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Tool for Sanding Inside of Curved Pieces


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Hey Group,

I'm gearing up for my first framed build next year and wondering what is the preferred tool for sanding interiors of curved pieces - is the desk top stop spindle sander the best solution or could you simply mount a dremel rotary tool in a drill press attachment and use that ?  Dimensions of the wood should be no larger than 1/4 inch thick.  Just wondering if the spindle would be too high powered for this sort of operation.

Thanks,

Chris

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Almost any power tool would be overkill.  Look for round files, some come bent to a curve, wrap sandpaper around a dowel or piece of broomstick if you can 'run off' the end of the piece.  I have a tool (wand) that uses a small belt and has a rotating curved head you can position and then lock to match the curve of the hull.  The belt can be run through until you've used all of it.  I did a quick search and this may be discontinued.

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I like a sanding table.  I had no interest in the oscillating function so I built my own around a Fasco D226.

 

I prefer using readily available sheet sandpaper so I use sleeveless sanding drums.  More choices for grit. Less expensive.

The drums weight less than the hard rubber sleeve drums and I find that sleeve drums can get out of line when tightened  to hold the sleeves.  I added a fence to turn it into an edger/shaper . I have a 3" sleeve sanding drum, but it was out of round when tightened and vibrated the motor because of it weight.  And, 1/20 HP motor will not allow for aggressive wood removal.

 

For inside curves, the smallest drum I have is 3/4" - so the keelson area requires hand tool work. 

 

The sanding table is also great for outside curves and I like sanding with the grain.

 

The table is OK for sanding to the line on the max outside lines, but freehand seems to work better for outside bevels and inside everything.  It also allows use of the whole 3 inch face of the drum.  I use mostly 220 grit paper so not too much can go at once.

Unlike a disc sander or sanding belt, it will try the throw the piece if it can.

 

The impediment to this is that the D226 has a CW 5/16 shaft.  CW is good - I am right handed.  Mating a 5/16 " motor shaft to a drum with a 1/4" shaft requires custom metal work.   I have a lathe - Unimat SL1000 - so it was not difficult to use pieces of 1/2" cold rolled steel bar - most any hardware store has it - as well as the set screws and taps - to bore a 5/16" hole in one end and either a 1/4" hole (or 3/8" hole for the smaller drums) or turn a 1/4" shaft on the other end.  (Some of the drums have a removable 1/4" shaft.)  Turning and boring steel is messy to clean up - you can't ignore the kerf  - and it takes a while - tungsten carbide twist drills seem to hold up well for boring.

 

 

  Being able to adapt a 1/4" / 3/8" / 5/16" / or 1/8"  shaft to the motor shaft opens the table up to being able to use other attachments -  for me so far - Microplane shapers and carbide cutting burrs - the finest grit is more than enough- for removing bulk stock when there is a lot of bevel.

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Chris,

 

One tool I found works well is a variation of a floor polisher/sander I picked up from DaveS.   I take a large Dremel felt disk and counter sink the hole a bit. The disk is then attached to the mandrel and then sticky back sandpaper is pressed into place the disk and trimmed to something approximating round.    In the

Dremel 90 degree attachment it gets me into the hull with ease.  Just don't press hard, keep the disk moving and the high spots come down pretty quick.  Finish is with another bit sticky back sand paper on small sheet of cardboard like the back of note tablet.  Something flexible. I also use this on decks.

 

Here's a pic:

post-76-0-81670200-1448679335_thumb.jpg

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Thanks for the replies - just picked up a new dremel (mine was 35 years old and still works !) to fit in their workstation (basically their drill press) - thinking I mount the dremel at 90 degrees and dial the motor to a lower speed  and it should work - any input here is appreciated.  I wish Jim Byrnes had some sort of spindle sander as good as his disc sander....

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Hi Chris.

 

I've used the dremel in their drill press stand, a bench top drill press with spindle sanding drum and a full sized oscillating sanded for thicker pieces. All worked for me you just have to get a good rhythm. Speed wise a low to medium speed worked well. Anything faster burned the wood.

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There are many options. and which might be most suitable depends upon the curvature and clearances.  My workhorse power tool is a Rigid  Model EB4424 Oscillating Edge Belt / Spindle Sander.  It's possible to do many things with this sander by making various fixtures that can be mounted on the table.   

For hand sanding, I've traced around a set of french drafting curves on to wood, cut the curvers out, and put self-stick sandpaper on them, or made self-stick (see below) in various grits.

 

Self-stick sandpaper can be made by laying down a strip of masking tape, and then spreading some CA glue, and then abrasive paper of the desired grit.  For flat sanding tools (e.g. a carpenter's level), a printer's brayer (a roller) might help in smoothing the paper down on to the tape.   For curved tools, a rubber or credit-card squeegee can be used.  Spoons and butter knives can be fitted with this technique, as well as common bench chisels.  When the paper wears out, then it's easy to peel it off, wipe clean with naptha, and then reapply.  

 

There is also a new product by 3M that can be very useful.   It is a stretchy film of silicone plastic/rubber that is coated with grit, called 3M Ultraflexible Sanding Sheet.  

Edited by Bob Blarney
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Just another tip about freehand sanding of small pieces, especially with power tools

 

Do not attempt to hold on to any tiny piece with your fingers -- it will likely vanish, and you'll probably trim your fingernails at best and maybe your fingertips painfully too.  instead, wrap a single layer band of paper masking tape (sticky side out) or double-stick tape around 2-4 fingers, and then stick the small piece on the tape. This way, you can feel and lightly feed the tiny piece to the abrasive, but you're not directly holding the piece.  This prevents too much feed pressure, and gives your fingers a buffer skin if the piece should fly away.   Do not use cloth tape -- paper tears away much more easily and you'll naturally draw your hand away.

 

You can also hold a small piece by the same method while using a popsicle stick or other holder instead of your fingers -- that's much safer.

Edited by Bob Blarney
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If you're building a fully framed model there is a lot of sanding on both surfacess of the frame. One could cut close to the line with a scroll saw and hand-finish it with files but I find the oscillating spindle sander increases both speed and accuracy 100%. You want one with several different drum sizes. The oscillating function minimizes the possible burning you get with a stationary drum sander. For the outside of the frames I use the Byrnes disk sander and oscillating spindle sander.

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Besides hand sanding, rifflers, and files, I also use a number of power tools. I have a disk sander that I use to sane the outside of curves/frames. I use a spindle sander to sand the inside curves/frames. Once the frames are on the ship I use a Dremel with the EZ Lock arbor and the EZ Lock sanding disks. These come in various grades from the course to pretty fine.

 

I would caution that these can burn if run at too high of speed so need to be run at reduced speeds.

 

Once something in on the ship, or I need to do some quick fine sanding, the Dremel is my tool of choice. However all three power tools are well used in my shop as I work through building frames.

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Hey Bob and Greg,

Thanks for your input - I took dremel and drill press back - I think a spindel is a better piece of equipment.  Im not too worried about the parts dissolving since the frames are pretty big at 1/36th scale.  So if you have any reccos for a good sander - Id appreciate it.  

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We had a club member who used a mini belt sander and said it worked out okay just using a light touch just have a good dust collection system running and wear a mask.

post-227-0-21672100-1449011093_thumb.jpg

Harbor Freight and other Hardware stores carry them just have a reliable air supply and I think they make electric ones as well.  We had one where I worked and it was great for removing material in tight places.

David B

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I found the Grizzly spindle sander to be a pretty good one. It is small enough to go on the bench top  but light enough to move it off when I don't need it. Less than $200 on Amazon.

 

http://www.amazon.com/Grizzly-G0739-Oscillating-Spindle-Sander/dp/B00DQJPCFU/ref=sr_1_fkmr0_1?ie=UTF8&qid=1449023210&sr=8-1-fkmr0&keywords=grizzly+model+g0739

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