New Shopsmith DC-6000 Dust Collector

[dusty]

I'm curious. Why do you suppose the rotational direction was changed?

[DLB]

I'm curious. Why do you suppose the rotational direction was changed?

One guess, maybe one or more of the parts that 'have direction' is off-the-shelf or modified off-the-shelf.(?) Thereby reducing development costs. Those parts, from what I've seen so far, are the motor, fan/impeller, LH bolt, and fan housing. The fan housing, for example, has a square or rectangular flange with mounting holes in it, neither of which seem to be relevant in this installation. And its cover has an extension adapter to ultimately make if fit into the main housing. So it doesn't appear to me to be designed uniquely for the SS DC. It wouldn't surprise me if all of those parts came from some other air movement system, not necessarily a DC, and were modified to integrate with the existing SS DC design. Seems like a wise approach, when viable. But purely a guess.

- David

[RFGuy]

Yeah, impeller is the proper term and a "fan" should include the impeller + motor technically. However, some use the impeller and fan terms interchangeably.

Thanks for the side by side comparison. Interesting that they changed the direction of rotation. I believe the DC-3300 impeller was a forward-curved design, so if they changed rotation then they are now using a backward-curved impeller design. Below is a good document that explains the differences between forward-curved vs. backward-curved fans including their fan curves for comparison. As I understand it, forward-curved fans are less efficient and tend to be motor hungry, whereas backward-curved fans are more efficient and won't overload a motor provided it can meet the peak horsepower required. By switching to a backward-curve fan design, they could shrink the size of the impeller...

Fan-Performance-Characteristics-of-Centrifugal-Fans-FE-2400.pdf

(143.03 KiB) Downloaded 120 times

[DLB]

...I believe the DC-3300 impeller was a forward-curved design, so if they changed rotation then they are now using a backward-curved impeller design. Below is a good document that explains the differences between forward-curved vs. backward-curved fans including their fan curves for comparison...

Looking at the two, and the document you attached, I'm seeing them both as backward-curved types. Looking at the front view of new/old: New spins CW, so the leading edge of the curve is the convex side. Old spins CCW, so the leading edge of the curve is also the convex side. Or I am not understanding something.

- David

[dusty]

I'm curious. Why do you suppose the rotational direction was changed?

Answering my own question:

The blade was changed (reversed the curve) so they had to reverse rotational direction???

Or

They (for some reason) reversed rotational direction and therefore had to reverse the curve???

[DLB]

I completed the installation of my upgrade and have a few positive and negative initial observations.

Pro's: Airflow is definitely improved, to the point that I kind of wish I had an objective means of measurement. My DC has the 42" hood and, as observed by me and at least one other member, it previously did not fully inflate the hood even with all three ports open and no hoses attached (max airflow). It now fully inflates, even with one port blocked. Highly subjective, but I am favorably impressed.
Also, 4" hose support is going to be easy. The extension piece that goes between the fan housing and the three port plenum is an off the shelf 4" hose connector. So it's remove plenum, connect 4" hose.

Con's: Most exasperating to me right now is mine leaks somewhere. I can see fine sawdust particles being emitted or redirected by the cooling fan, suggesting a leak between the main cavity and the motor housing. I'm not seeing any large pieces, only fine sawdust. I've mentioned the deteriorated seal at the top of the motor housing in another thread, but the upgrade came with a new seal. Further investigation is needed, but I am unimpressed by that fat foam seal trying to seal a fairly substantial gap.
There were also visible gaps between the air inlet and the main housing. This is going to cause some degree of recirculation. On the DC-3300 the part that fit here, the fan housing, was rounded to fit the main housing, and there seems to have been some type of sealing material used here (mine was deteriorated). On the DC-6000 it is the above 4" hose adapter that goes here, the end is not rounded and does not match the main housing. There is no seal. Performance would likely be improved slightly by sealing added to this area to prevent recirculation.

- David

[algale]

I am dubious about that Shopsmith seal. It looks too porous to keep fine dust out of the motor.

In this thread, br549 used 1/8" x 2" self-adhesive rubber pipe seal. It looks like it has an impervious surface. viewtopic.php?p=234151#p234151

[DLB]

I've disassembled my DC-6000 Upgrade and see multiple issues that could cause the leak I'm chasing. I'd prefer one. (Zero would be good.) The first pic is the "U" in the main housing where the motor housing sits. Two major issues, possibly related but I don't think so. 1) Note the end of the screw protruding at the bottom. This is the end of one of the screws for the dust bag retaining clips. Mine is precisely located to prevent good seating of the motor housing in two directions, seating all the way down in the "U" and seating as far outboard as possible to reduce the size of that top gap. 2) Note the discoloration in what should be the clean side of the top 'seal.' IMO this is because the 'seal' is acting like a somewhat porous filter and has trapped some of the larger particles. The top part is clean because I vacuumed it before disassembly.

Main Housing w/ Seal

Top Motor Seal.JPG (267.62 KiB) Viewed 934 times

Next are two pics of the mating surface of the motor housing where it mates to the fan housing. (With apologies for the focus on the first.) There is no gasket or seal between the motor housing and the fan housing, though there is a rubber gasket between the motor itself and the fan housing. That might be okay if the surfaces of the motor and fan housings were flat where they mated, but as you can see they aren't. It looks like there was some kind of buildup on this surface that someone tried to clean up with a power tool, leaving both high and low spots. There is differential air pressure between the two volumes when the machine is running, so a leak here seems inevitable. The motor housing is held to the fan housing with four sheet metal screws, not particularly close together. The motor is through-bolted to the fan housing, so the motor housing is just a cover, unlike the DC-3300.

Motor Housing

DC6K Motor Housing.JPG (252.69 KiB) Viewed 934 times

Motor Housing Closeup

DC6K Motor Housing Closeup.JPG (169.25 KiB) Viewed 934 times

I'm not very happy with my upgrade.

- David

[RFGuy]

David,

I have used a product called "air-sealing tape" from the hardware store before to seal up my DC-3300. At one point of dis-assembly/re-assembly one of the original factory seals fell apart. One product I used to replace it, is called "foam window seal" and one was called "sponge window seal". Both products had "air-sealing tape" listed on the package as well. Both are kind of a medium density foam tape product. As such there are no discernible air holes visible to the naked eye, so to a 1st order these should seal and prevent dust leaks. I never observed any air leaks after I made the change, but shortly thereafter I moved my DC-3300 into my attic so I don't use it as much anymore. It is in the attic because I hope to one day use it for dust collection from overhead using a Shark Guard. I would agree with you that the type of sponge gasket that Shopsmith sent you is too porous to use for dust collection sealing...that is the same stuff they sell to go with cheap window air conditioners to seal the window sash.

Is that how Shopsmith shipped you the new motor housing, i.e. with all those rough machining marks, etc.? Shouldn't it look like a new part, rather than a hack job? Let us know how Shopsmith responds on this one. Definitely disappointing to buy a new upgrade kit and receive something like that.

Dusty,

Did you get any airflow measurements on your DC-3300 with upgrade yet?

[DLB]

David,
...Is that how Shopsmith shipped you the new motor housing, i.e. with all those rough machining marks, etc.? Shouldn't it look like a new part, rather than a hack job? Let us know how Shopsmith responds on this one. Definitely disappointing to buy a new upgrade kit and receive something like that...

Yes, that is just as I received it. It shows evidence of quite a bit of machining for a plastic part IMO. I was looking at the last pic in this post earlier in this thread for reference: viewtopic.php?p=285499#p285499 and his has a different shape than mine. Which, again, just seems strange for a plastic part. That shaping is not in a critical area, but for example if you look at his you see areas where the motor housing protrudes out beyond the fan housing. Mine does not protrude anywhere. But both have that weird cutaway at the top that serves no obvious purpose, and on mine this was clearly machined after the part was formed. If you look at my closeup you can also see machine marks on the inside of the motor cavity. It makes no sense unless the mold allowed overflow that interfered with the motor. But the part I'm concerned with it looks like there was extra plastic formed proud to the mating surface . Someone cut most of it away but cut too deep, and did not get it all, leaving both highs and lows.

I'll see what SS has to say. The only think I've done is cut and ground that screw. And confirmed on another main housing that the protruding screw is "normal" or that another main housing is equally deficient.