gundog
05-25-2011, 01:22 AM
I have just completed or almost completed a huge rebuild of my vacuum table. I am really happy with the results I will post some pictures later. My old system was a very simple vacuum table design that had a manifold made from 2" & 3" ABS sewer pipe. The old design had no valves and the spoilboard was just laid on top of the plenum with some wooded dowels in the corner to align the spoilboard.
The system worked OK but I lost allot of vacuum from the lack of any seal between the plenum & the spoilboard. I use an automotive vacuum gauge to indicate the level of vacuum pressure it is not real accurate but to me it never mattered how much vacuum I was actually getting it only mattered that I had an indication to let me know if the parts would hold. With all the plugs in the old system it would indicate 8" of vacuum. When I would hold parts I never got more than 5" (half sheet the other zones plugged) the rest would leak from my setup. If I held a full sheet about 3" is the best I could get if I used tape around the edges.
With the old system the vacuum motors attached directly to the manifold I will post a few pictures of the old system to show the difference. I use a couple of the Lighthouse 220V vacuum motors shown in the open source vacuum thread. The motors have ran in parallel at all times and it was really needed with my old system.
The new system uses Valtera 2" knife valves for each vacuum port. I have 2 small zones that measure 13" x 24" they are located @ 0, 0 & 0, 24". The rest of the table has 4 more zones that are 21" x 48". The small zones each have one vacuum port with a valve and the large zones have 2 vacuum ports with a valve on each port for a total of 10 valves.
I decided to remote the vacuum motors to try and cut down on some noise. I have a small office about 10' x 12' in the corner of the shop and I just use it for storage so I have moved my air compressor, dust collector & now vacuum hold down motors to the noise room. The vacuum motors are connected to the manifold with a small manifold the connects the motors to some 3" ABS schedule 40 pipe there is about 45' from the table to the noise room.
This is much nicer than before it is not quite but it has removed the high pitch noise so now it is much easier on the ears.
The new vacuum manifold at the table is still made from 2" & 3" ABS similar to before but with valves now for controlling the zones and like Gary Campbell I have extended the handles for the valves to the end of the table. I have the first 4 zones handles on one end and the other 2 zone handles at the far end of the table. I only use those last 2 zones when cutting full sheets. I cut 54" x 48" sheets and 42" x 48" the most so that is why the table is setup the way it is. The small zones are great and I did nt have any on the last table I have already used them several times since completing the upgrade.
I now can pull the same 8" of vacuum with all the valves closed and even with the extra 45' of 3" it is almost instant. The big change is holding the 54" x 48" pieces I now get 7" of vacuum before the best I ever got was 5" holding the same size sheet. I am now thinking I could add a couple more valves to separate the 2 vacuum motors because I don't think I need them both running anymore. I will put in an extra switch so I can run just one or turn on both switches and run them both.
I was cutting yesterday and after 3 hours I was changing between sheet 2 & 3 and when I turned the vacuum motors on I got a funny noise coming from one motor I turned it off and then back on and it was normal. I checked to see how much air was coming out the exhaust of both motors and it was not much that is when I got the idea I may not need them both all the time. I cut plastic sheet most of the time and do not cut through so the motors are really sucking hard and not moving very many CFM.
Sorry for the long post I will update it with more pictures later. The pictures shown are of the old system the drawing is the new plenum I forgot to take a picture of it before I glued the spoilboard down.
Mike
The system worked OK but I lost allot of vacuum from the lack of any seal between the plenum & the spoilboard. I use an automotive vacuum gauge to indicate the level of vacuum pressure it is not real accurate but to me it never mattered how much vacuum I was actually getting it only mattered that I had an indication to let me know if the parts would hold. With all the plugs in the old system it would indicate 8" of vacuum. When I would hold parts I never got more than 5" (half sheet the other zones plugged) the rest would leak from my setup. If I held a full sheet about 3" is the best I could get if I used tape around the edges.
With the old system the vacuum motors attached directly to the manifold I will post a few pictures of the old system to show the difference. I use a couple of the Lighthouse 220V vacuum motors shown in the open source vacuum thread. The motors have ran in parallel at all times and it was really needed with my old system.
The new system uses Valtera 2" knife valves for each vacuum port. I have 2 small zones that measure 13" x 24" they are located @ 0, 0 & 0, 24". The rest of the table has 4 more zones that are 21" x 48". The small zones each have one vacuum port with a valve and the large zones have 2 vacuum ports with a valve on each port for a total of 10 valves.
I decided to remote the vacuum motors to try and cut down on some noise. I have a small office about 10' x 12' in the corner of the shop and I just use it for storage so I have moved my air compressor, dust collector & now vacuum hold down motors to the noise room. The vacuum motors are connected to the manifold with a small manifold the connects the motors to some 3" ABS schedule 40 pipe there is about 45' from the table to the noise room.
This is much nicer than before it is not quite but it has removed the high pitch noise so now it is much easier on the ears.
The new vacuum manifold at the table is still made from 2" & 3" ABS similar to before but with valves now for controlling the zones and like Gary Campbell I have extended the handles for the valves to the end of the table. I have the first 4 zones handles on one end and the other 2 zone handles at the far end of the table. I only use those last 2 zones when cutting full sheets. I cut 54" x 48" sheets and 42" x 48" the most so that is why the table is setup the way it is. The small zones are great and I did nt have any on the last table I have already used them several times since completing the upgrade.
I now can pull the same 8" of vacuum with all the valves closed and even with the extra 45' of 3" it is almost instant. The big change is holding the 54" x 48" pieces I now get 7" of vacuum before the best I ever got was 5" holding the same size sheet. I am now thinking I could add a couple more valves to separate the 2 vacuum motors because I don't think I need them both running anymore. I will put in an extra switch so I can run just one or turn on both switches and run them both.
I was cutting yesterday and after 3 hours I was changing between sheet 2 & 3 and when I turned the vacuum motors on I got a funny noise coming from one motor I turned it off and then back on and it was normal. I checked to see how much air was coming out the exhaust of both motors and it was not much that is when I got the idea I may not need them both all the time. I cut plastic sheet most of the time and do not cut through so the motors are really sucking hard and not moving very many CFM.
Sorry for the long post I will update it with more pictures later. The pictures shown are of the old system the drawing is the new plenum I forgot to take a picture of it before I glued the spoilboard down.
Mike