My One Surviving Fein Turbo III Has a New Job

[jim_vv]

I have been using two Fein Turbo III vacuums for hold down successfully for the past five years. Within the past six months, one of the vacuums has failed a couple of times. After all of the internal plastic parts melted for the second time, I decided, rather than pay for another non-guaranteed $200+ repair, to build a vac-box inspired by Gary Campbell's design. You can see Gary's "Black Box Vac Source" post at http://www.talkshopbot.com/forum/sho...t=black+source. A huge THANK YOU to Gary Campbell and Don Thomson for sharing their knowledge and experience with their vacuum systems. Also, I wish to thank Brady Watson for sharing his wisdom which inspired the check-valve.

I had originally planned on using only two 120V LH6765-13 Lighthouse motors, but I am glad that I heeded Gary's advice and recommendation for using four 240V LH7123-13 motors instead. The 240V motors draw less amperage, run cooler, and I will never be at a loss for CFM when it is needed. My surviving Fein now has a new job and is doing what it was designed to do . . . serving as a vacuum cleaner. I used some of the parts (casters and buckles) from the dead vacuum to build a much needed cyclone/vac-cart, while the vacuum's container will become a rain barrel to catch water for our chickens. I modified Gary's design only slightly. Since I did not plan to use all of the control electronics which Gary used, I ducted the cooling air through the rear "electronics compartment" rather than through the end panel. I also added an inch to the width of the baffled exhaust sections to allow for .5" thick insulation board. I do not know if there is a difference in sound levels as I do not have a vac-box without insulation against which to compare, but for a few dollars worth of insulation board and adhesive I thought that it could not hurt.

As I can only attach five pictures of my project per post I will divide them up into subsequent posts.

Some Pictures

[jim_vv]

I used Shop Grade Birch Plywood for my box. When I have time I will paint it with white lacquer. My check-valve is not as nice as Gary's, but appears to be working nicely. When the first stage motors are turned on a solid "clunk" confirms that the valve is being sucked shut. I used a scrap piece of PVC and some inexpensive tee hinges to make the valve.

More Pictures

[jim_vv]

I rebuilt my manifold so that I could connect it to the single inlet on the box. With all zone valves closed, the vacuum gauge reads 11 in.Hg; this is up from 5 in.Hg with my Fein system! I used a 1/2" ball valve to allow bleed air into the system for the times when I get a perfect seal. With all the zone valves closed, the vacuum drops 1 in.Hg when the bleed air valve is fully opened. I installed a sintered bronze muffler on the valve to help with noise and to ensure that nothing gets sucked in. Before installing the muffler, the bleed air was the noisiest part of the system. I think that I now have a most efficient vacuum system for the money I spent. Again, Gary, thank you for sharing your design.

More pictures

[knight_toolworks]

I think the melting issue was just not enough leakage. a vac check valve is the easy way to eliminate this about 30 shipped.
http://i154.photobucket.com/albums/s266/knighttoolworks/posting/df52d4e1.jpg

[garyc]

Jim...

Looks good, and I know Ward will like the relief valves!

After you get a few days of use under your belt, how about a report on how your new system compares to the old?

[Ajcoholic]

I have been reading and watching you fellow's make these vacuum assemblies up... and I have a few questions.

- how does something like this 4 vacuum + valves, etc compare to just buying something like a 10HP to 16HP regen blower? (not counting the costs differences, just the actual vacuum holding potential).

- what is the kind of materials and parts that can be held down suitably enough to machine? Say, if you are cutting parts from plywood - would you be able to cut parts as small as a foot square, or a few inches square, or just a few square feet minimum or??

I would love to invest in some sort of vacuum system eventually - but, unfortunately, I still havent read anything describing what exactly you can hold down to cut. I know that will vary a lot - but say you are cutting parts from 1/2" or 3/4" thick plywood with a 1/4" bit, in 1/4" deep passes at a reasonably fast speed.

Thanks,
Andrew

[garyc]

Andrew...
In a word, a qualified yes.

Its hard to actually compare to regens, etc. as they have higher duty cycles and usually pull higher vac numbers. With that said, they also usually require use of a more dense bleeder (MDF) and sacrifice a good portion of their vacuum to holding that bleeder down.

For comparison; my current favorite vac motor, the LH7123 specs show that it has a max CFM of 110.3 cfm and a max inH2O of 141.98. (10.44 inHg) Using multiples of these (using my anecdotal rule of 1.85) gives a 2 motor setup 204(+/-) max cfm and a 4 motor setup 377(+/-) max cfm. Both are capable of 10+ inHg at zero flow.

For hold down what is important is being able to maintain vacuum as the parts are cut thru, which creates leaks. This increases flow and decreases vacuum. The LH7123 flow charts and my testing shows that a 4 motor system will pull 10inHg on a clean table with a full sheet and hold 6.5 (+/-) inHg while flowing 200 cfm. Works perfect for sheet cutting, as a 3/8 bit kerf leaks around this amount. (Less if packed with chips or smaller diameter bit.) Many sheets end up showing near 8inHg on the gauge when done.

As it applies to cutting:
This has allowed a good number of us to complete onionskin cuts (full depth minus .030") at speeds ranging from 6 to 10 ips in the climb, then conventional cut direction. I have cut parts using these hold down and toolpathing methods down to about 3" by 8" and 2" by 20. (one caviat: the SB Link settings will allow the final (cut thru) cuts to slow down proportionally based on parametric settings. For lower than cabinet grade cutting, there would be no problem cutting 2 sqft pieces at 6-10 ips of 3/4 plywood in a single pass and maintaining hold down.

These cutting speeds are based on my experience with the current model Alpha machines.

Note: there are few if any vacuum cures for cheap warped plywood. :rolleyes:

[dlcw]

Andrew,

I have Gary's setup and I can say that the vacuum hold down capabilities are excellent. I regularly cut 4" round parts out of 1/4" MDF on two of the four motors and have never had one of the parts move.

I am getting ready to cut 800 letters out of 1/2" MDF with laminate on 1 side and shellac sealer on the other. Based on the samples I've done so far, on two motors I've not had any letters move and some of the 'dots' for the 'i' are about 2" square.

My previous setup of 4 of the LH motors mounted directly under the table would not come close to holding like this. Gary's setup is fantastic.

The only time I have to switch on the second two motors is when I'm cutting prefinished plywood for cabinet parts. This material is very slippery. But four motors holds it with no problem.

I've also been able to flatten some pretty twisted plywood for cutting with this setup.

So, with no hesitation, I would highly recommend taking the time and investing the money to put this setup together.

[Ajcoholic]

I am assuming you need the "trupan" material for the bleeder board for this type of vac?

I have inquired with my suppliers, for an ultra light fiber board. Doesn't seem to exist here in Canada.

If I can find something suitable, I would like to try this system out..

AJC

[knight_toolworks]

you choices are feins or separate fein type motors or the big guys. there is not much in between. for 1000.00 for a good pump would get me about the equal of one of the smaller motors or a bit better.

[pkirby]

My previous setup of 4 of the LH motors mounted directly under the table would not come close to holding like this.

Why does this box setup provide better holding power compared to 4 LH motors bolted directly to the table?

On a side note, I recently redid my vac table with the LH vacs (120 volt) bolted directly to the table. I cut the plenum out of 3/4" PVC and used ultralight as the bleeder and am only reading 7.5"Hg

[curtiss]

With all that vacuum are there any safety release options should the operator be sucked down onto the table with no escape ???

Some of these set ups look to be approaching "black hole" forces....

[jim_vv]

Greetings, Paul

I am no expert, but I think that more vacuum can be achieved when the motors are ducted through a common manifold. Based on my past experience with the two Feins, the amount of vacuum pulled is only going to be as high as the weakest motor.

I am curious, how do you measure your vacuum with your motors bolted directly under your table? Also, have you sealed the edges of your individual zones?

Kind regards,

JIM

[pkirby]

Jim,
I ran the vacuum gauge lines into the grooves of the plenum (see 1st pic below). The 2nd pic shows how the vacuum is bolted to the table. The zones are separated just by the grooves in the plenum. The bleeder was glued directly onto the plenum and I was very careful to make sure the glue did not go in the air space of the grooves. I then sealed the edges of the bleeder with 3 coats of shellac.

Also, to clarify my situation, I tested the vacuum motors before I put the bleeder on and I was measuring 7.5"Hg and then after the bleeder was glued on, I am still reading 7.5"Hg.

So I'm still confused on how it's possible for Gary's box to create more Hg than would be possible with the motors mounted directly to the table? Maybe it's just that everything Gary touches turns into an engineering marvel :D

14809

14810

[knight_toolworks]

it is more that you loose less hg because you have more airflow as you have all the motors working at once. Plus I think he changed motors.

[knight_toolworks]

how is that mini cyclone working does it get fine mdf dust?

[garyc]

Paul...
:D You keep that rumor going! ;)

Actually the motors cannot develop more Vacuum (inHg) with a parallel system, they develop more flow. (CFM) This means that in a cutting situation with a given amount of leakage they will maintain a higher level of vacuum.

Each brand and model of these motors has its own set of specs. The LH7123 has higher specs (10inHg+) than most. Thats why I use them. There are many times I have seen higher level of vac at the end of cutting a sheet than the Fien equals have with an uncut sheet on the table.

[jim_vv]

Paul,
The specs for our motors are slightly different.
Per his website your motors on average should pull 141” H2O (10.37” HG) and my motors on average should pull 148.8” H2O (10.95” HG). I am not sure why you are reading 7.5. Your gauge may be suspect or perhaps your input voltage is low?

Steve,
My little shop vac cyclone has served me quite well for a couple of years now. I built it for my sanding station because I was tired of how fast my old shop vac’s filter would cake up with fine dust. The bucket under the cyclone catches practically all of it. Here is a good article (http://lumberjocks.com/SimonSKL/blog/10097) on building one.

The attached images speak for themselves . . .

Maybe we should ask Gary to design a "Hot Rodded" version of a mini shop vac cyclone with a Lighthouse motor as well! :)

JIM

[pkirby]

Gary, thanks for the explanation. I'm currently using the 120volt model LH6765-13 motors, so I guess the moral of the story is use the 240volt LH7123-13.

Jim, I think the voltage is fine but I will try to test it later. I believe the gauges are fine because I'm getting the same reading on all of them (within 0.5"Hg)

[knight_toolworks]

Paul,

Steve,
My little shop vac cyclone has served me quite well for a couple of years now. I built it for my sanding station because I was tired of how fast my old shop vac’s filter would cake up with fine dust. The bucket under the cyclone catches practically all of it. Here is a good article (http://lumberjocks.com/SimonSKL/blog/10097) on building one.

JIM

oenida makes one now and it is not expensive. the only problem I see with it is that it is tall enough to get in the way of loading sheets on the bot unless I move it out of the way. so it could get annoying.

[Brady Watson]

Also, to clarify my situation, I tested the vacuum motors before I put the bleeder on and I was measuring 7.5"Hg and then after the bleeder was glued on, I am still reading 7.5"Hg.

Doesn't sound like your bleeder is bleeding...Are you 100% that it is ultralight MDF and not just LDF? You should ALWAYS throw the bleeder board up on top of the plenum & pull vacuum BEFORE you glue it down to make sure that it bleeds.

In my experience anything from 0 to 2.5Hg" is acceptable for a bleeder. Just keep in mind that if you can pull 7.5 max and you pull 2.5 with nothing on the table, all zones open, then you now have a max vacuum potential of 5 Hg", which would give you around 2.5 pounds per square inch of holding power...which ain't much in the grand scheme of things. On a pro pump running 14 Hg", 2.5 less isn't as big of a deal...acceptable, but still not ideal.

-B

[pkirby]

My bleeder was sold to me as ultralight and has the brand name "Masisa" on the edges of it. I should also state that my method of testing was pretty redneck and not scientific. Here was my method:

1) I cut the vac plenum out of 3/4" Fypon PVC (same stuff used on architectural millwork but they claim to be solid all the way thru without having foam in the middle)
2) I layed a scrap piece of domestic birch plywood over one zone (no gasketing), turned on the vac and it read 7.5"Hg
3) I glued the ultralight bleeder to the plenum, turned on the vac (with nothing on the table) and it read 1.0"Hg
4) I then put an entire sheet of plywood on expecting it to read 6.5"Hg (7.5-1.0=6.5) but to my surprise it still read 7.5"Hg.

I've come to accept the fact that everything I do, does not work as expected:D

[Brady Watson]

OK - that's GOOD! The vac will still read 7.5, but you will only have 6.5 Hg" that can be used, since the bleeder isn't as free flowing (like @ 0).

-B

[pkirby]

OK - that's GOOD! The vac will still read 7.5, but you will only have 6.5 Hg" that can be used, since the bleeder isn't as free flowing (like @ 0).

-B

Thanks for connecting the dots. It makes since when you phrase it that way.