Replies

1. 
   Routerman | Mar 10, 2004 05:32pm | #1

   Would like to see a link to that bit.

   Believe it is one with many tapered fingers? If it is, I  know of no other cutter that is more power consumptive nor with more traction in the stock. I would not be surprised if you're having problems.

   That cutter has no business in a router.

   Nonetheless, it will work in stages, (many stages), given good fixturing and the biggest of routers. (Routers Like Bosch 1619 and PC 7518.)

   Routers

1. 
   Crunk | Mar 10, 2004 07:39pm | #2

   Finger joints on the Fine Woodworking website.

   We've sunk to a new low, don't you think?

1. 
   UncleDunc | Mar 11, 2004 02:17am | #5

   >> We've sunk to a new low, don't you think?

   No.

   What makes a finger joint lower than any other joint?

1. 
   ian | Mar 11, 2004 03:49pm | #7

   It can be argued that a finger joint is superior to many other joints as using it allows you to join together many small pieces of show wood into one long piece of trim. 

2. 
   Telemike | Mar 20, 2004 06:57am | #13

   <<What makes a finger joint lower than any other joint?>>

   It's ugly!!

   Subjective - oh well.

2. 
   AlanWS | Mar 11, 2004 12:31am | #4

   routerman:

   Do you have a rule of thumb to decide which bits commonly sold for routers would, in your opinion, not belong in a router? A horizontal panel-raising bit would seem to take a pretty big cut too, at a big diameter, so would you put that in a similar category, or are the many surfaces of the finger joint cut a big part of the problem?

   (By the way, the videos of you on the Fine Woodworking site are appreciated. The fixture you show would be relevant to this query. The way you show to cut rabbets made my first tapered sliding dovetails fit beautifully.)

1. 
   Routerman | Mar 11, 2004 04:59pm | #8

   Damndest issue. When I got into this (routerdom) the biggest cutters were <~1-5/8" in diameter and length and safe for most routers, (whether hand held or upside down in a router table). Later, in the early 80's, my study of the leading bit makers showed that >95% of cutters in most cutter inventories were equal to or less than 1-7/8" in diameter and 1.5" was the nominal max flute length.

   Whence (mid to late 80's) the Asians got in the game the whole picture changed. Cutters up to 4.5" were here in a America. Arhictectural, glue joinery, and doormaking cutters filled the shelves. It was clear, anything found on a shaper spindle was fair game for the 1/2" router bit shank. And here is where I draw the line: Cutters derived from big shaper bits are compromises when shrunk for use in routers. They require special fences, work holders, a nearby power plant, and multiple stage routing. They present risk to the work and worker, they wear out the router and don't last too long themselves. In my view, cutters greater than 2" in diameter and length (on 1/2 shanks) are beyond safe engineering limits and require far more than cursory safety practices. All of the cases this woodworker has been called for (as an expert witness) invloved oversized cutters.

   To be sure, woodworkers are doing kitchens with routers every minute. But, in my view, door, drawer, window making, and archetecutual milling should be done on the shaper. Shapers are designed for the stress, their cutter inventories and grinds are far superior, and they (shaper cutters) last for shifts not minutes like router bits. Router bits needn't be so G.damn big. Mulitple passes with small safe cutters can and should be exploited. A 2" wide rabbet, for example, can be cut with 1/2" straight bit.

   Routers

1. 
   AlanWS | Mar 11, 2004 06:58pm | #9

   Routerman:

   Thank you. I appreciate your perspective that clearly comes from experience. Your books provide a different idea of the desired router table size and top from most writing on the subject, and your approach to jigs and fixtures is also a little different: on the one hand simple and solid, and on the other, worthy of precision and finish. But I particularly like your direct manner and emphasis on explaining what works and why, rather than spending your time insulting others.

2. 
   AlanWS | Mar 11, 2004 12:31am | #3

   Here is a link to what MLCS provides as instructions for a finger joint bit: http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/graphics2/23finger.pdf

   And here are the instructions for infinity's bit:

   http://www.infinitytools.com/Images/FingerJoin61-500.pdf

   CMT:

   http://www.sommerfeldtools.com/products.asp?ID=56

   Woodline sells a video:

   http://www.woodline.com/scripts/prodView.asp?idproduct=26

   Whiteside (picture only):

   http://www.whitesiderouterbits.com/catalog/gluejoints2.pdf

   Amana and Freud also make finger joint bits.

3. 
   ian | Mar 11, 2004 03:41pm | #6

   I'm guessing that your problems are related to a combination of router power, router speed, material feed rate and the height of the bit.  My first response would be to cut the fingers in two or three passes to minimise the risk of bogging the router down and hence distorting the finger shape.  I'd also check the bit height.  The instructions in my CMT catalogue imply that the left side of the joint is cut with the face side down and the right side with the face side up.

   However Routerman is here so I'll better defer to him

4. 
   raylo | Mar 19, 2004 11:00pm | #10

   Guy's, enough belly-akin about size of bit and size of router. All I want out of this is how to properly set the height of the bit above the table top to get the fingers to integrate properly.

1. 
   Routerman | Mar 19, 2004 11:24pm | #11

   It's a cut and fit proposition. Would set the fence to take the full profile + .005-.010". That will require an offset fence. 1 full thickness+ cut will assure you that fingers are not short. The bearing, on bearing guide assemblies, can also be used as the max fence setting.

   Cutter depth: Take best first guess and cut. Fit the work and measure the error in the north/south fit of the parts. Change depth of cut x 1/2 this error. If the router is still working and the cutter not too badly burnt your parts should meet flush top and bottom and the fingers should fit as well (but clearly no better) as the grind. For your safety (end-grain cuts) use fixtures and multiple stage cuttings.

   Routers

   Edited 3/19/2004 4:27 pm ET by routerman

2. 
   MBL | Mar 19, 2004 11:30pm | #12

   Dear raylo,

   You can save a lot of hassle by routing pieces slightly over-wide, and then table-saw trim to final size based on having matched the finger joints first. You'd get perfect matches that way.

   -mbl-

3. 
   ian | Mar 21, 2004 11:00am | #14

   I'm assumng you're cutting finger joints with tapered fingers.

   what are you currently doing when you cut the miss aligned fingers?are you cutting both pieces with the face side DOWN ?  or are you alternating between face side down and face side UP ?

   The finger joint router bits I'm familar are designed on the asumption that one side of the joint is cut with the face side DOWN and the other side with the face side UP  you DO NOT adjust the height of the bit. do you have this sort of bit ? are you following this cutting sequence?

   if yes and it's still not working it is probable that you have a defective bit, in the sense that the manufacturer hasn't mated the spacers and cutters correctly – take it back

   If your bit requires that you cut one side of the joint and then adjust the bit's height for the other side it will be critical that you get the bit's height correct to within about 0.001in or less.

   Now if you are cutting finger joints where the fingers are not tapered, the recommended method is to cut the slots 0.002 in wider than the fingers.  For 1/4in fingers you would cut the fingers at 0.249" and the mating slots at 0.251"   The 2 thou will disappear when you glue the joint. 

   does this help?

   Ian