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 Post subject: Drum Sander question
PostPosted: Thu Nov 25, 2021 9:04 am 
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Brazilian Rosewood
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Happy Thanksgiving to those of us in the U.S.! :)

A question about drum sanders. I’ve been doing some non-luthiery projects and I see in a few woodworking forums the topic of sleds coming up with a drum sander.

The way I’ve always used a drum sander is to take one side down until it’s being fully sanded on a single pass. At that point it’s parallel to the drum. To do this I lower the drum until it’s just touching the piece and proceed to lower the drum 1/8 of a turn and let the piece go through twice rotating 180 between passes, then lowering another 1/8 turn. Do this until the full side is being sanded.

Then flip the board to the other side and repeat the process. This has always resulted in a very uniform board and rotating between passes accounts for the few thousandth drop across the width of the drum. Side note: I’ve tried like heck to get the drum fully parallel across the whole width, I’m not sure it’s possible, at least with my sander. :)

In the woodworking forums people talk about how the sled holds the board parallel to the drum. What does this achieve that I don’t get with the method above? I could see making a sled if the drum was not close to parallel to the bed and the sled could be sanded to the machines profile.

Thoughts?

Brad


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 Post subject: Re: Drum Sander question
PostPosted: Thu Nov 25, 2021 9:33 am 
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I do it basically the way you do it and it works well for me. I don't want the drum exactly parallel but like it to be about 0.005" or so high on the open end (I have a Jet 10-20) so I don't groove the middle of the tops and backs. For any part thicker than about 0.050" I don't see any need for a sled.

That said, I do have a sled which is just a piece of plywood. I use it when I want to run really thin pieces through the sander like if I'm trying to make a piece of veneer for something.

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 Post subject: Re: Drum Sander question
PostPosted: Thu Nov 25, 2021 12:21 pm 
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Brazilian Rosewood
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I actually prefer the middle of the top or back to be very slightly thicker than the middle, so using the method you have described is what I do. The difference is pretty small and as mentioned having the open end slightly higher is preferable.



These users thanked the author Clay S. for the post: bcombs510 (Thu Nov 25, 2021 1:55 pm)
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 Post subject: Re: Drum Sander question
PostPosted: Thu Nov 25, 2021 12:21 pm 
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perhaps I'm just not able to visualize this correctly, but I see no way to get a uniformly thick piece of material with a drum sander that's out of parallel with its bed...at best one would get a piece that is the same thickness on the edges and thicker in the middle..again, this is what my head comes up with visualizing what's going on...

now, using a sled...obviously (to me) the only way to make this a viable technique is to run the sled through the sander thereby creating a surface parallel to the sanding drum....then of course place materials on top of sled to thickness



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 Post subject: Re: Drum Sander question
PostPosted: Thu Nov 25, 2021 12:28 pm 
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That's what I have done, as my 10-20 bed is unevenly dished,. Just sanded a board, then flipped it upside down.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.



These users thanked the author Colin North for the post: bcombs510 (Thu Nov 25, 2021 1:55 pm)
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 Post subject: Re: Drum Sander question
PostPosted: Thu Nov 25, 2021 12:57 pm 
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I made sleds for different pieces, long ones for sides and binding, 24" for tops and backs. The outside edge is marked with direction arrows to maintain the same orientation. Sandpaper (pieces of used belts) contact cemented to the top keeps pieces from sliding. Flip them end for end as Colin describes to tune them up once in a while.



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 Post subject: Drum Sander question
PostPosted: Thu Nov 25, 2021 1:54 pm 
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Thanks, all. Sounds like a sled could overcome an issue with the table / drum alignment but if not working around that issue present no advantage.

This is what I suspected. As I mentioned, this was shared in a woodworking forum as the “only way” to get a flat surface. My drum is about .005 high on the open end. I tried to dial it closer but to be honest my ability to accurately measure the test board is probably not within .005 anyway.

This was in a forum about making cutting boards / charcuterie boards. So the output is 3/4” thick or more. I couldn’t see any value in a sled in that scenario. It’s important that a cutting board be flat. If I can get it within .005 it’ll be fine. At least until the customer puts it in their dishwasher!! :D


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 Post subject: Re: Drum Sander question
PostPosted: Thu Nov 25, 2021 2:09 pm 
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Cocobolo
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A sled is needed for smaller pieces. And super helpful if your table bed is not perfectly flat.

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These users thanked the author mountain whimsy for the post: bcombs510 (Thu Nov 25, 2021 2:19 pm)
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 Post subject: Re: Drum Sander question
PostPosted: Thu Nov 25, 2021 2:17 pm 
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Brad - I use the same approach you describe of rotating pieces between passes. No sled and it works fine. I'm guessing that with a sled that holds the piece parallel to the drum, you would end up with a uniformly thicknessed piece in fewer passes, but would end up with close to the same result. To me, using a sled for pieces that aren't small or very thin just adds a hassle factor without much return.

I'm with Steve and Clay on alignment of the drum. I like it slightly higher on the outboard end for the same reasons (including making the edges of the top or back slightly thinner than the center). Also, when sanding smaller pieces, you can home in on a final thickness in very small increments by running the piece in several passes progressively closer to the inboard end without adjusting the drum height.

The only things I use a sled for are very thin pieces and small pieces like bridge blanks which get double stick taped to the sled.

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These users thanked the author J De Rocher for the post: bcombs510 (Thu Nov 25, 2021 2:19 pm)
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 Post subject: Re: Drum Sander question
PostPosted: Thu Nov 25, 2021 4:19 pm 
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I only use the drum sander for the grunt work of thicknessing, I now do the final thicknessing with a hand plane for tops and a scraper plane where warranted for backs.
Sides only see the drum sander though.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.



These users thanked the author Colin North for the post: bcombs510 (Thu Nov 25, 2021 5:27 pm)
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 Post subject: Re: Drum Sander question
PostPosted: Thu Nov 25, 2021 5:43 pm 
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bcombs510 wrote:
As I mentioned, this was shared in a woodworking forum as the “only way” to get a flat surface.


I think that perspective starts from assumptions that aren't true for everyone using a drum sander. For instance, I am blessed with a drum sander that has pillow blocks at both ends of the drum, and the drum is wide enough for any workpiece other than a wide tabletop (25" wide). I don't have any trouble with drum/drive bed alignment issues, so I would only need a sled if I wanted to sand something thinner than my drum sander will allow, and I've never needed to do that.



These users thanked the author doncaparker for the post: bcombs510 (Thu Nov 25, 2021 10:39 pm)
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 Post subject: Re: Drum Sander question
PostPosted: Thu Nov 25, 2021 7:19 pm 
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Don has a good point. The type and size of sander makes quite a difference. Open ended sanders might need sleds more than close ended. I've been using a Performax 16-32. The 10-20 would need rotation more than wider ones. Recently picked up a used 22-44 orbital but haven't used it yet.



These users thanked the author CarlD for the post: bcombs510 (Thu Nov 25, 2021 10:39 pm)
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