My BT48 Vac Table Project

[Simops]

OK this has been a long works in progress project.....got it to a point now to show and tell. The regen pump and plumbing done. Still have to do the plenum and hook-up.

The pump is 2.2 KW (about 2.2Hp) single phase. I don't have 3 phase hence this was the largest pump I could get on single phase. It's hooked up to its own breaker and I'm using a contactor (relay) so a small toggle switch can be used to turn it on and off.

The pump has a silencer attached giving a max 70 db noise level when standing at my usual spot.

The plumbing includes a relief valve with its own filter and a main inline filter that has a lid that can be easily opened and filter replaced.

Being a sceptic with the power of my 2Hp pump being sufficient I have zoned my 4 x 4 table into 4 zones......with 4 valves that can be opened and closed individually. Each zone has its own vent valve as well to release vacuum so as to avoid turning off the pump between reloading the table.

I have tested the system (by closing the 4 zone valves) and the vac gauge shows 5" hg when the relief valve kicks in maintaining this pressure.

Below pics showing so far.....more to follow.
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[Joe Porter]

No wonder it is taking you so long..Beautiful Work!!!....joe

[Brady Watson]

Lookin' good. Very nicely executed.

I'm not sure 5Hg" is going to be enough for smaller parts though...but it will be OK for larger things. The tighter you can make that system (leakage) the more you'll get out of it. I don't know the specs of the pump, but you'll want to be sure that it the BOV is adjusted to get as much suction as possible. I tweaked my regen to run @ 9.5 Hg" compared to factory specs of 8 Hg". It runs fine for hours...then again I don't care if I smoke it - I don't have a lot wrapped into it.

-B

[Simops]

Yea Brady.....I'm sceptical that it will be enough too. I have made it so I can add another pump ...Pump per two zones.
What's BOV?

Cheers

[Brady Watson]

Yea Brady.....I'm sceptical that it will be enough too. I have made it so I can add another pump ...Pump per two zones.
What's BOV?


BOV = Blow Off Valve...sorry turbo term. Same as pressure relief valve.

2 pumps will give you the same amount of suction (assuming run in parallel) and twice the CFM/airflow. I doubt the pumps are designed to be run in series (one pump sucking through the other) - but you can probably send an email/call the engineering department of the pump manufacturer & ask.

-B

[David Iannone]

That is a great looking setup there. And the computer stand too. Very well thought out indeed!

Dave

[Simops]

BOV = Blow Off Valve...sorry turbo term. Same as pressure relief valve.

2 pumps will give you the same amount of suction (assuming run in parallel) and twice the CFM/airflow. I doubt the pumps are designed to be run in series (one pump sucking through the other) - but you can probably send an email/call the engineering department of the pump manufacturer & ask.
-B

Yep OK.....I tried to adjust the relief valve (BOV) but if I push it too far the pressure reading fluctuates widly just above 5" and warbling sound heard so I back off.

Yep in parallel ......I've plumbed it so that I can add another pump in parallel so that one pump supplies two valves....two zones only independently of the other pump with its two zones. In this way each pump will do max 4 x 2' area. Before I spend another $1!k doing that (the Aussie $ has sunk badly) I'm going to try the one pump first.

The next big effort is working out the most efficient plenum chamber and the zones. I have already made the aluminium hollow rectangular tubing to go under the table.
Cheers

[Ajcoholic]

If you believe me, I was just thinking about you two days ago and was going to PM you about your table... but the weekend here has been crazy with Easter, and my son's 4th B day.

Glad to see you are back at it. My plenum works well, with the 1/2" grooves and 1/2" lands. I dont think youd be able to cut that close in MDF though as I think the 1/2" square pcs left would snap while machining unless you went super slow. I guess the more channel and less "left" the better.

I'm glad I bought the pump, etc last summer, our dollar also took a dive VS the US buck. Big time.

I'd still like to know how the "vacuum booster" I am using compares to a simple relief valve. The guys I dealt with said that the vac booster is designed to dead head your pump and get the max suction, VS the simpler (and cheaper relief). Also it doesnt whistle.

[Simops]

Yay
If you believe me, I was just thinking about you two days ago and was going to PM you about your table... but the weekend here has been crazy with Easter, and my son's 4th B day.

Glad to see you are back at it. My plenum works well, with the 1/2" grooves and 1/2" lands. I dont think youd be able to cut that close in MDF though as I think the 1/2" square pcs left would snap while machining unless you went super slow. I guess the more channel and less "left" the better.

I'm glad I bought the pump, etc last summer, our dollar also took a dive VS the US buck. Big time.

I'd still like to know how the "vacuum booster" I am using compares to a simple relief valve. The guys I dealt with said that the vac booster is designed to dead head your pump and get the max suction, VS the simpler (and cheaper relief). Also it doesnt whistle.

Yea Andrew...the plenum chamber will need some thought. Iv left that for last to gather up more info and to consider the design further.....no hurry....waited this long can wait a bit longer to get it as right as I can.
I remember you mentioning the vac booster some time ago but could not source one (probably due to lack of knowledge, more so than anything and mentioning it here just got me blank stares) so gave up.

Cheers

[Simops]

That is a great looking setup there. And the computer stand too. Very well thought out indeed!

Dave

David, yes I have the computer station on that side of the Bot because of the position its in. Hence I have the X and Y axii reversed from the factory default location with the 0,0 position at the corner next to the computer.

Cheers. 24698

[Brady Watson]

The shame of it is, that little Festool probably sucks harder than the pump.

-B

[Simops]

Quick question about the plenum......
Does it matter how dense the grid pattern is? In another words, does a less dense or more dense pattern make a difference with the sucking power?

Ta

[bleeth]

Larger air volume is better than lower.

[Ajcoholic]

So how is the vac project going??

[elcar903]

Very nice Idea, looks good

[Simops]

More to follow soon.......plenum done (something out of the ordinary) and now 3D printing some custom clips and brackets to hold the ally square tubing underneath the table.
Been busy finishing off my sim demo centre and getting civil aviation certifications that has had me tied up in red tape......so have not had a chance to do anything on the bot for a few weeks.

Standby.....

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[Brady Watson]

FYI - 1" squares with .25 to .5" channels are fine. You can go .125 to .25" deep and get all the airflow you'll need. Use a downcut bit to keep from knocking the squares off.

-B

[Simops]

Oops too late Brady....already cut the plenum.....0.375" deep, 0.75" x 1" gap........
Ah well see how it goes......worse that happens is I do it again.......
Thanks for the advice anyway!
Cheers
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[Brady Watson]

All that fancy cutting won't give you any better performance than just a downcut with channels...It's been tried 6 ways from Sunday, including ball vs V-bit vs square etc. As long as you have channels to evacuate the air from the plenum, you're good. What you have will be fine - unless you throw a really high Hg" vac at it - you may get some dimples in the surface.

-B

[Simops]

Yea I know......must have been my arty side that made me diverge to a fancy cut. Next time I'll be more practical!!!

Cheers

[Simops]

Vac table finished......at last!!

4 independent zones......each 2 x 2'. Reason is that I only have the 2.2hp blower so decided that instead of throwing plastic sheets down to restrict flow I'd use more zones as quite often I only use half the table or less.

I sealed each zone from the other and all round the table. I went to a lot of trouble to make sure the whole system was as airtight as a drum. The rectangular aluminium tubing under the table are held in place with 3D printed (ABS) brackets ....had to come up with a solution for the tight space between power stick and rollers with using two tubes per side.

Preliminary tests are very positive.

With the one zone on it sticks like mud
With two zones open (4 x 2' area) and with a 1 x 1 foot piece of ply sitting in this 4 x 2 area it stick like mud. So that's good as I didn't need to mask off the open space.
But if I start opening more zones then that 1 x 1 piece stops sticking like mud.
If I open all 4 zones and put a 4 x 3 piece of ply on it it sticks well if the ply s flat but if there is a warp in it it won't pull it down.

I think that a 2.2Hp blower is certainly the minimum for a 4 x 4 table. If I had another 2.2Hp blower added it would rock and be useable over the whole 4 x 4 area with any size piece with no masking!! I might just do that yet!
I took a video of my experience with this project and when I get a chance to edit it together I'll post it.
This project is now done and dusted.....

Cheers
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[Joe Porter]

Very nice, Michael...joe

[Simops]

Thanks Joe.....
Already been put to good use......pic attached......no clamps or screw hold down and no tabs for through cut:D

Cheers
25380

[Ajcoholic]

Sweet set up Mike. Man, you really made it neat and tidy...

So you see now why I was so excited last year?? It really does change the way you machine stuff!

[Simops]

That's my weakness Andrew......I over engineer!
It can be done a lot quicker and simpler for same result.....

Cheers

[Simops]

Just a quick feedback after a few months of use.....

First of.....if you don't have vac get it.....makes CNC life easier for sure.
Pictures attached show cutting 2mm aluminium.....this is now a breeze. Cuts cleaner as no longer is the aluminium sheet riding up the bit spooling the cut. The cut is accurate in Z. The material is sticking to the bed like the perverbial brown stuff :D
Also cutting wood such as the 1.25" thick piece in the pic that I'm pocketing. No clamps.

I'm thinking of adding another 2Hp regen in parallel??? Or series???? To make it even more powerful.....maybe??

Cheers273352733327334

[Ajcoholic]

Just a quick feedback after a few months of use.....

First of.....if you don't have vac get it.....makes CNC life easier for sure.
Pictures attached show cutting 2mm aluminium.....this is now a breeze. Cuts cleaner as no longer is the aluminium sheet riding up the bit spooling the cut. The cut is accurate in Z. The material is sticking to the bed like the perverbial brown stuff :D
Also cutting wood such as the 1.25" thick piece in the pic that I'm pocketing. No clamps.

I'm thinking of adding another 2Hp regen in parallel??? Or series???? To make it even more powerful.....maybe??

Cheers273352733327334

I remember life before my vac table. No way I'd ever go back now!!!

It's just too handy.