This is the first time I’ve used a router. I’m attempting to rout a rabbet on a board edge using a bearing-guided router bit.
I’m running the router from the left edge of the board to the right edge, and generally the rabbet looks fine. But right near the right end of the board I’m seeing a small “ramp” down in the corner of the rabbet that starts maybe a couple of inches from the board’s end. I’ve gone over this area now 2 or 3 times making sure that the router is tight to the board’s face and that I’m not somehow “lifting off” near the end of the board. I can’t seem to get rid of the ramp. What am I doing wrong?
Replies
I'm guessing that the board is not flat. The edge of that board was probably sanded to a slope near the edge. Your second pass had the router in a flatter plane relative to the middle of the board. Put a W I D E baseplate on the router and go again, using the middle of the board as the referance surface.
I'm going to take a leap in the dark and disagree with @_MJ_ here. Always unwise as he's usually right, but this time maybe...
I don't think it's unflatness as the rest of the rabbet is good. You'd expect to see this problem on the other edge too, or all along the edge, not just on the last part of the last cut, which to me is telling.
This is a progressive change in the rabbet depth and is most likely caused by the bit slipping in the collet.
This can occur if you have a dirty bit or collet, if too deep a cut is being taken, not enough of the shaft in the collet or if you have not tightened the collet enough, or if you grounded the bit in the collet before tightening (ideally don't let the base of the bit touch bottom to give it room to move when tightened) or just because routers can be a sod like that at times.
If you have not changed the settings, have a look - If your bit is riding above the base of the other good cuts, that's your trouble.
This can also be caused by the router rising up a bit, especially plunge devices don't always stay as locked as they should, which can cause a change.
The change in height of the ramped part of the rabbet seems too even to be a loose or moving-in-the-collet bit. It does look more like the effect of something used as a reference surface for the router base plate changing height.
Since the previous rabbet - that less inboard of the edge - seems to have routed correctly (it meets the rabbet around the corner at the right height) it seems likely that the top of the panel used as the router base plate reference is changing height or angle as the router is moved inboard for the next pass making the inner part of the rabbet. But only towards the corner.
This might be because the panel top has a shallow chamfer around the periphery that isn't a regular slope, especially at the corners where two chamfers meet, altering the angle of the router base plate on the top as it goes along. This could produce a ramp.
The photo doesn't give a clear view of the top of the panel being used to reference the router base plate. I'm guessing there's a large shallow chamfer around the periphery of the top ....? If not - if the top is dead flat - Rob might be right
In all events, if the top looks OK to the eye but is nevertheless causing that ramp, it might be best to chisel away the ramp rather than alter the top to make the router change it's behaviour in that corner. Call any wonk in the top "hand of the maker". :-)
Lataxe
Lataxe's chamfer is about what I'm trying to say, as the router was moved in it landed on a flatter surface towards the middle of the board. The lable shadow shows that the surface was not dressed for this project.
Rob, thanks for the kind words. I've never had a bit climb up deeper into the collet, or a plunge base creep to a higher setting. Most times my miscuts are deeper, where this one ramps up.
Are you doing this in a router table or freehand?
If on a table, your more likely to get something like this is the board isn’t perfectly flat.
If it’s by hand, either the board or check the tightness if the collect. I would loosen the collet and make sure the bit is not inserted all the way to the bottom, as this supposedly can prevent the collect from tightening all the way.
I’m betting you put the bit all the way in and it’s not tight enough.
Thank you to everybody that responded.
I couldn't really make a good after the fact determination of why this was happening so I used a chisel to remove that small ramp. The board face itself is perfectly flat and what's really confusing is that a good part of that rabbet horizontal surface in the area where the ramp was located was at the correct depth.
I did have the router bit installed fully bottomed out so perhaps that's the issue, or maybe my (hand held) router technique was to blame. I'll have another go at it with a different board and see if things improve.
I'm going to take a stab at this and ask is it possible that your router has a discrepancy built into it? It is common when using a router to let the router remain static as we revolve around the work piece bringing a different face of the router in contact with the work piece as we route. Most experienced woodworkers know that few routers have their bits truly centered in their bases so it's important when guiding against a straight edge to always guide against the same face of the router or small discrepancies will often occur. In this case I could see this occurring if the router spindle was not truly perpendicular to the base and you brought a different face of the router into play. The best way to check this would be to chuck some drill rod into the collet and run a square around it to see if there is a problem. Barring having truly straight drill rod you could probably raise a winged bit above the base then lay a straight edge flat on the base and lower the bit until it makes contact then rotate the bit and straight edge around the base. If the spindle is not perpendicular I would expect either a gap to appear or the bit get tighter on the straight edge. Just be sure to keep the same wing of the cutter in contact with the straight edge.
I hope I was able to express this clearly.
@esch5995
You expressed yourself clearly, thank you. I'll check that out.
In this case I wasn't routing around the corner here, at least not intentionally, but I do believe I was holding the router improperly with both hands parallel to the long edge I was routing as opposed to what I now understand to be the more correct position with hands at right angles to the edge. It could have been just dumb luck that the other long edge didn't have the same defect.
When you routed this, did you have another same-thickness board next to it, holding up the other side of the router base so the router is balanced and not creeping?
PS a shoulder plane would be a good tool for cleaning this up, as I find a chisel to want to follow the grain or go off in unintended directions.
I apologize in advance for the soap box, and I am really glad you got your project finished, but consider this: You lost your only chance to understand what happened and prevent it from happening again. Woodworking is about learning new skills and learning from mistakes is part of that process. By focusing on finishing the project instead of acquiring a skill you can no longer set the router in place (unplugged) and do a "post mortem" to prevent the same thing happening again.
Sorry about the preaching.
Beasler,
You make a good point.Those of us who aren't making furniture commercially can have two sometimes competing main motives for making a thing: to make a useful thing; to enjoy some play.
Personally I'm still a big kid so I enjoy the playing at least as much as making the useful thing. More, really. In fact, once I've played out a useful thing - enjoyed all those opportunities to make mistakes then correct them - I can't wait to get the useful thing out the shed door so I can begin the next new Game of Planks.
The thing about play is that it is a teacher (via the various mistakes and consequent improvements) as well as an enjoyable way to while away some hours that might be otherwise spent gawping at the idiotbox or typing blather into a forum. :-)
It is easy, though, to fall victim to the modern mantra "time is money" and other similar cultural pressures to "get on with it". But being in a hurry and focussed on the end result is, as you intimate, often the cause of never-corrected error; and sometimes of the establishment of bad habits.
But some are content with only the "how" whilst others want also the "why".
Lataxe
I have to go with MJ. The problem's not with the router or you. Sounds like you're dealing with an unnoticed flaw in the board. More routing will only serve to increase your angst, not solve the problem.
Mikaol
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