Triangular Linkage Evaluation Criteria and Measurements

[MeticulousMaynard]

Sorry for the delay in responding to you. I was reminded of the linkage slip in @Gero’s troubleshooting thread.

@dlang

first, add a nut (doesn’t even need to be a nylock nut, it can be a slim ‘jam nut’ which may fit on the thread), where you show it, without the plywood spacer support that you show. See what happens (you don’t need to do calibration, just see how easy it is to get the linkage to ‘snap’

I tried to do this first, but I didn’t have enough thread on the bolts to make it work. I might be able to give it a try with threaded rod, but…

@dlang

second, go back to the original all-plywood riser/spacer approach, just make the top layer be 3/4" wide (you may still have to notch it slightly to let the washers clear). NoDerlin spacer involved at all

This worked as a solution to the issue. I took one of my old plywood risers and ripped it to 3/4" wide to make sure that there was enough clearance for the bolts. Where the previous setup would jump at about 610mm (~24") from the centerline of the machine, now it slips at 1000mm+ (~40"+). And where it does slip, it no longer seems like the bolts aren’t aligned well as much as I’m reaching the limit of travel of the mechanism:

@dlang

Another test I’d like to see you do is to go to the outer edge and see how far you can go to (and off) the side before the sled starts tilting.

do we really need a skirt off the side to machine all the way to the edge.

I also was able to test this. I took a video, but I don’t have my camera with me right now to post the resulting video. I will try and post that tonight when I have access to the video and my editing software.

I would recommend a skirt around the edge of the sheet though. At about 1’ in from the edge of the machine, I had pretty good stability. I have a 4’x8’x3/4" sheet of MDF as my spoilboard, so I effectively do have a skirt for the edges of my machine. When I jogged the machine over to the edge of the sheet, however, things got harrier. With the bit at the edge of the sheet, the sled was webble-wobbling quite a bit. I think having a skirt that is a similar thickness will improve stability greatly.

Again, I’ll post the video tonight when I get the chance so you can see better.

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I have switched the linkages back over to Logan’s. I need to start cutting projects, and currently it has the least distortion so I will be using that for now. This will be really important for cutting my new sled.

In response to this criticism I had for this linkage kit:

@MeticulousMaynard

The other design consideration is that the lower right mounting point really crowds the Z-Axis. It’s not impossible to fit both the standoff and the axis’s brake, but it’s something to be aware of:

I took @madgrizzle’s suggestion on how to mount the bracket, and I think it’s quite a slick solution to the problem:

So far so good!

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And finally, I’ve been able to put my test sheet to good use! I needed to make a countertop for another project. It’s going to get nosing on the front, and tile on top, so you’ll never see all my test patterns once it’s done!