Official Luthiers Forum!
http://w-ww.luthiersforum.com/forum/

Upcut or downcut??
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=17314		 Page 1 of 1
Author:  Chansen [ Thu May 22, 2008 1:21 pm ]
Post subject:  Upcut or downcut??
I am about to buy an end mill from LMI and the 3/32" (1/8" shank) looks like it only comes in upcut. Is that indeed what I need for my 3/32" saddle? Thanks!
Author:  Dave Stewart [ Thu May 22, 2008 1:33 pm ]
Post subject:  Re: Upcut or downcut??
Don't do saddles (archtops) but Stewmac has downcut 3/32"....cleaner.
Author:  Dave Fifield [ Thu May 22, 2008 1:41 pm ]
Post subject:  Re: Upcut or downcut??
Downcut. [:Y:]
Author:  BobK [ Thu May 22, 2008 1:46 pm ]
Post subject:  Re: Upcut or downcut??
I use these bits from micromark in my drill press and they do a great job on saddle slots in ebony. I've also used them in a router for cutting rosette channels and they leave little or no fuzz.

http://www.ares-server.com/Ares/Ares.asp?MerchantID=RET01229&Action=Catalog&Type=Product&ID=80247
Author:  Andy Matthews [ Thu May 22, 2008 1:46 pm ]
Post subject:  Re: Upcut or downcut??
Downcut's definitely going to be cleaner, but don't remove too much material at once as chip clearance suffers...
Author:  Dennis Leahy [ Thu May 22, 2008 1:55 pm ]
Post subject:  Re: Upcut or downcut??
Hi Christian,

I think it depends on how you do your jig.

Do you have an accurate plunge base?

If not:
Unlike CNC, it is really difficult to drop a 3/32" bit straight down, rout, then either stop it or pull it up still spinning without making a spot slightly larger than 3/32" on entry and exit (or spin-down spot.) You might want to try an 1/8" bit instead. You could set two blocks as guides, the opening between them as wide as your laminate trimmer or Dremel base plus 3/32". Put a piece of heavy paper (like a thin business card) on one guide, and push the edge of the router base against that paper and drop down for the plunge cut. As you cut, pull the paper out, and go fully down and back using first one guide as a fence, then the other. Finally, sneak the piece of paper back in and run the edge of the router base over it, turn off the router, and let it spin to a stop before you lift it out. (easier to do than to explain)

Obviously, practice on scrap is a good idea.

Here's a source for solid carbide downcut spiral 1/8" router bits (one of them has a 1/8" shank): Carbide.com

Dennis
Author:  David Collins [ Thu May 22, 2008 8:45 pm ]
Post subject:  Re: Upcut or downcut??
I use upcut, downcut, straight, and they all work just fine for me. Any spiral will make it easier to cut with less chatter on the sides, but if you have a good saddle mill setup even a straight bit should cut smooth. And I've never had any tearout issues with an clean upcut bit, though again, this will probably depend on the stability of your cutting system. Downcuts are not normally recommended for closed slots, but if you move in shallow passes they will work fine.
Page 1 of 1 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/