Quick and cheap vacuum setup?

[ron_churches]

I know there are dozens of posts regarding the various vacuum systems available and I've read through most of them. However, I'm in a time crunch and was hoping someone could address my particular situation and recommend the cheapest and easiest vac hold-down to meet my needs.
I've been asked to bid on a project to cut 1,400 30x18 rectangles with .25" radius corners out of 1/2" NAUF particle board. I have a 2005 PRT Alpha 9648 with the PC 7518 router. I have been using screws/clamps with tabs up until now. I've calculated that this project will require 175 sheets of material and I'm thinking that a vac system is the way to go. Would a single central vacuum motor from Lighthouse be sufficient to hold the 8 rectangles per sheet I will be cutting? Would a single zone with a Trupan plenum work?Also, can someone recommend what cutter and RPM/feed I should use in order to cut these parts in a single pass as fast as possible?

[Gary Campbell]

Ron...
For 175 sheets, vac is for sure the way to go. Problem is that you want (1) quick, (2) cheap and (3) able to hold parts for agressive cutting. You will not get all 3 with one solution. I assume NAUF PB is not too porous, and your parts are fairly good sized, so I would recommend the following:

Quick and Cheap: Single zone and 1 direct mounted vac motor centrally located.
pro/con: Cheap and quick, (only). may be good enough to hold your parts for this job, but will leave you wanting in the future. May not have enough hold down on a used spoilboard to cut as aggresively as I do. YMMV

Quick: 2 or 4 direct direct mounted motors and a zone for each. (I would do 4) This will allow you to cut smaller parts and will not leave you wanting for hold down, but will have a higher noise level. 4 zone system should allow you to cut parts down to about 4-6" square on a fresh spoilboard. OF course, costs more.

Able to hold parts for aggressive cutting: Once you go VAC, you will never go back! Place the 4 motors in a selectable system like my Black Box. http://www.talkshopbot.com/forum/showthread.php?t=11813. Important is keeping cooling intake and exhaust separated. MAke it as simple or complicated as you like. Add it to a 4 zone manifold to allow combining vacuum to a single zone: http://www.shopbotblog.com/index.php...cuum-manifold/. I have used this down to 2" square parts on a single zone with moderate cutting speeds, and 3 by 8" parts at 6-7 ips full depth with an onionskin.

[bleeth]

You want it quick, cheap, and fast? That sounds like the prospective clients I throw out the door!
In reality the multi zone universal vac set up that Gary designed is cheap and not too tough to set up. With all the parts and design in hand you can probably get the whole thing done in a day or two. I would "guesstimate" between 1000-1500 for all the parts and although it isn't a 15HP regen the results are incredibly impressive at a fraction of the cost.
Single zone probably would not give you results that you like. On the other hand PVC fittings to go multi is a few hundred bucks max.

[srwtlc]

Sorta fast and cheap....You could make a "dedicated to this job only" vacuum surface/jig that would have the area under each piece cut out (with some support areas) and some gasketing just in from the perimeter of the part to keep the vacuum directly under/on the part. I've done this in the past (way past) and cut 0.5" Appleply with just a 6hp ShopVac. It wasn't pretty, but it got the job done which was 1400 8" x 8" squares.

In your case, since you have a few inches left at the end of the sheet, you could overhang the end just enough to hook the vac hose underneath the jig. I've use two sheets of MDF and cut the plenum in one face and the through openings and gasket track in the other. Glued together and sealed the edges. When I was done, I just pulled it off and kept it for next time and then chopped it up for other stuff when there wasn't a next time.

Quite similar to a large "Brady Vac" setup, but two pieces instead of one. http://www.shopbotblog.com/index.php...bradys-tricks/

[ron_churches]

I'm having a hard time finding Trupan in my area.Is there any other product that would work? I think I'm going to try the BradyVac2 with a single motor from Lighthouse. I intend to expand with two or more motors when I have more time (and money), but am hoping I can get through this job with one. Also, assuming the 1/2" sheet will stay in place, what bit is recommended to cut this material in one pass (if possible) and at what speeds?

[Gary Campbell]

Ron...
Many of the ULDF (ultra lite density fiberboard) will work. You may want to post your area and see what guys are using there.


Your cuts speeds will be determined by the power of your machine and hold down, but I would use a 3/8" 2 flute compression bit. 1/4 compression if you have to. I cut this material around 6-8 ips, but most with an alpha are in the 4-6ips range. Standard in the 2-3ips range. You may also be limited by hold down, so do a few test cuts and see where your combination works best.

EDIT: IF your move speeds end up being less than 4ips, you may want to try a single edge compression.

[ron_churches]

Gary, I'm near Detroit. I did find some Temple ULDF as well as Masisa in my area so I guess Ill try one those. They have roughly the same density rating (32lbs/cubic foot) as Trupan. Also, Thanks for the info on the compression bits

[Brady Watson]

You don't need ultralight MDF if you use a BradyVac II. Vacuum goes right to the back of the part. No bleeder necessary. Perfect for large runs of parts, it holds great and you can haul butt with the move speed.

-B

[ron_churches]

Thank you everyone for the advice. I've designed my jig and wonder if I have the ratio of "island" to vac chamber correct. I'll be sucking this thing with a single Lighthouse motor that is similar in specs. to a Fein Turbo III. Also,
Would a sheet of white melamine particle board from HD work well for the plenum/jig?

[meatbal80]

If you are cutting a rectangle over each spot and not any hole in the center, i would add some more holes to the plenum there in the center of each rectangle. The amount of force holding each part is directly proportional to the surface area being held.