No Weld Grinder Tracking problem

T

teter09

Well-Known Member
Not sure where to put this, so please move to the appropriate forum if I guessed wrong!

I was out in my garage trying to finalize the frame of my NWG. I figured that since I had my VFD in hand and a bead on a motor, I should finally finish it so I can just pop on the motor and run!

Everything assembled, I inserted the tool arm (which uses the multi-tool swing arm that comes with the plans, it uses a 10" and 4" contact wheel). Slapped on a belt and started to turn the drive shaft by hand and adjust the tracking/tension knob. A few quick twists and I'm set! Realizing I can reverse my motor if I want, I start rotating the drive shaft in the other direction. Despite my best efforts, the belt simply slides off given enough rotations.

I have adjusted everything I can think of, to no avail. The machine is built with the frame on the left so the belt is slid on from the right side. When rotating the belt so it comes in contact with the drive wheel and then the Tracking wheel, I can get it to track perfectly. Its when the belt would hit the tracking wheel and then the drive wheel that the belt gradually migrates off the machine to the right (as if I were removing it).

I've adjusted the drive wheel since I found it to not be perfectly lined up to the contact wheels. I rotated the attachment so it only ran on the 10" wheel alone, then the 4" wheel alone, same result. I even removed the tracking wheel entirely and just ran the belt on the contact wheels and the drive wheel, SAME thing! I've adjusted the tracking wheel since it was out of alignment. I've double checked the contact wheels and now, each wheel is directly on center with all the others. But I'm stumped. I was out in the garage for the better part of 4 hours trying to figure this out and I just can't.

If the belt walked off in both directions, I'd still be trying things. Its the fact that it tracks true in one direction and not the other that has me LOST!

Any help would be greatly appreciated!
 
Shoptalk is the appropriate forum for this IMHO.

It is normal that the tracking will be different while running in reverse and needs adjusting. When I switch to reverse the belt will track itself maybe 1/2 to 3/4" towards the "fall off the wheel side"

Spinning the belt with your hand you may be getting a slightly different result that what would happen with motor power but that shouldn't be so extreme that your belt walks off the wheels.

My first guess is that you don't have enough movement in the tracking wheel. Don't be shocked if the tracking wheel appears cocked way up to track straight in reverse.

My second guess is that your tracking wheel is offset a little from the drive wheel and contact wheels. If it's off you'll end up with all your adjustment on one side and very little on the other. To correct this if it is an issue you may need to add a shim under the wheel to bring it out or more likely shave the one you've got in there a little to move the wheel in.

Third guess is that the axles (bolts) should all be perfectly parallel with each other. If one is a little out of square it'll steer the belt one way or the other. Let's assume for conversation that your drive wheel is "out" a little. The tracking mechanism will compensate for the error to get the belt tracking centered on the wheel BUT You've used up some of your tracking range in that compensation so you lose some tracking in that direction by the reduced range of motion for the tracking mechanism.

As a little test spin the belt forward and track it as far to the left as you can. You should be able to track to left at least until the belt is 1/2" past the left side of the wheel.

Pictures of your tracking mechanism may be helpful for diagnosing the issue.

-Josh
 
Josh is absolutely right. Be sure to check that everything is as close to parallel as humanly possible. When you are building your own grinder and you dont have professional grade machinery it may seem difficult to get everything perfectly aligned but you should check and recheck everything. Alignment is the number one reason for tracking errors. If you are using pillow blocks for your drive wheel check to make sure that the drive rod is running as perpendicular to the wheels as possible. A simple hand square from your local hardware is invaluable in this process.
The tracking wheel is a compensator, but it can only compensate for so much. When you run your machine under power you will see the results of your tacking amplified forward from reverse.
You might scratch your head from time to time trying to figure out what needs adjusting, but it will all be worth it in the end.
 
Hi,
sorry to to hear about the trouble.

first, this isn't all that unusual when firing up a new grinder build.
second, this always get solved but it should would be nice if it didn't happen from your point of view. I've had to work on this every time I have built a grinder myself.

There have been thousands of these built. We will get you taken care of.

Tracking in reverse is difficult on a 3 or 4 wheel set up because the tracking wheel is the last wheel before the drive wheel. The setup just doesn't like that sequence all that well. I'd forget about reverse for now and get it tracking true forwards and tracking in reverse will get better but it's never going to be as good as "forward".

four things always seem mess up a brand new build if there is a tracking issue:
1. the belt isn't tight enough. it has to be tight enough to strum like a guitar string. - double the spring if you need to
2. the wheels are not lined up in a single plane - center all three wheels to each other. you have three different width wheels if you got the parts from me.
3. the wheels are not exactly plumb, especially the drive wheel. - this one is the toughest. check the angles. you may need to adjust the pillow blocks or shim between the uprights and the 4" tube adjust the wheels.
4. It is possible, one of the wheels is drilled off center. I have sold thousands of wheels and found less than 10 drilled off axis....but it could happen.

It is one or a combination those 4 things.
keep us posted.
 
Grinder Problems

I agree forward to reverse could definitely change tracking, however having said that, I think the closer the tracking is too perfect the less you will have to adjust the tracking wheel, if you do decide to reverse direction!

I found out when I built my KMG clone that I was good as far as all wheels being in line. I could make it track but not like I felt it should, when tracking right with the drive wheel and the platen or grinding wheel, it wanted to run slightly at an angle across the tracking wheel.
When laying out and assembling I tried to make sure everything was square to one another and then once assembled I had to get all the wheels in line with one another, with some minor tweaks.
However when I first got the machine tracking, it would track OK on the main wheels but as it came across the tracking wheel it appeared to run sideways. I suspected that it was due to the tracking arm being every so slightly off.

Let me try to explain it this way. I am a fourth generation carpenter. I use to get on too my men when framing a house about being off on a level. The average level is four foot, having said that if you say that is close enough and you are off by 1/8" in four foot, in eight feet it becomes 1/4" off and in twelve feet it becomes 3/8" off, etc, etc. In other words it multiplies the further the mistake continues out.

No two belts are exactly alike in length or stretch, etc. Thus the reason for the spring on the tracking arm of such a grinder, and the lift or drop of the tracking adjustment on that wheel is what pulls on the belt to make it align correctly with the other wheels. However if the arm itself is ever so slightly out of square with the machine it makes it increasingly hard to get tracking across all three correct!

I have seen this accomplished in two manners. You can see in this pic where I have marked the two areas that an adjustment can be added. Either too the mount for the tracking/tensioning arm or at the mount for the tracking adjustment wheel!

KMGClone_zpsf94f9be7.jpg



I was concerned on my grinder when I built it that the torque might move the arm and so it was welded to the top of the slide arm for the grinding wheel. After double checking I realized that the part was square. However I have seen a clone that had an adjustment at that point. The picture I put up was actually taken before that adjustment was built in. But the arrow points to the backside of the tensioner arm itself where the bolts for the tensioner mount come thru the arm. There was an adjustment screw drilled and tapped between where the bolts that holds one side of the the mounting blocks for the tracking wheel. Allowing for the mount to be pivoted, thus moving the entire arm. I am sorry I do not have a picture with a view from the other side!


On my clone it was the slot for the pivot of the arm itself that was my problem. Either when drilling of the arm pivot in the mount or the arm itself the bit had wandered and it was ever so slightly off. To compensate for that I drilled and put the a fore mentioned set screw in between the two bolts that held one side of the tracking adjustment pivot bar.
Then I dressed off a couple of thousands of metal from that side. By using the adjustment screw I had just installed I can now adjust the whole tracking assembly forward or backward to compensate for any alignment to the other wheels! In other words the tracking wheel can be adjusted not only up and down which pulls the belt into tracking alignment but the whole mount can be adjusted forwards and backward which pulls the tracking adjustment into 90* alignment with the other wheels.Once I adjusted to one belt properly I locked off the mounting bolts to that side and that pretty much ended those problems. The belt now rides all three wheels pretty much perfectly once a tracking adjustment has been made!

We all want to save money and whether it be a KMG clone, or welded up grinder or a no weld grinder it has to be perfectly aligned to get it too run right!

Rob from Beaumont is a stand up guy and will answer pretty much any question you may have about grinders even if it is not one of his KMG's. However the reason the cost of his grinders are what they are is just this, his machines have the precision built into them and the cost of the thousands of dollars of machinery he uses to achieve that precision!

So in short check the adjustment wheel for 90* alignment to the other wheels. Even if they are in line, if that tracking adjustment wheel is slightly off of 90* to the others wheels then you have a problem! The up and down adjustment pulls or pushes basically on the belt for tracking but when out on the 90* alignment it is real hard to get the tracking correct and keep it there because of any differences in belts!

I hope this all makes sense and that it may help solve your tracking problems!
 
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The tracking wheel is the tracking wheel,that's why it is adjustable. When running in reverse the belt tracks where the drive wheel tracks. I can't imagine why you would want to run it backwards,but then I don't have a good imagination anyway.
 
Thanks everyone for the suggestions! I've pretty much taken it to be that one of my wheels is out of alignment. Being that my 2 contact wheels are both mounted using identical size washers to 1/2 thick piece of aluminum, I'm assuming its either the tracking wheel or the drive wheel. I will start looking there tomorrow....and I will keep everyone posted! (not to mention document it in my WIP thread!) Now I'm not quite sure how I'm going to be able to measure...or check the alignment of those....but I will start trying!

I was busy this weekend with family and having a bit of fun so I will be back to working on this tomorrow after work. Thanks everyone!!!!
 
A little bit of backround on Teter09 since he's pretty new to KD's

He lives a little over an hour from me and came to the house for a shop visit a couple weeks ago. Of course we had a great time hanging out and talking shop and I enjoyed the lesson he gave me on the electrolysis process :)

Don't sweat your tracking issue too awful much. You've got an open invitation to come back anytime so if necessary you can throw the entire works in the truck and bring it over for trouble shooting. Of course we can fabricate anything we may need in house so we shouldn't have too much trouble getting you straightened out.

Unless you find a certain problem I wouldn't fool with it too much until you've got your motor up and running for testing under power.

-Josh
 
Well, I finally got back to this and managed to figure it out! A huge thanks goes to my dad since he came back from working in North Carolina (he is a general contractor) and stopped in. He has one of the really nice self leveling multi direction laser levels. It allowed me to verify my base tube was level, and my vertical arms were directly 90 degrees from the tube. I was then able to verify my tool arm and my swivel arm where perfectly aligned as well.

When I checked my drive wheel, while it was plumb to the contact wheels axis, the center line was about 1/4 inch off. Meaning the center of my drive wheel as you trace the wheels like the belt rotates was off to the right. I fixed that and then moved on to the tracking wheel.

I discovered a few things here. I built two tension arms since I wasn't sure how I wanted my spring, in the back like the NWG plans or in front like a KMG (suggestion I had read). When I had tried the spring in the rear, I felt I couldn't get enough tension, even with two springs as suggested. I tried a compression spring which I had purchased to give me more tension but locate the arm in about the same spot as the door spring when attached at the rear. When comparing these while hand turning the belt backwards, I realized something. The higher the tracking wheel, the more off of plumb it's adjustments get!!!

With this I changed a few things. I found too much play in the tension arm. When a belt was mounted and i was adjusting the tracking i could see the arm moving from left to right. It turned out that the 3/8" bolt was bending. I drilled out the holes to accept a 1/2 inch bolt and also got one which only had the last inch threaded, so the threads couldn't have any play. I kept the spring in front. I also chopped it in half so that the arm is practically parallel to the tooling arm, but it is a stout spring so it adds more tension than there was with the spring in the back. Finally I aligned the center with the centers of the contact wheels and drive wheel.

After all this.... It now tracks forwards and in reverse!! Though reverse doesn't stay on the wheels 100% aligned, but I feel it is close enough for now and I think I am set up pretty well with it for now!!

Now on to wiring up my VfD since my motor will be here this week!!
 
Teter - I just found this thread and was reading thru to put my two cents in - but you beat me to it. The tension arm sure seems to work better when it's parallel to the tool arm. That gave me a hard time when I first built my KMG clone. Once I learned to adjust the tool arm so the tension arm was pretty well parallel to the tool arm, everything just seems to work better.

Ain't it fun building things - and then they work<:)

Ken H>
 
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