Post By cash
Post By RH68
Post By ortho
Hello Guys, I'm seeking advice on grinding printer rolls. They are about 14" long and 0.750" in diameter. I have a tool post grinder for my lathe and several different stone. I assume that the courser the stone the better. I was wondering if it is better to use a silicon carbide wheel or Aluminium Oxide wheel for it? Any Speed and Feed suggestion would be great.
Thanks for you time.
A bath i liquid nitrogen can make rubber machine very nicely, but you have to be quick about it. Sorry if that's not helpful.
I worked in a textile factory long time ago and there the had a sort of centerless grinder for rubber rollers
For the grinding stone they used a long steel drum with 5cm wide emery cloth wrapped around it spirally
Many years later we had to turn straight some 5mtr long and 400mm diam rubber rollers
The fastest way was with a beltsander on the topslide of the lathe with the lower wheel touching the roller
Easy and cheap to change from coarse to fine too
peter from Holland
Contact Tunco Manufacturing. They specialize in making tungsten carbide grinding wheels for grinding rubber with.
I was hoping to use AO or SC grinding wheel.
You can use standard abrasives, but it just makes the job a lot tougher to do.
Well ... which one have you got?
Originally Posted by Bassdoctor
It's been a few years, but I always had good results with a coarse aluminum oxide wheel with a coarse dress on it.
I don't have any numbers for you, but what worked for me was ...
Run your lathe in reverse so your "cutting" against the rotation, keep your sfm up and your feed rate low.
Maybe these will help:
Resin Bonded Grinding Wheels from Phoenix Abrasives
i heard its best to use a silicone grinding wheel because the a/o will load up and keep loading with rubber and eventually shatter. I don't know how true this is my boss told me this and somebody who would grind rubber told him that. I know iscar makes a high polished positive rake tcmt insert that will turn the rubber very well, i have cut rubber at room temp with these inserts. granted it was 70-90 durometer.
I've done this type of rubber grinding a few times before. Basically you would be looking for high speed abrasion and slow feed like what other guys are saying. One thing to expect: high volume of fine, black powdery residue that gets in everything and everywhere, far and near. Cover all that you don't want to clean up. Might be a good idea to vacuum while you grind.
I've ground lots of rubber rolls with an induced porosity al wheel,commonly called a bubble wheel.I've wanted to use a belt sander but never got around to making one.
I worked in Pulp/Paper mills for many years, we had big rubber covered press rolls up to 240 inches face width and 44 inches diameter. Standard machine to grind the rolls was a big Ferral Roll Grinder using a Norton Belt grinder with 4 inch wide belt. Started with a 36 grit then to an 80. Sometimes went to 120 depending on the roll covering material and where the roll was used in the paper machine. Water cooled to flush the rubber off the belt. (Belts are waterproof). Sorry, don't have photos.
However, a smaller belt grinder is really easy to build, all you need is a contact wheel and a crowned idler wheel. If you are into grinding rubber on a regular basis, I recommend building one.
Here is the basic belt grinder, just think vertically, build it to fit your compound rest and have the contact wheel on center with the roll you are grinding. Be sure to use a reversible motor, variable speed. This one uses 2-1/2 inch wide Norton belts, 60 inches long. The mount for the crowned idler wheel is spring loaded and also has a pivot so the idler may be swung for adjusting belt tracking.
Below is a tiny one for gun barrel work. It has a DC motor, variable speed controller. Build one similar but scaled up for 1 inch or 2 inch wide belts. The little wheels are rubber covered contact wheels. The motor wheel is flanged. The sliding arm is spring loaded to tension the belt.
The belt grinder cuts 10 times faster than a wheel and does not clog or burn, you will love it. Talk to your Norton Rep, they are the experts in belt grinding rolls.
You can do this too, called "slack belt grinding", for a final finish. Note the vacuum hose. Belt is running in reverse, against the direction of rotation of the barrel, this plumes the grinding dust up and the vacuum grabs all of it. Use the contact wheel to get the rubber roll round first, then finish with the slack belt if needed. Experiment!
I use a belt grinder made by Dynabrade. It spins the belt at 4500 sfm. It uses a 2x36 belt. It is toolpost mounted in a 120 inch bed lathe. I am grinding rolls that are either 8 x 72 or 9 x 68. 46 rpm in reverse, .012 feed per rev. Typical surface finish in the 40 rms range. It does create a lot of dust. I have a dust collecter on the lathe and it still gets everywhere.
Originally Posted by badams
Grind under water and your dust will go away.
A flattened nozzle or a series of spray nozzles for a slight flow the width of the belt directed into the grind point. We used CoolLube 20 mixed at about 50 to 1 to keep the rust away. Depending on belt speed you may need to shield the operators side of the belt to avoid a shower.
Here are some photos of the belt grinder I use. Had to wait till I needed to grind a roll before I could get pictures.
Badams and Silveradohauler are correct in their instructions for grinding large rolls. For a small number of rolls of your size, you can use your tool post grinder. Use an open bond stone in the largest diameter you can fit. Turn the roll and stone in opposing directions. Try several feeds and speeds if you can control the wheel rpm. You are taking too much if the rubber starts to revert to solid coming off the wheel. You should get fiiine powder. As noted above, it will get into every nook and cranny in your shop. A water coolant may help with the dust and roll finish. The above pics of the belt grinders show what you need if you plan to do more than a few rolls. The belts will do a superior job in less time with lower cost. I assume that you are resurfacing rolls. If you are paying to have new rubber covering applied, you should let the rubber guy grind for you. He has the stuff and knowledge. Regards, Clark