Flush trim

[Stephen]

I am working on some outdoor furniture, and while I have had no problems flush trimming the larger pieces to the 1/4" MDF patterns I made using the handheld router, the small pieces are a different story.  The pieces are too small to secure, so my thought was to use the flush trim bit in the router table.  I use the starting pin on the table, but as I ease the piece into the bit, it takes a huge chunk out of the wood.  I secured the pattern to the wood using double sided tape, and I am not flush trimming much; maybe 1/16".  The bit I am using (when mounted in the table) has the pilot bearing on top.  Do I need a pattern tracing bit with the bearing on the bottom?  Any thoughts would be appreciated.  These are the silliest, small pieces and I am making them over again!

[Jay Boutwell]

Hi Stephen.  It gets tricky flush trimming the small pieces.  If I'm reading your question correctly the bit is grabbing the material as it enters the bit.  What you need here is a bearing to guide it around the pattern.  The starting pin is used to stabelize the piece as you enter the material into the bearing.  As you enter the piece onto the bearing it will stop the bearing allowing you to guide it around the bit.  Once it is on the bearing and there is a pattern for the bit to follow it will cut smooth.   From my experience the starting pin will not follow a pattern very well as you have too much friction to push the material around it like you do when you have a free wheeling bearing.  Of importance be sure to feed the material into the cutting edge of the bit and continue the cut around the material.  Entering the material into the bit with rotation of the bit will grab and pull your hand into the bit and or throw your material across the shop.

There is two types of pattern bits with the difference is haveing the bearing mounted on the top of the bit and the other with the bearing mounted on the bottom of the bit.  Either will work however it depends on your work piece and pattern set up as to which one is the best to use.  They are called pattern bits and sometimes refered to as pattern making bits.

  Please be careful here as router do not mind cutting into your fingers or hand.  Use eye protedction and Work safe.

[Ken Darga]

It can be extremely dangerous, machining small pieces on a router table---

one can get injured or the work piece will get damaged.

  A small work piece can be affixed to a larger suitable piece---

using hot-melt glue.  

When completed, the small piece can be readily removed.

  Alternate method---

secure the small work piece into a ''wooden hand-screw clamp'' ,

and use a guide pin, along the clamp. 

  

Works for me.

[Ken Darga]

Alternate method

Machine the small pieces with a Dremel, or equiv, rotary tool,

using an suitable burr or cutter, for the applicable profile. 

[John Schaben]

A couple of things, sounds like the bit is grabbing the wood before the bearing has control of the cut. On small items, I found it helps some to extend the template a half inch or so ahead of the stock so the template actually hits the bearing before the stock gets to the cutters. The other suggestion would be to use one of those rubber faced push blocks like come with a table saw, place it on top of the workpiece and feed it with that. Keeps the block between your fingers and the bit and the rubber provides enough grip to even do some maneuvering if it's not a straight piece.

[Stephen]

Thank you for the speedy responses.  

The bit has a bearing (on top, when in the router table), so I am only using the starting pin to ease the workpiece into the bit/bearing.  It just seems like the bit is grabbing the wood before the pattern makes contact with the bearing; it is essentially grabbing the 1/16" that I want to trim.  The problem is that it grabs the 1/16" and keeps cutting.  

Ken, I am guessing that the clamp, other than the obvious safety benefits of keeping hands far from the bit, provides a much more stable and secure grip of the workpiece, correct?  

John, I had seen a video (I think it was at wwgoa.com) that showed the technique of extending the pattern.  It made sense, but how does that work with a piece that is being flush trimmed on 3 of the 4 sides?  I think I will give the push block or clamp a go.  Again, I appreciate everyone's time spent on this question.

[John Schaben]

One technique you could use, with caution, is to start your cut a quarter inch or so beyond the actual starting point and climb cut that 1/4".  Then go back and restart the cut where it has already been routed. Leaving just a little bit of stock like that doesn't leave much for the bit to get ahold of before it runs out.
 
Stephen said:

Thank you for the speedy responses.  

The bit has a bearing (on top, when in the router table), so I am only using the starting pin to ease the workpiece into the bit/bearing.  It just seems like the bit is grabbing the wood before the pattern makes contact with the bearing; it is essentially grabbing the 1/16" that I want to trim.  The problem is that it grabs the 1/16" and keeps cutting.  

Ken, I am guessing that the clamp, other than the obvious safety benefits of keeping hands far from the bit, provides a much more stable and secure grip of the workpiece, correct?  

John, I had seen a video (I think it was at wwgoa.com) that showed the technique of extending the pattern.  It made sense, but how does that work with a piece that is being flush trimmed on 3 of the 4 sides?  I think I will give the push block or clamp a go.  Again, I appreciate everyone's time spent on this question.

[Ken Darga]

Stephen said:

Thank you for the speedy responses.  

.............

Ken, I am guessing that the clamp, .................

provides a much more stable and secure grip of the workpiece, correct?  

..........................

That is Correct.