Replies

1. 
   Samson | Feb 13, 2009 10:13pm | #1

   Just out of curiousity, what are these flat bottom holes for?  I'm curious as to the application where one would care about tear-out inthe bottom of a stopped forstner hole.  Thanks.

   I guess what I'm saying is that you may be using the wrong tool.  A router, for example, might be better at this.  Or even some sort of rosette cutter.

   
   

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   Edited 2/13/2009 2:16 pm ET by Samson

1. 
   pancakeman | Feb 16, 2009 04:47am | #10

   Hi Samson,

   The project is a special-purpose display case, similar in concept to a spice rack, for small specimen jars. Given the problems with the tear-out and the fact I already have to deal with the small indentation from the bit's pilot point, I think the router is a better choice.

   Thanks.

   Dave

1. 
   PeteBradley | Feb 17, 2009 03:44am | #12

   For this application I suggest you glue felt to the bottom of the holes.Pete

2. 
   user-54856 | Feb 13, 2009 10:17pm | #2

   The hole is certainly big enough to use a router with template.

3. 
   JohnWW | Feb 14, 2009 06:15am | #3

   The cutters on the face of the bit are lifting chips at all different alignments to the grain as the bit revolves so they never do all that good of a job, especially in larger bits. Other than making sure the edges are sharp there isn't much you can do. As someone else suggested a router will leave a much better finish.

   John White
   (Former Expert and retired FWW Shop Manager)

1. 
   ring | Feb 14, 2009 08:22am | #5

   John, I just have to mention...
   Your tag line says "Former Expert and retired FWW shop manager". Now what exactly does a former expert go on to be?
   I realize that it's referring to the "Ask the Experts" section, but I humbly suggest you change that tag line. Unless of course you really meant it that way, kinda like "I was so much older then, I'm younger than that now."regards,David Ring

   http://www.touchwood.co.il/?lang=e&id=1

1. 
   heartwould | Feb 14, 2009 06:38pm | #6

   Experts almost always have a job.  Former experts seem to gravitate toward politics.

2. 
   joinerswork | Feb 17, 2009 01:34am | #11

   David, (and John),

   A buddy of mine, when you ask him, "How are you?"-- says, "I was all right, but I got over it."

   I don't know if you've heard the definition of an "expert' that says,

   An "ex" is a has-been.  A "spurt" is a drip, under pressure.  Put them together, and you have an expert. 

   Better to be one of those, formerly, than currently...

   Ray

4. 
   Frank Vucolo | Feb 14, 2009 08:10am | #4

   Pancake,

   620 RPM sounded high to me for a bit that size. That outer rim is moving pretty fast. I looked for speed recommendations by FAMAG but can't find any. There are other resources out there for recommended speeds.

   Here's one link that says you should be spinning that thing at 250rpm. http://www.raygirling.com/dpspeed.htm

   I think the speed is the biggest issue. My drill press goes down to somewhere around 300 and I always use that with forstners and take my time.

   Are you clampping the stock to the table? At least that will eliminate much of the vibration and allow the cutters their best chance at some smooth slicing.

   You could also hog out the hole with your forstner, leaving it a sixteenth or so short of the depth you are looking for, then finish out with a router and pilot bearing, referencing the walls made by the forstner, using a bit something like this one from MLCS.

   View Image

    

   Good luck. Let us know how you make out.

    

   Frank

1. 
   pancakeman | Feb 16, 2009 04:37am | #8

   Hi Frank,<!----><!----><!---->

   The blister pack that the bit came in has a chart showing speed (vertical axis) versus bit diameter (horizontal axis). It is hard to read the chart exactly since it is pretty small, but it looks like the recommended speed for a 44mm bit (that’s reasonably close to 1.75”) is about 650-700 rpm.<!----><!---->

   Given that the slowest speed on my drill press is 620 rpm, and assuming that speed is the culprit, any suggestions for how to get a slower speed?<!----><!---->

   I think the router bit suggestion merits investigation. I hadn’t thought of that. Yeah, I think that’ll work.<!----><!---->

   Many thanks!<!----><!---->

   Dave<!----><!---->

5. 
   mike4244 | Feb 15, 2009 12:30am | #7

   I had a similar job years ago with the same problem. I contacted Connecticut Valley tool. They now are Morris Wood Tool. I wound up buying two of there forstner bits,1 1/4" and 1-5/8" . They were pricey I had thought,until I actually used them. They did the job perfectly, I then only bought their forstner bits when I had a production run.

   Try a google search for Morris Tool Co. I believe they are located in Tennesee.

   mike

1. 
   pancakeman | Feb 16, 2009 04:41am | #9

   Thanks for the reply, Mike. Actually, Conn. Valley Tool (Morris Tool) was my first thought until I read that the FAMAG bits were rated higher in the FWW @009 tool guide.

   Regards,

   Dave

6. 
   Don01 | Feb 17, 2009 07:33am | #13

   I bought some Rover bits from Bad Tool Co at the Edmonton Woodworking Show in October.
   I was using the 3/4" for a very small job just before Xmas and it was still in my 10" drill press. I only have the 1/4" to 1" set.
   I drilled a few holes in a variety of woods - oak, teak, lyptus and my favorite for tear out - Kentucky Coffee Tree.

   No tear out on the bottom, nice clean edges. The dimple left in the bottom from the guide point would still be a problem for you and these bits have guide spurs that leave a recessed cut on the outer circumference.
   I have no idea what RPM I was using. I have never changed the RPM since taking it out of the box.
   It is also possible that a different board, from a different tree, cut at a different mill might have treated you more kindly.

   Thats the joy of wood.

   Don

7. 
   Tinkerer3 | Feb 17, 2009 09:42am | #14

   Unless the splice would be objectionable, you could drill on through and then glue a thin sheet of wood on the bottom?