[jharvey407]

I just received my two Lighthouse LH7123-220 motors for a universal vacuum system for my 36"x52" router. I have read a few of the posts in the shopbot forums about these motors, and they seem to be a reasonably priced solution for universal vacuum.

You can see some ideas here:

Black Box Vac Source - Let's Talk ShopBot
The QUAD - Let's Talk ShopBot

Has anyone else used them?

For my table I will be using the two motors in parallel. I'll be setting up a test plenum at some point to test the equipment before I go through the trouble of converting my existing t-track table to vac.

Any input is appreciated.

James

[jharvey407]

Here are the 2 vacuum motors, and the box I built to hold them.

I borrowed the design from the guys over at ShopBot.

I am using two motors in parallel. The inlet is 2" PVC.

[jharvey407]

My cutting area is 36" x 52". I have a planning bit that I use to surface the spoilboard that is 2" in diameter. I decided to make my plenum and spoilboard 1 1/2" larger than my working area. This is about the max size I can surface with the 2" bit.

I am having a bit of trouble cutting the plenum though. I haven't been able to find very specific information about the best design for a plenum except that it is a bunch of channels for directing the air to the vacuum. I figured a quick and easy plenum design would be 3/4" material with 1/2" grooves 1/2" deep and spaced 1/2" apart. I tried to cut the first plenum out of MDF with a 1/2" bit, but the small squares broke out while I was cutting it. I changed to a piece of 3/4" ply, and switched to a 1/4" down spiral bit, but I am still losing some of the little squares. The problem got worse as I started cutting the X axis grooves ]I moved the grooves to 1" apart, and only 1/4" deep and that seemed to help a little, but I need a better design if anyone knows of one.

I am sealing the bottom and the edges of the plenum with lacquer sanding sealer. I will glue the LDF spoilboard to the plenum along the perimeter and then seal the sides of the spoilboard with lacquer.

Attachment 219562 Attachment 219560

[fixtureman1]

my squares are 1.5 inches and the hole is in the center. I did X from corner to corner also

[jharvey407]

my squares are 1.5 inches and the hole is in the center. I did X from corner to corner also

I've seen some pictures where people have cut grooves radially from the vac inlet. That seems like a good idea.

What material did you use for your plenum?

How wide/deep are the channels for the air?

Thanks for the help.

[fixtureman1]

I used .75 MDF .5 bit cut .375 deep sealed the edges with 2 coats of 50 50 glue and water. surfaced a piece of ultra lite MDF on one side the flipped it and glued it down using the vacs to suck it down with a piece of ply on top of it. Ran the vac for about 2 hrs then let it set over night surfaced the top top open it up and level it. Hope this helps

[jharvey407]

I used .75 MDF .5 bit cut .375 deep sealed the edges with 2 coats of 50 50 glue and water. surfaced a piece of ultra lite MDF on one side the flipped it and glued it down using the vacs to suck it down with a piece of ply on top of it. Ran the vac for about 2 hrs then let it set over night surfaced the top top open it up and level it. Hope this helps

Thanks, I'll give this a try. I guess my problem was cause by making the squares to small.

I have seen some pictures of plenums with fairly large squares, that have small, maybe .125" grooves milled into the top of the squares.

[jharvey407]

I finished the plumbing for the vac table. I used 2" PVC and 2" hard vacuum hose.

I haven't glued the PVC yet because I feel like there will be some changes before this project is completed, but I did seal it well with silicone tape. When I plug the inlet in the plenum the vac pulls - 7.5" hg. I feel like this isn't going to be adequate, but the first test will tell.

There is a 1/4" hole drilled in the vac box (as per the instructions) so that there is always some cooling air reaching the lower bearings in the vac motors. When I cover this hole the amount of vacuum created increases by about 1/2" hg.

I don't have the test instruments to test the actual airflow, but it's a lot. These two vac motors pull A LOT more air than my 6.5 hp (yeah, right!) shop vac.

I should be receiving the LDF for the spoilboard today. I'm hoping to have the spoilboard mounted and sealed by the end of the day. Then we'll see how much vacuum this setup reads with an empty spoilboard, versus the spoilboard covered in plastic.

[fixtureman1]

When you say sealed spoil board I hope you mean the edges and not the top and bottom. The top and bottom should be milled to remove the waxy surface to let the air flow through

[jharvey407]

When you say sealed spoil board I hope you mean the edges and not the top and bottom. The top and bottom should be milled to remove the waxy surface to let the air flow through

You are correct.

Here's my plan.

1. Lay spoilboard on plenum, hold down with vac.
2. Remove hard layer with surfacing bit.
3. Flip spoilboard and glue to plenum along the perimeter.
4. Surface spoilboard with surfacing bit.
5. Seal edges of spoil board with lacquer.
6. Get back to work.

With the fresh LDF spoilboard just laying on top of the plenum the vac is showing just under 4" hg.

J

[jharvey407]

I misses a step.

I should have leveled the plenum with the planning bit before putting on the spoilboard. The plenum is not quite flat, so milling the spoilboard was a bit uneven.

Although I would worry the milling the plenum would disturb the squares. I guess I could level the plenum, then cut the grooves.

We'll try that on the next one.

J

[jharvey407]

I did some tests this weekend with 1/4" acrylic. The vac held it down no problem and I was able to make 1/4" passes with a 1/8" endmill and the acrylic never moved.

This morning I used it for the first time during an actual job, and it worked flawlessly.

I cut 4 glass racks out of 1/2" PVC. I ran a 1/8" endmill in 1/4" passes (spiral toolpath) and the PVC did not move at all. The drops were circles about 2" in diameter, as well as some grooves for wine glass stems. All the pieces stayed in place.

One thing I noticed though, is that the swarf is not being pulled out of the kerf as well as it used too. This must be due to the vacuum pulling through the kerf once the endmill is all the way through the material.

I don't think it is going to be a problem. In the future I could run passes almost through the material, leaving 1/16" or so, and then make the final pass full depth. I was also thinking about this strategy if the parts are very small, with insufficient area to be held down by the vac.

You can see in the picture that I used a little plastic to cover the exposed spoilboard areas. I am going to make two simple 'curtains' of plastic on dowels. One will be aligned along the X axis and one along the Y axis. I'll be able to unroll just enough plastic to cover any exposed spoilboard areas to maximize vac power.

With nothing on the spoilboard the gauge shows 2 1/2" hg. With just the PVC it read 5" hg and with the spoilboard covered it read 7 1/2" hg.

I think that these vacuum motors are a great low-cost alternative to a large regen vac pump.

I will be redesigning my vac motor box to include a filter. I am going to size it for a standard Shop-Vac hepa filter to protect the vac motors from debris. Right now I am using white scotch-brite pads for filters.

I hope everyone finds this information useful.

James

[ger21]

How loud are they? I was planning on running 3 on the new machine I'm building.

We have two 10HP pumps on our 5x12 table. All parts under 400 sq in are onion skinned. First pass leaves about .007, then the second pass cuts through. We can cut parts as small as 4"x12" at 1000ipm this way.

[jharvey407]

In a word, LOUD.

I don't have a db meter, but I would say that the two motors produce a little bit more noise than my 5.5 hp 10gal shop vac, and a bit less noise than a 7000 series Porter Cable router.

I haven't done anything to mitigate the noise yet. Both motors exhaust ports are open directly into the room.

I think a proper sound box could bring the noise level down considerably.

James

How loud are they? I was planning on running 3 on the new machine I'm building.

We have two 10HP pumps on our 5x12 table. All parts under 400 sq in are onion skinned. First pass leaves about .007, then the second pass cuts through. We can cut parts as small as 4"x12" at 1000ipm this way.

[dsnellen]

Had the opportunity to see James's vacuum table in operation this AM. Very impressive!! It has some serious sucking power. By covering the unused section of the table, the vacuum will hold very tight even small pieces. I can see one of these in my future. Thank James for showing me around this morning.
Dave

[davemcollins]

Masking the rest of the vacuum table off with plastic sheeting works great, but beware of it getting moved around with the dust shoe / dust collection airflow...I just managed to wrap a 1' x 8' sheet around my bit. I now use packing tape to fasten the edges of the plastic around the part I'm holding down.

Cheers,
Dave