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:
- Place the first link of the left chain on the left sprocket as shown on the image on the left.
- 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.
- Once you got 100 mm out, press the “100 mm” button and change the value to “1000 mm”.
- 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.
- Press “Extend” button again.
- 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.
- Place the end of the left chain on the right sprocket as shown in the picture on the right.
- If you haven’t changed the 1000mm to a smaller value, do so… go with 10 mm… I don’t know.
- 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.
- 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.