Page History: Delta 6x48 Sander Drums
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Page Revision: 2018/04/21 18:09
Examples of Drum Condition
By Bob VaughanOutside ends of worn drums
Belt sander drum details:
Inside of worn drums:
The damages shown in the previous two pictures are generally the results of worn bearings that have frozen on the shafts.
The images below are examples of improper crowns caused by wear, in this case shown on a Powermatic 6x48 sander.
Worn drum on 6x48 sander
The crown needs to be corrected for proper tracking.
Additional images of the usual W-shaped drums
Delta 6x48 31-730 sander repair details(16 pictures):
Re-Crowning Drums
Turning on a Lathe
By Bob Vaughan{Reference:http://owwm.org/viewtopic.php?t=41577|Worn drum on 6x48 sander}{Reference:http://www.owwm.org/viewtopic.php?t=41918|Delta 6x48 31-730 sander repair details(16 pictures)}{Reference:http://owwm.org/viewtopic.php?t=41720|PM 30 sander belt tracking blues}I'll put the shaft in the lathe, then put on both drums with needed spacers, then turn both drums at the same time using the compound over at some slight angle like 1º or so per side, giving a slight V crown rather than a round one. The angle will likely dictated by the thickness of the drum. When I re-crown, its a matter of reacting to the geometry of whatever's in front of me. The big thing is to get rid of that upturn profile on the outer edges. Its those outer edge diameters that makes tracking impossible under load.
The above drive drum chucked up the lathe:
Below is an idler drum restored on the lathe.{Reference:http://www.owwm.com/photoindex/detail.aspx?id=3715|Belt sander drum details}
Re-Crowing Lower Drum While On The Machine
By Shane Whitlock{Reference:http://owwm.org/viewtopic.php?t=49974|Rockwell Belt Sander Restoration Pics (updated all finished)} You can see here the drive drum is a little wallowed...
I could of mounted it in the lathe but wanted to try something else out first. I took an old sanding belt and cut a long strip about 2 inches wide out of it. I removed the sanding belt from the sander and turned the machine on. Using the strip of sandpaper I carefully sanded it flat and then slightly crowned the drum. It worked great.
Tracking is great now.
More on Crowning On The Machine
By Bob Vaughan{Reference:http://www.owwm.org/viewtopic.php?t=47121|Powermatic 30 sander restoration, belt won't track straight}
Redneck machine shop job:
- Rip a 1/2" wide strip of belt.
- Install on machine.
- Turn on machine and get belt tracking one side or the other to drive the top drum.
- Crown the wheels by hand, first one side, then the other.
Caution: You've got to clamp up a rest to put the tool against. The tool can be the sharpened end of a file at about 10º back from vertical. A scraper, if you will. There should be no more than 1/16" of tool contacting the drum at any one time, so the scraper will be sort of spear pointed. A 1/2" diameter round nose will work well. Contacting the drum with 1/32" is best. Lots of very, very light cuts. Lots of fine hair-like shavings will occur. The scraper should be sharpened several times during the process.
All you're working on are the outer edges anyway.
The bottom drum won't need the driving band.
I've done several this way and I'm not sure its not faster, its just that each time I did it on the machine, I had to find or make a new scraper.
Wear a dust mask and face shield.
Light small paint brush like cuts at or very slightly below center line
Probably the last time I used that method was in the late 90's. It does work, but the metal lathe setup is faster for me and slightly more precise. The crown doesn't have to be perfect on both sides, just as close as you can reasonably get it. Even a sloppy job will work fine, ridges and all.
Forming a Crown With Tape
For a quick repair, masking or duct tape may be used to build up a suitable crown. One user reports a machine still running fine after 7 years. {Reference:http://owwm.org/viewtopic.php?t=28081&highlight=31730|Delts sander drum crown importance}