6 replies to this topic
Posted 05 October 2008 - 09:16 AM
what is the best type of drill bit to use to drill balsa? to prevent chipping of the wood when you start the hole.
Posted 05 October 2008 - 12:09 PM
Vodkaman is darn right , only sharp and well maintained tools will provide best results !
I also agree with him , that the spur point bit would work best in wood , but rpm speed and feed must be matched to the kinda material , that you are working on , for balsa I'd suggest a very high speed of the drill bit and a moderate feed to prevent wandering and chipping in that rather soft material .
Also pull the bit out of the hole a fraction ocassionally whilst drilling , so that the woodchips would come out , his provides a better quality of the bore .
The problem about drilling in wood , also with these spur point bits , is the exit of the hole , not so much the entry !
As the bit has almost passed through , one hardly can avoid the thin remainder of wood to crack up and chip under pressure of the bits feed .
I have found out about this , when drilling crosswise holes through lureblanks(no balsa)for inserting rattles .
Not that important , since I'd close the holes with some sort of putty again , anyway .
But to achieve a clean exit , I drilled carefully as far through for just the spur point of the drill bit to slightly come out , after I switched the workpiece around and finished the bore from the other side , using the small spur's hole for centering .
Since one only drills a fraction deep from the second side , the little lack of alignment of the two hole directions may be ignored .
If your workpiece is still plane at its bottom side and you have a chance to lay it flush upon a piece of scrabwood whilst drilling , this chipping of the exit won't easily occur !
But in my case drilling through already rounded blanks I could not do so !
Maybe this would help a bit , good luck:yay: , diemai
Posted 08 October 2008 - 08:45 AM
Brad Point wood bits bore clean, fast holes. Bits with a 25 degree flute design offer excellent guiding.
Posted 08 October 2008 - 10:11 AM
Actually, a true Forstner bit will cut a much cleaner hole than a brad point/spur point bit.
A brad/spur point bit has a centering point, and two sharp "spurs" at the outside, sharp little teeth that cut the outer diameter of the hole, and then some kind of spiral cutting twist on the shank to complete the cut and remove the chips.
A forstner bit has a truly circular cutting head, with an elogated cutting blade at it's perimeter, and a shearing chisel blade running from the spur back to the centering pin. The spur blade slices a really clean cut on the perimeter, and the chisel blade, which is a little recessed from the spur blade, cleans out the center of the hole like a plane.
If you're drilling in finished materials, especially veneer plywood, a forstner bit is the bit to use.
In smaller diameters, a forstner will also cut cleaner holes than a brad point in most woods, especially softer ones like balsa, pine, and poplar.
Over 40 years as a carpenter, and that's all I've learned!
Posted 08 October 2008 - 12:27 PM
I'll have to agree with Mark the best bit by far to drill in to most woods is the Forstner bit, it will make an excellent hole. The key is to have either a good drill press :yes:or a steady hand :yes:for the hand drill. Some wood requires the bit spin much faster than other woods to prevent chipping. Has anyone tried the new airbrush by Passche called the Talon I understand it is a gravity feed system? Also does anyone have a good supplier for circuit board material, I can find every color but the off white I am looking for.
Posted 08 October 2008 - 01:15 PM
I like to use the drill press for both brad/spur point bits and Forstners. For small stuff, up to 1/2" diameter, I usually center punch where I want the hole, hold the lure in my hand, and raise it into the bit as it turns in the press. This way is still prone to tear out, so you have to go slow. And the lure can't be too small, or you have no way to hold it if the bit binds.
For anything larger than 1/2", I use some kind of vice or clamp. Too much leverage with bigger bits to hold the work by hand. Good way to break/tear up you fingers.