Planning my Vac table part II

[gundog]

Thanks to everyone who has helped so far. I have been doing a lot of thinking about this and I finally got caught up for now and can afford to tear into the table. I have gathered 2 vac motors & 2 mufflers from lighthouse, 40' of T-track a bunch of ABS pipe and fittings and I am going to start tomorrow.

My plan is to remove the particle board top piece on my table first. I do not machine much wood so I have some basic questions. What tool bit will work best to machine off 5/8" of particle board top that was glued to my plywood base? The particle board was glued on with Tight Bond wood glue. What bit speed and feed would be best? I have the starter bit set and a bunch of special duty plastic cutting spiral up cut O flute bits. How deep can you cut with the surfacing bit in one pass? I am thinking it may take a long time using the surfacing bit.

Now once I get the particle board off I have a base of 2 sheets of ¾” cabinet plywood on the machine I plan to leave it and start up from there. I plan to run the T-track between the 4 zones. I am also going to run T-track around the perimeter of the whole table outside the 96x48 cutting area. I bought some 4x4’s that I will rip down to the right height and they will be bolted to the steel bed frame of the machine the T-track will be sunk into that. I will also add some pieces bolted to the ends outside the cutting area. The reason I am doing this is so that I can add some cam type fixtures to hold a 4x8 sheet solid from shifting the vacuum will hold the sheet flat. I machine plastic and that stuff is slick I was worried about the sheets shifting so this is my solution.

I should be able to hold about any size piece on the table and secure the perimeter this way.

My next departure from the norm is the way I plan on making my zones. The T-track will separate the zones and each zone will have a reversible spoil board with the grid cut on one side. When using the plain side I have some plugs that will fill the 2" hole and they will be recessed so they don't stick up but will have some small holes drilled in them to allow for a little vac in that space. I am using the temp style plugs they use for future stub outs or temp caps they use on new const they are very thin.

The other non standard thing I am going to do is not use any valves. I will have six 2" vac inlets in the table. My plan is to build a 3" manifold with 2" running off to each inlet. When I am not using a particular zone I will just put a temp plug in that inlet and only leave open the inlets for the zones I am using. I got this idea in the plumbing isle when looking at the $12 price tag for each valve.

I hope I explained this OK because if any of you see a problem with my plan please let me know. I will take some pictures as I get going so I can post them.

Mike

[gundog]

One more question is particle board the same as trupan? I was looking around Lowes and Home Depot they had MDF and particle board for flooring. Is particle board ULDF? I am not a cabinet maker and I don't know much about sheet goods.

Thanks Mike

[thewoodcrafter]

Trupan is a brand of MDF not particle board.
I can't get Trupan so I buy light weight MDF.

[cabnet636]

i have not seen a significant difference between mdf and ldf when it came to spoil board use, any one else use both?

jim

[erik_f]

I haven't used both...but I was able to get ULDF (ultra light weight) and have been pleased with the holding power...granted I am using the 9-15 vacuum set up for a 2'x4' Buddy (in parallel only motor setup) so I'm sure my set up is more forgiving than using the same vacuum motors on a 4x8' table. The big boxes won't carry uldf, I go to a specialty sheet goods distributor.

[beacon14]

To remove the PB: Here's one suggestion. Use a 1/4" bit, I'd skip the nice new ones and use a slightly dull one since you don't care about cut quality. If you rout parallel grooves (full depth) leaving uncut ridges say 1/2" to 1" wide, you should be able to knock most of the ridges off with a hammer. Then surface with the spoilboard. If you try to machine the entire sheet it will be a LOT of cutting and a LOT of dust etc. I'd use a 1/4" upcut or straight bit at full depth, I know I can cut that at 5 or 6 IPS with my PRTAlpha/spindle but your machine may differ.

With two vac motors and a well-built table the likelihood that a 4x8 sheet will move seems pretty small, but you can't go wrong with extra T-track.

I like the idea of plugs instead of valves but I don't understand the need for small holes in them "to allow for a little vac in that space". If you are not using a zone it's best to have it completely off or it will rob vac power from where you need it.

Looking forward to seeing the pics and progress reports.

[gundog]

Thanks for the replies. The holes in the plugs are for the plugs used when reversing the spoilboard for that zone. I wanted to be able to use the grid side up or grid side down when pulling vacuum through the spoilboard. I am thinking since I cut plastic and do not cut through that grid side up may be best but for smaller parts a gasket and grid side down may work better. I have no experience here so I planned to experiment with one zone to start with. When the grid side is up a hole corresponding the inlet would need to be made to allow the vacuum to access the grid but when I use the grid side down that same hole would make a huge leak. The plugs I bought were 25 cents each so I will have some with holes for that purpose but when plugging that zone they will be with no holes. This may not work and I may find I don’t need the reversible spoilboard so this part may be abandoned.

The guy that sold me the vacuum motors told me that I needed 4 motors for a 4x8 area but I don't have the right size electrical service to run 4 motors so I was hoping by using the T-track to keep the sheets from shifting I could get by with 2 motors. I have a #12 service wire good for 20 amps ran to the table for vacuum (walls are sheet rocked) and these 2 motors draw 7.5 amps each at 220V.

I am not sure if the sheets would have shifted or not but my material is very expensive lowest cost stuff I use is $180 a sheet and the 40' of T-track was $180 so I am not wanting to experiment. I have been screwing stuff to the table and vibration has been an issue with finish quality. Plastic is unforgiving for edge quality, you can't just sand it if it is rough it has to be cut.

That makes sense to cut groves and chip the PB off I will try that and then surface it when complete. I knew someone would have a good idea.

Thanks Mike

[erik_f]

Well as far as I know running two of the motors suggested in the 9-15 thread you would be pulling more vac and more cfm than two feins...and that is what I know a few guys are running. You can always buy more motors. I don't do plastic, but I would guess since you are going to get very little leakage you should get those parts to hold down pretty darn nice. Obviously the more cut through area you have the more vac you will loose...this is where the higher cfm number come into play. Just to give you an idea...and temper this with the fact that I'm only cutting on a 2'x4' area...when I put a MDF blank down to be cut and put my zero plate down on top of it I can feel it getting sucked down to the mdf blank. The vacuum on the zero plate is pretty mild but impresses me anyway. If there is some way for you to leave some material in the kerf this will help maintain vaccum. Something you can try also is once you have your system set up put a piece of material on the table and start the vac motors. Try to move your work piece...for me I can't. If I try and peal up a corner I can usually do that with a good amount of effort, but I'm pretty sure that is because my set up is kind of sloppy. I don't have the edges of my spoil board seal with anything but aluminum duct tape. I had a little bit of a time getting used to going from vacuum from screws. At first it seemed a little more of a PITA to get going with vac instead of just dropping some screws into a piece. I have found after getting used to it that I love using the vacuum. My z depth of cut comes out MUCH better and I can use more of the material and haven't used any tabs since my second run with the vac. I think your edge quality will come out a lot better since your parts will stay put instead of flopping up and down. Also I find I'm not destroying my spoil board as often since I don't have to go as deep to cut through since I don't have to worry about z variations as much from material warp.

[beacon14]

I think the 4 motors per 4x8 is a general recommendation from the vac seller based on a few earlier setups where the motors were mounted directly to the underside of the table, hence, one motor per zone. With your manifold system you can distribute the two motors' force over the entire table. I do this now with two Fein vacs as Erik mentions and can cut 4x8 sheets of plywood and melamine (with appropriate toolpathing strategies.)

If you find the right spoilboard material (Trupan or lightweight MDF) I think you will find the grooves-down method works so well you will not want to bother flipping the spoilboards just to put the grooves up. With the grooves up it will much more of a challenge to mask off any areas of the zone that are not covered by the workpiece. With the grooves down you can just slide a piece of scrap plastic up to the workpiece to cover the rest of the zone, the scrap also gets sucked down, helping to keep the workpiece from shifting.

Trying it out with a smaller setup is a good idea. It takes a lot of effort to make a decent table and most people, after they get done, say "now I know how I should have done it".

I think you are on the right track (no pun intended).

[carlcnc]

Michael
occasionally I get a rough cut on plastics,
I have found a sharp cabinet scraper does a great job smoothing it out. it works so well that I now do a couple passes on any edge that will get flame polished before I fire up the MAP torch.

Carl

[gundog]

I have a few new questions to ask. I have 2 of the mufflers from Lighthouse for my Imperial vacuum motors but I did not buy the fittings to fit them. I took the mufflers to the hardware store and could not find any fittings that fit inside the 2" opening 1.5" pipe is close but slightly under size and 2" is way too big. They want $30 for the fittings I am too cheap to spend $30 for a few fittings what did you guys that used these use? I am thinking of not using them and just making some after looking at these mufflers I wish I had made them to start with.

The other thing I need to do is seal the MDF. After reading through the archives it looks like I should use polyurethene or shelac to seal the MDF. I would like to use something that will toughen it up some. I have some edges on the grid that chipped by just running the shop vac over the top cleaning up the grid after cutting the grid in. What would be the best product to use?

I still can't figure out how to post pictures on here? I belong to many different forums and this is the only one I can't figure out how to post my pictures on. Are they ever going to update this site to V bulletin or something better?

Mike

[billp]

Michael,
Shellac sealer with an epoxy topcoat will thoroughly seal MDF.....
Use "upload attachment"on the bottom of this page to upload photos...

[angus_hines]

Mike

I just used Shop vac hose from the blue borg and a lot of silicone for the mufflers.

As for pictures I post them on another board and just direct people to see them there. Cause your right this board is a little antiquated. I'm thinking this forum software was invented about the same time Al Gore invented the internet.

But the info is always fresh and relevant so I cant really complain.

[curtiss]

.....Shellac sealer with an epoxy topcoat will thoroughly seal MDF.....

"expoy topcoat" means Polyurethane ?

thanks

[br928]

Michael, The PVC pipe I used just pushed tightly into the mufflers. You might try using a different schedule pipe with a larger OD. I used flexible couplings with hose clamps to attach the pipe to the blowers. All purchased at Lowes in the plumbing dept.


7886

[billp]

"epoxy topcoat" means epoxy resin, as in boat building resin. My favorite flavor is MAS (www.masepoxies.com (http://www.masepoxies.com)) while others have their own preferences...

[gundog]

I got a little bit done this weekend here is what I have so far. The first picture is the vacuum grid I sealed it with fiberglass resin What a job!!

The second picture is my manifold. I have to make some mounts for the motors they will attach to the extruded sides on the X rails on the inside between the cross braces. I will take more pictures when I do that. I have to hook up my 2 shop vacs to hold down the plastic I am going to make them from.

I did mess up in one part that I will have to redo. I did not allow for the fiberglass resin on my T track now the slots are too small I will have to run the tool path again to open it back up.

I was thinking about glue the manifold with silicone in case I need to take it apart has anyone used silicone rather than glue? I was just going to go around the outside of the fittings I figure it is vacuum so it should work.

Mike

http://img.photobucket.com/albums/v292/millnut/DSC05529.jpg


http://img.photobucket.com/albums/v292/millnut/DSC05528.jpg

[beacon14]

I get excited seeing pictures like that. Keep 'em coming. Nice work.

[gundog]

I have a question for next time I work with fiberglass resin can it be thinned with accetone like you would thin paint to make it apply easier?

Mike

[billp]

Mike,
Not sure if you are speaking about polyester or epoxy here. With epoxy you can use a number of reducing solvents ( lacquer thinner, acetone,xylene/tuolene (all of which are not healthy to be around) and I believe denatured alcohol as well). You HAVE to mix the epoxy completely first, and THEN add the solvents or you risk getting a "bad batch"of improperly mixed epoxy which may never cure.
Haven't played with polyester (not nearly as strong as epoxy,not truly water proof, too easy to get a bad mix in small batches due to the ratio of harder to resin, and "fragrance"...) since I learned about epoxy.
On the plus side, it's cheaper, but as with most products you get what you pay for...

[gundog]

I will look at the can when I get home tonight, to be honest I bought it at Home Depot and I have never used fiberglass before so I did not know the difference.

It was really strong smelling and really thick which made it hard to get into the edges. I probably should have sealed the MDF with something else first that may have made it easier to apply.

We learned real fast not to mix too much at a time. We mixed 8 ounces for each of us and it hardened before we could use it all we then started mixing 3 ounces at a time for each of us my son was helping me.

Should I sand the top edges or should I run the surfacing tool and remove a very small amount to make sure it is flat?

Mike

[Gary Campbell]

Mike...
Nice job on the plenum! That looks very well done.

Even tho it will add to the "aroma" of the job, use styrene to thin polyester or vinylester resins. Add after mixing in the MEKp and thoroughly stirring. There is probably some in there already, as Styrene is most of what you smell anyway. On a quiet day you can hear the brain cells exploding.
Gary

[billp]

Mike,
Sure sounds like polyester...One of it's "issues"is that by adding/subtracting more/less catalyst you will change the curing time.And if you don't add enough you might not get the proper strength you'd like.
Whereas epoxy is a thermo setting resin which means that you always use the same ratio of resin/hardener but you can use heat (OR the absence of heat) to change it's curing times.
Sanding polyester will not be fun.I'd be tempted to use a surfacing bit and take it down in small passes.
As far as the exploding brain cells I defer to Gary's expertise in that department...

[ljdm]

The brain cells don't actually explode - they just kind of ooze out of your ears. Chemical reaction creating a "brain-cell slime". This effect was more prevalent in the post-60's era. Coupled with acute hearing loss (chemical reactions like this were usually accompanied by loud music). Hmmmm............

[gundog]

I just checked the can it is polyester resin made by Bondo.

Mike

[bcondon]

Be careful with Epoxy. I use it in building Dinghies and you can/will grow more sensitive to it over time if you get it on yourself and this includes any sanding dust.

I am not alergic to it (yet) because I cover my hands and arms when using it, and wipe it quickly off if you do get some on yourself.

Many boat builders, after a few years, can no longer work with it because they break out in rashes.

Epoxy does not have much of a smell while vinylester or polyester stinks of styrene.
If you don't know what that smells like, go to any autobody shop and you will smell it!

BC

[rb99]

I think the problem is isocyanates?

It apparently glues the air sacs in your lungs closed, and then you cannot breath anymore...

RB

[billp]

Bob,
That's one of the reasons I use MAS epoxy. They have the least amount of VOC's on their product, and I know people who have "sensitized" to other "name" brands that can now ONLY use MAS...

[chipster]

Richard, isocyanates are actually in polyurethanes. However, that does not minimize the fact that some people can certainly become sensitized to epoxies.

As with any chemicals, always use precautions as outlined by the manufacturer.

(yep, I'm a chemical guy!)

[gundog]

I got a little more done today; here are the vacuum motor mounts they will bolt to the inside of the X rails. The mounts are made from scrap HDPE the donuts are made to except standard 3” ABS. The donuts and motor are sealed with silicone. The donuts are held on with SS screws.

I hope to get the manifold and vacuum motors mounted tomorrow.

Mike

http://img.photobucket.com/albums/v292/millnut/DSC05530.jpg

http://img.photobucket.com/albums/v292/millnut/DSC05531.jpg

http://img.photobucket.com/albums/v292/millnut/DSC05532.jpg

http://img.photobucket.com/albums/v292/millnut/DSC05533.jpg

[gundog]

Here are the rest of the pictures for my vac table.

This photo shows the table top with plugs in 6 ports.
http://img.photobucket.com/albums/v292/millnut/DSC05541.jpg

This photo shows how I mounted my motors and attached them to the manifold.

http://img.photobucket.com/albums/v292/millnut/DSC05536.jpg

This is the switch for the vac motors.

http://img.photobucket.com/albums/v292/millnut/DSC05540.jpg


This is a view of both motors with the mufflers I will be adding some 3” muffler clamps drilled through the legs to support the mufflers I have them temped with zip ties.

http://img.photobucket.com/albums/v292/millnut/DSC05537.jpg

A view from the bottom.

http://img.photobucket.com/albums/v292/millnut/DSC05538.jpg

Another view of the bottom.

http://img.photobucket.com/albums/v292/millnut/DSC05539.jpg

The garden fence I had to build for mom in between trying to get the table done.

http://img.photobucket.com/albums/v292/millnut/DSC05535.jpg

This is my cheap version of a vac table I used the engineering and ideas from many posts and advice from this forum thanks to everyone who contributed. I may add valves later if I decide they are necessary but for now I will just plug the zones I am not using with the temp ABS plugs. My motors are ran in parallel all the time one switch turns them both on. I could have switched the motors separately but I would have had to add a valve to separate them.

For my use I will not be using a spoil board my parts are small but thick so I can’t cut all the way through. I cut my parts and leave a .050” skin that I trim off with a laminate trimmer.




Mike

[erik_f]

Mike I would use a spoil board just in case you cut through. Otherwise your motors are at risk.

[gundog]

The table top with the plugs in. The above post is more than 30 minutes old so it won't let me edit it. The first photo did not work.

http://img.photobucket.com/albums/v292/millnut/DSC05541.jpg

[gundog]

Erik,
How are my motors at risk?

I cut the same parts over and over I know my files won't cut through unless something malfunctions. I may use a spoil board later for other projects.

Mike

[angus_hines]

Dust and chips will get into them. I would at least put some sort of filter pad in the ports of the section your using.

[gundog]

I do not cut wood I cut plastic the plastic does not create dust like wood it creates large particles. What I am wondering though is why would it hurt my Vacuum motors to blow a little through even if it did? I am not a vacuum expert but I have seen the inside of many pumps maybe vacuum is different but I am thinking it would just blow through.

I think the plastic I cut will seal the top of my grid pretty well and I don't cut through when making pockets or profiles. My last step on one part I make is to drill a .5" hole through the part but all the side force machining is complete at that time and the hole only goes through because the parts have been machined on the other side first. The through hole is hitting the center of a counter bored hole from the other side so even though it pierces the part it only goes through half the part and no where near the table surface.

Absent in the picture is the T slot that I am installing around the perimeter of the table outside the cutting area. The plan is to add side clamping to the plastic to make sure nothing shifts the vacuum is to pull the sheets flat when I am cutting .5" material. I cut more 1.250" material than any other thickness. If I start cutting wood which I would like to do I will then add a spoil board for those jobs.

I have not cut anything on this table yet so only time will tell if it will all work the way I hope it does.

I use my machine the most making 3 parts over and over from UHMW plastic.

Mike

[billp]

Mike,
if you are ALWAYS planning to leave an "onion skin"on your parts you might want to consider using some gasket tape on your jigs. This has a few things in it's favor;
1- you will get a MUCH better "seal"between your UHMW and your table surface (hard to believe but there IS an "air space" between the parts and the table which will bleed vacuum...).
2- if you use a gasket in the 1/8"thickness range your part will be slightly elevated above your table surface (depending on the strength of your vacuum that is) and this will also give you a slight 'buffer"between the bit and the table. it's been covered here many times but you can get a "Shopbot sample pack"from All Star Adhesives for around $50 that will send you just about every type of gasket you'd want to use.
You are fortunate in the fact that UHMW is non porous so it will develop a great vacuum seal, and it also cuts like butter so you shouldn't "lose"pieces due to a poor vacuum bond...
You are also fortunate that you have a limited range of products (at the moment) so you can easily make designated vacuum jigs for each of these...

[erik_f]

If you are confident you will never cut through then it will be fine...just a precaution.

[gundog]

Here are the final shots of my table with the T-track installed.

http://img.photobucket.com/albums/v292/millnut/DSC05547.jpg


http://img.photobucket.com/albums/v292/millnut/DSC05548.jpg

Mike

[beacon14]

Beauty!

[joe]

I'm resigned, there is no end to Vacuum Babble.

Over the years, Vacuum Tables, have probably taken more time with posts than any other topic. Not to mention the exercises in making these. I've seen more beautiful carved plenums that a soul needs for a life time.

I build one with hight hopes but it was soon discarded. It worked Ok however the time and effort wasn't worth it. And there was plenty of noise too. Now, all those parts have been a cardboard box, under a table, for several years. It was a total waste of time for my kind of work. So you Newbees might save some time and money with a little investigation. Read on if you have extra time.

http://www.talkshopbot.com/forum/messages/312/28690.html

Lets go make some nice signs.
Joe
www.normansignco.com (http://www.normansignco.com)

[wberminio]

Joe

I believe it depends on what you are doing.
I have found that in cutting cabinet parts,a vacuum is indispensable,
When I doing other work,signs,v-carve....
I usually use other,more traditional methods.

I use what ever works best for the project.

BTW I agree-Lets go make some nice things-signs included!

Erminio