Hard wood vs pattern template and straight bit
Hey all! I am starting to play with routing patterns but I can say that my first attempt was a bit frustrating. I made a template out of 1/4″ MDF with a simple shape (a regular cut board). Then I cut the plank (hard wood) using my jigsaw and attached the template to the wood using double sided tape. Finally I installed a bearing straight bit to my router table, set up the height of it to ensure that the bearing was touching correctly the template and started trying to trim it. Right in the beginning I started to get some small kick-backs so I stopped immediately because something wasn’t right. When I inspect the wood I realized that instead to trim the wood the bit seemed to be “chopping” and tearing it. I then gave up to proceed and since then I didn’t try to make a pattern copy again. First I thought that it could be because I was using a straight bit against a hard wood and that maybe I should try a spiral one, but then I remembered that people has been used straight bits with templates for several decades so it should not be the issue. Any ideas?
Replies
Could be many things, or a combination of them.
-feed too fast
-rpm not high enough
-template not secured enough
-router body not tightly secured
-router bit not sharp
-not having a firm grip on the piece
-taking deep cuts
My preferred pattern bit is a 5/8 diameter, 1/2 shank straight bit with dual bearings and I turn over the piece so I can cut with the grain. Maximum material removal in one pass between 1/8 and 1/4 inch .
Here is a link to a FWW video on template routing basics.
https://www.youtube.com/watch?v=EzDWHcqgdbE
Thank you very much!
That's tear out. When the bit it going against the grain it will grab for several reasons: taking too much material, pushing too fast, a dull bit, a suboptimal bit. Smaller diameter bits are also more prone to tear out.
The biggest problem for you is the straight bit. They are THE most prone to tear out. There are 4 basic types of trim bits:
1. Straight
2. Straight/skewed
3. Spiral
4. Compression.
You can get around it somewhat doing a climb cut, but I don't recommend that unless you're taking off just a little material.
My suggestion is get a good quality 1/2" spiral bit (up cut if using on a router table). Rough cut the wood as close as you can to the template contour.
You always want to route "downhill" grain direction-wise. One way to do this is to mount your template for the downhill cuts and then remount it to the opposite side of your blank for the balance of the cuts.
This process can be sped up and made more convenient by using top/bottom bearing bits. The template can be on top for some of the operation and then by flipping the template and the blank (still taped together) you can complete the operation without having to route against the grain.
Pattern routing on a router table using a pattern insert. This version allows you to control how much material you take by controlling the depth of cut. It's slower but allows you to take small amounts with each pass.