Taper for Drum Sander Paper.

[Mark Crenshaw]

Hello all.

EDIT: I jsut realized I used the wrong circ in my calculations. The drum is actually 3.5" I've updated the math below.

I'm currently building a drum sander with an 18" x 3.5" drum. I'll be using 3" wide paper. Does anyone know of a formula or calculator to determine the taper and length of the paper? I'm thinking I'll use printer paper to make a template but it would be nice to make the calculations to get in the ballpark. There are enough shop-built drum sanders out there, someone might have figured this out.

My initial thoughts are that I can figure length by using the diameter and length of the drum.

3.5" x 3.142 = 10.99". Then divide the length of the drum by 3" to get 6. So, 6 x 10.99" = 65.98"

But, as you angle the paper, does it shorten the length needed to cover the drum or is that a canstant?

Any input much appreciated.

[Cary Falk]

On mine the length of the taper(the line that you actually cut) is equal to to the circumference of the drum. I don't think there is a easy way to calculate the length. My drum is 18" long and 4" in dia. I am using 3" paper. Cary

[Mark Crenshaw]

On mine the length of the taper(the line that you actually cut) is equal to to the circumference of the drum. I don't think there is a easy way to calculate the length. My drum is 18" long and 4" in dia. I am using 3" paper. Cary

Thanks Cary. That's good info!

I did a test with printer paper before I saw your post. It worked out fine but I got different numbers than I would using your input. I think with the taper equal to the circ, I would use less paper per drum wrap than what I came up with in my test. My angle is farther from parallel with the end of the frum. Seems the closer the angle is to being parallel with the end of the drum, the closer I would be to having six bands of paper covering the drum.

Here's my test.

I started with some math. The drum is 18" x 3.5". d x pi gives me 2.5" * 3.142 = 10.99" or, the distance around the drum. The sandpaper roll is 3" wide so 18/3 = 6. So, 10.99" * 6 = 65.98" This is the area of the drum...I'm sure there's an easier way to get to this number. Then I put a few cut lines on an 8.5" x 11" Illustrator doc and printed it out. I included a .50" overlap so I could tape them in a straight line more easily. It also gave me an even 8" multiplier. By my math, I needed 8.50 strips.



After cutting the strips and taping them together at the overlap line, I started rolling them onto an 18" piece of PVC pipe. I knew it would be tricky to start on an end, so I started in the middle and got a comfortable angle were the paper wanted to lay side by side and not buckle. Then I worked a few wraps to the end of the pipe and taped it down.



Here's where the math fell apart. I knew it would because some of the area I calculated would be cut away in the tapers. This meant that additional length would be needed. So I had extra paper strips standing by.



I added them one at a time until I got to the end of the roller and taped that end in place. Then I trimmed off the ends with a utility blade.





After carefully peeling the tape off the ends, I have my template.






Just for grins, I measured the taper. This way I won't have to worry about lining up a template on the curly sandpaper and make sure it's all laying flat and tight. I can just cut a 76" length, mark it 10.25" from each end and use a straight edge to cut from each mark back to the corner. I only have to be concerned with the foot or so that I'm working on. Slide the straight edge down to the other end and cut the same angle.

[Mark Crenshaw]

Using Cary's input and the correct circ, I came up with an angle of 15.84° vs 16.25° from my test. And, I measure point of 10.57" vs 10.25" in my test. Looks like I got it pretty close. The difference in the two is negligable and my cut length should stay about the same. I'll likely go with the taper equals circ just to make it easy to remember.

Thanks again, Cary!

[mreza Salav]

The simplest and easiest way to find the taper (with no calculations involved) is:
- take piece of string/thread and wrap it around the drum to find the perimeter of the drum exactly (mark it on the thread).
- take that marked length and put it diagonally across the sand paper you have so that it touches the two opposite side edges; you have found the taper angle you need to cut.

This method works with any sand paper width.

The tapers at the two ends will be parallel to each other. If you start wraping the paper you'll find out where it needs to be cut at the other end; the angle is the same and you can find
it again using that piece of thread.

[Greg Portland]

Hello all.

EDIT: I jsut realized I used the wrong circ in my calculations. The drum is actually 3.5" I've updated the math below.

I'm currently building a drum sander with an 18" x 3.5" drum. I'll be using 3" wide paper. Does anyone know of a formula or calculator to determine the taper and length of the paper? I'm thinking I'll use printer paper to make a template but it would be nice to make the calculations to get in the ballpark. There are enough shop-built drum sanders out there, someone might have figured this out.

My initial thoughts are that I can figure length by using the diameter and length of the drum.

3.5" x 3.142 = 10.99". Then divide the length of the drum by 3" to get 6. So, 6 x 10.99" = 65.98"

But, as you angle the paper, does it shorten the length needed to cover the drum or is that a canstant?

Any input much appreciated.

A simple method is to remove the drum, roll the paper onto the drum, and then trim the edges to fit.

[Bruce Wrenn]

After you have it figured out, use paper template to make a hardboard template. Simply lay hardboard template over paper and cut angles and length at one time. Drill a hole in template so you can hang it up.

[Wes Grass]

I get 15.834° angle, which gives a helix length of 11.429 and makes the paper effectively 3.119 wide. So 5.771 (18/3.119) wraps, plus another helix length of 11.429 to finish off the end = 77.387

Or by using the drum area, it would be 10.995 X 6 (18/3) + another wrap (11.429) to finish it off because you lost the area at the start = 77.399 (probably within rounding errors of the first calc)

Or, circumference x # wraps to cover the length, plus an extra wrap to fill the tapered areas = 10.995 X 7 = 76.965

I think the last one is probably the best to use, as it's the easiest to remember and comes up a tick short. That makes up for the little bit of gap you need between wraps, and maybe avoids overhang at the ends.

[Mike OMelia]

I am bringing this thread back to discuss it more. Need some ideas for odd width abranet

[Mike OMelia]

The problem with the manuals for the Jet 16 and 22" sanders is they assume a 3" width and a 15 3/4" taper. Doing this with thinner widths will get you a good wrap, but the last end will not end up in the correct place for tucking into the clip.

https://www.youtube.com/watch?v=_DPC...ature=youtu.be

https://www.youtube.com/watch?v=Sx9g...ature=youtu.be

A friend of mine from another forum did the videos.

Mike

[Mike OMelia]

Never mind. There is no solution to this. Begs the question, why did abranet do this?

[George Bokros]

Buy the correct width paper and use an old piece to determine the angle and the length required.

[Mike OMelia]

Abranet does not make correct roll width for Jet sanders.

[John TenEyck]

Abranet does not make correct roll width for Jet sanders.

Per Mreza's post above you can use any width abrasive.

John

[Mike OMelia]

I’m beginning to think that is true. Well, within limits. Been playing with paper templates. It seems that the area of adjustment is just how much you insert into the clips. The clip gap is 1.25” wide. By using only half of that and the recommended 15 3/4” taper length, I got a 2 3/4” width to work. So is this the idea?