No Weld Grinder questions

REK Knives

REK Knives

Well-Known Member
I just built this thing within the past 3-4 weeks and have been having much trouble with it :2: First, it was an alignment issue, but I think I got that pretty much figured out (I took a piece of flat bar stock and put it up to the side of each wheel to make sure the other wheels lined up). I have a 3hp Leeson motor fyi. After that, I am having the following issues:

  1. Completely ate the rubber away from my lower contact wheel down to the bare aluminum (for some unknown reason) and this thing is expensive around $50, already had to replace one
  2. Popped a belt in two while I was using the grinder (this may be normal)
  3. My belt speed varies greatly, and right before I finished using it today it slowed down to lower than my lowest pulley speed (even though I had it on the fastest). I checked the belt and found that the rear pulley (the one that goes to my drive wheel) was so hot it actually melted the belt to it somewhat. I sprayed it off with water to cool it down, it steamed. I checked the alignment between that and my motor pulley and its off about 1/8", I wouldn't think this would be a big enough of an issue, but maybe it is? There was some of the belt melted to the motor pulley (see pics). I tightened my belt up pretty tight like the instructions say (loosen the motor bolts and pull motor forward) to the point that I had to actually rotate the wheel to get the belt to track over onto the right pulley.

Anyway, any help would be much appreciated. I am at a loss and quite frustrated. Thanks!

Josh

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If you need better pics, let me know.

this is what I'm working on but I REALLY need to get this project done and with my belt sander screwing up this is making it hard.

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If I had to guess, I'd say that you tightened your nuts a little to much on your lower contact wheel and siezed up your bearings. This would greatly increase friction and not only cause your wheel to get hot, but it could possibly cause your belt to out run your wheel, which would also factor into wearing the rubber off. It would also contribute to popping your belts.

Correct me if I'm wrong, but it also looks like you may have your nuts tightened directly against your inner bearing race? You really need to put a washer (or better yet, a flat bushing) in between, to help reduce the chance of side loading your bearings and seizing them up.

As for your speed issues, it sounds like the belt might be slipping (and looks that way from the worn/melted belt material left on the large step of your pulley). This could be due partially to added friction from a seized wheel, but also to having your belt a little loose.

With your belt on the pulleys, I'd say that if you were to press down in the middle, you should have less than 1" of deflection. Do you hear squealing when your grinder is running? That means the belt is slipping.

It's hard to tell from pics, but your steps seem a little deep. Are you sure you have the right size V-belt? You may not be making full contact with the pulley.
 
That little small wheel is NOT going to work on your flat platen. The smaller the wheel the higher the RPM of the bearings. Those poor things are probably turning 15000 RPM and will overheat in no time flat. Go with a 2" idler down there like this-

http://usaknifemaker.com/grinders-s...l-aluminum-with-bearings-for-a-1-2-shaft.html

You are creating mega friction on the belt by having your platen so far out from the wheels. Not a good thing IMHO. Put a straight edge from top wheel to bottom and get your platen in line. It won't hurt if it's just a touch out but you've got WAY too much.

This is stressing every component of the driveline and is probably what is causing your motor slowing issue and it will be greatly exaggerated when you put steel to the belt.

Heat anywhere is the enemy so where is that heat coming from to melt that link belt. It's either the driveshaft bearings or the motor itself. Are the driveshaft bearings too hot to touch ? You may have overheated the bearings and need to regrease them.

One more thing that can cause unwanted friction is over tightening your wheels. They should spin freely with no abrasive belt on.

With an abrasive belt on the machine you should be able to easily spin the belt by hand. If not you have a friction problem somewhere.

ReCap- replacing that small wheel is not optional. It simply will not work for this application.

Get the platen in line with the wheels.

Check that wheels are not too tight and spin freely.

Run moderate tension on the grinding belt so it'll spin easily by hand

Also. Is your work rest Plexi-Glass ? I cannot imagine a scenario where I wouldn't melt that in about two seconds flat. When I'm rough grinding I run my work rest close to the belt and get red hot piles of dust on the work rest regularly.

Hope this helps !

-Josh
 
BTW.... with your grinder belt off, you should be able to freely spin your contact wheels fairly easily. If you spin it quickly with your hand, it should keep turning for AT LEAST half a turn or more. If it stops immediately, your bearings are bound, and you'll have excess heat and friction.
 
Josh,
If I'm not mistaken, that wasn't a small wheel. I think he started with a 2" wheel, but the rubber melted/wore off.
 
ARCustomKnives said:
If I had to guess, I'd say that you tightened your nuts a little to much on your lower contact wheel and siezed up your bearings. This would greatly increase friction and not only cause your wheel to get hot, but it could possibly cause your belt to out run your wheel, which would also factor into wearing the rubber off. It would also contribute to popping your belts.

Correct me if I'm wrong, but it also looks like you may have your nuts tightened directly against your inner bearing race? You really need to put a washer (or better yet, a flat bushing) in between, to help reduce the chance of side loading your bearings and seizing them up.

As for your speed issues, it sounds like the belt might be slipping (and looks that way from the worn/melted belt material left on the large step of your pulley). This could be due partially to added friction from a seized wheel, but also to having your belt a little loose.

With your belt on the pulleys, I'd say that if you were to press down in the middle, you should have less than 1" of deflection. Do you hear squealing when your grinder is running? That means the belt is slipping.

It's hard to tell from pics, but your steps seem a little deep. Are you sure you have the right size V-belt? You may not be making full contact with the pulley.
Click to expand...

Yeah, I thought the same thing about having my wheel over-tightened... but when I tightened them the first time, I basically just finger tightened them until the bolt that went though the wheel wouldn't have any play, then I put the double nut on so it wouldn't come off. But it did seem a little tight (i.e. wouldn't spin freely at ALL). I have since loosened it up some.

No, the nuts aren't tightened straight against a flat washer or the wheel, I have a machinery bushing on either side of the wheel =)

Yeah I was thinking that the belt was slipping as well... That's the only solution I can think of, and you're right - it would explain the melted plastic on the side. I don't hear squealing, but I did notice it slipping somewhat. I just tried to re-tighten the belt.

I am not sure about the steps... i got both the pulleys and the belt from knifemakers supply as part of the NWG kit, so I'm sure its fine.
 
Josh Dabney said:
That little small wheel is NOT going to work on your flat platen. The smaller the wheel the higher the RPM of the bearings. Those poor things are probably turning 15000 RPM and will overheat in no time flat. Go with a 2" idler down there like this-

http://usaknifemaker.com/grinders-s...l-aluminum-with-bearings-for-a-1-2-shaft.html

You are creating mega friction on the belt by having your platen so far out from the wheels. Not a good thing IMHO. Put a straight edge from top wheel to bottom and get your platen in line. It won't hurt if it's just a touch out but you've got WAY too much.

This is stressing every component of the driveline and is probably what is causing your motor slowing issue and it will be greatly exaggerated when you put steel to the belt.

Heat anywhere is the enemy so where is that heat coming from to melt that link belt. It's either the driveshaft bearings or the motor itself. Are the driveshaft bearings too hot to touch ? You may have overheated the bearings and need to regrease them.

One more thing that can cause unwanted friction is over tightening your wheels. They should spin freely with no abrasive belt on.

With an abrasive belt on the machine you should be able to easily spin the belt by hand. If not you have a friction problem somewhere.

ReCap- replacing that small wheel is not optional. It simply will not work for this application.

Get the platen in line with the wheels.

Check that wheels are not too tight and spin freely.

Run moderate tension on the grinding belt so it'll spin easily by hand

Also. Is your work rest Plexi-Glass ? I cannot imagine a scenario where I wouldn't melt that in about two seconds flat. When I'm rough grinding I run my work rest close to the belt and get red hot piles of dust on the work rest regularly.

Hope this helps !

-Josh
Click to expand...

Thanks for the input Josh! I will try to respond to your points...

That small wheel at the bottom of my platen WAS a 2" contact wheel from knifemakers supply... that's what Tracy said he uses on the attachment so I figure it should be fine.

The problem w/ the platen is that I don't have any more adjustment room... the plans for the NWG called for the holes where they are, which puts the platen out too far for the wheels. This seems like its a design flaw. I will have to re-drill those holes in order to move that platen in some I guess.

I wouldn't imagine that the motor was the issue... I got it brand new recently. It's TEFC. But yeah, the pillow blocks and especially the pulleys are both SUPER hot when I'm done, so you're right, there is an issue somewhere. I think it may be a combination of 1. wheel too tight, 2. platen out too far. 3. pulley belt too slack.

My platen is Pyroceram glass that I have put in there with JB weld. The glass on top of my table rest is also put in with JB weld, but is just a regular piece of 1/4" thick glass. I realize now that I should have went with Pyroceram here too as it is much tougher. I will probably fix this at some point in the furture. I needed it so my jig would slide smoothly on the top - it was binding and being hindered with the metal only on my table rest.
 
Something else I just noticed (and I could be wrong), but it looks like your link belt MIGHT be on backwards. This may accunt for some slippage as well.

There are very tiny arrows on the sides of a small number of the links. Make sure you have them facing the same way as your rotation.
 
Just to clarify on the poly wheels.

I got a 2" and a 3" The 2" melted in short order. I caught it fairly quickly and switched back to my aluminum idlers.

The 3" I've never had a problem with. I run it as the top wheel on my belt conversion. However there is ZERO additional friction heat in this application just two wheels that both spin.

I believe the larger poly wheels would be fine but the 2" just couldn't take the heat of running full speed for whatever reason.

I would stick with an aluminum idler on the bottom of the platen. That's not a great location for realizing the benefit of a contact wheel for me personally. Other's use may be different but I've never ground anything on that bottom wheel.

The 2" diameter I haven't found to be particularly useful either. Too large for finger grooves and too small for handle curves.

Drill and tap two more holes further back on the attachment side. I would also raise those holes an inch. No benefit to having all that platen below the work rest where it's unusable.

VERY often I'll have my work rest on but want to freehand grind something so having a bunch of platen between the work rest and the top wheel is a advantageous because I don't need to remove the work rest to freehand.

Getting ready to head out the door but will be home Sunday.

Take care,

-Josh
 
There have been hundreds, maybe thousands of these built and are running well. We'll get yours going too.

You are really close on this. It's a nice build so far and the hard part is done. Just a little tune up and it will be a good machine for you.

1. The bottom platen wheel had the nuts too tight. These should be tight just enough to not let them slide back and forth. Any more than that and there will be friction. Heat kills these things. They will all get warm but not boiling hot. Poly melts at 185F. Keep the wheels below that. This goes for all the idler wheels which are the small ones and the large contact wheels. You said you had used a machinery bushing against each side of the wheel bearing so the nuts (or additional washers used for spacing) should not be binding against the bearing and wheel at the same time.
2. Belts break occasionally. It's spooky when it happens - especially if you are grinding a sharp blade at the time. Cheaper belts break more than expensive ones. It is rare and if it happens again soon, there is a problem. My guess is the top of the ceramic glass on the planten was sharp and wore down the joint tape on the back of the belt. Make sure it is rounded over slightly to prevent excess wear on the back of the belt. You can grind this glass just like steel.
3. The platen needs to be brought back a bit to better line up with the top and bottom wheel. To do this, use smaller or no washers for the nuts holding the angle iron. This will allow it to come back more. If that isn't enough, drill new holes to hold the wheels closer to the front edge. Flip that piece over to drill these holes if the existing holes don't allow new holes.
4. I've never seen or heard of the step pulleys acting that hot like they did for you. I use them here on two different machines. We have several grinders here and the step pulley one is the grinder that gets used the most. Make sure the center steps are in alignment so the belt rides centered in the V channel on both pulleys. If it is crooked, the belt wearing on the on the side of the V channel is going to create a lot of friction. I can't tell from the picture if the pulley's are lined up or not. They *appear* to be off center but again, the picture makes it hard to tell. Belts like these need to be tight. Run them awhile and then as they stretch a bit, take out a link. They should sag no more than a 1/2" to 3/4" when depressed in the middle. Loose belts slip and heat up and cause massive loss of power.

Keep us posted. Call me if you need to. We'll get it going. Like I said, this is very close. It just needs to be tuned up a bit which is really normal. You will have a great machine when you are done and you will know it better than any other machine in your shop.
 
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In this picture, you can see the small arrows I'm talkinga bout. It looks like they go the opposite direction of the "V" in the links. Looking at your picture, it does appear that your belt is on backwards.
 
ARCustomKnives said:
In this picture, you can see the small arrows I'm talkinga bout. It looks like they go the opposite direction of the "V" in the links. Looking at your picture, it does appear that your belt is on backwards.
Click to expand...

good catch. it is on backwards.
 
ARCustomKnives said:
Something else I just noticed (and I could be wrong), but it looks like your link belt MIGHT be on backwards. This may accunt for some slippage as well.

There are very tiny arrows on the sides of a small number of the links. Make sure you have them facing the same way as your rotation.
Click to expand...

man... thank you for pointing that out! the NWG plans don't say anything about that... I had it going the wrong direction.

IMG_20130824_112128.jpg
 
Josh Dabney said:
Just to clarify on the poly wheels.

I got a 2" and a 3" The 2" melted in short order. I caught it fairly quickly and switched back to my aluminum idlers.

The 3" I've never had a problem with. I run it as the top wheel on my belt conversion. However there is ZERO additional friction heat in this application just two wheels that both spin.

I believe the larger poly wheels would be fine but the 2" just couldn't take the heat of running full speed for whatever reason.

I would stick with an aluminum idler on the bottom of the platen. That's not a great location for realizing the benefit of a contact wheel for me personally. Other's use may be different but I've never ground anything on that bottom wheel.

The 2" diameter I haven't found to be particularly useful either. Too large for finger grooves and too small for handle curves.

Drill and tap two more holes further back on the attachment side. I would also raise those holes an inch. No benefit to having all that platen below the work rest where it's unusable.

VERY often I'll have my work rest on but want to freehand grind something so having a bunch of platen between the work rest and the top wheel is a advantageous because I don't need to remove the work rest to freehand.

Getting ready to head out the door but will be home Sunday.

Take care,

-Josh
Click to expand...

Thanks Josh... I may have to get the aluminum idler wheel for that bottom one. I would just go with my 3" poly wheel but it won't fit because the platen is so low, so your point there is spot on.
 
Ok, I switched out the bottom contact wheel with a new one and tried to move the platen in as far as it would go without washers on the inside and this is what I get... is the platen still too far out?

IMG_20130824_111838.jpg


I tightened up my belt to where there isn't more than 1" deflection in the top and 1" in the bottom, does this sound right? I will also change it to go the right direction lol. I also loosened up that bottom contact wheel some, so it spins 1/4 to 1/2 turn after i take my hand off if free spinning it.
 
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