Trunnion Design - Router Forums
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post #1 of 17 (permalink) Old 06-26-2019, 08:21 PM Thread Starter
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Default Trunnion Design

I know my question is not related to routers but perhaps one of you may have the info I want

Iím building a small table saw with a 5.25Ē blade. Itís a hobby project and l looking on the web for any tips I noticed a Trunnion is used to have the blade tilt but I canít find any info on how to design a trunnion.

Basically I want to know how the half circles used on the Trunnion are designed. Are they based on the blade diameter and if yes whatís the relation to the blade?

Does anyone has an idea how to design a trunnion or where I can find any related info?

Thanks

Nicolas
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post #2 of 17 (permalink) Old 06-26-2019, 08:44 PM
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The center of the trunnion radii should be located where the blade intersects the table surface. That way, as the blade tilts, it will remain in the slot instead of moving to one side or the other.
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post #3 of 17 (permalink) Old 06-26-2019, 10:00 PM Thread Starter
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The center of the trunnion radii should be located where the blade intersects the table surface. That way, as the blade tilts, it will remain in the slot instead of moving to one side or the other.
Very important to know

Thank you

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post #4 of 17 (permalink) Old 06-27-2019, 10:58 AM
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there are a series on how ro make, and full plans available from Mathias
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post #5 of 17 (permalink) Old 06-27-2019, 11:25 AM
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https://www.youtube.com/watch?v=RBucMKhrL8M
there are a series on how ro make, and full plans available from Mathias
He definitely has talent. And I like the fact that he uses push sticks so much.

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post #6 of 17 (permalink) Old 06-27-2019, 12:32 PM Thread Starter
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https://www.youtube.com/watch?v=RBucMKhrL8M
there are a series on how ro make, and full plans available from Mathias
The tilt blade mechanism he is using (with hinges) is not the same as using Trunnions. Iím only looking for info on how to make the Trunnions.

Thanks for the video, quite interesting

Nicolas
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post #7 of 17 (permalink) Old 06-27-2019, 01:46 PM
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You can get an idea by looking up the parts schematics of various makers saws. Just pick some models and then search for their parts diagrams. Making one that doesn't tilt is really simple. You just need an arbor and some pillow block style bearings but you won't have much depth of cut with a blade that small. Maybe only an inch.

Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.
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post #8 of 17 (permalink) Old 06-27-2019, 02:49 PM
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The radius of the trunnion can be any size and is only limited to the size of your overall project. Like Mike pointed out earlier you want the radius point to be centered on the intersection of the blade and the table top or you will create other problems that will limit the usefulness of your tool. You will want tight tolerances between the two trunnion parts and it would be better to right or left tilt the blade instead of tilting both ways to help maximize the bearing surface of the two parts.

One part is basically a curved slot and the other part would have a mating raised slide. These two parts would be a set and you will need two sets for the mount. You might want to see if there is a CNC owner near you that can help cut parts.

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post #9 of 17 (permalink) Old 06-27-2019, 04:22 PM
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The more I think about the Mathias saw, the more I think I may make a simplified version. His homemade saw fence is what started it. For now anyway, all my sawing is plywood, in just straight lines, and repeat widths - so with a set of homemade spacers, could change my cut widths in seconds. My old HF saw works, but needs tuning, and a couple of other issues, so thinking of converting that to a large disc sander, which it would be perfect for. I've got a old circular saw my younger son gave me, he pulled it out of a trash can, it had the cord cut off because the trigger switch now is continually on. Other than that it works fine, and would be perfect for my use. For smaller length pieces have already figured out a simple saw sled to use with it. I made a saw with a sabre saw mounted on the bottom of a plywood top awhile back, and it works great for odd jobs. Seldom use my bandsaw now - but that's mostly because I haven't made a stand for it so I can sit and use it - as is I have to stand to use it, and that kills my back after a few seconds; same with my bench drill press. For the saw all I would need to do is screw the saw down to a top, cut thru, raise the blade to just cut thru a piece of 3/4" plywood, and that's about it; I won't be cutting angles, just straight lines. Already got some ideas for variations on this - think I need another circular saw. I 'know' I need another circular saw; just thought of a 'sort of' portable panel saw.

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post #10 of 17 (permalink) Old 06-27-2019, 04:48 PM Thread Starter
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Originally Posted by MEBCWD View Post
The radius of the trunnion can be any size and is only limited to the size of your overall project. Like Mike pointed out earlier you want the radius point to be centered on the intersection of the blade and the table top or you will create other problems that will limit the usefulness of your tool. You will want tight tolerances between the two trunnion parts and it would be better to right or left tilt the blade instead of tilting both ways to help maximize the bearing surface of the two parts.

One part is basically a curved slot and the other part would have a mating raised slide. These two parts would be a set and you will need two sets for the mount. You might want to see if there is a CNC owner near you that can help cut parts.
Mike you hit it right on! thatís what I was expecting since I have seen a lot of trunnion schematics but I could not figure out where the center of the curves was. Also I thought the curve was related to some part of the saw.

Now I have enough to get going and although a cnc would make the task much easier I can do the same with my router and my circles jig.

Much appreciated.

BTW as I mentioned this is a hobby project and I know my small blade would not be very useful cutting bevels to any serious depth but I plan to go into ships modeling where I will use thin pieces of wood and this saw will be useful
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