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How To: Get Calibrated!

#6

Step 5: Measuring Distance Between Motors

Out of all the steps, this one causes people the most problems… and it’s really not that hard.

The first thing to do is to READ THE INSTRUCTIONS… ALL OF THEM

Regardless of how you plan to deal with the slack of the chain (over-top feed or under-bottom feed), you will do the distance measurement just like shown:

  1. Place the first link of the left chain on the left sprocket as shown on the image on the left.
  2. Press the “Extend” button. The left sprocket will rotate clockwise and feed out 100 mm of chain. Make sure it doesn’t wrap around the sprocket. I hold that chain and put tension on it during this whole process of feeding out chain because for whatever reason, my chain LOVES TO WRAP.
  3. Once you got 100 mm out, press the “100 mm” button and change the value to “1000 mm”.
  4. Press “Extend” button again. Again, here I hold onto the chain pulling it so there’s tension on it to keep it from wrapping around the sprocket.
  5. Press “Extend” button again.
  6. Press “Extend” button again. At this point, you should have about 3100 mm of chain extended. I think this will be enough to place the first link on the right sprocket as shown in the picture on the right. If not, change the 1000 mm value to something smaller… maybe 10 mm and click it a number of times to get you to where you need to be.
  7. Place the end of the left chain on the right sprocket as shown in the picture on the right.
  8. If you haven’t changed the 1000mm to a smaller value, do so… go with 10 mm… I don’t know.
  9. Click “Retract” until you remove most, but not all the slack.

It’s been reported that during the next step, the chain can come off the right sprocket and smack you pretty hard. It can be under a lot of tension and if it comes off, things might hurt. I’ve only had this happen to me once, but it was while the chain was just starting to tighten up and the end just fell to the ground. Others, however (need to find the post) had it happen further during the tensioning process and can have some force behind it.

  1. Click “Pull Chain Tight and Measure”. During this step, the slack will be taken up and the motor will determine, from its perspective, the distance between motors based upon how much chain is fed out. After it’s done (it’s pretty quick) the chain will slacken up. This will allow you to remove it from the right sprocket. Try to pay attention to the motors and frame during this time. If you see the motors move or the frame flex, you’ll end up with low accuracy so you’ll need to make some repairs to your frame.

Frequently asked questions about this step

99% of the problems on this step is because people don’t use the buttons to feed out the chain… they just drape the chains over the sprocket manually and then click pull chain tight and measure. You must use the extend button to feed out enough chain to get it to reach the right sprocket. There’s no shortcut here.

What you need to know to skip this step

As long as you’ve done this measurement before and the controller knows where the sled is, you can safely skip this step, but you will also need to skip the remaining steps (except for the very next one) until you get to doing the calibration cuts.

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Error message during uploading Arduino
Calibration moving one motor wrong direction in Ground Control V1.20
#7

Step 6: Pick Your Chain Feed Arrangement

Pretty simple step. Referencing the left sprocket, if the slack of your chain hangs vertically down from the sprocket, you are in “Chain Off Top” configuration. This is how the early frames where built.

If, however, you take up your slack “horizontally” along the top beam, then you are in “Chain Off Bottom” configuration. This is how most newer frames are built.

Click the button for whichever configuration you use.

Note: The following steps will differ depending upon what configuration you are in.

Frequently asked questions about this step

Which configuration do I pick? Seriously? I just explained which one to use.

What you need to know to skip this step

If you’ve never picked your configuration before, pick it otherwise you run the risk that the default value is incorrect and the following steps will end in nothing but misery.

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#8

Step 7: Review the Measurements

It might be a good idea to jot down the numbers and make sure everything is correct. If something looks wonky, it probably is. (Don’t concern yourself with the numbers in the above picture… these are old numbers from an old frame of mine that I’ve manually messed around with).

If something is off, click the back button to go back and redo the steps that are wrong. If happy enough to move forward, click “Looks Good”.

Frequently asked questions about this step

What do I do if something is wrong? Click back until you get to the step that’s wrong and redo it.

What you need to know to skip this step

I don’t think it makes any difference if you click skip or “Looks Good”. The settings should have already been saved by this time.

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Calibration issue, Sled is not centered at the end of the measure and center operations
#9

Step 8: Generate Calibration Procedure

Take a deep breath and hold for 4 seconds. Exhale. If you did it right, it should have moved on to Step 9 by the time you are done. If you did it wrong, it should have still moved on to Step 9 by the time you are done.

However, what comes next depends upon whether you picked “Chain Off Top” or “Chain Off Bottom”. So this thread will fork… like one of those “Choose Your Own Adventure Books”. As it stands now, you only need to do Steps 9 - (whatever) if you are in “Chain Off Bottom” configuration. If you are “Chain Off Top” go to Step 10!

Frequently asked questions about this step

Why is this step here? Well, as I mentioned above, the next steps are different depending upon your chain feed configuration so the software has to ‘build’ the steps for you to take. It’s a code thing.

What you need to know to skip this step

Only that you can’t skip this step.

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#10

Step 9A: Remove the Chains - CHAIN OFF BOTTOM USERS ONLY

Pretty simple step. Take the chains off the sprockets because they aren’t installed the way they need to be… Then click “Next”.

Frequency asked questions about this step

Do I need to take the chains off the sprocket? Only if you want things to go well.

What you need to know to skip this step

Well, if you chains are still attached to the sled because you skipped other steps, then please, skip this step because.

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#11

Step 9B: Set Sprockets Vertical - CHAIN OFF BOTTOM USERS ONLY

image

Didn’t we just do that in Step 4? Yes, and we are going to do it again but this time, through the miracle of technology, you are just going to hit “Automatic”. If that doesn’t set the 12 o’clock sprocket tooth to 12 o’clock, then something is seriously wrong and you need to take a break and come back and start this process all over again. Edit: Don’t Panic! So it appears that the “Automatic” button may have a bug in this step. If the automatic button doesn’t return you to 12 o’clock, go ahead and readjust the sprocket through the buttons..

If it does work, then click “Set Zero”.

Frequency asked questions about this step

Can I use “Automatic”? Yes. Edit: Don’t know for certain. If you find it doesn’t work, report your findings here:

Can I do it manually? Yes.

What you need to know to skip this step

If the chains are still attached to your sled because you skipped other steps, please, skip this step.

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Sprocket does not reset to 12:00 automatically in calibration step 9b
#12

Step 10: Enter Rotational Radius Estimate

In this step you will enter in a value for the rotational radius of your ring or linkage kit. So far, there are three main types of linkage kits:

  • Ring (now the stock kit shipped with Maslows)
  • Wooden Linkage (@PillagethenBurn’s kit)
  • Metal Linkage aka Top Pantogragh (@dlang’s kit)

Values are provided as estimates for these three kits. If you have better numbers, use them, if not, use the values provided. Notice the note about the values being rough and should be updated. Someday they will be.

Click “Enter Measurement” and enter the appropriate value.

Click “Next”

Frequently asked questions about this step

_What's the rotational radius?_ Rotational radius is the distance from the center of the router bit to where the chain ends (more precisely, it's to the middle of that first link..) It's basically the "extra" distance the program needs in order to calculate how much chain to feed out. If you have a custom built linkage kit, the radius could be different. But if you into it enough to build your own custom linkage kit, you probably aren't reading this.

What you need to know to skip this step

Actually, this is a good step to skip as long as you have entered a good value during a previous calibration. Sometimes you are doing this calibration again just because you want to tweak something and if you skip this step, then the program will keep your existing value.
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#13

Step 11: Adjust Chain Lengths, aka "The Tricky One"

So, for this step, the lower left image differs based upon whether you are in “Chain Off Top” or “Chain Off Bottom” configuration. Here, we fork again…

  • If “Chain Off Top”, go to Step 11A
  • If “Chain Off Bottom”, go to step 11B
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#14

Step 11A: Adjust Chain Lengths - CHAIN OFF TOP ONLY

So if you are here, you should:

  1. Have the left chain still on the left sprocket with a bunch of it fed out over toward the right sprocket… and it’s probably still attached.
  2. The right chain is balled up in a tangled mess because you haven’t used it yet and kicked it a few times trying to do the previous steps.

The process here is not too complicated.

  1. Remove the left chain from the right sprocket. LEAVE IT WHERE IT IS ON THE LEFT SPROCKET
  2. Click “Adjust Left Chain” while holding on to the left chain… you don’t want it flopping around.
  3. The left sprocket will turn counter-clockwise and retract the chain to a determined length (suitable for connecting to the sled).
  4. When that’s done, place the right chain on the right sprocket as shown in the picture on the left. Basically its a mirrored image of the left chain when we first started the process to measure distance between motors in Step 5.
  5. Press “Adjust Right Chain”. GRAB THE CHAIN BEING FED OUT AND GIVE IT TENSION SO IT DOESN’T WRAP AROUND THE RIGHT SPROCKET. I don’t know about you, but if I don’t babysit my chains during this part, they are guaranteed to wrap around the sprocket. Don’t let that happen.
  6. When the right chain has stopped being fed out, connect the chains to your sled.
  7. Press “Move to Center” and hopefully if your measurements and estimate for rotational radius were close to what they should be, your sled will move close to the center.
  8. Press “Next”

Frequently asked questions about this step

My chains don’t reach the sled… whatsup? Most likely you have a 12-foot top beam (or at least you motor spacing is further apart than would be with a stock frame. You need to Go to Settings->Advanced Settings and set the Extend Chain Distance based upon the following:

  • If using a 10-foot top beam, set distance to 1651 mm
  • If using a 12-foot top beam, set distance to 2032 mm

The key to the setting is to make it a multiple of 63.5 mm and long enough so you can attach your chains to the sled when the time comes. If you have a 10-foot beam and they don’t reach, then your rotational radius or vertical measurement of motor height is probably wrong. Check those measurements and go back to correct.

My chains fell off the sprocket… whatsup? If you removed the left chain from the left sprocket and reset it so the first link is on the 12 o’clock tooth, you didn’t follow directions thereby causing the chain to fall off. At this step, the controller thinks the left chain is extended all the way to the right sprocket. So when you tell it to adjust, it’s going to retract the chain (turn counter clockwise) and if you had reset the chain, it’ll fall off pretty darn quick.

What you need to know to skip this step If you never removed the chains from your sled (i.e., skipped previous steps) then please, skip this step.

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I'm having trouble calibrating. The chain length portions are the most difficult
#15

Step 11B: Adjust Chain Lengths - CHAIN OFF BOTTOM ONLY

So if you are here, you should:

  1. Your sprockets are pointing at 12 o’clock
  2. Your chains are not attached to either sprocket.

The process here is not too complicated.

  1. Place the left chain on the left sprocket as shown in the picture on the left.
  2. Click “Adjust Left Chain” while holding on to the left chain… you don’t want it to wrap all the way around the sprocket and get tangled up.
  3. The left sprocket will turn counter-clockwise and extend the chain to a determined length (suitable for connecting to the sled).
  4. When that’s done, place the right chain on the right sprocket in a mirror image of what’s shown in the picture of the left. Here’s a picture just to be crystal clear:

image Yes, I took the picture and mirrored it.

  1. Press “Adjust Right Chain”. GRAB THE CHAIN BEING FED OUT AND GIVE IT TENSION SO IT DOESN’T WRAP AROUND THE RIGHT SPROCKET.
  2. When the right chain has stopped being fed out, connect the chains to your sled.
  3. Press “Move to Center” and hopefully if your measurements and estimate for rotational radius were close to what they should be, your sled will move close to the center.
  4. Press “Next”

Frequently asked questions about this step

My chains don’t reach the sled… whatsup? Most likely you have a 12-foot top beam (or at least you motor spacing is further apart than would be with a stock frame. You need to go to Settings->Advanced Settings and change Extend Chain Distance from the default of 1650 mm to something bigger. I think I used 2032 mm for 12-foot beam. If you have a 10-foot beam and they don’t reach, then your rotational radius or vertical measurement of motor height is probably wrong. Check those measurements and go back to correct.

What you need to know to skip this step If you never removed the chains from your sled (i.e., skipped previous steps) then please, skip this step.

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Calibrating problems
#16

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#17

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#18

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#19

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#20

There are two steps 11A here. Obviously the second should be 11B. It only matters because on a small laptop screen it was hard to find.

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#21

we should change the default to triangular, the majority of maslows out there are triangular, and anything new that’s shipped is going to be triangular

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Calibrating problems
#22

once we get the new calibration calculations worked out, step 3 should not be needed for triangular kinematics

on step 5, add instructions to watch for the motors moving or the frame flexing

It would be good to measure the motors with a tape measure before you apply tension and while it’s under tension, if the measurements differ, find out what’s moving and fix it, otherwise you won’t get a good result (and in addition, we will want the manual measurement eventually to figure out chain slop)

step 9b, the machine knows where the motors are compared to the 12 o’clock position they started at, we should change the code to move there without having to have someone manually do this (if they skipped earlier steps, they will need to fix it here)

step 10, technically it’s the distance from the center of the bit to the point in the chain that is at the 12 o’clock position when you start)

step 11a, I still say we should have the chain removed and manually reset. The difference in time saved by retracting the chain vs feeding it out is minor, and dwarfed by the time lost due to people doing it wrong and having to ask for help (or just giving up)

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#23

I made the posts wiki… thought I had already… but I’ll add to step 5 and 10.

The other points require code changes.

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#24

We should try to have a list somewhere of ‘desired, but not implemented changes’
that a newbe could look at and take a stab at implementing.

David Lang

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#26

how big of a deal is it to eyeball the tooth alignment to 12 o’clock (I don’t have a means to attach a level to the chain, at the moment)?

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