|Topic Review (Newest First)|
|04-14-2011 10:52 PM|
|Cherryville Chuck|| |
Originally Posted by allthunbs View Post
|04-14-2011 06:54 AM|
Ok, next lesson please: |
I have to cut a "stepped groove" in a piece of maple. The objective is to create a place where my wife can put some stained glass. The cut is 3/4" wide and goes through a 3/4" piece of maple. Another cut expands the 3/4" groove to make a shoulder that the glass sits in. I do the first cut by dropping the workpiece down on the bit. I have to turn it end for end to do the next cut. This is the one that's tricky. The bit is not pulling the workpiece into the fence, it is pushing it backwards and pulling it from the fence. If I do it the opposite direction, it gets worse and potentially propels the workpiece out the door. How would you widen a slot?
|04-14-2011 06:35 AM|
|Jack Wilson||What everyone seems to have avoided saying, and what I often do, is place a second "fence" in front of the bit. The work piece is trapped, but only a minimal amount of bit is exposed and the work cannot 'jump' out of place. At times I have even screwed a piece against the fence as a hold down so that the work piece cannot rise either. If this is a bad idea I'm sure to hear about it now!|
|04-13-2011 09:52 PM|
Hi Alan - thanks for the very thorough explanations, and for illustrating a good way to evaluate the options before cutting. |
I've certainly learnt a few things as a result of my mistake :
1. never feed between bit and fence
2. always feed against the bit rotation
3. where possible, use featherboards - but don't rely on them
4. always use a push stick
I did do 3 & 4 above - I'm being very careful due to my inexperience (for example, even clamping the stock to my finger joint jig even though I could safely hold it with my fingers) so hopefully I'll continue to stay safe.
|04-13-2011 06:33 PM|
You want to control what happens. One simple way to evaluate the cut is to think about the direction the bit is pushing on the stock. |
You want it to help to hold the work against the fence as it cuts. A and C do that, while B and D push away from the fence - bad.
You also want it to push opposite the feed direction, so it can't be pulled away from you with your hand pushing toward the bit. B and C are against the bit direction, while A and D are climb cuts - bad.
Finally, if the stock wobbles a little, you don't want that to cause damage to the work or loss of control. Pulling a little away from the fence causes the bit to take a deeper bite in A and B, with consequences dangerous to the work and you - bad, while pulling away from the fence a little causes only a little less cut for C and D. This is not dangerous, and can be fixed with another pass.
These three things should be considered for any setup. In this case it leaves only C. There are situations where special equipment like power feeders can enable operations that would not be safe by hand, but if possible, stick with these ideas and don't count on featherboards to protect you.
|04-13-2011 05:20 PM|
Matthew, our best ability is the ability to learn from our own mistakes. |
We all make mistakes especially in the early days.
|04-13-2011 07:14 AM|
Hi Mike |
Hmmm...I must have been lucky. Actually, probably a good dose of luck, and the fact that I had on two feather boards (one vertical, one horizontal) and was using a push stick. The stock did get dragged away from the push stick - but only slowly - at about normal feed rate. As it moved away, it veered away from the fence, chattered a bit and was then spat out onto the RT and sat there.
I've learnt a lesson!
|04-12-2011 08:38 PM|
How about pictures to show how risky what you did was;
|04-12-2011 08:27 PM|
Had not thought of it but glad you mentioned it
Originally Posted by jschaben View Post
|04-12-2011 08:20 PM|
|jsorrell||"C" is correct as the stock moves against the bit direction and the stock is not between the bit and fence.|
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