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Surface Drum Sander Build

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rdean

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I will be building a 10" wide surface sander mostly from pieces and materials in my shop. I have checked several different machines and down loaded the owner manuals to get some ideas. It will be open ended so you can sand 20" wide by turning the part around and running it through again.
I have a 3/4hp 1725 rpm motor that will be direct coupled to the drum. This power unit will be raised and lowered by a hand crank and using linear bearings.
I am making this as I go long so no drawings or sketches.

First the drum assembly
I have a piece of 3" 40 schedule steel pipe that I will use for the drum and two round steel disks. The disks were something I picked up out of the trash many years back and thought I can use them for something someday. The shaft is 30mm because I have the shaft and some bearings to fit. What I have in the shop will determine how it ends up. I will need to buy some materials and parts but I like to use what I have.
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I bored the disks to fit the shaft and added a set screw in each. I turned down the outside of the disks to just fit inside the drum and welded them in place.
Next to the lathe to true up the outside of the drum.
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Drum completed and inside painted.
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The bearing retainers were turned from some mystery steel chunks out of the scrap bin.
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Here they are painted with the bearings fitted and the holes drilled and tapped.
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And on the drum.
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That's all for now.
Thanks for looking
Ray
 

Tom1948

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Looks good Ray. I cant wait to come see it in person...... Tom
 

7milesup

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I built a 26" wide drum sander about 30 years ago. Still have it in my shop and still use it. 5hp main motor with a 1/4hp geared motor driving the conveyor belt.
 

brino

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This build is off to a great start......I'll am "watching" it.
Thanks for sharing it!
-brino
 

rdean

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More progress

Made a bracket for the upper motor support, cleaned up and painted the motor.

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The Love Joy coupling came in so I assembled the head assembly and ran it up.
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Ran nicely but getting some noise from the Love Joy no matter how I adjusted the motor. I think I will order a softer rubber coupling and see if that helps. It's not terrible but I would like it quieter.

Thanks for the comments all

Ray
 

rdean

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Latinrascalrg1 I received a set of these to allow the main assembly to move up and down smoothly. The height adjustment is taking shape in my head and will be a threaded rod of some sort but not nailed down yet.
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This caused a engineering change to the motor mount plate as there was not enough room for the linear bearings. One of the joys of designing on the go as to say. I had to shorten the square mounting bracket and cut slots in the motor mount plate. I now have two holes that won't be used.

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Bearing blocks test fitted.

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Thanks for looking

Ray
 

Latinrascalrg1

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Ok after seeing how you have the linear bearings mounted i see the direction it is moving, Keep up the Nice work :clapping:
 

rdean

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Feed pressure rollers next.
Some mystery steel and a piece of chain link fence rail.

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I made two rollers by pressing in the slugs and then turning them down for the axles. They turned out well and I was feeling perty good about them until I tried to locate them between the outer support rods and the drum. There just wasn't enough room.

Engineering change number 2.
I moved the lower support rods inboard and slotted their old holes for the pressure rollers.

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Problem solved.

Next the pressure roller spring mounts.

Thanks for looking
Ray
 

rwm

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How in the world do you get that thin walled tubing straight and true. It seems like if you take off much material you might go right through!
Robert
 

rdean

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Robert you are right if you are trying to make the tube true along its entire length it would be hard to do. In this case the tube doesn't have to be a consistent diameter or even perfectly round. It just holds downward pressure on the work piece with spring pressure.

I did get the spring holders made and installed yesterday. On the motor end of the housing they had to be about 2" wide in order for the mounting bolts to clear the linear rail so I just made them all the same size. I don't know how much pressure is needed so I just installed some springs I already had to see how it works out.

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Thanks
Ray
 

rwm

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I see your point. I guess just the sanding drum needs to be true. This thing is looking great. Is your plan to use it on wood? Could it be used on aluminum to achieve a brushed finish?
Robert
 

rdean

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I have been planning to use it on wood but...


Two more questions:
Where can we submit our orders and what's the lead-time?
I have to make one first and another engineering mistake today.
I now have four holes I won't be using.

I cut the linear rails to the required length today and had a surprise. The rails were hardened all the way through. For the low price I paid I expected them to be only surface hardened so I had to get out the chop saw.

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More tomorrow maybe.

Ray
 

rdean

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About 10 years back I was working on a project that didn't work out and when I went looking for something to make the base out of I ran across it again. It looks like it will work fine so I cleaned and painted it up.

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I made the upper and lower rail brackets and installed the unit on the base.

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That's all for today

Ray
 

rdean

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The triangular shaped supports are bolted directly to the frame for rigidity. They are used to accurately adjust the sanding drum horizontally to the conveyor. The adjusting bolt in the center of the rail is locked in place after the adjustment.

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The drum height adjustment is by a 1/2" X 20 threaded shaft which results in a 0.050 per revolution movement.
This showes how I cut the threads on the lathe.

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When I motorized my home made winch last month I had this six spoked handle left over so I will see how it works here. The maximum thickness of the sanded piece of wood will be somewhere around 4".

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The project is getting close to making the conveyor system and the conveyor belt is something I have been thinking about. I have some treadmill conveyor belt material that may work but how to do I attach the ends together?

Please reply if you have any ideas on the belt.

Thanks for looking
Ray
 

f350ca

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Great progress Ray. I'd sure like to have a drum sander. I seam to work in fractions in the cabinet shop, a 16 tpi jack screw would be easier for me to deal with.

Greg
 

7milesup

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If you plan on wrapping that drum with sandpaper, you will need x-weight sandpaper which will stretch. Maybe your sander is short enough that it will not be an issue, but on mine that I designed I ended up designing and fabricating a take-up mechanism on the right side of the drum. If you don't do that, the sand paper will eventually bunch up and self destruct.
 

Latinrascalrg1

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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

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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

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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

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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

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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

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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

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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.

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rdean

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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.

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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.

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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.


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

Thanks for looking

Ray
 

rdean

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

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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.

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The conveyor is next.

Thanks for looking
Ray
 

rdean

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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?

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Thanks for looking

Ray
 
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