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| Pitch of spiral router bits http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10101&t=52601 |
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| Author: | TRein [ Sun Nov 03, 2019 10:26 am ] |
| Post subject: | Pitch of spiral router bits |
Needing some more 1/4" downcut spiral bits and noticed one by CMT that has a shallower pitch to the cutting spirals (i.e. closer to a straight bit) than the usual. Any tool geometry experts on OLF that could illuminate pros/cons of this orientation? Thanks |
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| Author: | Clay S. [ Sun Nov 03, 2019 5:23 pm ] |
| Post subject: | Re: Pitch of spiral router bits |
If you are talking about the shear angle straight router bits the advantage is they should be cheaper and you can touch them up with a diamond hone to keep them sharp (similar to a straight bit). Professional sharpening shops should also charge less to sharpen them than they would for a spiral bit (if they sharpen spirals). They give a shearing cut , smoother than a typical straight bit. |
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| Author: | Mike_P [ Sun Nov 03, 2019 10:54 pm ] |
| Post subject: | Re: Pitch of spiral router bits |
since you didn't give a product number, I can only guess... from the description I see they describe something my brains agrees with...and that is because of the shallower spiral material is not forced downwards as quickly which keeps things cooler (both bit and material)...blah,blah,blah...basically they are arguing their design works better in the big picture. what I can say from using Amana down cut bits for this and that is that you end up with material getting clogged in your routed slot which causes it's own type of hassle... I guess the only way to know is to use both side by side and make a determination |
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| Author: | TRein [ Mon Nov 04, 2019 9:04 am ] |
| Post subject: | Re: Pitch of spiral router bits |
Mike, Yes, in a blind slot a downcut is not the right bit. I am using downcuts in my LuthierTool binding jig. The downcut is recommended by them and for good reason. Chip out is practically non-existent. And, there is always an open area for chip clearance. First pic is standard pitch degree spiral from Grizzly. Second pic is CMT, which they are referring to as "low angle". The bottom facet of the CMT looks different as well. Intuitively the CMT seems like a more efficient configuration. |
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| Author: | Clay S. [ Tue Nov 05, 2019 8:44 am ] |
| Post subject: | Re: Pitch of spiral router bits |
The shallow spiral router bit is one I haven't seen before. It's possible that for the shallow depths of most binding ledges the shear angle bit might give the same performance for about a third of the cost. For deeper plunge cutting the upcut shallow spiral would be better. |
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