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Belt Tensioners

Discussion in 'General Talk' started by Ronald4418, Mar 10, 2017.

  1. Ronald4418

    Ronald4418 Journeyman
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    Has anyone yet come up with a suitable Belt Tensioner? One that increases the tension on either side of the Drive Pulley rather than at the end of an axis. I've tried the Tensioner Springs as advertised in the store and they are little more than than a nuisance. I've also tried using the addition of a smooth wheel inside of the mounting wheels on the Y-Axis. All to no avail. I have actually modified my OX CNC Router to use a 1.5 meter Leadscrew on my X-Axis as I have my machine setup in a Landscape Profile. I'm using my long axis as the X-Axis and the Shorter Axis as my Y-Axis. That way when I perfect a design in either Artcam. Fusion 360 or VCarve Pro. I don't have to rotate the entire design 90 degrees to match up with the machines co-ordinates.
     
    Joe Santarsiero likes this.
  2. hairyMug

    hairyMug Well-Known
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    sorry, I don't know about a belt tensioner, but thanks for the tip about swapping X & Y axis!
    I am just starting my build and will be using Vcarve...
    >> I will be thinking about a tensioner as I build since my build also uses belts.
     
  3. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    That's why the stepper mount holes are slotted. Once you have fixed the ends, you can increase the tension in the belt by raising the steppers. Be sure to use padded blocking against the pulley as you jack it to prevent damage. If the reason you're asking though is due to belts skipping, you may also want to consider using idler pulleys to create more surface contact on the drive pulley.
     
  4. hairyMug

    hairyMug Well-Known
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    I think Joe has a good idea... Setting-up a system to insure the tension remains constant seems to be better than loosening servo mounts...
    >> Just my 2 cents...
     
  5. Ronald4418

    Ronald4418 Journeyman
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    I have added a pair of smooth idler wheels on either side of the pulley . I was looking at the Belt Tensioner that Chris has listed that mounts to the outside of the gantry plates at the top. But I don't understand how they would add any more tension than the system I'm using now that was adopted from the X-Carve and Shapeoko Groups Assembly catalog.
     
  6. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    Let's start over. You have never actually stated the problem you are trying to overcome. Yes, you want more tension, but why? Tension is required to keep the belt from slipping on the pulley and idler pulleys are used to increase contact area to help keep the belt from slipping on the pulley but it sounds like neither of these are solutions to your problem so what is the problem you are trying to resolve?
     
  7. Ronald4418

    Ronald4418 Journeyman
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    I'm trying to alleviate belt slippage. My machine has a 1500mm x 1000mm x 500mm footprint and no matter what I tried on the longest axis. My belts would slip repeatedly. I tried everything I could think of from Smooth Idlers between the 20T Stepper Pulley and the first set of Extreme Wheels with both 3GT and 2GT belts all to no avail. To which I replaced the long axis drive with a 12mm x 3mm Pitch Leadscrew. I have the taller set of Gantry Plates as supplied by Chris Laidlaw and I don't have access to a system wherein I can modify the cross carriage backing plate to accommodate at leadscrew nut, or I would convert it over to a leadscrew as well. If I can at least get the system stable enough without any slippage on the cross access for the Z-Axis. I will modify it so that belts will not be needed at all and I will post CAD Drawings for others to use as well. As it stands right now I have absolutely flawless movement on the 1000mm and 500mm Axis.
     
  8. Rodm

    Rodm Veteran
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    Hi,
    I'm working on my first build and like to follow - hopefully understand what's going on in the posts. I'm a bit lost here. is it slippage or stretch that's your problem. in my mind slippage would be the pulley or belt jumping a tooth or the pulley slipping on the drive motor. are you using a one or two belt drive system? after I finish the c-beam plate maker I'm working on a larger maybe 1500 x 1500 x style build is the plan. I was thinking a db belt dive would do well. Not so sure now. A lot of builders seem to be " upgrading " . I hope you find a good simple inexpensive fix!
     
  9. Ronald4418

    Ronald4418 Journeyman
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    I haven't tried the double belt system as I wasn't able to get a clear demonstration of it or how it is suppose to work. And the majority of the problems that I incurred center around both slippage and the belt jumping over numerous teeth of the drive pulley. I was looking for something that would give the same amount of accuracy in all of my axis movements that is available in the Z-Axis as standard. Seeing as my X-Axis is 1500mm I decided that an 8mm. leadscrew would be to whippy and went with a 12mm leadscrew. Personally, if the C-Beam had of been available when I began my construction process and was available in 1500mm lengths. I would have gone that direction from the get go.
     
  10. Giarc

    Giarc Master
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    I am a little confused. Your system is 1500x1000x500 and you replaced the long axis drive with a 12mm lead screw. Then you say the 1000mm and 500 mm axis work flawlessly. Are you saying the screw is off? Or did you mis-type and mean the 1500mm and 500 mm axis are OK. If it is your 1000 mm length that needs a lead screw, DazTheGas has an easy mod for the Ox. Custom Ox Mods You should be able to cut and drill the aluminum by hand or with a press.
     
  11. Ronald4418

    Ronald4418 Journeyman
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    Yes it was a miss type and you are correct. I still have the leadscrew on the 1500mm axis.
    Anyways thanks for the video link. I wouldn't have even considered adding a leadscrew to the Y-Axis in that fashion.
     
  12. Giarc

    Giarc Master
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    Here is another good way. I took some of his ideas for my large lead screw driven design. The Frog: CNC Router
     

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