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Vacuum Tables


What is the difference between your Grid style tables and your Hole grid style tables?

The RAL vacuum table is the waffle looking vacuum table that uses a gasket cord to close off a vacuum area and the vacuum ports are just in from the edge of the vacuum table. Each vacuum hole directly in front of the port can be used as a separate vacuum area controllable with the provided hand valve on a manifold if your vacuum table has more than one port. With the RAL you cannot cut all the way thru the material into a vacuum area, however you can purchase our extra thin rubber (0.015”) and place it in a vacuum area for it to stand up off the surface for full profiling. This type table requires less vacuum than the hole grid tables as it is completely sealed off during machining.

 

The RAL-V works like the RAL but the difference is you have the ability to remove plugs across the surface of the vacuum table to expose vacuum. In this situation you can have multiple vacuum setups at the same time. The bottom part of the vacuum table acts as a plenum so there is only one vacuum cell but can be accessed by any of the plugs in the vacuum table surface. This table is listed with a venturi for vacuum generation but can be purchased with an electric vacuum pump for additional cost.  


The GAL vacuum table is a hole grid style vacuum table that uses a vacuum mat in between the material you are cutting and the vacuum table top. This protects the vacuum table top as well as helps seal off the vacuum. An additional solid rubber mat is provided with this table to cover unused holes. Additional mats can be purchased on our website. With the proper vacuum generator, this table can be used with exposed vacuum holes during operation but covering a large number of open holes with the solid rubber mat will give you more holding strength. Also each port represents a separate vacuum cell that can be turned on and off at the manifold. With the hole grid type vacuum tables you can cut all the way thru into a vacuum area without losing all your holding power. We recommend if you do cut all the way thru, just cut 0.005” past the bottom of the material into the vacuum mat. It is our policy in our own shop not to cut parts smaller than 4” x 4” solely with vacuum. Regardless of the vacuum generator strength, with this size and smaller it does not have enough vacuum area to build up enough force to be held solely by vacuum against the forces of typical machining. This does not mean that you cannot cut smaller parts with the help of vacuum. It only means that you need more creative means to get the job done. We commonly use the skin method. This means that we leave a 0.010” thick skin of material at the bottom of say aluminum as this gives a larger vacuum area thus more vacuum holding force. With this method you would also need to leave a frame of material around your parts in order to prevent “tear-out” at the edges of your grouping of parts. The skin can be removed with a file, buffing wheel or with a manual router with a flush cutting bit (custom bit with a bearing). Some customer use the method of leaving break away tabs at the bottom of their material but you have to keep the vacuum loss in mind with this method if you have a lot of uncovered holes. All tables will require liquid separation for dry running pumps or venturi. We sell separator tanks or mechanical separators for this. Larger GAL or GR tables can be ordered with a thicker table top so that it can be used as a floating table as well. Inquire about our vacuum/floating table setups.


The GR is the same as the GAL except is has side stops and stainless steel threaded inserts imbedded across the surface to be able to be used to mount jigs, stops or small vises to the surface of the vacuum table.              


Honeycomb vacuum tables


What is the difference between your tables and the honeycomb type tables? Attached is a copy of a competitor’s quote.

Thank you for showing us the competitive quote. This is partially our fault for not informing the public more on the differences. It is hard for us to compete on PRICE ONLY against a honeycomb vacuum table but as the saying goes, "you get what you pay for". It is very frustrating for us when customers do not let us know that the competitor's table has a honeycomb core. This is not in any way comparing apples to apples. Our type tables are vastly different than a honeycomb type. Leave the honeycomb for the bees! We use to carry a series of vacuum tables that were produced just like the honeycombs but we discontinued them because of the number of problems we encountered. We have sold many of our systems to replace customers’ vacuum tables who originally bought the honeycomb type table due to all the problems.


Just to name a few of their problems:

- Their warpage problems caused by their welding process - the heat from welders cause a great deal of warpage and cannot be mounted completely flat. Once warped, always warped. That’s if they weld. This one uses glue? Really??

- Hole grid spaced too far apart

- Base and top plate way too thin, 1/8” thick top and bottom? Seriously? - It may as well be sheet metal - Not structurally sound for machining. Better handle it like it’s a piece a glass, not a tool.

- Held together with epoxy? What’s wrong with steel screws? That’s right, their shell is too thin to hold a screw.

- vibration issues

- Flexing issues with heavy materials placed on the table

- Much more loss of Z travel height

- Top plate not replaceable, actually any damage and you have to throw it away - not repairable.

- Coolant  clogging problems and no way to clean the inside - flushing it out does not work!

- Cannot be surfaced to match your machine’s flatness because again, surface is too thin - not true with our vacuum tables, in fact we recommend surfacing our solid aluminum vacuum tables and can be re-surfaced again and again.

- Vacuum holes not small enough - Our tables have counter-bore holes with inside holes so small you can operate with many surface holes still open with no c logs- not possible on theirs. Your savings and then some with a honeycomb table will need to be spent on much bigger pump to make up for all the vacuum loss.

- Tops not replaceable - if you accidentally tool crash or cut into the top of the table, the top is not replaceable unless you want to break the epoxy free and re-glue a new top back on, good luck with that. The list of issues just continues on and on.


The number one problem with honeycomb is if the table is dropped, damaged in shipping or anything dropped on top of the table, it is permanently destroyed and cannot be repaired. This is where we have replaced many of these for frustrated competitor customers who didn't understand all the differences. The scrap yard wouldn’t even accept their tables because of mixed materials . Our tables are SOLID!!


Our vacuum tables start with a pre machined SOLID block of cast aluminum tooling plate, 7/8" thick with a replaceable 1/4" cast aluminum top. Our tables are a much heavier vacuum table, much more flat and stay flat, and can take a beating. IF YOU ARE SERIOUS ABOUT MACHINING, BUY A SERIOUS VACUUM TABLE.  


Rubber Mats


What are the rubber mats for?

The perforated rubber mat’s holes match up with the top of your hole type vacuum table. This mat must be used under your material you want to machine. This creates a needed vacuum seal and protects the top of your vacuum table. Perforated mats are about thirty thousands thick. The second solid rubber is made for uncovered holes to maintain as much vacuum hold as possible.


Do I put the solid mat over top of the perforated mat to cover holes?

Yes it’s okay if you have a strong pump. If your pump is borderline power for the table you have it may work better not to put the solid mat over the top of the perforated mat to cover unused holes as this may give more vacuum leakage between the mats and reduce holding force.


How far can I machine into the rubber mat when I cut all the way thru my material?

We recommend cutting maybe five thousands of an inch past the bottom of your material. If you go too far into the rubber mat, tooling can pull up on the mat causing the material to also pull up from the vacuum table and become a projectile. This problem of a part becoming a projectile can also happen when you have loose or curled rubber mat sticking up around your material in the path of your cutter.


Should I cut up the mats with holes to fit my material?

Absolutely, customize the rubber mats to your needs. You can simply cut them with scissors. We recommend cutting the perforated mat to the size of your finished part and cut the solid mat for the covering of the unused holes. We sell additional mats in sets of five that can be ordered right on this web-site.


Vacuum Pumps


I’m new to vacuum clamping. Can you give me any general information on how this process works?

A common misconception is that compressed air is the equal opposite of vacuum. It is not. The stronger the compressor motor and tank the more you can force air into a tank gaining pounds of air in the hundreds (PSI) of compressed air. Once you remove air from this same tank using vacuum, there is nothing else to be gained with vacuum. With vacuum you are limited to the atmosphere around you. This is where the term sea-level comes into play. If you are at sea-level, you get the best performance a vacuum generator is rated for. If you live in the mountains you get less due to the atmosphere pressure. This can be calculated based on your altitude above sea-level. The maximum vacuum at sea level is just over 29” Hg. There are several ways to measure vacuum. I commonly use Hg or Bar. The way it works for vacuum clamping is you need a good amount of negative vacuum pressure to hold materials (inches of Hg). If you have zero or next to zero vacuum leakage then you only need negative vacuum pressure to hold material and CFM is not so important. This situation is where you may have seen people using a reservoir vacuum tank from their pump to store vacuum similarly to a compressor with compressed air. On a table like our RAL or pods, this is possible with minimal vacuum loss but for most other type tables like hole grid vacuum tables, vacuum loss is an issue so we need the CFM to make up for the vacuum loss in order to maintain enough negative pressure to hold material being machined. We typically recommend a MINIMUM 25” Hg for RAL vacuum tables and pods and a MINIMUM 25” Hg with 8 CFM for most others. These are only the starting points of what is recommended. The larger the table and/or more vacuum leakage the higher the requirement.   


I just got my vacuum table and my material does not hold on the vacuum table and I’m using the mats with no open holes. What’s wrong?

Most customers assume the problem is with the vacuum table. Majority of the problems end up being with the pump. First ensure the pump intended to be used is sized for the vacuum table (we can help with that) and is working according to the pump specifications. Most issues are found when the pump is too small for the table or application or the pump is not wired correctly.


Can I use any vacuum pump with one of your vacuum tables?

No, one vacuum pump does not fit all. We can recommend a pump or pump specification for a particular vacuum table type and size for general use but may not work for any/all applications. The pump selection has to be carefully considered as to what the end user is trying to accomplish. We have never received a complaint that a vacuum pump was too strong, only complaints when a customer selects a pump that is not strong enough for what they are trying to accomplish. There really are no shortcuts in this area. I’ve had some customers think they could just remove a pump off a refrigeration device and it would be as strong as a pump costing over a thousand dollars. If there was another way to cheaply get the same vacuum performance that a high end pump will do then there would be no need for high HP pumps.


What can I do if I accidentally forget to empty my liquid separator and the coolant gets sucked into the pump?

This is a very good question. To help answer I will tell you of an actual incident of a customer that did exactly that. We had a customer that had a pump they purchased and only had it for three months and sucked coolant into the pump by forgetting to empty the separator. Upon discovering this they immediately shut the pump down and since it happened on a Friday they thought it best to leave it for the weekend to dry out. By Monday it did indeed dry out but would no longer turn so it was seized. They sent the pump in for service and the repairman opened the pump to find it was internally rotted and totally not repairable (I will post pictures at some point). They could not get a replacement pump under warranty as sucking liquid into a vacuum pump will void the warranty. They had to buy another new vacuum pump.

The best thing to do in this situation is first to cut power to the pump at the the circuit beaker. Disconnect from the separator, remove any excess coolant from the hoses. With the power off turn the pump to the side to drain any coolant inside without getting the electrical side of the pump wet. Remove the hose from the vacuum table manifold and if everything on the exterior is dry, run the pump open (best to use the circuit breaker as the on/off switch for safety) and let it dry out from operation (this could take hours) provided the exterior of the pump is not wet or sitting in a puddle or any wetness near or on any wiring or electrical boxes. Be extremely careful to avoid electrical shock in this situation. Do not come in contact with the pump at all when power is supplied to the pump if any wetness is suspected. Follow all safety instructions provided by the pump supplier, electrical code and all industrial regulations such as OSHA.


Maintenance


How do I clean out the vacuum holes in the table? Can I blow air into the vacuum table?

Compressed air can be used blowing straight down over the top of the vacuum table to clean out the particles in the holes. Remember to always wear safety glasses. A shop vac can also be used with a brush attachment to vacuum out the holes. Compressed air, especially at high PSI is NOT recommended blown into the table as this can blow out the gaskets and warp the top plate as too much pressure introduced into the table may force it’s way out between plates as the vacuum tables are not designed for high PSI flows. If the holes are gunked up with wet oily residue, flushing with warm water will help clean them but remember vacuum pumps typically do not like liquids sucked up in them.


Operation


I want to machine a bunch of tiny parts out of a large sheet. Can I do this with a vacuum table?

Yes and no. The smaller the part the less vacuum area (strength) to hold it. Smaller parts require more planning and may need additional assistance in addition to a vacuum hold. Some practices include the use of “break-aways” meaning the individual parts are still connected by small material tabs and a second operation is used to remove the tabs. Pump selection plays an especially important role here as many vacuum holes end up open during machining so there is a much greater need to vacuum power especially with smaller parts. Another practice is to leave what is called a “skin” at the bottom of the material. This helps to maintain vacuum suction as it reduces vacuum loss but also requires a second operation to remove the bottom skin. Other practices may include the use of heat activated adhesive material that works under vacuum called Vil-Mill. Custom templates or jigs in conjunction with the vacuum table might also be the answer.      


Venturi


What is a venturi and how does it work?

Typical venturi needs about 60 to 90 PSI CONTINUOUS pressure for operation depending on the venturi. Venturi uses a lot of air so  we usually recommend a minimum of a 20gal compressor for this or it may not keep up. Venturi does  use a lot of air.The venturi needs to stay very clean as if a particle gets stuck inside the venturi it can vastly reduce it’s performance and unless you have a large compressor, the compressor cannot be used for anything else at the same time. However you can add an additional vacuum tank to help with a venturi keeping up but there is only one type table that a venturi with low CFM will work with and that is the RAL or pods as they  seal very well so there is very little vacuum loss. The drawback is that you cannot cut all the way thru your material into a vacuum area and still hold the part but there are ways to work around that such as using a thin rubber mat under the part and inside the vacuum area. This will make the material stand up off the surface slightly so you can dress the edge of the part without cutting into the vacuum table. You can also leave what is called a skin at the bottom of your material meaning you don't cut all the way thru and remove the skin in a separate operation. With the RAL you can hold just about any material. We created RAL type tables /pods for a customer holding concrete and it worked so well they came back and bought several more systems. We also have a clear flexible PVC mat (about 1/4" thick) that you can customize where you may be able to cut all the way thru material for the RAL type tables. To use any hole grid type tables you would need  more CFM than the requirement for a RAL. Our Standard type table works well with a shop vac because shop vacs usually have 70 to 90 CFM but  you still may need to cover at least 30% of the vacuum table with your material and cover the rest of the holes with the rubber mat. Even though the shop vac has very high CFM it has very low pressure like 3-4 Hg so you can't really use it for smaller parts. A strong vacuum generator would be necessary for smaller parts on a hole grid type table. The other drawback of a shop vac is most stay cool from airflow so if you run a shop vac too long on a vacuum table it can overheat.ed. However there are some shop vacs on the market that have a separate cooling system and higher Hg but may be pricey.


Spoilboards


Can I use an MDF spoil-board on top of your vacuum tables?

It will work on top of our RAL type series vacuum tables but will require a great deal of CFM to make up for the vacuum loss. The vacuum generator will be dependent on the size of the spoil-board. When getting up to sizes like 4ft. by 8ft. You may need a minimum of 200CFM and better depending on what you plan to do. Pumps or blowers this large typically will be 3 phase power. There are many forums out there that discuss the use of MDF spoil-boards with their the tricks and practices.