What Is the Proper Gasketing To Use for the Channels of My Router Table/Pod?

All Star carries a product group called Grid and Pod Gasketing. It is a non-adhesive product in a variety of shapes, sizes, and densities. Each router manufacturer is a little different in terms of the size channel they use with their table. In fact, two different routers from the same manufacturer may also be different, based on model number, year it was built, or if there was a custom/retrofit change to the router table or pod.

When determining what the right size is, our standard response is to measure both the width and depth of the channel you are gasketing. You want a gasket that will be just about the same width as the channel (a 1/4” wide channel wants a 1/4” gasket). And stick above the surface of the channel by about 1/16” (a 1/4” deep channel wants a 5/16” gasket). Also, channels that are rounded or dove-tailed should utilize a round gasket, while channels that are squared should use a square or rectangular gasket.

How Do I Determine Which Is the Correct Density Level for My Gasketing?

The correct density is determined by a handful of variables that exist at individual locations. They include the strength of the vacuum system you are using, the weight of the substrate that you are routing, how much gasketing you are using, even factors like the altitude and humidity at your location. Luckily, if we ever prescribe the incorrect density level, there are only two ways we can be wrong: it’s either too stiff or too firm.

You want your gasketing to be dense enough to recover time after time. If it flattens out too quickly, it needs to be firmer. On the other hand, if the gasketing does not compress and seal when the vacuum is engaged, it is acting like a platform and needs to be softer. Most customers use our medium density (CR and CRS series). Those with lower volume vacuum systems (less than 6-7 horsepower) may opt for the low density (CE series). And customers working with very heavy weight materials (such as stone, aluminum, thick wood products) may use our firm density items (IR and IE series).

What Are the Differences Between Using In-Board Gasketing and On-Board Gasketing?

Typically, in-board gasketing is used by customers who are making dedicated fixtures for long-term, repeat job applications. The advantages of using an in-board gasketing in applications like these are that by recessing the gasketing (usually a 3 parts into a 1 part above the fixture ratio), the gasketing will have an extended lifetime. It is only compressing to the level of the fixture, rather than fully compressing each time. The tolerance of the Z-axis will also be much tighter as there is a solid reference point to use. Also, one can program the channels to bring the gasketing to the very edge of the part, maximizing the vacuum area for the part and therefore improving holding power. However, it does take some extra time to construct a dedicated spoilboard using in-board gasketing.

The on-board gasketing advantages are for individuals who want to quickly set up a fixture, hold their part, and move on to the next job/program/application. The gasketing is applied directly to the surface of the spoilboard (no channels or additional programming needed) just to the inside of the intended tool part of the part. The foam perimeter creates a “suction-cup-like” hold when compressed by the vacuum.

How Thick Should My On-Board Gasketing Be?

To help reduce vibration, the thinner the on-board gasketing is, the better off you are. However, you need enough thickness in the gasketing to counteract any variances your sheet material may have (such as a warp, grain, texture, etc.). A standard rule-of-thumb is that customers working with wood materials will use our 1/16” thick foam, while customers working with plastic substrates will utilize our 1/32” thick gasketing. Those dealing with extremely inconsistent surfaces may go as high as 1/8” thick.

How Wide Should My Gasketing Be?

The most common variable used to determine how wide a gasketing product should be is the radius you are attempting to turn with the gasketing. A 1/8” wide gasket is going to have a much easier time making a tight angle than a 1/2” wide gasket would. But a 1/2” wide gasket will have a much wider surface contact area, resulting in a better vacuum seal. The 1/4” width is the most commonly ordered size.

What is the best spoilboard material for use with vacuum on my CNC router?

We like to say that there are two types of materials to utilize vacuum hold-down.  There are Spoilboards and there are Dedicated Fixtures.  A Spoilboard is what most facilities are familiar with.  The most common is usually an MDF or LDF board that allows vacuum to pass directly through because it is porous.  It is what is recommended when parts being produce are not high volume parts.  Constantly changing jobs, nesting applications and  With adequate vacuum, parts can be held directly to the board without any channeling needed.  On-Board Gasketing can greatly improve the vacuums effectiveness in holding smaller parts on a spoilboard.

A Dedicated Fixture, on the other hand, we consider for long term use for producing the same parts over and over.  In that case we recommend a non-porous material (such as HDPE, Baltic bearch, etc.).  The advantages are that it does not loose as much vacuum through the board itself which creates better holding power.  Also, a non-porous material will not warp and/or swell like an MDF board might over time as it sucks moisture into the spoilboard.  By using In-Board Gasketing on a Dedicated Fixture, the highest quality parts, yields and tolerances are achieved.

How small of a part can I hold with or without gasketing?

Holding parts with vacuum effectively on a CNC router is, in our opinion, a pass/fail test.  “Did you the part?”   “Kind of”.   That sounds like a No.  Every facility brings an enormous amount of variables to the table (excuse the pun) when looking to determine if the the needle is going to tip towards PASS or if it is going to tip towards FAIL on their particular parts.  Obviously the size of the part is a big one.  But what also factors in are things like vacuum strength, is the material being cut porous or not, what are the feed rates, is the gasketing under the spoilboard doing a proper job, what kind of spoilboard is being used?  Even elevation changes can have an effect on how a facility in Florida can vacuum hold particular parts effectively that someone in Colorado, with the same exact same other variables, cannot.

We encourage you to contact us with any further questions. Our professionals are happy to work with you. Located in Grass Valley, CA, we can ship products to clients around the world.