Shop Made Blast Gate Experiment

glenn bradley

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Some of the methods I am using are due to limitations and not the recommended methods per se :D.

First there was a plan and the plan was good . . .

6 inch blast gate dims.png

I will have a few variations but, most will be like these; hose on one end and ASTM-2729 pipe on the other. The tongue will be smooth-both-sides tempered hardboard. That material and my 1/4" MDF are not convenient right now so I picked up a handy-panel of 1/4" MDF at the BORG and will use that for the prototype. Break down some blanks:

BG-GCS-no-shop.jpg

Spend 45 minutes trying to find my circle cutter. I have one that does 7". Measure and mark for the "pipe" side, clamp things down and cut a hole:

BG-No-Shop (2).jpg

Patting myself on the back a little for being able to find my drill press AND move enough "stuff" to make it usable :). My DP only goes down to 250 RPM. This often bugs me but, not often enough yet I guess.

BG-No-Shop (3).jpg

I did a test board to make sure I could fit the coupler section and then cut the MDF.

BG-No-Shop (4).jpg

I should explain a bit. I cut a section out of a stick of pipe to reduce the diameter so the hose would fit over it snugly. I then cut this pipe into 1-3/4" sections. This leaves 1-1/2" sticking out to accept the hose and clamp. The pipe end is made by cutting a 6" coupler in half trying to split the "stop" rib that is in the center. I did these cuts by scribing around the pipe sith a blade in a marking gauge, cutting at least through the pipe wall with a hand saw and then following the scribe with a jig saw. I really should have had some pictures of that; it was pretty funny.

Time for the other side . . .
 
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glenn bradley

Member
Messages
9,763
Location
SoCal
OK, pretty boring stuff but, I'm desperate ;-) The piece I cut out of the pipe to reduce the diameter got PVC cemented across the seam. Probably overkill in hindsight and I may skip this when I do a production run.

BG-No-Shop (6).jpg

I could struggle through making the stop and handle (see diagram above) but, I think I will just wait. Look, it's open.

BG-No-Shop (7).jpg

Closed.

BG-No-Shop (8).jpg

Open.

BG-No-Shop (9).jpg

Closed.

BG-No-Shop (10).jpg

Whew! That was exciting. I better go sit in my rocker on the porch for a while ;-)
 
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Chuck Ellis

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5,406
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Tellico Plains, Tennessee
Glenn, pretty neat design, but a question for your... my gates, bought from Rockler or Woodcraft -- years ago, so memory doesn't go back that far -- have small ports on the slide... yours doesn't.... if you wind up with all the gates closed at the same time, won't that dead head your vacuum? My gates all suck a small amount of air when closed.
 

glenn bradley

Member
Messages
9,763
Location
SoCal
Glenn, pretty neat design, but a question for your... my gates, bought from Rockler or Woodcraft -- years ago, so memory doesn't go back that far -- have small ports on the slide... yours doesn't.... if you wind up with all the gates closed at the same time, won't that dead head your vacuum? My gates all suck a small amount of air when closed.
I don't know if it is the same for high pressure, low volume systems like vacs but, a DC works the least when moving no air so, I am not worried about accidentally having all gates closed. I have generally setup a tool for use prior to firing up the system. I do leave it running when doing production runs but, those are few so my chances of dead heading the system are also few.

My new shop will be larger than my previous shop so I am trying to squeak out every drop I can from my little 2HP cyclone. Part of this is designing the most smooth and direct paths I can. Another part is to replace my leaky gates (that were fine in a smaller shop) with ones that seal better. I will also probably tape my pipe seams even though a smoker test showed no draw at the slip-fit seams in the past.

I'm hoping a little extra effort will save me from buying a new system. To do that within my budget I would probably have to pull the HVAC design and I really want AC here in the desert basin ;-)
 
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Chuck Ellis

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Tellico Plains, Tennessee
Okay, makes sense to me now... I have one of HF's 2 hp impeller DC... I only have 3 machines hooked to it, the band saw and two lathes... my longest hose run is about 20' from the big lathe... the pipe goes up and overhead across the shop to tie in with the hose from the band saw, then both tie in to the little lathe pipe, then under the work bench to the back wall where it goes through the wall to the "outhouse" that houses my DC.... I use the wire spiral hose that WC or Rocklers sold... the part under the work bench is actuall the aluminum dryer vent hose... I've run the system for about 13 or 14 years now and it seems to serve me well.... my shop is still covered in dust though.
 
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