fields which increases torque and keeps RPMs down.

You didn't give us much information to evaluate the motors on.  I don't know what motors you are considering.  Typical can motor size recommended for HO locomotives where space is not a real issue are 16 or 20mm diameter cans (1620 up to 2032 in the larger locomotives).

Once you go down to smaller can sizes, the questions of whether there is enough torque for the anticipated load, and the RPMs are suitable for the gearing you plan become planning points.  I would be leery of a 6mm can unless you know the gearing will be quite free, you are not expecting to pull many cars, and you can get the speed where you want it. 

Heat in a motor is caused by lack of efficiency and load - and is indirectly measured by current draw.  More efficient motors, such as coreless designs, run cooler for a given load, but cost more.  Coreless motors are also more susceptible to damage from overheating due to lack of metal to dissipate heat that does occur.  For a given type of motor and load, the larger motor will generally run a little cooler.

Fred W

[jeffrey-wimberly]

 You can use a motor slightly smaller than the inside diameter of the boiler. With today's smaller high torque motors it shouldn't be much of problem. This would provide a little space around the motor for cooling. If you feel heat still an issue find or construct a small ducted fan that can be mounted on the motors shaft so the motor can be cooled in the same manner as a cars alternator.

[richg1998]

 I have no idea what the diameter of the vertical boiler is but there is a Maxon coreless 7 pole motor that measures 13mm X 22mm with a 1.5mm X 9mm shaft on ebay for $40.00. I have one of the motors from the seller. Nice motor.

Rich

[LooseClu]

Thanks for the input but I still have questions (and a few answers/clarifications). Fred, The boiler I'd most like to use is 5/8 inch inside diameter with a max length of 1and1/2inches.  The diameter could be increased to 3/4 Inch diameter but the smaller one would look better.  I like Jeff's fan idea fan and could easily add a fan to the top of the motor if it had drive shafts at both ends.  I also thought I would investigate the possibility of a combined flywheel and fan blade- rebalancing a hacked up flywheel ought to keep me busy for quite awhile.  Rich, I looked on eBay for the Maxon motor but came up with nothing.  That price is about my limit but if it’s a very good motor it would be worth it I suppose.  Just figuring where to start is a bit of a problem.  I've made a few (roughly scale) drawings, have guesstimated maximums and minimums for trucks, boiler, frame, and driveline (really rough on driveline).  So far I have the motor inside the vertical boiler (motor 90 degrees to the frame).  The motor drives a NWSL gear reduction box mounted so the output axels point down the middle of the frame at both front and rear trucks.  The input shaft for the gear box would be pointing up slightly off center in the frame.  A 'rather large' gear on the reduction box input shaft is driven by a worm gear on the vertically mounted motor.  U-joints and drive shafts to the geared trucks finish up the basic plan.  Bells and whistles include a Tsunami 750 decoder inside the oil tank (or wood pile) and a speaker in the water tank.  I use to repair antique clocks and hope I've enough eyesight and ability left to build this loco- I only wish I still had all those clock tools, especially the lathe.        Roy       

 

[fwright]

LooseClu

Thanks for the input but I still have questions (and a few answers/clarifications). Fred, The boiler I'd most like to use is 5/8 inch inside diameter with a max length of 1and1/2inches.  The diameter could be increased to 3/4 Inch diameter but the smaller one would look better.  I like Jeff's fan idea fan and could easily add a fan to the top of the motor if it had drive shafts at both ends.  I also thought I would investigate the possibility of a combined flywheel and fan blade- rebalancing a hacked up flywheel ought to keep me busy for quite awhile. 

 

Roy

 

Disclaimer - These are just my thoughts and opinions.  I'm hoping to semi-scratch a horizontal boiler (t boiler?) Class A Shay one of these days myself.  I had planned to use an NWSL Keystone Shay drive as the basis for the drive (NWSL catalogs it minus motor and Keystone parts).  But I haven't actually done it yet.  I am currently remotoring an HOn3 FED 2-6-0 using Hobbytown (now Micro-Mark) universals and a LocoDoc remotor kit (24V coreless motor), and am currently building an HOn3 Keystone Shay - but that's the limit of my actual experience.  I have picked up a lot of good information on the Yahoo Repower and Regear Group (http://groups.yahoo.com/group/repowerandregear/ and associated links to web sites and suppliers.

 

The 5/8" internal diameter translates into just under 16mm.  Can motors diameters are sized in millimeters, with the diameter first, length second.  I think you have adequate room for a strong enough motor (a 10 or 12 or 14mm dia can or coreless) - that should not be an issue.  Nor should cooling - most model motors get precious little airflow.  Unless you are making the entire model of lead or are using traction tires and are planning to haul 30 car trains with it, motor torque and heat should be non-issues.

 

I would forget the fan idea - these are inherently noisy.  I would leave the stack open, and create some openings at the firebox, and of course, the bottom where the drive exits.

 

I love flywheels.  But in your case, flywheel diameter is quite limited.  You'll want to make the flywheel as long as possible.  And the flywheel will create a slight fan effect.  I am not a big fan of putting flywheels directly on small diameter (less than 2mm) shafts that are now seen on some motors.  Instead, I would put the flywheel on its own bearings, linked by a universal. 

 

So far I have the motor inside the vertical boiler (motor 90 degrees to the frame).  The motor drives a NWSL gear reduction box mounted so the output axels point down the middle of the frame at both front and rear trucks.  The input shaft for the gear box would be pointing up slightly off center in the frame.  A 'rather large' gear on the reduction box input shaft is driven by a worm gear on the vertically mounted motor.  U-joints and drive shafts to the geared trucks finish up the basic plan. 

 

Reading articles on remotoring the FED, some writers are strong believers in a straight drive through universals to minimize noise.  I agree, which has caused me to mount the motor in the FED with the rear end high to align the drive shaft.  This meant cutting and redoing the plate under the tender load.

 

In your place I would consider a gear, chain, or belt from the centered motor shaft to the off-center input to the gearbox.  Hollywood Foundry (http://www.hollywoodfoundry.com/ makes Bull Ant products, including some new belt drives to get away from gear noise.

 

You are going to need access to the inside of the boiler to mount and maintain the motor and drive.  I would consider splitting the boiler in half vertically to provide you with the required access.  I would also consider using metal tubing for the boiler to add weight to the model.  Just some thoughts. 

 

Bells and whistles include a Tsunami 750 decoder inside the oil tank (or wood pile) and a speaker in the water tank.  I use to repair antique clocks and hope I've enough eyesight and ability left to build this loco- I only wish I still had all those clock tools, especially the lathe.

Roy

 

A word of caution - the Tsunami will be more of a heat problem than the motor.  They tend to run quite warm, especially if the speaker is cranked up.  Soundtraxx put in a thermal shutdown to protect the decoder from overheating.  Some HOn3 guys use a special 3M mounting tape that has some heat transfer capabilities.

Look forward to hearing great things about your model.  And I won't take offense if you choose not to use any of my suggestions.  

Fred W

[Allegheny2-6-6-6]

 Try these guys I have installed many of their motors none in what your building unfortunately but they are noted for their torque and smooth running. I can't imagine that you would generate that much heat in a newer style can motor but I may be wrong.

 

 

 http://www.alliancelink.com/alp/