Revisiting the Gas/Spring Cylinder belt tensioner

Since a lot of the folks here have heard/read me speak out against the gas/spring cylinders as a tensioner on grinders, I thought I'd best let everyone know.... I had a situation occur recently, that has lead me to revisit their use. That being said, I now have one mounted on my KMG....just in case somebody walks into my shop and sees it on there.

For those who don't know, I tried these devices in the past, and it always ended in the failure of the gas/spring cylinder, within a matter of weeks, because of steel dust/debris tearing out the seals. This time I have a "boot" zip tied on, so we'll see if that might delay/prevent the failures.

It might not make sense to some, but my old tension spring was shot, and when searching for a new one, I found the only one I could get in the proper poundage was 1 1/2" longer than my old spring..... the additional height changed the angle of the tracking adjustment, and made it much coarser.... So to keep everything where it needs to be for the fine tracking adjustment I'm used to, I've relented and am giving the gas/spring cylinders another go. Here's hoping I have better results with the "boot" on it, then I had before with the bare rod showing.

Were you able to mount it with the seal on the bottom?

I did. I did the same thing with the previous two that went out on me too, but on those I didn't have a "boot" installed. Hopefully the boot will make this one last a while.

I got a couple of months from mine till I changed to a threaded screw tensioner that is foolproof.

When researching grinders before I made the plunge, this was one of the considerations and some of the reason I went with the TW-90.

I really like the way Travis did the tensioner. Simple, completely adjustable and will never wear out.

the gas cylinder on mine is made by the same folks who make slightly bigger ones for Honda. it is mounted shaft down so there is no easy way for dust and such to get inside the cylinder. belt tension and tracking has never been an issue with my Wilmont LB1000.

I've purchased several different ones (lbs of force) from McMaster-Carr. I started out with the 30lb versions, which are the ones that failed after only a week or two on the machine. I've also tried the 60lb and 90lb versions.... I think I've come to the conclusion that I like the 60lb version best. The 30lb has too much "give", and I've noticed some belt "movement" while grinding. The 60lb version seems to have solved that.

I find it interesting how the various tension mechanisms display different characteristics.... by far my favorite is a typical, old school spring. Just the right amount of "give" when needed, and the right amount of "stiffness" when needed...provided you can find the "right" one. The gas/spring cylinders offer those things too..... if I could just get the darn things to hold up/last more then a few weeks. Hopefully the installation of the dust boot will accomplish that.

At one time I built/tried a "rigid" belt tension system, and didn't like it....for lack of a better way to explain it, the belt has almost no "give", and the overall grinder operation was just too harsh for my liking.

I think that's one of the short comings of the square wheel machine, your limited to adjustment, which usually is ok but sooner or later a used belt stretches and one click down on the adjuster and it's too loose, one up and it's too tight.
I've had belts snap on that machine that were traveling at the speed of light, with nary a ticking of notice. talk about having the wits scared out of you.

Amen to that! My first "real" grinder was a Square Wheel. I still own that machine, but it's been relegated to duties in the hot shop for deburring and other non-critical grinding tasks. I went through several "belt blows" with it, and none were every a pleasant experience!

Well, been grinding for the past couple of hours and ran across a problem with the 60lb gas/spring cylinder.....on "J" weight belts 400 grit or finer, it's too much tension. The belt stretches so badly that the edges are no longer straight/true. I suppose I'm gona have to back up and order a couple of the 30lb ones, and give that another go. Darn it! Just when you think you got it figured out....... ya don't.

Ed have you thought about trying am air cylinder with a regulator? This would give you the ability to adjust tension as needed.

I have used air cylinders in the past..... they work, most of the time, but I'm not fond of them. To me it just means more pieces and parts, which means more things to go wrong/break, and more things to spend time repairing/fixing, when that time could be spent grinding blades. I don't begrudge anyone who uses them, but the fewer things there are to go wrong on any machine, the better I like it.

Basically it's the same reason I tend to warn people off of things like PID controlled forges...... the more you overtake the plumbing, the easier it is to stop up the drain.