Vac System

[ger21]

Also, I've never had to flycut both sides of the MDF. It will pull vacuum through it either way if the system is sealed well. I don't know anyone operating these machines professionally who does that either,

We do, on our 5x12 Morbidelli with 2 10HP pump. I honestly have never tried only surfacing 1 side, but it's what the operators were taught when the machine was installed. I've also read many posts at Woodweb from commercial users saying that you need to surface both sides.

The vacuum will travel right through the MDF, but only if you have a deep level of vacuum (minimum of around 18 in/mercury and best if closer to 24 in/mercury)

Guys using vacuum motors on Shopbots are getting by with 9-15in/Hg, provided the CFM is kept high.

While I've used a commercial pod machine with a 5HP Becker pump, it's also possible to use pods or fixtures with much smaller pumps, provided the material is not too porous and you get a good seal. I have a 1/4HP Gast pump that has been used with a vaccum fixture to cut hardwood parts.

[mmoe]

It is interesting to hear how manufacturers are training people, I thought that the Laguna guy was just being particular about something that didn't need it. Having never bought a brand new machine, I've only had minimal training from the used sales guys around 10 years ago, and everything else I've learned on my own through personal experience. For what it's worth, I've never found there is any additional benefit when I finally do flip the sheet, so planing both sides doesn't seem necessary at all. In a blind taste test, I don't think you could identify which sheet is machined on two faces and which is a new sheet machined on one face based on actual performance (let's assume they are the same thickness so there is no visual cue). I'll see if I can take some measurements next time, both before and after flipping the sheet, but I expect it won't make a whole lot of difference either way based on my experience with both.

Regardless of CFM, you won't get the atmospheric pressure applied to something unless it sits on high degree of vacuum. I know it does work, but using flow is less efficient than using atmospheric pressure. While there are some benefits, mostly that you can run the pump nearly indefinitely with poor vacuum because of the pump design, I think that smaller part probably hold down better with a deeper vacuum with less flow. I've also heard of people using ultralight MDF with high CFM pumps because they need flow instead of pressure.

I've also used a 1/2 hp membrane pump for pod applications when I've made specific fixtures, but I don't think you could use a table pod system with that kind of pump. The volume of the system is perhaps a bit too large, but i can't say as I've actually tried it that way so that's just speculation. When I've used a small pump, I usually have it on the machine table near the fixture itself, and the fixture bolts to the table.

[kolias]

Well mmoe, I learned a ton from you about vacuum tables with your description and drawings and I greatly appreciate your time. I'm sorry I misunderstood your previous drawings.

So my table top will be a waffle design as you described and now remain to select the vacuum pump. Is it possible from this site to suggest one of the systems?

http://www.joewoodworker.com/docs/vacuumpresschart.pdf

Please note that the Excel1 and 2 systems have the pump run continuously and that I don’t want. I think the Project EVS with either the Thomas or Gast pumps will be a good choice

[ger21]

So my table top will be a waffle design as you described and now remain to select the vacuum pump. Is it possible from this site to suggest one of the systems?

In one of his earlier posts, he mentioned needing a 3-5HP pump. You won't find one at JoeWoodworker. I'd suspect a used one would cost over $1000.
V
The amount of vacuum required for these types of systems makes them quite expensive.

Please note that the Excel1 and 2 systems have the pump run continuously and that I don’t want.

Unfortunately, there's really no way around a continuous running pump. You always want the most vacuum you can possibly get, which requires a continuously running pump. With a system where the pump cycles on and off, you might lose 20% of your vacuum while the pump is off. If your part comes loose, it;s typically catastrophic. A continuously running pump is cheap insurance.

For a lower price system that would probably work for you, I'd look at an electric pump that can pull at least 26" Hg and at least 3 CFM.
Then make your table similar to a pod, but with a grid that lets you adjust the gasketed area. If you spend some time searching through the forums here, you should be able to find something similar. I think Greolt has a good example here somewhere.

Regardless of CFM, you won't get the atmospheric pressure applied to something unless it sits on high degree of vacuum. I know it does work, but using flow is less efficient than using atmospheric pressure.

The main benefit of these is 100% cost. Shop bot guys are running 4 of the vacuum motors, and can build complete systems for well under $1000, which is typically a fraction of the cost of a good pump for a "proper" vacuum system.
I don't disagree with anything your saying, but a good system is out of the price range of 98% of the hobbyists here. Which is why you see so many alternatives, even thought a lot of them don't work well.

[kolias]

You said it so well Gerry, thank you

I will try to find the thread from Greolt

[mmoe]

For sure a vacuum system is not for the faint of heart when it comes to the wallet. I think, though, that it can be done with a good pump and a decent table for under $1000 with a similar design to what I've shown. The pump would be used, but so long as it's in good condition that's not such a bad thing. I see used pumps for under $500 with relative frequency on craigslist and know a guy that bought two 5hp Becker pumps for $400 (I'm almost certain he meant total).

I guess you'd just need to make some tough choices if you have a budget. Do you want to be able to do nested based machining? Get a great pump (even if used) and then make a waffle style table with melamine coated MDF (the melamine seals the MDF). It wouldn't be as durable as plastic or aluminum, but it would be very inexpensive and very functional. It could then be piped with PVC, with "T" style connectors glued up into the waffle. Total cost of a table like that would probably be under $200, so if you can find a decent pump used for under $500, you'd be set. Using pods with that table would not be a good idea because they would likely damage the table after some use. If you start with a good pump, you can always upgrade the table surface later as well.

If you are willing to use a pod or pod/like system as Gerry suggests, you can get by with a lot less pump expense, but I think to do the table right and durable you'll spend more there. I suspect there isn't a good way to make a table like that which is durable enough to last any reasonable length of time without spending some money on durable materials, which means you'll need $400 worth of plastics or aluminum. With the nested based system, you don't have to worry as much about that because the wasteboard protects an inferior table material, where a pod based table will be more exposed.

Whatever way you go, I highly recommend taking some time to consider how effective the result will be. There is no point in spending $500 on a vacuum table that doesn't really work anyways and the obvious fact is that you need good vacuum to hold parts down well. Otherwise, you may as well just buy some double stick tape instead as it will hold the parts better and costs a lot less. 2" wide Grip tape from a golf shop (basically double sided masking tape) runs $15/roll and would probably last a hobbyist a month or two at a time if they use it a lot. As far as holding things, if you clean the surface of both the table (just blow dust of thoroughly) and the material, it will hold better than a nested based vacuum system and nearly as well as a pod system. The problem with that is never holding things down, it's getting them off.

[kolias]

Good points mmoe and all are under consideration

So how critical is the required pipe size for a system? If I divide my table top into 3 zones and each zone is approx. 36"x15" how many vacuum outlets per zone and what size? I don’t expect an exact size but what we are talking about 1/2" or 2" ? I would say 2 outlets per zone at 1" each ???

And how about the piping from each zone to the manifold? That is a distance of about 50" to the farthest zone and I would say perhaps 1" ???

Does it matter if the pipe / fittings are in SCH 40/80 PVC or copper?

[ger21]

If you are willing to use a pod or pod/like system as Gerry suggests, you can get by with a lot less pump expense, but I think to do the table right and durable you'll spend more there. I suspect there isn't a good way to make a table like that which is durable enough to last any reasonable length of time without spending some money on durable materials, which means you'll need $400 worth of plastics or aluminum.

You don't need a plastic or aluminum grid table to mount the pods to. You run separate vac lines to each pod, rather than drawing vacuum through the table. This gives you far more flexibility, as you can simply bolt your pods down anywhere you , or even use double sided pods to stick anywhere you want to a smooth flat table.

So how critical is the required pipe size for a system? If I divide my table top into 3 zones and each zone is approx. 36"x15" how many vacuum outlets per zone and what size? I don’t expect an exact size but what we are talking about 1/2" or 2" ? I would say 2 outlets per zone at 1" each ???

And how about the piping from each zone to the manifold? That is a distance of about 50" to the farthest zone and I would say perhaps 1" ???

It really depends on the type of system you'll be building. Individual pods can be connected with simple 1/4" tubing, and length doesn't really matter. As MMOE said earlier, when you're pulling vacuum, there's nothing flowing through the tubing.

Systems using vacuum motors like the Shopbot guys are using rely more on CFM, so pipe size is more critical. With air flow, you want shorter, straighter runs to keep the flow higher. I'd look at the Shobot threads to see exactly what they're doing, but I think that most are using close to 2" PVC.

For reference, I've used two $100,000+ industrial routers. One with individual pods and a 5HP Becker pump, that used 8mm (I think) tubing from a manifold to the individual pods.
The one I currently use for nested cutting uses two Becker 10HP pumps, connected to an aluminum table with 2" tubing. There's a "T" to connect the two pumps to a single 2" line. This pulls vacuum through a 5x12 MDF spoilboard.

[kolias]

That's enough to get me going Gerry, thanks

I intend to make an experimental table top and I will start a new thread to show the progress with photos / videos. This experiment will be enough to give me a feel of what we are talking about

I may come back here to ask more questions if I stumble somewhere before I start the build

[kolias]

Here is a site with inexpensive vacuum pumps http://stores.ebay.ca/Weberdisplays/...=3718961010&_s

Price looks good but I noticed the vacuum produced is very low and dont know why

[mmoe]

Kolias,
The pump shown at the Ebay link specifies the pump to achieve 5 pa of vacuum, which is almost nothing really. I don't know if it's a typo or not. Even if it were 5kpa, that would still only be somewhere around 1 or 2 inches of mercury (full vacuum being roughly 30 inches). I'm sure that pump couldn't possibly be that poor, but that's already giving them the benefit of the doubt on what is probably a typo and it's still not anywhere close to what you need. I think I would stay away from that one just because there does not seem to be any reliable information about them. They may be fantastic, or they may be as bad as the specs suggest.

Regardless of the size of the pump you use, it's going to be a certain amount of "you get what you pay for". My 1/2 hp Leybold pump actually cost more than I paid for my 5hp pump that can work on an entire table. It could also achieve a vacuum level of 28inches of mercury on a sealed system such as the pods Gerry is suggesting as well as being quiet and capable of running continuously for days if needed. That's not to say that you NEED a $500 1/2 hp vacuum pump, but there is going to be a difference between a $100 1/2hp pump and a $500 just as there would be in any piece of equipment. I do, however, think that for a pod system you will absolutely need to be able to pull over 20 inches of mercury. For a table system where you pull through the MDF, surface area is what helps you hold parts down, but in a pod system, high levels of vacuum on small areas is what lets you hold parts down. If the vacuum is low on a pod, it won't hold the parts.

Gerry,
I really like the double sided pod idea! I have never seen anything like that but I can see where it would be extremely useful. Even on a waffle table you could design fixtures that clamp down like you suggest by having the bottom side of the vacuum directed to a roped off area of table with no ports. That would solve one of the biggest problems when it comes to using a small pump on a waffle table like that (which is otherwise difficult to bolt worktables down to). Thanks for the idea!

[mmoe]

If you are going with a small pump, I'll assume you will be using it with pods or similar vacuum fixtures. In that case, you don't really CFM at all. Once you get to vacuum, there isn't any air left to move and the system should be sealed so that new are is not being pulled through. Here's an example of the type of pump I'd consider (it actually comes in a pair, which is pretty awesome):

Vacuum Pump | eBay

These pumps are diaphragm type and literally could run for days on end without stopping. This type of pump is quiet and generally doesn't generate any significant amount of heat, which is what ultimately determines how long you can run a vacuum pump. The specifications sound about what I'd expect from these pumps, and should be able to hold parts down in a pod setting. The spec sheet is below, and shows the pump will achieve 20.7 in./HG, so right around the minimum I'd recommend for good hold-down with pods (it's the M161 standard on the chart)

Miniature Diaphragm Pumps | Mini Dia-Vac® Performance Specification


This one appears to be rated for 24 in/Hg (found PDF, but the model number is outdated I think, all others in this series are rated at 24in/Hg):

Gast Diaphram Pump Model MOA V111 AA | eBay

There are quite a few of these on ebay, and they have both high vacuum levels and higher CFM (27in/Hg and 3.5CFM). Probably used more than the others:
Thomas Compressor Vacuum Pump 2619 2639 Aerate Pond | eBay
Thomas 2 Stage Fresh Air Pump Vacuum 25 HG Aquarium Pond Pool Paint Suit | eBay

Those are the type of pump I'd recommend. Keep in mind, these are pumps in the $400-500 range when new, so you'll get a better quality pump for a similar price to the imported stuff by going with these in used condition. With a diaphragm pump, there isn't much that can go wrong with them, so they last a very long time. They basically use a pushrod of some sort to flip a rubber diaphragm up and down. Not very much in the way of moving parts that wear out and I'd bet that replacement diaphragms are very inexpensive and easy to install (if you even ever need to).

[ger21]

I'd say that the pump from the Ebay link is definitely a typo. However, stay away from the Oil pumps, as they will pump an oil mist into the air as they run.
You definitely want an oil-less pump. I'd too recommend either a Gast or Thomas pump. I purchased mine from a surplus store for $90, but they run from $300-$500 new.

[kolias]

I have said it before mmoe that I consider you guys down south so lucky because you can buy anything you want from any state. Us up north we have many limitations and even when we find a place in US to buy something a lot of them they don’t even ship to Canada like we are in N. Korea or something, LOL and its very frustrating.

The links you provided (I thank you for your time), although a very good deal, they say "may not ship to Canada". Even if they ship to Canada, the freight cost along with the customs / taxes fee will make the pump very expensive. In addition, I still need some controllers, gauges and what not to make the pump work. So I decided to buy a "pump kit" from the link I provided in my post #23.

I found another pump supplier locally and will go Monday to see what he has. Still don’t like this because I don’t think you can buy any pump and just plug it and works; I guess you still need filters, silencer, controller, gauge etc to make it work and all this means more searching to find all these small items. So it looks like the "Kit" idea is the best

[mmoe]

I've looked at more similar pumps to the 5 Pa rated pump and it appears that pumps ranging from 3 Pa to 10 Pa are in fact common. They appear to all be rotary vein pumps for automotive air conditioning applications. Even brands name pumps of this sort do not pull more than 1 or 2 in Hg.

It looks like the main thing is to look at diaphragm pumps only as they all pull deep vacuums.

Edit:
After some more decoding of what the specifications are, I think that it may be that the scale starts at "0" being a perfect vacuum, and if a pump is rated at "5 Pa", there will be 5 Pa of air pressure left in whatever the pump is pulling vacuum from. If that is the case, and this is how they are doing the specs, then 5 Pa would equate to nearly a perfect vacuum (assuming "0" is a perfect vacuum). In fact, that would be so close to perfect that I again have to doubt the specifications as we'd be talking a vacuum in excess of 29.92 in/HG, which would be one of the deepest vacuums I've ever seen (and therefor seems a bit unlikely). Even a 10 Pa rating on that scale would be in excess of 29.92 in/HG.

It is hard to imagine that a rotary vein pump would be so useless as to produce 2 in/HG vacuum, so perhaps contacting the seller and asking them to show you a reading of what the vacuum actually is in in/Hg would be wise. If they have a vacuum gauge, it would only take them a second to measure exactly what the pump can do in a way that is more clear than the specs as they are now. Plus, as Gerry suggests, a rotary vein pump will potentially create a mist of oil, or even burning oil which is sent into the shop air. Also, they are extremely loud compared to a diaphragm pump.

[kolias]

...... skin seals to the rope gasket at the edges, and if you have zoned your table off then you would run a rope gasket between the zones to allow only part of the table to be used...........

Hey mmoe, any idea where to source the rope gasket? I found locally a foam style rope gasket but I don't think its the right kind. Searching on eBay I didn't get anything either

Thanks

[mmoe]

I buy the rope gasket locally at a gasket supply house that specializes in selling gasket raw materials (as opposed to gaskets that are already cut to shape). I don't know exactly what it would be called, just that it's a closed cell foam rope gasket. Hopefully you have a similar supplier in your area. The only other source I could recommend is Mcmaster Carr, but that would be mail order and as you said earlier that can be hit or miss for you. Plus, without actually feeling it I couldn't say for sure if it's the correct product. However, this would be my best guess from the Mcmaster Carr catalog and perhaps Gerry knows the actual trade name or can verify that this would be similar:

McMaster-Carr

I can also call the supply shop Monday and ask them for the actual trade name of what I use. They just go in the back and cut it off a roll, so I never actually see the packaging.


Here's another supplier, but they don't really say what it is exactly.
http://store.piersonworkholding.com/...t-25_p_60.html

And yet another, but this one is a better price and looks like a good product (if they will ship to you):
http://www.akhurstshop.com/product/w...-router-table/

[kolias]

Thanks mmoe

McMaster do not ship to Canada and its a real pity because they have tons of good stuff. But your second link is in Canada so (assuming they sell retail) I will call and see what I can get

[daniellyall]

McMaster dont ship to New Zealand ever thay say usa export rules prohibit shiping to nz ball S___

[ger21]

Try Allstaradhesives.com