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Thread: Cheap little red blower guts and internals

  1. #1
    Senior Member r4z0r7o3's Avatar
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    Cheap little red blower guts and internals

    There have been some inquiries about this blower's potential for supplying combustion air for furnaces. I can't directly answer whether or not that's the case (yet), but I happened to need a new DC motor for my home-brew impeller scroll, and guessed this one might be about the right size.




    TL;DR; Summary: This unit is dirt-cheap, has a small universal motor (AC or DC), roller-bearings (~30k RPM), solid brush-holders, and has some potential for modifying / hacking. It is not a panacea, there are many potential short-comings. IMHO, the main one is that it relies on internal and air resistance to prevent it from over-speeding and by-pass airflow to keep the windings (24ga / 10amp max) cool.

    At it's rated 16k RPM, it's not very quiet, and because of it's ABS plastic (Tg 221*F) construction (even at 2mm thick) is going to be susceptible to internal/external heat deformation. The motor size seems "about right" for a keg-size foundry-furnace.

    Overall, I'd rate it medium-level Chinese junk (as opposed to complete Chinese junk). It might be perfect for scrappers, scrapers, hackers, tinkerers who's $20 is worth less than their time. Though you'll have to make the final call for yourself. If you can find a more "solid" blower/motor second-hand, at about this price, don't buy this one.
    Last edited by r4z0r7o3; 01-14-2017 at 01:22 PM.
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    Senior Member Zapins's Avatar
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    Interesting to see the insides. What are you planning to change on the inside or are you just having a look?

  3. #3
    Senior Member r4z0r7o3's Avatar
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    The outlet nozzle is fairly thick rubber, flexible but thick enough it won't collapse too easily (I'm squeezing at a low/moderate strength)


    View down the business-end, you can see the "L" shape twist-lock connection (exactly the same on the inlet). You can also see how thick the plastic is.


    This is the nozzle connection to the unit.


    This is the nozzle's output w/ small flange on the end.


    Removable plastic retaining ring. Also an almost-worthless vacuum bag comes with it - possibly useful to scavenge an extra retaining ring.


    Plastic is about 2mm thick, same for the impeller though the trailing edge is sharpened. It's all marked "ABS", it's not very heat resistant (glass-transition temp is about 220*F) but it is impact and chemical resistant.



    Note:
    It may not be critical, and it totally depends on your particular application but at least be mindful of how the motor-windings are cooled:

    There's a set of small bypass inlet slits in the case (pic below) with matching impeller slits near the shaft (pic above). The designed intent here, is that a small amount of airflow is sucked past the motor (it has it's own inlet on the brush-end) and combined with the main air-stream.

    In other words, if you desire to maintain this cooling air, I don't recommend blocking off both the inlet/outlet at the same time (leave one open). This will allow a passage for the cooling air to escape (either down the outlet or backwards through the inlet). Also, if you block off the inlet, be aware that there will still be a small amount of air blown out the nozzle.

    However, since this is a brushed DC motor, controlling the speed is possibly a better option (since that also implies less current and cooler windings) since then you don't need to worry at all about the cooling at all (except maybe at max speed). All depending on your application/use, of course.



    The shaft has two flats which engage with the impeller. Shaft diameter is 8mm hardned steel, threaded on one end.


    Field-windings are 24 guage, so max of about 10-amps at room-temp. Resistance increases with heat, so they can pass more amps if they're kept cool.


    Brushes aren't the best, but not complete garbage either. They seem to be a standard size/make with an embedded braided copper wire inside a spring. The brush-holders are (curiously) made from machined solid-brass stock. This is impressive considering where this was manufactured. They're most certainly not going to ever wear out or distort from heat, in fact I'd even consider them slightly overbuilt.


    The handle contains the "electronics". A nice positive-grip strain-relief on the (short, 4-6-inch) mains cord. The line runs into a not-too-shabby, positive, snap-action switch with lock. Not complete junk, and actually may last quite a while. From the switch the line goes to the field-windings, it comes back (bottom, blue wire) and goes through a single diode (heat-shrink around it). So it's running at around 70v (not measured yet) half-wave rectified DC.


    Got the field windings out. Be-careful if you do this! You can see the chinsy little springs which loop around the base of the brush-holders (in a groove). These are simply crimped onto the windings, and can be easily pulled off (I did it). So if you take the windings out, be sure you use a dental-pick to un-hook the sprint-loops from the brush-holders first. My guess is this setup was done for ease of assembly and to provide some shock/vibration tolerance to the connection.

    If you leave it alone, it's probably a perfectly fine setup. However, since I need to fix mine now anyway, I'll probably solder a longer wire directly onto the brush holder, using the wire-length to help with vibrations instead of the stoopid brass-spring.


    Interrior view, you can see the commutator, brush-holders, and tail-end shaft roller-bearing. There's another metal-shielded roler-bearing supporting the top of the shaft. The tail-end bearing is press-fit into the end-cap and will be difficult to remove w/o risking breaking the motor cooling mesh (plastic)


    All-in-all, this thing is totally worth the $30 I paid for it (with "free" shipping). Others have seen these in stores for around $20, though I have no idea if there are any copies-of-copies of this design floating around.

    What I really like about this is the way the case is made. It's easy to separate the impeller housing from the motor, and then use a home-brew mount to drive some small load (like a better/bigger impeller). I also like that the motor and electronics are simple. DC motors don't loose lots of torque at low-speeds like induction motors. So this is well-suited to connection with a cheap triac-based speed-controller.
    Last edited by r4z0r7o3; 01-13-2017 at 03:44 PM.
    "Things that are complex are not useful, things that are useful are simple."
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  4. #4
    Senior Member r4z0r7o3's Avatar
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    I have no sound or airflow measurement equipment on-hand, but my best guesstimate is it's putting out around 100-200 CFM (unrestricted). The motor is suppose to be 16k RPM but I haven't measured. Sound-wise, it's listed as 96 dbm but to my carefully calibrated ears, it seemed a bit quieter. Perhaps somewhere between a vacuum-cleaner and a hair-dryer.
    "Things that are complex are not useful, things that are useful are simple."
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  5. #5
    Senior Member r4z0r7o3's Avatar
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    Quote Originally Posted by Zapins View Post
    Interesting to see the insides. What are you planning to change on the inside or are you just having a look?
    My plan is to remove the blower/impeller housing and bolt the motor + electronics onto my metal impeller.. This will protect the plastic from the heat (a bit) and allow me to drive about a double-size (metal) impeller. But mostly I'm doing it because my impeller housing is already mounted to my burner.

    I already have a cheap Chinese "router speed controller" (triac-based) that I plan to use to adjust the airflow to my burner. I'll use a similar bypass air design to make sure I keep the windings cool - especially because my impeller is probably 3x heavier than this plastic one.

    My backup plan, is to use this unit as-is after figuring a way to couple it onto my burner and shield it from my furnace heat.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  6. #6
    Senior Member Jammer's Avatar
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    I'm impressed by the brass blocks for the brushes. My big leaf blower has plastic mounts for the brushes and one of them melted under normal use, blowing leaves and such. Well, my old boss gave it to me and it was melted when I got it. I imagine he was blowing leaves with it.

    Nice breakdown of the blower, looks well built. I doubt if the plastic impeller will be a problem as long as it's not too close to the furnace. I wonder if it has something like a duty cycle and if it will hold up running for an hour or so?

  7. #7
    Senior Member r4z0r7o3's Avatar
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    Quote Originally Posted by Jammer View Post
    I doubt if the plastic impeller will be a problem as long as it's not too close to the furnace.
    Not likely, though I think the whole thing is made from ABS, including the plastic that retains the shaft-bearings. So best keep the whole thing shielded from heat (radiation mostly). As long as the connection to the burner is via the included (or another) rubber piece, head-conduction isn't much of a worry. I'll probably go with a simple heat-shield (i.e. piece of scrap sheet-metal) type of arrangement and call that good enough.

    Quote Originally Posted by Jammer View Post
    I wonder if it has something like a duty cycle and if it will hold up running for an hour or so?
    This is the question of the hour. Heat (internal or external ) is nearly almost always going to be the killer of something like this. Though with 24ga field-windings, I think it might have a shot at handling continuous duty. They're so damn cheap it won't hurt much to test it out. Gathering some current-draw and temperature measurements at various points during a several hour run. I may have a go at this.

    Bedsides the spring-loop winding-attachments getting beefed up, the other area that would improve reliability (IMHO) is where the rotor winding's are soldered to the commutator contacts (where the brushes rub). On quality motors, that area is almost always potted in epoxy of some sort to prevent vibration from work-hardning, then breaking the joints. OTOH, mine seemed to be really well balanced, and the back-bearing is hard to get out, so I'm kind of hesitant to try this mod.
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  8. #8
    Outstanding review. My local tractor supply has one on order for me. I like what I see in these photos and really like the 19.99 price tag too. I already see me needing 3 of these. At that price, if it lasts a year or two, I won't complain... (much) lol When mine shows up, I'll whip out the amp clamp and do some testing on her too.

    Zap, you going to try one on your oil burner?
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  9. #9
    Senior Member r4z0r7o3's Avatar
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    Update & Correction

    Wiggle-wiggle, jiggle-jiggle, pop! Out came the rotor.

    Here's a shot showing what I suspected: No epoxy coating on the commutator to winding connections.



    Solution:
    • Mask off the area where the brushes rub, and protect the end bearing.
    • Mix up a batch of really thin (i.e. laminating) resin.
    • Wait for resin to just go almost-green (state).
    • Dribble drops on, while turning the rotor by hand so it doesn't glob up all one side.
    • Once it went firm/tacky I used a piece of wood to kind of smooth it out and clean it up.



    (Sorry, forgot to take a pic before I re-assembled the thing)




    Next mod: I cut the shrink tube off from the round springie-thingies that I pulled off the field-windings (on accident). Cleaned up the wire-ends, jammed them back into the crim-connectors, then solder the whole thing through-and-through in a large-ish blob. Also flowed the blob up a little ways into the springs (maybe 1/16th inch). I replaced them onto the brush-holders, which took some extra effort. Now they're really solidly attached, yet free to move and vibrate as they need to.




    Final mod (and a surprise): While it is a "snap-action" switch, this is a very common failure point and for my application, totally unnecessary. My speed-controller will take care of the on/off. So I removed the switch, cut away all the shrink-tube on the wires, and whoa!

    ummm

    There's no diode!

    Got out my multi-meter, checked the switch contacts, disassembled the switch, then looked all over the windings. There's NO diode?!?!?!?!?

    Is there such a thing as an A/C brushed motor???? News to me if so!

    Proceeding...I chopped off all the silly crimp-on connectors, stripped/tinned all the wires. Then I placed new shrink-tube over all of them, soldered the ends together (remember I removed the switch), and heat-shrunk everything.

    I was a bit apprehensive to plug it in, so I stuck it on a power-strip and warned my family that the lights may go out...and...there might be a "smell"


    *click*


    ZOOOOOOOOOOMMMMMM!!!!!


    Hahahahahaha Itz Verks! Itz Verks!


    A brushed-AC motor?????

    Maybe the brushes/commutators/windings are such that it runs synchronous with the 60 Hz?

    Or maybe it spinamathins so damn fast that it can just pretend the current and voltage are DC?

    I dunno!

    Mind...boggled
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  10. #10
    Quote Originally Posted by r4z0r7o3 View Post
    Is there such a thing as an A/C brushed motor???? News to me if so!
    Universal Motor - These days pretty much every shop vac, router and higher rpm woodworking tool 15 amps or less.....and many others

    https://en.wikipedia.org/wiki/Universal_motor

    Best,
    K
    My furnace build ----- I toil and fettle then foam turns to metal!

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