Yes, those sanding drums can be useful for "pushing the bumps around" on a cut edge.
One challenge is maintaining alignment of the drill's shaft axis - parallel to the cut edge and perpendicular to the flat surface adjacent to the edge. Two solutions are:
- Skill created through long practice and multiple ruined workpieces
- Three or more eyes carefully calibrated to gauge perpendicularity
The smaller sanding drums - up to about 1" or 1-1/2" diameter - can be used in a hand-held drill. Like those circle-cutters with a single-point cutter mounted on a beam, the larger sanding drums present safety and control problems. I think the mechanical engineers describe it with terms like "rotational inertia", "radius of gyration", etc, but us mere mortals may better identify with "flywheel effect" and "gyroscope precession". The problem's foundation has to do with a fair amount of mass, rotating at a significant distance from the center of rotation. Even at low drill RPM's the outer edge of the tool is moving at a high linear speed, and has quite a bit of energy. Accurately controlling it with a one-hand drill grip can be difficult.
Dale
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The same concepts used to make some of the circle-cutting jigs for routers can be applied to jig saws - though for the size you're talking about, I'd be tempted to use a draftsman's compass to draw the circle; carefully drill 6 or 8 holes around the perimeter; and use my tri-focaled eyeballs and grubby hands to guide the jig saw blade from hole to hole.
If I expect to keep a jig for more than a few uses I often use sheet acrylic (Plexiglass, Perspex); sheet polycarbonate (Lexan) or occasionally canvas-based phenolic. I pick up useful-sized pieces from the cutoff bin of commercial plastic suppliers. Commercial sign shops are sometimes a good source, too. Thicknesses of about 0.200" and up are useful. Acrylic machines cleanly and creates moderately strong threads when tapped for UNC #8 up to about 5/16". Polycarbonate is ultimately stronger but flexes more under force. The phenolic is the most rigid and durable, but also more expensive and difficult to find.
For limited-use jigs, TEMPERED hardboard ("dark" Masonite), MDF, or even scraps of wall paneling can be used.
Dale
- LOWEST SPEED AVAILABLE. 300 - 400 RPM if possible.
- Maintain firm downward pressure, but be patient and don't force the tool faster than it wants to cut.
- Securely clamp the workpiece. If the cutter "grabs" the workpiece and pulls it loose, the workpiece can spin at the drill RPM - possibly injuring you, ruining the tool, or damaging the drillpress spindle.
- If you notice an increase in vibration or chattering, stop the machine and make sure the setscrews on the cutter are still tight.
- The operation is probably quicker, and the result cleaner, if you do it as two cuts - each one going only half-way through the material, from each side of the board. The center hole will let you get the alignment correct for starting the second cut from the back side of the panel.
agree, they deeper they go, the harder they work. So yes need to flip the board (plus you don't want to hit the table).
One ploy I use on bigger holes (over 5") is to cut a smaller circle then needed, about 1/8" smaller. Do not go all the way thru (save that for the last pass). Once the smaller circle has removed some of the material - reset - the last pass/cut will cut easily.....but again, this is for larger circles.
One ploy I use on bigger holes (over 5") is to cut a smaller circle then needed, about 1/8" smaller. Do not go all the way thru (save that for the last pass). Once the smaller circle has removed some of the material - reset - the last pass/cut will cut easily.....but again, this is for larger circles.
The outside diameter (OD) of a "coupling" used for so-called "4-inch" PVC drain pipe is about the right size - though your kitchen may contain a coffee can, sugar canister, or margarine container of suitable size. Double-sided "carpet tape" can attach the sandpaper and keep the sandpaper edges from snagging on the workpiece.
Dale
This thread reminds me that 30 years of speaker building, including 6 years of car audio, taught me some stuff: i/2 inch of mdf, which I will no longer touch, can be milled with a decent trim router/bit. Note that I have thousands of hours logged with this stuff. A jig saw is a distant second when it comes to making a precise hole of this size. Oh and I own dozens of hole saws and jigs and let me say: just do it (with care).
I can see why some don't like mdf, it is like dirt and glue - the better grades are way better. (E.g. Medex)
Back to the wing cutter, for those with more than one cutter, you can cut up to an 8" hole by switching back and forth (post 64). One a bit smaller (1/8") and the second one set at the size you need.
Also, they work better if you swap out the drill bit with a smooth shank; you would need to drill a 1/4" in the board first.
General used to make one with two smooth/round ends, darn &^%$ that was the best one and they quit making them.....Flebay I guess.
Back to the wing cutter, for those with more than one cutter, you can cut up to an 8" hole by switching back and forth (post 64). One a bit smaller (1/8") and the second one set at the size you need.
Also, they work better if you swap out the drill bit with a smooth shank; you would need to drill a 1/4" in the board first.
General used to make one with two smooth/round ends, darn &^%$ that was the best one and they quit making them.....Flebay I guess.
well, not exactly dirt and glue - this is a highly engineering product
- but I can attest that more than once in the past 20yrs we've encountered metal waste (as in machine bolts and wood screws - no fugginkidin) in the core of budget priced MDF - guess how we found them?hint - it wasn't by magnetic scanning before cutting - that's a case where a $20 sheet of material cost over $200 in retipping of a 14" blade on a $150K beam saw - damned lucky that was all the damage or that it didn't happen with a router
I'll grant that mdf has its virtues. It seemed a final solution compared to particle board but...it is paper not wood. And my sinuses, as well as my lungs, have had more than enough. Finish carpentry in the 90s was all about mdf paint grade. Powder everywhere. Plywood is good, except that the face veneer is vanishingly thin. So we keep on adapting. And practicing mindfulness around that saw blade. Every time.
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