Third Brick On The Sled

Ok, I have the Triton TRA001 router and I’ve found it fine, except that when the Z Axis is wound out from the work surface the weight of the motor assembly causes the sled to tip backwards. I think when it’s wound all the way in it doesn’t push into the work very hard, either. I suspect the Ridgid router has a centre of gravity further forwards than the Triton.

So, the only thing I can really think of to do is to add a third brick at the top of the sled to try to move the CG further forwards (into the work surface). Is this a benign thing to do from the geometry point of view? I think it’ll be ok and will probably try it, just wanted to see if anyone has an instant reason why it won’t work.
I think the motors are easily powerful enough to handle the extra weight. I think. The chains are probably rated for tons of force too? (Well, many Newtons).

Raise the chain one hole higher on the brackets first. You don’t need that weight on top. The brackets help with tipping center of gravity adjustment.

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I’ve done that before. The problem I have with that is that the chain starts to mis-align with the sprocket and jump, or at least make bad noises. Are you running the standard frame? Are the motors angled, or mounted in front of the work surface?

Like @Blsteinhauer88 said, start by finding the attachment point that balances the sled. Then look at whether the chains are parallel to the work area. If so, you’re good. If not, move the motor mounts to correct that. If the chains are not parallel to the work surface, they can jump a tooth on the sprocket, spoiling the piece being cut. Make sure the sprockets are parallel to the work area as well. In practice these adjustments won’t need to be made often, though it’s a good idea to check them every 5000 miles or so :wink:.

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So on the standard frame the chains are parallel to the work surface? If that’s the case then surely there’s no force from the chains pulling the sled to the work surface? My motors are a bit behind the work surface (just how I built the frame) so there’s always force pulling the sled forwards. It’s just not quite enough when the Z axis is a way out.
Wouldn’t moving the motors forwards to make the chains parallel reduce the forward force from the chains?

disclaimer: I have not built a working Maslow yet, so the following are assumptions…

I believe that the force that holds the sled to the work comes from the angle of the work surface (combined with the weight of the sled). I feel like the chains really need to be as parallel as possible to the work for the reasons mentioned above. Also it stands to reason that the chain attachment points (and therefor the motor sprockets) should be near the sled/router center of gravity (along the z-axis). If you don’t have enough sled pressure after balancing things like that I would add a little weight or increase the angle of the entire frame.

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@pillageTHENburn put his finger on it. It’s gravity that applies the force that holds the sled to the surface. An angle between 12 and 17 degrees seems common. Sorry I forgot to mention that, it’s one of the fundamental principles, like the chains being parallel to the surface, and fundamentals can become assumptions. :confused:

  • Work surface angled from vertical - 12 to 17 degrees
  • Chains attach to sled near the z-axis balance point
  • Motors mounted so that chains run parallel to the surface
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What about setting the whole machine on a different angle? To adjust the position of the sheet material for the centre of gravity that works better with your router.

I’ve just checked the sled balance point and it’s at about 20 degrees when the router is fully forward level with the cutting surface. So I think I’d have to tilt the frame past 20 degrees.

Why are the bricks at the bottom of the sled? Could they go at the top, or at least higher up? I think that would help me here. I have managed to cut test pieces so it’s not a massive problem, but there’s very little force pushing the router into the cut.

Would it be a disaster to add another brick at the top?

the sled balance point is not a thing of degrees.

you should move the chains so that when you hold the sled in mid-air by the
chains, the sled is (close to) straight up and down, not tilted in any way.

(this is with the motor in about the position that it would be when using it)

Then you need to move the motors out so that they are basically parallel to the
work area.

Only after that do you then look at the tilt of the machine.

Yes, if you have the chains mounted too low to the sled, adding more weight to
the sled will bring it closer to balanced, but just adding weight and hoping
it’s better isn’t right, you can balance the sled with the standard two bricks
without adding another one (you can also balance it with a single brick, which
some people have said works better)

tilting the machine will make it so that more of the weight of the sled is
pushing the bit into the machine, but it also increases drag and makes it so
that less of the weight of the sled is keeping the chains tight, so you may have
some troubles in the bottom corners.

no, it’s not a disaster to add a brick to the top of the sled, just make sure
you tell the machine where the center of gravity of the sled is so that it can
make the correct calculations for how much the sled is tilting.