Workholding and Vaccuum

[james mcgrew]

http://www.bockworkholding.com/

[james mcgrew]

placed new vacuum pump and it would not fit under the table so we built a structure over it then put dustcollector on top by the time we were finished we named it tony the tower for an employee who was out today!!

jim

[james mcgrew]

vacuum table grid

[james mcgrew]

http://www.grizzly.com/products/Shop-Fox-Cam-Clamp/H5740

[TomM]

another cam clamp site

http://welcometothesandbox.com/index.html

[Angus_Hines]

And David has posted the files and explanation for these in his ShopBot woodworking articles section. So you can cut your own third article down - June 2007. Look towards the bottom in the fine print area...LOL

http://www.shopbottools.com/notes_from_the_sandbox.htm

another cam clamp site

http://welcometothesandbox.com/index.html

[james mcgrew]

needed to revive this as there are lots of new machine owners

this fellow uses a piece of slatwall counter sunk to his table with clamps!!

the other fellow has screwed slats to his sloted aluminum

[Bob Savage]

Excellent thread. They're a little pricey, but I bought some of the screw downs from the sandbox guy. The channels thing look nice, but I'm going to keep it simple for now until I get a little experience and better understand my needs.

[fixtureman]

I used the slotwall clamping system and made my own cams with T nuts before I went to a vac hold down. It worked good for some stuff but I started cutting a lot of .25 and thinner and sometimes the thinner stuff woudl buckle and release.

[Joey Jarrard]

fixtureman show us some pics

[fixtureman]

I have no pictures of that set up but did use it for a year now I have a vac system with 2 Fein vacs

[Eric Mims]

I'm having trouble holding down sintra sheets on my table. I am having to use a down spiral bit and it rewelds just a little bit, but then I have to clean up every piece and also have to use a couple tabs. But my parts still seem to be coming out different. I did another sheet today of 8 identical parts and there is noticeable differences in sizes (ie. an 1/8" or more). So even though I used 15 screws in strategic places on the 4x8 sheet, I guess the thin Sintra is still moving.

My table isn't cut for vacuum (though it was supposed to be and is supposed to be done if I decide I need it).

Do I have any other options right now other than shelling out for a vacuum pump (no $$ to get one right now)? I have many, many signs to make for them and I want to get them the best quality parts.

[Joey Jarrard]

Just let me know on the table Eric.
What is the feed and speed?
what is the diameter of the tool?
thickness of the centra?
Have you tried onion skin?
double comp bit?

[Eric Mims]

I do 1/8 and 1/4 sintra (Komatex), 4x 8 sheets. I use a down spiral single flute onsrud 1/16" bit at 80 ipm and 17000rpm. They need sharp inside corners, that's the only reason for the 1/16" bit. I do not think the bit is flexing. On 1/8" sheets I do a pass, leaving maybe .02 for the 2nd pass to cut through and leave a few tabs. 1/4" I am having to do 3 passes.

Just concerned about parts coming out different sizes as well as part cleanup time.

[Joey Jarrard]

all sounds good but the feed and speed. drop back the router to around 14000 you need to make a bigger chip to get the heat out to stop the melting back. the 2nd pass could be hitting some of the chips that are melted and pushing the part.
also if this still leaves you with parts moving use the trusty 3m double sided tape. I use it and it works like a champ.

[PJS]

I just wanted to throw in some information here. When it comes to holding sheet goods in place, I use only the Fein vac system. On my current job I'm skin cutting a 48 x 48 x 1.5 thick MDF material using a 1/2" up tool running at 10K RPM and 225 IPM in 3 passes at 0.5" per pass. I leave about a 0.020" skin and make a cut through pass. I'm only using one Fein vac although I have two hooked up to the table in 4 zones. I've cut 3/4" Sintra with a 1/4" down cut bit in two passes, no skin at about 150 IPM. I was amazed at the holding power of those little vac systems. I had to go this route due to available power, noise and money. The Feins are quiet in comparison to the larger systems.

Paul

[james mcgrew]

i used two feins on the older camaster, they pull 7"merc and some heavy cfms, a regular shopvac pulls 1.5 - 2"

[fixtureman]

I cut a lot of sintra komatex and I find that a 1 flute straight cutter ae 12,000 and 4,5 IPS works really well. 2 Feins on my 4 x 8 table cuttin full sheets on material only very small parts seem to be the problem. I cut most of it in 2 or more passes depending on the thickness that way it leaves the chaff in the cut and I still get good vacuum. No problem with rewelding running the=is way.

[Eric Mims]

are the Feins able to run continuously for long amounts of time?

[james mcgrew]

i have run mine two hours, it has been a while since i ran them as i purchased larger vacuum

jim

[Eric Mims]

what did you get Jim?

[james mcgrew]

eric i have a 5hp fpz regen and a 10 hp fpz together i get a good hold with a bit of decent strategy for smaller pieces

[PJS]

I've run my Feins over 4 hours on some longer run jobs with no problems. They will put off some heat but I was always told this was normal. I've had two of them for over five years although I don't run them every day.

Paul

[fixtureman]

I have run my Fein's for 8 hrs in the summer 90 degree heat with no problems the Feins have a bypass cooler so they don't over heat.

[scottw]

Anyone have photos of vacuum set up using Fein's?

Thanks

Scott

[Eric Mims]

I picked up a lobe blower vacuum pump for nothing and am going to give it a shot. I am going to make a filter box for the intake with a vacuum gauge on each side. Do I need a relief/check valve anywhere, and if so, what kind and where?

[james mcgrew]

my relief valve is between the table valves and the blower

[Eric Mims]

anyone have a link or description to what type of valve is needed? I assume it is used so the pump doesn't go beyond it's working max. vacuum (in my case 15"hg).. if you were to close off the main table valves, the relief valve would open to let air keep flowing.. right?

where do I get one?

[Eric Mims]

will this work? http://www.mcmaster.com/#48935k25

very last item at bottom of the page

[james mcgrew]

http://www.fpz.com/modules_cms/prcatpage.php?cc=36&pc=82

http://www.midwest-control.com/safety_valves_Kunkle_vacuum_215V.html

[james mcgrew]

valves,,,,

[james mcgrew]

made a small video of the festool clam table i use

jim

http://www.youtube.com/watch?v=vXEtdSEVq1w&feature=related

[Eric Mims]

hey thanks for those pics. The one I picked up is smaller, but I'm gonna try it and if it doesn't work I'll just change it out for a $$ one.

[scottw]

Anyone have photos of vacuum set up using Fein's?

Thanks

Scott

Bump...

Anyone?

[james mcgrew]

scott, the valve setup is the same with the fein collection hose attached at the manifold, i will see if i still have any pics from when i used it

jim

[scottw]

Thanks Jim,

Joey has quoted a router for me but the vac and phase converter adds over 6k. Can I get away with Feins or am I just going to wish I spent the extra $$? Right now I'm about 5 k over budget with the vac system included...

Scott

scott, the valve setup is the same with the fein collection hose attached at the manifold, i will see if i still have any pics from when i used it

jim

[james mcgrew]

sorry ended up asleep, will answer more later in the am

jim

[Eric Mims]

search the talkshopbot.com forum for pics of the Fein setup. also, you can find an interesting discussion on using smaller vacuum blowers in series or parallel with many photos.. search for open source vacuum on the shopbot forum.

I'm building a filter box setup today and hopefully start cutting my plenum table.

[Eric Mims]

Well I am just about finished with the vacuum install. I am using a Sutorbilt lobe blower that is rated to run at 15"hg in the 160-180 cfm area. It will pull more than that, but that's the safe limit.

Since this was done on a shoestring budget and these cost between $150-$300, I had to make my own vacuum relief valve. Joey sent me some photos today and I stopped by Lowe's and got what I needed.

Essentially I made a 2" screw-in PVC valve. I used my drill press to drill out 3/4" baltic birch for the bottom plate. I drilled .5" holes in it to allow enough CFMs to flow through to keep the vacuum level down. I used data from this page (http://nasvi.com/database/_215.pdf) to help calculate how much flow area would be needed. I will most likely remake this part out of aluminum when I get a piece with large enough diameter, and add a nipple for the spring to center on.

I used my lathe to turn the top piece, it has a nipple underneath to center the spring. 2 nuts with a lock washer keep it from springing off. The top PVC piece steps from 2" to 1" reducer.. the aluminum piece is about 1.7".. big enough to always cover the hole, but with enough airflow around the outside of it when forced down to allow the proper CFM.

I tested it and when I closed all the valves, the relief valve opened and the gauges read 12". So I added a couple washers and now it reads 14" when all valves are closed, or if one is open but something is sitting on it.

Next step is to fit a filter on it.

Then, remake bottom piece from aluminum and possibly make an extension for the top that looks like a spider, so the bolt can continue on through and keep centered.. helping to center the stopper more accurately.

the pipe wrap tape is temporary, obviously.

Eric

http://mimsworks.com/images/vrv1.jpg

http://mimsworks.com/images/vrv2.jpg

http://mimsworks.com/images/vrv3.jpg

http://mimsworks.com/images/vrv4.jpg

[james mcgrew]

now that is impressive!!

jim

[Eric Mims]

forgot to mention, it cost about 10 bucks to make, and several hours to figure it out. I'll be interested to see how it performs as a piece is being cut and slowly you start losing air through the spoilboard.

[Joey Jarrard]

Eric,

looks better than i dreamed it would good for you man. thats about $215.00 back in your pocket.

Great Job [fantastic]

[Eric Mims]

added a screen and filter to it today and realized it can be a fine line between CFM and spring pressure. First I had the spring tensioned where when you closed all valves, it went briefly above 20" and then dropped to 14" and stayed there. When I added a filter, it would no longer activate.. I guess reduced cfm.

So I removed two washers from the spring to make it less tense and it went to 15" down to 12", and with the filter, it goes up to 15" max and drops to 14". It's interesting to try and dial it in just right.

[Eric Mims]

OK, so I made my first cuts with the vacuum table. .25" sintra was the material. I am still having an issue with parts not matching. I am beginning to think it could be bit deflection. I am using 1/16" bit, upcut instead of the downcut I was using. My edge quality is better because the chips aren't rewelding.. virtually no cleanup which is nice. But why are my parts coming out weird.. we are talking 2' by 1.5' parts.. not very small. They are nested at random angles on the board, and I will try to do a set with them all facing the same direction.. but wouldn't bit deflection be similar regardless? I am seeing an error of pieces up to .125. You line up 2 corners and the others don't line up. Typically by 1/32 or 1/16, but up to 1/8" off.

I have triple checked the geometry in Rhino and each copy is identical.

Should I cut climb or conventional? I really need these parts to come out consistent.

thanks

[james mcgrew]

try a 1/8th inch bit

[Eric Mims]

unfortunately my 1/8 broke today for some reason. it's really strange because the error seems too big to be deflection. but surely the pieces aren't moving. I am really perplexed, but I really need to figure it out.

[Joey Jarrard]

I did this about 3 months ago and had to dig it back up for a new customer to look at.

What we see here is a typical vac set up. With inline filter and pop valve. Just thought the info could be of use here.