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Throwing my hat in the sled modification ring


#545

I would love to see a photo of the new laser cut kit mounted on a maslow that shows the clearance from the router with z axis and vacuum outlet on the router.
Also what do you have to change in ground control settings to get this all to work?


#546

Here’s one from @bdillahu:

It appears he does not have dust collection plugged into it at the moment but you can see where it would connect below the router. The linkage itself clears the z-axis with no problem but the mounting block is an admittedly tight fit - but from the feedback I’ve received so far it does work fine if your block isn’t too wide.

If you wanted to, both linkages could be “slid” (moved) down along the same line that the pivots are mounted to. If you moved the linkage 1 inch you would need to re-drill the 1/4" chain attachment holes 1 inch in the other direction and all would still work perfectly. I didn’t design it this way because I was afraid the lack of symmetry could cause confusion with mounting; but it would be a super easy change. In fact, if you want a kit with moved holes I can do that for you. Just let me know.

In Ground Control under Advanced Settings the 9th option is “Kinematics Type”, it will allow you to switch to “triangular kinematics”. You’ll also need to know the Rotation Radius for Triangular Kinematics, this should be about 270 mm.
-Logan


#547

Here’s another one with the z-axis moved over enough to actually fit, and the vacuum hose attached.

Fixing to test some with the larger hairpin cotter pins installed from the original Maslow kit to have easier chain attach/detach.

I will note… make SURE you screw on the vacuum adapter piece BEFORE you block that screw with the z-axis bracket.

Sigh.


#548

That looks great! Have you checked clearance of the original Maslow hairpin cotter in the lower left/right corners of the work area?
I did find long hairpin cotters that will fit the chain pin-hole (just like the small cotter pins I sent), I didn’t order them yet because I want to see if the originals will work first. But if they don’t I think I now have some solid solutions to the small cotter pin problem!


#549

I checked them best I could figure at each corner and they seemed fine.

Note that the way I have my frame at the moment, the sled isn’t clear to run off the bottom, so the lowest I could get would be the radius of the sled (say 9").

Regardless, it seemed fine to me.

The only other caveat to that is that my “c” and “d” linkage (where the arms pass through each other) are binding just a little on one end. The single bar is too “thick” for the slot at one end. I figure a quick hit with some sandpaper will fix that. So that said, if it got “stuck” then the sled wouldn’t rotate right and you could get into the extremes, but if I unstuck it and got it to rotate back to “normal”, then all was fine.


#550

Awesome! It looks like I might have a couple hundred spare cotter pins now… ha!

I do think that would help! I meant to include in the instructions to sand both sides of “C” (but not to the tips) and at least the insides of both “D” pieces… For my first test I sanded everything and it was great, then for the set I made (and photographed for the instructions) I didn’t sand anything at all and it seemed okay but I could tell things could get tight if I wasn’t careful.

I’ve also considered not gluing the wooden “washer” between the “D” pieces, just letting it float… in theory this should work fine as long as all forces remain only along the x/y plane, but if there’s torsion it might not be good? I don’t know, I haven’t tried it yet but it seems like they don’t actually need to be glued there. If they aren’t glued then that would allow the two pieces to find their own “happy place” around the C bar.

Also, I like that you faced the lettering in on your glue-ups!


#551

:slight_smile:

You mentioned it in the instructions and I just couldn’t resist. Then I was about regretting it when I wanted to write which bars were rubbing and the letters are all hidden :slight_smile:

I will also toss in (sorry, forgot it when I wrote above) - I cut a long straight line 4-6" down from the top edge of my test sheet… I couldn’t check it really close, but for various definitions of close, it was straight. No particular bow. I have read that the stiffness of the frame helps with this and I have a pretty hefty piece of unistrut across between the motors, so they aren’t pull in.

I want to do it again in better wood that doesn’t “fuzz” and cover some of the inaccuracies, but it was straighter than I would have probably managed with a skill saw and guide, which is about my goal. Anything better is icing on the cake.

I do find that all my measurements are just a shade small on a square/circle test shape. They are pretty consistent, but slightly off. Not sure what that means yet.


#552

just a note that the advantage of trianular kinematics really show up in
horizontal movements, not vertical movements (and especially not vertical
movements near the center where both chains are moving the same amount)


#553

That’s a good point. Especially when testing different solutions!
The way I interpreted it it sounded like he cut a long horizontal line 4-6" down from the top… I might be wrong though.


#554

Yes, it was a long horizontal line 4-6" down from the top of the sheet.

But flip side is there are really two variables in my experiment… I have your linkage kit which should improve things, and I also have a stiff motor mount, which also seems to improve things from some other folks’ experiments.

Regretfully I never tried that particular test before your linkage, so I can’t swear it is all one or the other variable, or a combination of both.

Either way, it was a straight line, which pleased me :slight_smile:


#555

Thanks that helps a ton. Any trouble with the brick clearance as well?


#556

I hate to admit it, but I still haven’t gotten the bricks on there yet… these tests have been without (a few times some weight would appear to help).

I do have the brick holders in place and from visual inspection, I don’t see an issue with putting the bricks in, just haven’t grabbed any yet.


#557

Throwing another design into sled modification.
Top link 140 degrees.
As I have designed it now, it will be offset on engine mount at about 1" and has the possibility of moving from 0 to 60 degrees


#558

I like it.
I’d be concerned about the chain attachment points not being on the same plane. In my limited wooden tests of different designs like this I have found that having the chains offset from each other like that makes things sit a little weird. All of my tests have been basically vertical though, I do not have an angled frame set up so the “problem” I’m seeing might go away once you lean it against an angled workpiece.

This idea allows for lots of lower-router clearance though!! You would still need to contend with the compression-tension problem of the linkages but I think that can probably be mostly accounted for.

I have a version of the “balanced 45˚” design that pulls the linkages way up and out of the way which is great, but it becomes more complicated to install; instead of just tracing 4 spots onto right angle lines using one of the linkages you now have to worry about specific degrees of angles and such. Totally not a deal breaker for some but I wanted to make it as completely simple as possible.

One idea I’ve been playing with to account for slop, droop, wear, flex or any other variable that might move the router bit away from the tip of the triangle that the chains create is slotted holes for router attachment so you could move the router up or down on the sled to perfectly align the bit with your chains. In a compression-tension design like this (or the top-mount design) this idea could not account for all of the “slop” but it would probably improve things. In a balanced design (like the 45˚ version) all slop is in the same direction and runs parallel to the line of the chain, if the slop in each linkage joint is the same then the overall outcome is no loss of accuracy. If the router tip falls below the point where the chains would complete the triangle this can be (theoretically) completely removed by moving the router up on the sled…


#559

@pillageTHENburn , kind of a random thought, but have you considered making a template that could be printed out, put over the sled, then used to mark drill points for the attachment points. Something like crosshairs for a center punch.

Particularly once the router hole is cut it’s difficult to precisely locate the drill locations. Even harder if you have hooves instead of fingers, and are already a bit naturally uncoordinated.

Same comment for @dlang 's shiny stainless steel version. In addition it could be useful to have a dxf to cut a completely new sled for those whose Maslow’s aren’t currently hung over a pile of rocks


#560

Yes! In fact I already started making a file that could be used with the linkage kits. I haven’t finished it yet because I’ve been trying to get kits built and shipped and I didn’t feel it was really needed*, but I will get it done soon. The tricky part is aligning it with a router in a sled that already has a large center hole. This can probably be done by carefully cutting an “X” at the center and slipping it over an extended router bit.

*The way I suggest marking the holes right now is to use one of the linkage pieces as a template. Simply slip the center hole of one of the “B” pieces over a 1/4" anything chucked into your router (a 1/4" drill bit, 1/4" rod etc.) and the outer two holes in the B piece are exactly where you should drill through your sled. You just mark two sets of holes 90˚ from each other.

The paper template is what I was planning to do if I ever make a “weird” design that isn’t as easy to simply trace like that.


#561

My quandary exactly. I was thinking I could chuck up a 1/4" something in the router (I think the R2200 comes with a centering tool like this) and work on the bottom of the sled per @pillageTHENburn’s instructions. It would require that I drill perfectly perpendicular holes, though. Sigh. It needs accuracy to achieve accuracy.


#562


The same can be done with the angle solutions.


#563

Yes, in every instance I can think of the linkages should be able to trace their own holes. For the design I’m talking about it isn’t the spacing of the holes that I was talking about being a challenge but the angle between the two lines that the holes fall on. Obviously this can be measured or solved with a paper template like @mooselake and I were talking about. Like I said, it’s totally not a deal breaker, I just wanted it to be as simple as possible and since I had already started on the kits I decided to put my time into getting something working and available asap for people who wanted them.

I really like your top mounted solution, a couple of my design ideas use curved bars too but I’ve never gotten around to testing them. When you make it be sure to post pictures and feedback so we can learn from your process!


#564

That looks like the same mechanism as the top pantograph design, you just don’t
put both sides on the same mounting point to the sled.

you need to be able to move from ~10 to 80 degrees, so your 0-60 isn’t quite
enough (but that’s a fairly minor modification)

it does solve the headache of the angle between the chain and the arm getting
small

it looses the advantage of moving the chain stress off of the sled and onto the
mounting.

and it uses different shape links, which complicates manufacturing a little.