Linkage kits are now available! 🎉

There’s also a new auto calibration function which should find it automatically :grinning:

Mine converged to

So maybe it even works! :upside_down_face:

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Finished assembling my kit! Check it out at https://www.youtube.com/watch?v=3__VClHnD8M

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Very nice!

Good job… looking forward to how it works for you…

@pillageTHENburn is there a design file I can look at, or something theoretical I can read?

When I search for “triangular kinematic” or similar I get horribly sidetracked and confused :slight_smile:

Any more accuracy tests

Yes! The files I have are .ai files designed specifically for a laser cutter (so they are not typical CAD) but I’d be happy to share them! I added most of the development updates in the thread throwing my hat in the sled modification ring. But I know that thread is prohibitively long so here are some “chapter markers” for you :slight_smile:

  • This is the original concept and also the reason why many people still call it a pantograph (though technically all current versions are double-crank parallelogram four bar linkage mechanisms. I plan to do a short writeup explaining the simple misconception soon)
  • This post sort of explains the different concepts for linkages, this post was made very early on and the diagrams are not to scale at all. But it lists my different original design ideas and most of the criteria that must be met in order to make them function properly. (I’ve since had a few other ideas but haven’t posted them yet).
  • This post has some better diagrams of the 45˚ version.

Also @dlang put together a relatively comprehensive overview of the triangular vs quadrilateral kinematics issue here:

Hopefully that helps clear it up a little? Perhaps this is not what you were asking…

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What is the lead time on your linkage kits you are selling?

I’m a bit behind at the moment because I was waiting on a shipment of specialty hardware (and more wood) but that has since come in and I am filling orders again as fast as I can (I have many hours of late night laser cutting in my future). Most of the people who have ordered them do not yet have a Maslow so it hasn’t been a big problem for them, but I can work with you if you need it sooner. Just let me know and I will see what I can do.

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Hi @pillageTHENburn, I just ordered the linkage kit thought I don’t have the Maslow kit or equivalent parts yet.

You mentioned that you’d be willing to supply the SVG, .ai or other source design files under a free/libre license. Have you done this already? If so, could you point to where this was made available? If not, would it be possible to put them somewhere (and with the appropriate license) so that we can take a look? Maybe the MaslowCNC Mechanics repo?

Thanks!

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Thanks for all the detail,

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Bar can you please do a quick write up walking through or explaining the steps to take in doing machine calibration after switching to triangular kinematics.

I set up my temporary frame and cut all my permanent frame pieces using quadrilateral kinematics on version 0.86 firmware and GC.
I followed the calibration step by step instructions within ground control for that.

Now I have assembled my permanent frame and bought and assembled a linkage kit from pillagethenburn. I also installed the newest version of GC and firmware at v0.96

My question is what do I need to do as far as the step by step calibration process now for triangular kinematics? Do I still need to enter the measurements for sled cg and all of the other sled specific geometry measurements? What about this automatic process converging to a solution like you mention in your post etc…

Thanks in advance

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once you change the kinematics, there should only be one value to set for the
sled, the added effective chain length from the linkage.

If you are seeing anythingelse, you aren’t in the triangular mode.

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What David said:

And that added length should be around 270mm depending on how you mount your chains in the clevis; if you’re getting a number that’s hugely different than that then something else is wrong.

Yes, I will make a step by step walk through.

The short version is that what you need to do is click Action -> Calibrate Machine Dimensions and follow the steps on screen. A lot of it will be a repeat of what you did last time. You could technically click skip for the steps to measure the distance between the motors and the vertical offset of the motors, but I haven’t tested the whole process with those steps skipped.

If you find any part of that process confusing, please, please let me know. Your feedback is SUPER helpful.

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I am on firmware and GC versions 0.96 for both.

I assembled a linkage kit from #pillageTHENburn and switched the mode to triangle kinematics.

I was nervous doing the auto mode where you let the chain measure it for you because I was nervous to tension the chain using the motors of fear something might break. I decided that it seemed more accurate to carefully tape a steel tape (not a regular tape measure) on center of one motor and measure to the center of the other motor and got 2881.3 mm center to center on the motors.

I did the calibrate chain lengths to let it feed out the chain. One thing I noticed on this step is that both motors are moved to start with a motor gear tooth pointed straight up 12:00 high. After I let it auto feed out the appropriate chain length the left motor tooth it ends up on is not pointing straight up. the right motor had a tooth with a chain link on it pointed straight up after auto feeding out the chain. This is very confusing why they would be different.

I carefully measured the height from the top of my 4’x8’ sheet of wood up to the motor centers and got 428.75 mm.

I entered my workspace dimensions as 4’x8’ height and width in mm for the standard plywood sheet size

I carefully measured the added effective chain length from the inside face of piece G2 of the linkage kit which has the cotter pin resting against it going through the hole in the last chain link to the center of the router bit and my measurements were 272 mm on the left link and 271 mm on the right link so I deem that close enough to the 269.7 that was recommended and I entered it as 271.5 mm to split the difference of the two measurements I made.

So after all of that when I tell the machine to return to center, it’s centered left to right but it’s .6 inches off above the center of the 4’ height direction of the sheet of plywood. It seems that the added effective chain length number changes the vertical center location as does the height from the top of the work piece to the motor center.

I am confused why this is so far off anyone have any ideas or experience similar problems?
Tomorrow I will try to get some pictures uploaded of my setup.

I was nervous doing the auto mode where you let the chain measure it for you
because I was nervous to tension the chain using the motors of fear something
might break.

It the machine bends or breaks from the tension of the calibration, it’s going
to bend during normal operation. In fact the tension during claibration is only
about 1/2 to 1/3 what you can hit during normal operation.

I did the calibrate chain lengths to let it feed out the chain. One thing I
noticed on this step is that both motors are moved to start with a motor gear
tooth pointed straight up 12:00 high. After I let it auto feed out the
appropriate chain length the left motor tooth it ends up on is not pointing
straight up. the right motor had a tooth with a chain link on it pointed
straight up after auto feeding out the chain. This is very confusing why they
would be different.

this sounds like a problem, they should both move the same amount. This
indicates to me that you are probably loosing some steps on one motor.

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David is right, it shouldn’t break anything. I’ve tested the linkages to ~80+ pounds each with no breaking. There are some variables there like how much glue you used, what type, how you clamped them etc. etc. but I would say generally speaking the linkages should be stronger than any force the motors can supply. I even hung my entire body weight on a singe wooden clevis (that was NOT glued), that’s about 145 pounds.

That 269.7mm number was just an estimate based only on my files, in reality the laser kerf in the slots on G1 and G3 and a tiny design tweak I made early on will usually make it closer to 271-273mm so I think you’re right in the right place :+1:t3:
Even if that measurement was off by a couple mm I don’t see how that would give you .6" error vertically! The different length chains is a red flag I’d look into a little more.

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Any news on availability? Not nagging, just trying to figure out my schedule now that my machine has arrived.

I’m filling and shipping orders as fast as I can! (@DaveDurant I’ll PM you with details about your order specifically).
More generally speaking I’m sending out batches of orders a couple times a week and I’m filling them chronologically. There was a pretty big surge in orders when Bar mentioned the kit in his newletter and I’m still catching up on that pile.

Just to be transparent with my situation, I have a full time job and a young family so I’m doing my best to balance my time between family, work, sleep, and maslow kits :slight_smile: I’m making kits every day and I’m sending them out as fast as I can make them!

If anyone would like a more specific idea of where their order is in the “chain” please feel free to message me (preferably message me through Etsy so that I have an order number with the message; Unless it’s just a general question, in that case the forum is a great place). I’m willing to work with deadlines and schedules (within my means and within reason) so just let me know if you have a specific need (for instance one guy had a trade show and needed his kit by a certain date and I was able to make sure that happened, so I’ll do my best to work with you).

I’m sorry for anyone who has experienced a delay, I have already messaged everyone who’s kit is “late” through etsy. Feel free to contact me with any questions!
-Logan

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Awesome - thanks for the update!

They say it’s better to be busy than bored…

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