3 elbows hard pipe or flex

[James Pena]

Im sure I am probably overthinking this for a 6'-7' run. I have the blower in the attic bolted in a fixed position. I'm trying to do my run with straight pipe with as few elbows as possible. The trusses make it difficult to get from point A to B so I think I would either need to do 3 90 degree elbows (1 coming up from the garage, 1 making a turn, and 1 into the intake of the blower) with the straight 6" pipe or I could make it a lot easier with a the semi-rigid pipe would make a more continuous run but not hard pipe. Thanks!

[Glen Monaghan]

Depends on the capability of your blower but, for such a short run, the semi-rigid is probably fine (assuming it's not that spiral wire stuff). If you can form it into smooth and gentle turns, it actually might be better than solid pipe with 90 degree bends. If you use the solid pipe, try to use multiple 45s instead of 90s, or 5-section adjustables rather than 3-section adjustables, for lower losses.

[Keith Winter]

Im sure I am probably overthinking this for a 6'-7' run. I have the blower in the attic bolted in a fixed position. I'm trying to do my run with straight pipe with as few elbows as possible. The trusses make it difficult to get from point A to B so I think I would either need to do 3 90 degree elbows (1 coming up from the garage, 1 making a turn, and 1 into the intake of the blower) with the straight 6" pipe or I could make it a lot easier with a the semi-rigid pipe would make a more continuous run but not hard pipe. Thanks!

When you say 3 90 degree elbows do you mean they are actually at 90 degrees or.... What are the actual degrees you anticipate you will set them to?

[James Pena]

I am using the same 2HP 1550 cfm Harbor Freight blower that Keith mentioned in a previous post about his setup. Unfortunately based on where the motor is mounted and the positioning of the trusses, I would have to do 3 full 90 degree elbows.

Keith - I have the same blower as you. When I went to start the piping the 6 inch was too big for the port, but the 4 inch was too small. It really more like 5" and I put a 6" to 5" reducer which is extending the connection point out and is messing up my angles a little. What did you use to connect to the ports on the blower? Thanks!

[Kev Williams]

No matter what kind of plumbing you connect to 6" pipe, especially for less than 8', the amount of airflow affected will be absolutely negligible as far as sucking smoke out of your laser is concerned.

[Gary Hair]

No matter what kind of plumbing you connect to 6" pipe, especially for less than 8', the amount of airflow affected will be absolutely negligible as far as sucking smoke out of your laser is concerned.

Exactly right!

[Keith Winter]

Exactly what I did connected a 5" reducer to a 6" pipe. Going up to the 6" pipe as you are planning is a good idea, I went with 4" he first time, and had to rip it out to get more airflow. With as short as your run is I agree with the other guys go semi ridgid won't matter much.


I am using the same 2HP 1550 cfm Harbor Freight blower that Keith mentioned in a previous post about his setup. Unfortunately based on where the motor is mounted and the positioning of the trusses, I would have to do 3 full 90 degree elbows.

Keith - I have the same blower as you. When I went to start the piping the 6 inch was too big for the port, but the 4 inch was too small. It really more like 5" and I put a 6" to 5" reducer which is extending the connection point out and is messing up my angles a little. What did you use to connect to the ports on the blower? Thanks!