Heavy Duty Belt Linishers - Help

What do you mean by "keep it from moving". Linisher seems to be a UK term for belt sander.

Is this for wood or metal?

By "moving" did you mean to refer to belt tracking?

How wide is the belt? If tracking is the issue, what does the machine have for tracking adjustments?

sorry about the lack of information ...... thanks for the reply though,

Yeh i'm talking about a belt sander for metal pipes

we can't get the tracking right & the belt keeps moving off-center

atm the front wheel which takes the pressure from the metal pipes is crowned,

what i would like to know is, would it be a better solution to crown the back wheel too? or is it better to keep it flat?

the width is around 250 mm ( i think - i'm only the guy who does the research for the boys in the workshop )

You might be using the wrong type of sander for that application....If you're pushing against the the belt as you move from one side to the other, the belt is going to travel....What is the type of sanding operation?...or is this a grinding operation?

http://www.cuttermaster.com/grinder_20inch.php

This looks like a home made sander. Is it? All flat belts whether on sanders or threshing rigs must have a tensioner on one of the four corners. That is a way to apply tension greater or lesser than the other side. The running the belt will always move toward the side with the most tension. If your's does not have a tensioner but is closely aligned, try putting a very little belt dressing on the pulley on the side toward which you want the belt to move. If it is exactly aligned it will work. Be aware that the side that gets the most wear will get weaker and looser and the belt will move away from that side. and you will need to reset the tension, Or just be sure to use the whole belt.

The roller should have a fine tune alignment knob adjustment on it...this allows the roller to adjust to slight imperfections of uniformity that exist in sanding belts....the roller can be adjusted slightly closer or further out on either side to match the belt profile....then usually there is a metal alignment guide that the belt can rub up against during use to keep it tracking properly....

Ideally there should be pressure sensors that would be used to check uniformity of pressure on rollers....If you have uniformity of pressure across both wheels, then the belt should not have a propensity to travel....now of course during use the belt pressure is varied and some movement is to be expected, that's why you have the metal guides....

This is the Sander

http://2imgs.com/ca3285af7c

the front is a tiny bit crowned, the back is flat

would it be better to have the back crowned too? suggestions?

(When the machine is at work, the metal bar you see on the right hand side gets slowly pressured against the wheel creating a dent-like cut out in the tube)

Could you draw a profile of the cut you are making?

It looks to me from what I'm seeing is that a chop saw with a diamond cutting blade would be a better choice....

You're making a single pass curved cut in the bent pipe on the right? Will this curve be then welded or brazed to another pipe the diameter of that small front roller? It seems that the crown isn't needed. Is the crown a result of the sanding operation. It looks like the front roller is normally held down by two-screw caps. Does it get reversed by accident when it's removed for belt changes? Are the belts high quality or junk from some village in China or Pakistan?

Alignment and pressure.

The front roller looks incredibly small. The linishers I have all have a rubber nose wheel that is 'flat' and a crowned drive wheel. The nose wheel is able to be rotated slightly to effect tracking. Having said that; during use the belt always seems to travel across the nose wheel, and this worsens with use. The solution is to move the workpiece across the face of the nosewheel and not press too hard.

Have a look at these machines, they are much heavier than any I have used.

http://www.garrickherbert.com.au/Products/Grinding/heavy-duty-linishers.html

If you are applying lateral forces to the belt, then it is always going to move in the direction of those forces. You might consider fitting ceramic guides top and bottom to maintain alignment of the belt.

My experience with conveyers on paper collators and folders is that the crown is to keep the belt centered and tensioners keep enough tension prevent slippage. When the belt would not stay centered, a replacement was usually needed. Rollers that were not parallel due to warn bearings or shafts might be worth a look at.