Surface Drum Sander Build

[Latinrascalrg1]

Treadmill belt would be one of the best choices IMHO. As for how to connect the ends ??? There has to be some type of adhesive that would work on that material but in the end if all else fails I would think Sewing the ends together with some heavy Carpet/ Upholstery Nylon thread probably would work. If this were my project My next question would be, "should i cut the ends and connect them together at a angle or 90° square ends?"

 

[7milesup]

Angle cut ends. Also, if you use sewing as the method, you will get a "bump" every time it passes by your work. You WILL see that on your work. I would recommend using a thin fiberglass tape. 3M super 90 would probably work to hold it and still be flexible. The other thing I would do instead of treadmill belting is use an abrasive belt as your conveyor system belt. You will be much less frustrated in the long run.

Like I said before, I built my sander about 30 years ago and learned a lot about effective design parameters. My sander is 25" wide or so and weighs at least 700 lbs.

 

[Latinrascalrg1]

Oh i like the sanding belt in place of the treadmill idea. I dont think i would have ever thought of that and its the perfect option.

 

[rdean]

Greg before I got into metal machining an error of 1/32" was good enough but now I'm chasing a few thousands and some times tenths.

Some of the factory made machines use an abrasive belt and that is probally the way I will go too.

7miles up
Can you explain or have a picture of your system to hold the sandpaper?
I am thinking about a hook and loop system.

Ray

 

[7milesup]

I can post a couple of pictures later on this evening. We are unexpectedly showing our house today (not even on the market) so I'm running around here like a lunatic getting it ready.

 

[Latinrascalrg1]

7miles, Id really like to see those pictures of your drum sander.

I have a few Questions for you also if you wouldn't mind..... Did you use one single sanding belt for the bed? Do you think using the treadmill material as a supporting underlayer would be beneficial or is the belt more then strong enough to handle the job In Your Opinion?
Thanks in advance.

 

[7milesup]

Ok. Here we go. Attached you will find some pictures.
The take-up mechanism is an arc shaped device that utilizes a spring and finger to pull on the sandpaper. The spring pulls on the finger which then pinches the sandpaper along with providing tension on the sandpaper via an arc'd slot. Not sure if that makes sense. Basically one spring does two jobs of gripping the sandpaper and providing tension on the sandpaper.
The belt on my sander is an actual woodworking conveyor belt that I had fabricated for me. I would not go the same route again because after years of use, the "grippiness" is much less than it used to be because of dirt and the rubber aging. I have even raised the bed and "sanded" the belt which helps for a while by exposing new rubber to grip the wood. The sanding belt would be significantly better. I had my belt fabricated for me years ago and it was expensive, at least for me at the time.
I would use just the sanding belt as the conveyor with nothing as an additional backer.

You will find that the amount of wood you can remove at once in somewhat limited. When I originally planned mine out, I had the intent of doing "abrasive" planing with 24 or 36 grit sandpaper, since I did not have a planer at the time. I learned that that was not really a viable long term solution. I also wanted use 220 or 320 grit but at least for my applications, any variations in wood thickness would result in immediate burning of the wood followed by the sanding strip destroying itself and then the 90 durometer sanding drum coming into direct contact with the wood before I could shut it off. Man, that would fill the shop up with smoke real quick! It had the smell of a campfire and a dragstrip rolled into one.
Also, keep in mind that I have a 5hp main motor with a 1/4 horse geared motor driving the conveyor.
You will also note that simple duct tape will hold the abrasive to the drum because if you wrap it correctly, it self tightens and unless you sand right next to the tape, it will hold. As you can see in my pictures, I only have part of my drum covered. Don't remember exactly why I did that but probably had a remainder of a roll I wanted to use.

 

[rdean]

I should explain that I know nothing about large belt sanders or how they are should be made, I haven't even seen one close up. So throwing all caution to the wind I glued some hook and loop material to the drum. I used contact cement and trimmed with a razor blade. It was only 6" wide so you can see the seam in the middle.



I turned the sander on and nothing flew off or came loose so on to the next step. I had a piece of 6" wide piece of sand paper with a hook and loop backing that I wound around the drum and trimmed to fit. You can see I didn't do a very good job as it is about 1/4" too short. I fully expected the sand paper to become airborne as soon as the switch was flipped but it didn't it just stayed in place.





So will the sand paper stay on during sanding operations?

I made a make shift table by clamping a piece of pine board to the frame and found a piece of scrap poplar about 2" thick for a test piece.
I ran this through several times and eventually took of about 1/16" off to clean it up. It turned out almost perfect and was within 0.015 thickness on all four corners.




This absolutely not the way I will wrapping the drum but it really encouraged me to continue.

Thanks for looking

Ray

 

[rdean]

I went to the flee market over the weekend and got this 54" wide sanding belt.



I will try to make a conveyor belt out of it, we will see how that goes later.
The time has come for the sander to get it's own legs. It was getting too heavy and large to move around on the bench so I made a stand for it.



The conveyor is next.

Thanks for looking
Ray

 

[rdean]

Had some time this weekend to work on the conveyor.
I made some bearing blocks for the drive end and a couple of adjustable blocks for the inlet end.
2" angle iron for the conveyor base and a piece of steel panel I had cut out of an electrical cabinet for the monitor to fit into.
The rollers are from an old tread mill that I cut down to length. The drive end roller was made by pressing in a steel slug and turning the slug down to fit the bearings.
I was able to cut off a 10" wide piece of the sanding belt I got last weekend. I then cut the belt at a 45 and just taped the belt together to get a feel of how it would run.
I have watched many videos of different ways to splice a sanding belt and I am still not sure witch method is best.
Does anyone have a suggestion how to "but" splice a conveyor belt?









Thanks for looking

Ray