Procedure to Set Belt Tension

Robert, I have watched your videos on belt tension and followed your comments here in the forum. What is your latest recommendation for belt tension? The last I saw, it was about 3.5 pounds. Thanks.

I’ve dropped it down to about 3.2 pounds, but that was more to make my small (<3/16") circles perfectly round. Larger circles were still pretty much perfect at 3.5 pounds.

What about the higher belt tension affects roundness carved circles?

Thanks.

Actually, its 1/64" of deflection per inch of span, with a 2 pound force. The test-force is always two pounds in this method, for any length span. Which is an important difference! :slight_smile:

I’ll have to try this procedure! I keep breaking belts. I’m guessing because they’re to tight.

My theory is that the steppers don’t build up enough torque to move correctly when the belt tension is too high. For instance, going clockwise from the 12 o’clock position, if the Y belt tension is too high then the bit would move quite a bit in the X direction before moving Y, causing it to seem more like an oval pointing at the 3/9 o’clock positions.

Just a guess, but it seems to make sense.

I upgraded to 269oz-in NEMA steppers on x and y stage a few weeks back. Now I can run with a bit more v-wheel pressure and belt tension and never loose steps, which is really nice. However, these brutes ripped the teeth right off the 6mm belt when the bit crashed hard into a clamp.

So many tradeoffs.

@MattWheeler which controller are you running?

X-Controller.

I’m running into that problem right now. the xaxis belt is rubbing on the motor pulley on one side.
Is here a way i can i adjust this now?

You should be able to move the pulley in and out on the shaft a bit to align it. You need to make sure the belt is sitting in the middle of the rollers though.

1 Like

Hi Guys

my belts were tensioned with a fishing scale then a guitar tuner to get them exactly the same,
I got the idea from the instructions saying "taut like a guitar string)

G

2 Likes

Thank you. I loosened the xaxis belt, took 4 screws from back of xaxis motor, and was able to adjust it. Think it fixed my xaxis slipping problem.

1 Like

If you use a controller with proper feedback the stepper motor will not keep trying to turn when the router / spindle runs into a point it cannot go beyond.

The standard controller that comes with the Xcarve does not have that feature.
At some point I plan on getting a controller that I can set up that will not have this problem. That way when I try to home or something gets stuck the unit doesn’t keep trying to move and will go into a fail / warning mode letting you clear or reset it.

Something like this:
https://www.inventables.com/technologies/3-axis-dsp-based-digital-stepper-driver

1 Like

I tryed to centere the belt in the pukky and smoth idler and tited the belt and move in y axes 2 times or 3 and noticed that the belt was not aligment

Hi all
I have problem with circles
see https://discuss.inventables.com/t/aspire-why-my-circle-not-round-perfect/96222/5

I checked the belt tension it was x=1.8 , Y1=1.4 , y2=1.8

Do you think my problem from belt tension?

Hello. If I’m having issues where on the left side of my waste bored it cuts deeper vs my right side. Is that a tension belt issue? My Gantry is straight, so is my MakerSlide.

Na, depending on where your located humidity might be a factor in this. possibly your waste board needs planning for a well-tuned machine.

CNC BED LEVEL | Inventables

In addition to Surfacing the wasteboard as Ken is suggesting I also suggest to Surface the workpiece whenever possible and when it cannot be surfaced on the cnc for one reason or another I suggest trying this shimming technique to get the top of the workpiece to be parallel to the gantry plane of movement:

However I see that you’re new to the group and that makes me think that maybe you have a newer X-Carve and this video covers the most common first post from new X-Carve users and is worth checking out:

Noob alert. Here’s a crappy jig I built to tension the belts. The scale is from amazon. (Or search for " Didiseaon Spring Scale Spring Hook Scale") It’s pretty self explanatory. The belt lift distance is approximately one inch.