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Forum topic by Karda posted 06-29-2018 03:58 AM 773 views 0 times favorited 13 replies Add to Favorites Watch
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Karda

1711 posts in 1063 days


06-29-2018 03:58 AM

Hi, I have a Craftsman 8 gallon 3.5 HP shop vac with an 1 1/4 hose would I get better pic up with a 2.5” hose. Will a 3.5 HP vac support a 2.5 hose thanks


13 replies so far

View runswithscissors's profile

runswithscissors

3072 posts in 2535 days


#1 posted 06-29-2018 05:14 AM

Probably would if it were truly 3.5 hp. But Sears always overrates their motors. Realistically, you can’t get 3.5 hp out of 120 volts, with either a universal or an induction motor. Check the amps on the motor plate, that will give you a better idea what your horsepower is.

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

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Karda

1711 posts in 1063 days


#2 posted 06-29-2018 06:17 AM

Hi, the motor is 9 amp

View gmc's profile

gmc

64 posts in 2666 days


#3 posted 06-29-2018 10:43 AM

https://sciencing.com/convert-amps-hp-5946332.html

This should help answer your question. The additional size of hose probably won’t help that much considering the cost. Would need to know what application and problem you are trying to solve.

-- Gary, Central Illinois

View msinc's profile

msinc

567 posts in 1013 days


#4 posted 06-29-2018 10:52 AM

3.5 HP? Not even close with the numbers we have here. If I did this right, 9 amps, 120 volts even with a full power factor of 1 you only figure out to 1080 watts. There are 746 watts to a HP. This is assuming you are even pulling 9 amps. As to the bigger hose….no, that doesn’t work either. Like putting a bigger prop with more pitch on an outboard motor, not quite that simple. As far as vacuum pickup you want high velocity air. But, you only have so much power to pull it. So, it will be a given velocity in a certain size hose, but if you increase the diameter of the hose while retaining the same power pulling the air you slow it down. Maybe a better way to explain it might be if you are trying to pick up marbles. You have a standard typical shop vac with a 4” hose…wont even try. Now go down to a 2 1/2 inch hose and you might start to move a marble…now go down to a one inch hose and it will probably pick it up because you have increased the speed of the air in the hose.
I don’t know how the manufacturers of electrical devices get away with chronic false advertisement like they do, but they just about all do it. Small generators come to mind. I mean, it’s one thing to claim you have 3.5 when you really have 3.0, but to almost triple it????

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Karda

1711 posts in 1063 days


#5 posted 06-29-2018 07:58 PM

thanks for your insight, guess I will stick with the smaller hose. Got another question. one of the tools i want to use it for is my table saw. If I can’t find an adapter to fit my saw would it be ok to put a piece of hose on the vac port and direct it in to a bin rather than try to hook to vac. gotta do some thing because this is a vacuum port saw

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HorizontalMike

7797 posts in 3424 days


#6 posted 06-30-2018 05:27 PM

I have a 5gal shop-vac w/Thein-separator dedicated to ONLY my 12” Miter Saw. That alone pretty much max’s out a shop vac’s capacity. For all of my other shop tools, I drag the single hose from my HF-DC unit +Thein that I put a Wynn nano-filter on. FWIW, trying to hook up two or more tools at a time would be taxing the HF-DC, but in my one man shop it works.

The Harbor Freight DC unit is about as “economical”, aka cheap, as someone can actually get by on IMO.

The problems with shop vacs are that they are high suction, low capacity units. They don’t move enough air, and that is why others above comment on not trying larger hoses. Performance just drops off too fast/much.

Good luck building a good DC system. Don’t throw away that shop vac, but add to it with a full fledged DC unit.

-- HorizontalMike -- "Woodpeckers understand..."

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Karda

1711 posts in 1063 days


#7 posted 06-30-2018 06:31 PM

Thanks Mike, but to clarify. I can’t set up a system. I will have to connect the vac to each tool as I use it, not only that I don’t do that much work that a system is warranted. I was wonder out the larger hose because I could hook the hose to my TS no adapter’. The vac at sears are 2.5 hose and similar to what I have. I can stick with the small hose. One other thing, can you make a dust separator with a small hose, all I have seen on utube are larger hose. Thanks for the advice now I know what I need to do.sorry to be a pest but I am paranoid about doing the wrong thing

View Bill White's profile

Bill White

5227 posts in 4470 days


#8 posted 06-30-2018 06:40 PM

I guess that my Ridgid 16 gal. 6 1/2 HP (120 volt) is probably a JOKE!!!!!
I does work quite well, but the labeling is somewhat STUPID.
I’m laughing.

-- [email protected]

View HorizontalMike's profile

HorizontalMike

7797 posts in 3424 days


#9 posted 07-01-2018 01:09 PM



Thanks Mike, but to clarify. I can t set up a system. I will have to connect the vac to each tool as I use it, not only that I don t do that much work that a system is warranted. I was wonder out the larger hose because I could hook the hose to my TS no adapter . The vac at sears are 2.5 hose and similar to what I have. I can stick with the small hose. One other thing, can you make a dust separator with a small hose, all I have seen on utube are larger hose. Thanks for the advice now I know what I need to do.sorry to be a pest but I am paranoid about doing the wrong thing
- Karda

YES, I used the smaller hoses on my MS, with hose adapters, to set up my dedicated setup. The top is one from Grizzly http://www.grizzly.com/products/5-Gallon-Dust-Collection-Separator/W2049 and for less than $28. You will also need a 31gal metal trashcan. https://www.lowes.com/pd/Behrens-Steel-31-Gallon-Silver-Galvanized-Metal-Trash-Can-with-Lid/3475295 I also think I got the hose adapters from Grizzly, or maybe WC.

-- HorizontalMike -- "Woodpeckers understand..."

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ohtimberwolf

936 posts in 2862 days


#10 posted 07-01-2018 01:48 PM

You can do this. I do it often just go slow with the heat. larry

https://www.youtube.com/watch?v=cjLQo3GuvDo

https://www.youtube.com/watch?v=VrleBgNM8JU

-- Just a barn cat, now gone to cat heaven.

View HorizontalMike's profile

HorizontalMike

7797 posts in 3424 days


#11 posted 07-01-2018 03:26 PM

Karda,
I also forgot to mention is that I bought a HEPA filter for the shop vac. That also cuts down on the already poor performance of shop vacs for DC. Using this only for my MS, it works well, though I doubt that it will be acceptable for any tool with a 4in dust port.

BTW, my 10in Rikon BS also uses the smaller 2-1/2in dust port so that might be a consideration if you are in the market for a small BS. Sounds like that size would fit you existing shop constraints. I also think a dedicated router table setup could/would use the 2-1/2in hoses as well. Just a thought…

-- HorizontalMike -- "Woodpeckers understand..."

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Karda

1711 posts in 1063 days


#12 posted 07-01-2018 11:04 PM

thanks for the links on making your own fittings, that is an idea I am exploring. I don’t have a heat gun, have to use a propane torch or boiling water,any ideas on heat on working PVC with these heat sources . my BS is already adapted to 1.25 hose, what I need to adapt in my TS port. ITs 2.5 hose not sure of the inside diameter but its around 2.25. I want to make a cyclone dust collector when I can find the hose.

View ohtimberwolf's profile

ohtimberwolf

936 posts in 2862 days


#13 posted 07-01-2018 11:34 PM

I don’t and wouldn’t use a torch but that is me. Harbor Freight heat guns are cheap and I find a lot more uses for it than I thought I would. If you use a torch be sure to be well ventilated in your work area. Also, have a fire extinguisher handy using a torch. If you get the plastic too soft it will be hard to manage. I have built a wooden form to do some my shaping. larry

-- Just a barn cat, now gone to cat heaven.

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