I built a router table and put a router in it. Have used it only a little, but I need to make some 1/2″ x 1/2″ rabbets in some plywood. I have both straight cut bits (1/2 inch cutter diameter) as well as a rabbet bit with various bearings.
I assume I can use the straight cut bit to make a rabbet, but is there a time when a rabbet bit would be used and a straight cut bit not used?
If I was using a hand held router, would the rabbet bit be safer or give a better cut than a straight cut bit?
Can I make the 1/2×1/2 cut in one pass on the router table? I tried it and it seemed fine, but people seem to talk about not taking off too much material in one pass —
Thanks.
Edited 3/10/2006 4:58 pm by hotwheels
Replies
A rabbet bit has a variety of bearings so it can be used in a hand held router without need for a fence or a guide. Due to the mass of the body and circular cutting attack, it is better suited for making larger rabbet cuts in a single pass. 1/2" x 1/2" is a pretty stout cut. The cut may cause some large hunks to tear out and can leave the edges tattered. You can vary the depth of the cut by feel to a certain extent, only taking a little at a time until you finally make contact with the bearing. You could also vary the depth of cut by starting with the bit a little high and lowering it with successive passes. Since the bearing must contact the edge to control the depth of the cut, there has to be enough material below the rabbet to support the bearing. A rabbeting bit can be used in a router table with a starting pin to cut curved work. A straight bit would need a special guide for this operation.
A straight bit will need a fence on the router or a guide board to control the depth of the cut. One that is the same size as the rabetting bit will have as much mass and probably have about the same cutting attack but a smaller straight bit like a 1/2" will be under more stress in a large cut. Since the bit doesn't rely on a bearing, you can cut much deeper, only leaving 1/16" of material if that is what you need. Both types of bits can be used in a router table with a fence and the bearing could be removed on the rabbeting bit.
I would use a rabbeting bit to hog out a 1/2" x 1/2" cut if it was for a piece that wouldn't show, rough, utility type work. If it was for a cabinet or piece of furniture, where a split out or rough edge would show, I'd make the cut incrementally. My routers would also appreciate the work load reduction. Most of the time we are looking for accurate cuts in woodworking. Anything we can do to ensure that this happens is worth doing. Inaccurate cuts often mean problems later with assembly fit and finish. A more suitable way of making large rabbetting cuts in a single pass would be with dado blades on a table saw. Large rabbets can also be cut on a shaper.
Beat it to fit / Paint it to match
Thanks Hammer1 -- this raises the issues that concern me. This rabbet is for a cabinet that is a peice of furniture. I need to make multiple rabbets for different pieces, so repeating the cuts so they are accurate is important: without that, then there could be enough variation that the pieces will not fit together in different places The advantage of cutting in one pass is I can make that cut on multiple pieces and they should be mostly the same. Tired it on some MDF and it worked ok, but since the cuts will be cherry ply, it may not be a good test. The straight bit seems to work, but I am confused about when is a cut too much to do in one pass: the tradeoffs are accuracy, safety, and wear on the machine.Thanks for the reply.
"but I am confused about when is a cut too much to do in one pass: the tradeoffs are accuracy, safety, and wear on the machine."
Certainly when the shelf (rabbet) cut is > than the diameter of the bit you're taking too much/pass.
And if the cutter design & power supply won't allow it. 3/8 x 3/8 is ~ a max bite for any cutter/pass. For best results: Test on scrap. Small stage cuts will yield the best end results, speed kills.
Routers
Even through my table router (Milwaukee 5625)seems to make the 1/2 x 1/2 cut (tested in 3/4 MDF) without problems,I think you are saying it is too much. IN this case the diameter of the bit is 1/2" and by adjusting the fence I can make the 1/2 x 1/2 in one pass and not have to make any fence adjustments. If I use the spacer idea on Mr. Warners web site and Foresgirls suggestion for 1/4 spacers, then I should not have any problems in having to adjust bit height on repeated cuts. I will give this a try when I make the cuts in the cherry plywood (testing first on MDF. Great ideas, I would have sat in the garage all day trying to figure out a different way to do it without making any bit height or fence adjustments!
You can accomplish the same thing (incremental passes) by "padding" the table and the fence with removable ..... well, spacers I guess you could say. I'd try 1/4" Masonite, smooth side out. Attach a piece to your fence, and lay a piece on your table (relief hole for the bit obviously). Have the bit set to the ultimate goal, make a pass with the spacers, then remove them and make the final pass.
I'll look around and see where there might be pictures of a set-up like this.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Here's a good page at Pat Warner's web site:
http://www.patwarner.com/cutter_depth.html
I was thinking of something a little simpler, but you'll get the idea!
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
The 1/2 X 1/2" cut is too heavy for one pass. Try it in at leats two passes. Good quality rabbet bits generally have down shear so they will cause less chipping of the plywood than the straight bit.
Freud America, Inc.
Thnks Charles ... I will make a couple of passes using the techniques offered earlier ;... the issue is consistent cuts across numerous pieces tha tneed to be cut so I do not want to change the set up.
Another option, if you have a plunge router in the table is to use the depth stop to limit your final cut.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Wabbits, When doing rabbits, I really prefer using my jointer rabbiting ledge to hog out most of the material. With the 1/16" Initial pass on the jointer, you remove the possibility of tearout. then continue on in 1/8" steps till your within 1/8" of desired depth then finish up on the router table with at least a 1/2" Dia. Preferably 7/8" Straight cutter so that the attack angle of the cutter is shallow. Also jointer knives are easier to sharpen and resharpen many more times than a router bit.
I'll keep that approach in mind. Hope the original poster (hotwheels) saw your post.
Funny, last time I heard the subject of doing rabbets on a jointer here at Knots, it was members saying they never did that and what a waste that rabbeting ledge was. I'm glad there's at least one person out there who uses his!forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
I know that ledge is on my jointer but I don't have a clue about how to use it. I will check out that option for the future. I did a test cut trying one pass with my router to make the 1/2 x 1/2 rabbet and it did not seem to slow the machine at all. So, I pushed through the cherry plywood making the 1/2 x 1/2 cut and it seemed both controllable and not an obvious drag on the router. I can forsee making other cuts that will be deeper and require taking off material that will require other approaches. I will learn how to use the jointer to rabbet and I now know the spacer option. Thanks again.
Glad things are going well with those wabbits. Sounds like the ply is fairly forgiving. If you ever need to rout that 1/2x1/2 in solid wood, you might wanna test again, LOL.
Just to clarify the record, I personally have only used the rabbeting ledge on my jointer once, so I'm not promoting the idea. There seem to be some who think it's a really bad idea. I'm working at having no opinion on the matter, LOL.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
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