Replies

1. 
   eddiefromAustralia | Sep 15, 2004 03:40pm | #1

   Dave

   Try a hard block behind the sandpaper (doesn't round over the edges as much.)

   My initial thought for hand tools was a compass plane, for machine tools was a linisher

   Cheers,

   eddie

2. 
   IanDG | Sep 15, 2004 03:40pm | #2

   Compass plane

   A valid excuse for a new tool.

   IanDG

   
   

   ---

   Edited 9/15/2004 8:41 am ET by IanDG

3. 
   joe.roth | Sep 15, 2004 04:11pm | #3

   Hi Dave:

   My suggestion: make an exact template out of 3/4 MDF and over cut the cherry arcs by 1/16-1/8. Then mount the template on your rough cut arcs with two sided tape, a good carpet tape works well. Next put a 1/2" straight cut, bottom bearing router bit in your router and route the arcs to final size with the bottom bearing following the template.

   Joe

4. 
   jackplane | Sep 15, 2004 04:24pm | #4

   Others have suggested a compass plane, and that works excellently for this. Aside from a new tool, stuff a thick rag behind the platen of your belt sander to create a convex sander, then mount horizontally clamping it to a bench and sand, or sand with the stock clamped to the bench.

5. 
   BG | Sep 15, 2004 04:29pm | #5

   Daveb,

   I stole an idea from Rob Millard....which I apply to templates and then use the router.  What I did was to turn some rather large cylinders 4", 6",8" ,etc and cut open some 100 grit sanding belts and glued them to the cylinders.  I throw one on the lathe and sand away...it helps quite a bit on concave curves....less so on cabriole legs and convex curves and the like.
6. 
   JohnWW | Sep 15, 2004 05:41pm | #6

   Are the curves a constant radius or are continuously changing?

   John W.

1. 
   DaveBarker | Sep 15, 2004 05:54pm | #7

   They are changing radius (not a section of a circle).

   Thanks to all the suggestions so far!

   I had thought about using a template with the shaper, but wasn't sure how to fasten the template to the piece without making an elaborate template with clamps, etc. The two-sided tape idea sounds like a great idea...

   I've been a woodworker for almost 20 years, and in the past whenever I've had to do this I just kind of made do, but was never happy with the process or end result. Plus in this case, I need to make a lot of curved pieces.

   Thanks again, everyone.

1. 
   AlanTurner | Sep 15, 2004 06:21pm | #8

   My vote is for a spokeshave. I do my final finishing of most of my cabriole legs with the LN/Boggs spokeshave, which has a very fine mouth. The LV is nice too, but nearly as nice. (Of course, be sure that your spokeshapve has a curved bottom.)

   Another tool is never a horrible thing.Alan

   http://www.alanturnerfurnituremaker.com

2. 
   Clay | Sep 15, 2004 06:45pm | #9

   You could just screw the template to the back of the frame (rather than taping it).  I do lots of scribing with my 3" portable belt sander with a 40 or 50 grit belt (on countertops and cabinets).  With a little practice you can get pretty swift and accurate results.  If you have a disc sander and can rig a table large enough to spin the frames on that works well too and makes it easier to keep the edge vertical (versus the belt sander).

3. 
   SgianDubh | Sep 15, 2004 11:09pm | #13

   As others have suggested useful tools and techniques for smoothing non circular curves-- freehand drawn parabola's, irregularly curving sweeps and so on. These include,

   a compass plane, spokeshaves, rasps, etc-- handy for one-off curves in solid wood and man made board material.

   You can make a template made out of 9 mm (3/8") MDF and use a router + pattern cutting bit or spindle moulder with bearing guided planing head. The edge of MDF once rough cut is easy to shape with compass planes, spokeshaves, files, sandpaper, etc.. It's cheap material and if you mess it up you just get another piece out and rework it. In your case you can countersink screw the MDF into the wood which will later be removed-- that is screw into the rebate (rabbet) where the mirror glass will be fitted.  The rebate will probably be removed later with a rebating bit in a router/ spindle moulder cutter off an offset ring fence, or similar. Incidentally, I'm not at all a fan of double sided tape alone as a means of securing templates especially around big 2000W + inverted routers, overhead pin routers or spindle moulders (shapers) for obvious safety reasons. 

   Another method for fairing rough cut curves not previously mentioned is to use a 'fairing strip'. It's a long piece of flexible wood, ply, MDF, etc., with a strip of coarse abrasive paper (60- 80 grit) glued to it. Bend the papered side of the fairing strip around convex curves and into concave curves whilst rubbing back and forth. Like a long plane it takes off high spots first. A fairing strip can also be used to 'fair' the edges of MDF templates in readiness for routing/ spindle moulding curves. Slainte. RJFurniture

7. 
   PeteBradley | Sep 15, 2004 06:54pm | #10

   I'll second (or third) the router/template method. I built a craftsman-style table with arced rails. After I'd cut them out, I spent hours fiddling with sanding, etc. and it still didn't look right. The template didn't take long, the cuts were done inside of 15 minutes, and the resulting surface needed no more than a light sanding.

   Pete

1. 
   yotonyb | Sep 15, 2004 07:17pm | #11

   I have a sanding drum with a template bearing on the bottom.  Bandsaw as close as possible to the template then use the sanding drum to finish.  It's considerably slower than the router, but there's less risk of tearout on grain changes.

   Also, a file will work.  Again, bandsaw as close as possible to the line, then file until smooth.

   tony b.

8. 
   jazzdogg | Sep 15, 2004 07:31pm | #12

   The hard part is obtaining a trainable beaver...

   -Jazzdogg-

   Whether you think you can, or you think you can't, you're right.

1. 
   Elcoholic | Sep 24, 2004 10:01pm | #20

   I can think of at least 5 good comebacks for "trainable beaver", but they'd all get me in trouble.John O'Connell - JKO Handcrafted Woodworking

   The more things change ...

   We trained hard, but it seemed that every time we were beginning to form up into teams, we would be reorganized.  I was to learn later in life that we tend to meet any new situation by reorganizing; and a wonderful method it can be for creating the illusion of progress while producing confusion, inefficiency, and demoralization.

   Petronious Arbiter, 210 BC

1. 
   jazzdogg | Sep 25, 2004 04:09am | #24

   as would the beaver-Jazzdogg-

   Whether you think you can, or you think you can't, you're right.

9. 
   chatobob | Sep 16, 2004 12:31am | #14

   When you say you have tried a "straight scraper" I am assuming that you are referring to what some call a card scraper.  If so, I have found that the way to avoid the scraper following the ridges in the edge, is to draw or push the scraper at an angle to the edge, rather than perpendicular. 

   Does that make sense?  Let me try again:  in most cases the scraper is held perpendicular to its line of travel.  Instead, try holding it 45 degrees to its line of travel.  That way one part of the scraper will be on a "hill" and another part will be in a "valley" at the same time, and as a result, the scraper will take off the "hill" and leave the "valley", eventually giving a smooth surface.  More often than not, this technique is used when an edge exposes wood of varying hardness.

   -Bob

1. 
   DaveBarker | Sep 16, 2004 02:59am | #16

   Bob,

   Yes, I use a card scraper, and I use it at an angle so it doesn't follow the ridges. In general, this does work pretty well (and I use this technique on flat surfaces to remove planer marks). But for these long curves (3-4 foot) it's hard to get all the ridges out.

   I've found I'm getting lazier about some things as I get older and just don't have the patience I used to have. I thought young people were supposed to be lazier 8^)

1. 
   tufenhundel | Sep 24, 2004 05:35pm | #18

   As a smart Russian friend said to me one day as I watched him put a computer monitor on an office chair and wheeled it into another office:  "There would be no progress without lazy people."

10. 
    HowardAcheson | Sep 16, 2004 01:19am | #15

    For sanding the hulls of sailboats, a board sander is used. It's a long piece of 1/4" plywood about 4" wide and maybe 24-30" long with handle nobs on both ends. Roll sandpaper is attached to the bottom with spray adhesive. The board is springy and will conform to long curves.

    Adjust the dimensions to fit your need.

    Howie.........
11. 
    splintergroupie | Sep 16, 2004 08:22am | #17

    I made a fence for my 6x48 stationary belt sander which attaches in place of the table to the pivot arm using the three bolts already there--in other words, a surface at right angles to the belt, but in line with belt travel. I can get a smooth curve with the scratches going the right direction by holding the workpiece against the fence and rotating against the belt--or with it, if you keep a grip on it! This will also keep your edges sharp, if that's what you want.

12. 
    CRAIGCONEY_M | Sep 24, 2004 07:50pm | #19

    Dave,

    Somewhere in the archives, I beleive, I was doing some research on this subject and ran across using a long board, a router and pivot points to get the wide arch.  Maybe someone else can chime in here, but I can't seem to remember exactly where I found the setup.

    From what I recall is you mount your router to the board and slide the board between the points to get the arc. 

    Hope this helps. 

13. 
    Elcoholic | Sep 24, 2004 10:13pm | #21

    For a one-off I use a 4 x 24 belt sander and follow-up with a RO and hand sanding with blocks and/or a 3M hand pad for H&L discs.  Haven't tried stuffing a rag in the BS tough.  The unsupported area between the front roller and the platten has enough give to end up with a nice fair curve.  The trick is keeping it plumb and keeping it moving taking nice light passes.  If I'm doing multiples I'll make a template and use a router.  I've had carpet tape slip too many times and spoil the piece so I use Rockler's Face Plate Tape, much better.  I also use vacuum clamping and toggle clamps for template work depending on the application.

    John O'Connell - JKO Handcrafted Woodworking

    The more things change ...

    We trained hard, but it seemed that every time we were beginning to form up into teams, we would be reorganized.  I was to learn later in life that we tend to meet any new situation by reorganizing; and a wonderful method it can be for creating the illusion of progress while producing confusion, inefficiency, and demoralization.

    Petronious Arbiter, 210 BC

14. 
    IainEdwards | Sep 24, 2004 10:22pm | #22

    Dave a way to close the mouth up on a none adjustable spoke shave.....

    Take the blade, using the blade as a template, make exact paper (copier paper will do) copies of the blade, 3 or 4 of these bits of paper should get you about 1/32". Fit these onto the blade bed, fit the blade tighten dwn and have a go... this should have considerably closed up the mouth....have fun...Iain

1. 
   DaveBarker | Sep 24, 2004 10:30pm | #23

   Thanks Iain, I'll give that try!

   Thanks again to all the great ideas and suggestions, especially the trainable beaver. I'm still contemplating that one...