My solution for more belt tension

JTknives

JTknives

Blade Heat Treating www.jarodtodd.com
Knifemaker / Craftsman / Service Provider
Joined
Jun 11, 2006
Messages
8,633
I have been fighting a lack of belt tension for years and finely had enough. When I built this grinder WAY back I used a gas spring for a tensioner but even then it was not enough. Trying to accurately grind a bunch of Q3’s required even more tension then my spring could develop to prevent the belt from drifting. Yes I know what it looks like but man does it work fantastic. I’m looking at a way to make it permanent.

 
Why not just put a small pneumatic (air) cylinder there and use a small air regulator to adjust the tension. It is really simple and works well.
 
I had thought about that but I did not have one on hand. I have often wondered about the difference between dynamic and static tension. So far I’m liking this static setup but would be open to trying dynamic with an small cylinder and a two way valve and regulator.
 
Dynamic will win over static every time.

How much tension pressure is the hydraulic jack providing???? Who knows.
With dynamic pressure, set the dial on the gauge to 50PSI (eg) and that is what you have at the cylinder.

When running, the static pressure is always the same. However, belt tension can ... and will ... change as conditions change.
The dynamic pressure reacts to the need. If the belt loosens due to stretching, wear, heating up, a change of belt - it will keep 50 PSI of pressure at all times. If you need a tad more/less tension, just turn a knob. If you need to change a belt, just rotate the lever handle on a three-way valve and dump the pressure. Change belt, turn handle ... 50PSI exact again.
When you change belts, the length may not be precisely the same. This would require re-setting the static pressure every time ... and still not knowing what the pressure is. Not to mention you have to release then pump up the hydraulic cylinder every belt change. Also, no way to release tension when not in use that doesn't require re-setting when needed again. The air cylinder system eliminates all these.
 
I’ve had the same 50lb gas spring on my build now for several month. And the belt tension is perfect! Seems odd you can’t get yours to respond JT... I can even strum my belt like you were doing in the vid. (That was some Clear Water Revival you were playing on it, huh??) LOL!

The way it’s going, I wouldn’t even care if it only lasted a year. I think it was like $9, or $11 for the gas spring?? I would have no problem spending $11/year as “up keep” on my grinder. Setting up a Dynamic pressure tensioning system for your belt grinder just seems like a fix for a non existent problem to me. It’s cool, don’t get he wrong. I just don’t consider replacing a part once a year(assuming it even fails that quickly), to be all that inconvenient.
 
JTknives said:
I have been fighting a lack of belt tension for years and finely had enough. When I built this grinder WAY back I used a gas spring for a tensioner but even then it was not enough. Trying to accurately grind a bunch of Q3’s required even more tension then my spring could develop to prevent the belt from drifting. Yes I know what it looks like but man does it work fantastic. I’m looking at a way to make it permanent.

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Well ................ I like it :eek: Now , if you really want to do this you can separate that jack in two parts . One will be pump and reservoir/tank for oil and other one part will be hydraulic piston for tension .You can even shorten piston part in length to fit under tension arm .Of course you will need high pressure hose to connect pump with piston .It is easy to do that , my home build 50 tons press is build that way ......
BW , did you try to grind with this setup ?
 
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Why don't you drill and tap close to your idler wheel so you can put a threaded rod in there to adjust tension. it seems like you are throwing a good twist into that joint with that jack.
 
Yeah I ground with it quite a bit after I set it up. It was more of a what do I have around here to fix this problem “right now” kind of solution. There are the blades I ground after this. After grinding the belt seamed just as tight as when I started. I’m also wet grinding if that makes a difference.

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I have the stuff for pneumatic tension conversion sitting in the project boxes in the shop. The TW-90 doesn't need it, so I will install it up while sprucing up the Bader to give to Steve. I'll photo a build tutorial when I do. The whole conversion is $30-70 depending on your junk box and scrounging skills.
 
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I've got to wonder what the long term effects on your bearings and wheels are going to be, under that much additional load...
 
I agree that it seems too much pressure.

But, you are wasting your breath trying to convince JT that there is any such thing as "too much". After all, he built 75 calibre rifles for a while, and IIRC has a 5HP grinder.
 
I don't remember where I saw it, but there was a gentleman that I recently saw on a youtube vid that used a linear actuator for tensioning the belt. Seemed like it worked pretty well.
 
I have come around from my wild ways. There absolutely can be to much of somthing. As to my tension issue it was way to little and I need a solution right then. So that’s where this came about.
 
I don't disagree with Stacy in theory, but if this basic setup works in practice, then dynamic vs static may not matter. If that is the case, just notch a V in the top of the hydraulic ram, and bolt it to the bottom plate. the radius of your tension arm is sufficient that it shouldn't matter. For the sake of longevity, I might weld on a steel bar in lieu of the (what looks to be) aluminum handle. Otherwise, as long as you can run any belt you need and there are no deleterious effects, I say rock it, who cares about pretty.
 
knife to a gunfight said:
Found it:
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That's one hell of a grinder ...............BUT he make one BIG mistake , he should throw that spring in tension arm and leave only that linear actuator for tension .This way he use it only for lifting arm ???? Look how easy belt run in side...He has very little tension on belt ! I will give for free my scrap grinder with ratchet system if anyone menage to move belt on side while grinding....

 
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Natlek said:
That's one hell of a grinder ...............BUT he make one BIG mistake , he should throw that spring in tension arm and leave only that linear actuator for tension .This way he use it only for lifting arm ???? Look how easy belt run in side...He has very little tension on belt ! I will give for free my scrap grinder with ratchet system if anyone menage to move belt on side while grinding....

Click to expand...

I did notice that on the second vid. I suppose it still gives a variable tension and a little more flexibility, but I agree. Lose the spring.
 
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