Table Saw: non cast iron top, composites


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The needs of automotive and aircraft bodies and machine tables are rather different.  Composites are used in machines, belts are not leather anymore, a lot of guard parts and  inserts and so on.  Even sawstop now has an aluminum topped saw.  The thing is light weight is an advantage in a vehicle, it is not an advantage in a stationary piece of equipment like a cabinet saw.  The weight does help, yes it will not compensate for enough imbalance but nothing is perfectly balanced and get a little wear or a blade that is balanced near the edge of the tolerance.

 

I am not sure composites have the dimensional stability that is needed to maintain a good flat tabletop over a range in temperatures and over time.  Cast iron and granite are and continue to be the standards used for this.

 

I like new things, but there do not seem to be materials that would be better than these that would be cost effective.  People are not going to be happy with a $40,000 table saw top.

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The dimensional stability of many composites is far better than that of cast iron and aluminum. Whether it has the rigidity and tensile strength to hold it's flatness over time bolted down to a vibrating machine is probably a concern.

 

For a table saw the two main issues seem to be flatness and mass. Flatness can change with time and temperature, mass not so much. A rigid and strong composite that also has a low thermal expansion coefficient would seem to be a strong candidate.

 

I am aware that the thermal expansion of cast iron is relatively low when in the temperature range that we humans like to work in. With a composite this might be a minor or even negligible improvement - except when my sled starts getting sticky.

 

It really seems to come down to the mass. Perhaps if the saw cabinet was bolted to the floor.

 

Yeah, I'm still not finding any measurable benefits other than cost of transportation. The toxicity of manufacturing is also a concern for me. I'm not a big fan of creating more toxic products. I don't even like using MDF or poly finishes. I look like Walter White when I have to cut an MDF jig or wipe on some poly.

 

 

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Composites are usually used to give you the same strength with less weight but greater cost.  It may be worth the extra cost if you are buying a tripod and want to take it up a mountain.  Half a pound less might be worth $100 to you if you are going to be using it a lot.  In airplanes the additional cost upfront can be offset by savings in fuel over the life of the plane.  You do see some premium portable tools use more expensive materials to make them lighter, such as magnesium in circular saws.  But for stationary tools extra weight is an asset so spending more just to reduce to the weight is counterproductive.  Not only does it reduce vibrations, but you don't want your table saw moving or tipping over when you try to run sheet goods through it, which is a real problem with jobsite saws as it is. 

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  • 3 weeks later...

Composites in aerospace and automotive are accomplishing entirely different things than a table saw top. Airframes are designed to flex, and most composites applications get their inherent properties from an overall design (like cross section, core materials, etc etc)

Almost all composites are poor abrasion performers (aside from say, Kevlar), and the individual resins perform even worse than the whole.

Cast iron WORKS, and it's cheap.

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I can attest to that. 1 slot runner no problem. 2 slot runners, smooth in summer, tight in winter.

I wonder if this is why I had so many issues with my cuts being out of whack when I was building Christmas presents? My dados and crosscuts kept coming off the saw out of square, and I checked it a couple weeks ago with my new woodpecker square and it's dead on??? Would the cold cause that much change in cast iron?
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I wonder if this is why I had so many issues with my cuts being out of whack when I was building Christmas presents? My dados and crosscuts kept coming off the saw out of square, and I checked it a couple weeks ago with my new woodpecker square and it's dead on??? Would the cold cause that much change in cast iron?

Using a wooden sled, or miter gague with a wooden fence attached?
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Here in SW Oregon/NW Cal we have humidity in the winter and dryness in the summer. But my sled seems to get sticky/unsticky over a few hours, which I have associated with the temp diff and thermal expansion of my table top. I could be wrong by my sled guides are coated in oil/wax and I doubt they absorb/release moisture that quickly. I could be wrong as I'm just guessing based on intuition and few physics classes from college. We never studied the various expansion expansion coefficients of wood, so ...

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Using a wooden sled, or miter gague with a wooden fence attached?

negative, and the cuts were out of whack in respect to the blade tilt. I don't know, no more last minute Christmas presents this year, I'm starting in June!
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  • 5 years later...

Hi, I got a granite table saw top, I'm wondering if someone had an idea to use something just like magnet on cast iron, (stop and other things) would a doubleside tape would be strong enough or somekind of succion ..

 

Any idea ? 

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