Anyone out there notice any bogging down since they've switched over to either a spiral cutterhead or one with carbide inserts? The laws of physics dicatate that since something is ALWAYS in contact with the wood that you'd need more POWAH. Am I right, or am I right?
JP
***************** I'll tell ya' later.
Maybe not.
In the straight case, you have a free spin, then a "whomp" as the whole blade bites at once.
In the spiral case, you have a continuous but narrower cut.
Likely the total amount of work is similar. You might even need less power on the spiral cutter as it is a more even load.
Chris
I asked the question because I was at a tool dealer today who said that he doesn't sell any tools with spiral inserts because the companies don't upgrade their motors when they include the spiral heads - and that they should because those with such an upgrade really need 30% MORE power than their straight-bladed counterparts. Sounded fishy to me.
JP
******************************* He carries Delta and General Int'l.
Seems to me there was a discussion about this just a few days ago, the "consensus" being the spiral does NOT need more power.
"Jay Pique" wrote in news: snipped-for-privacy@g49g2000cwa.googlegroups.com:
Sales fellows spin all sorts of tales, for all sorts of reasons, in almost every field.
Patriarch
It takes more power to drive the carbide inserts than steel blades.
The laws of physics may dictate that something that is always in contact with the wood would need more power however the laws of physics also dictate that a shearing action will require less power than a non shearing action.
Perhaps feed rate should be slowed to offset the amount of waste being generated. Oddly single flute carbide bits cut better and or faster than double flute bits as there is more room for the waste chips.
A review in a recent woodworking magazine said that the spiral cutters used LESS power than the conventional cutters.
Know anything about calculus?
Where you arrive at an answer for the 'whole', by breaking the matter down into a bunch of smaller pieces, figuring out each piece, and then "add 'em up" to get the answer for the 'whole' thing.
Apply the same approach to the planer knife. consider the straight blade as a bunch of little pieces all lined up in a row.
Now, consider the same bunch of little pieces, offset into a spiral.
Is there _any_ difference in the amount/duration of blade contact with the wood?
"A numerical answer is left as an exercise for the student."
(I've always wanted to say THAT!! )
If you do that, there will be little gaps between the little pieces. You'd have to add up all those and subtract them from the total.
Is there any difference in the length of the spiral curve as compared to the length of the straight blade?
Not enough numerical input data to compute.
- Owen -
for a true spiral blade, where the cutting edge is at an angle to the direction of travel of the wood, the energy required is proportional to the cosine of the angle of the blade to the direction of travel, multiplied by the blade dimension.
Now, it just happens that said cosine dimension is the same as the straight-line measure that a straight blade would require for the same cut.
Actually, there *is.* *everything* cancels out. you end up with a 1==1 result.
Does this translate into reality? I mean, at the end of the day, will a jointer with a spiral head have enough power to do the job?
JP
Oh.. a Jointer... I was picturing a spiral router bit. Humm.... LOL... Did you see the article in the latest Wood magazine on 8" jointers? About half of them were with some type of spiral head cutter. I do not recall any complaints about power problems but there was a section that addressed the cuts that were less than perfect when compared to the standard straight knife cutter heads. Apparently the manufacturers are aware that the straight knife leaves a smoother and more uniform surface.
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