Raising panel question

[rcp612]

How many passes does it take to finish each cut when raising panels? I mean, after doing 10 rectangular panels I think I should ask. Does a router bit cut to its set depth on the first cut? I used featherboards on the table and on the fence to hold the work piece securely in place but, if I run the piece through again, it would cut more. It took about 3 passes to completely "clear" each piece. Is this normal?
I'm concerned now because my next panels are s-shaped for the top sides of a roll top desk. I will have to do these sort of freehand, using only the bearing as a guide. So, safety is my big concern, and I don't want to have un-foreseen difficulty doing these.
I'm using a shop-built table, a Bosch 1617EVS mounted to a Rockler Plate, and these bits https://holbren.com/product.php?prod...7&cat=0&page=1. I had no trouble with rails and stiles but am totally confused over the panel cutter. I cleaned this bit after every 3 panels knowing that the build up could cause problems. I'm running the router at (Bosch says), 13,500 rpm. The feed rate is just enough to bypass burning the wood..Oh yeah, it's red oak.
What's my problem? Or, should I say, do I have a problem?
Sorry for the long post,, I just don't know how to say what I'm thinking.

[Black wallnut]

I normally have taken at least 4 passes to raise panels. Increasing the depth of cut a small amount before each pass. The final pass takes a very small bite. For straight panels I use a fence and isolate the bearing. For arched panels I have to somewhat free hand them.

For your arched panels you might want to take 5 or 6 passes. Red oak for me has been real prone to chip out. Be sure to go across the grain , with the drain , across and finsih with the grain. This should clean up your chip out if you have any.

[rcp612]

I normally have taken at least 4 passes to raise panels. Increasing the depth of cut a small amount before each pass. The final pass takes a very small bite. For straight panels I use a fence and isolate the bearing. For arched panels I have to somewhat free hand them.

For your arched panels you might want to take 5 or 6 passes. Red oak for me has been real prone to chip out. Be sure to go across the grain , with the drain , across and finsih with the grain. This should clean up your chip out if you have any.

I may have hidden my question.
If you go back over what you just finished, without changing any settings, would the bit remove more material? I think that after 1 pass the bit would just run free in that situation, but, mine does not. It takes at least 3 passes, without any setting changes, for the bit to not cut again. Does that make sense?
In my example, raising the bit 1/16" after the first pass would result in a possible 3/32" cut or more for the next pass. Shouldn't the 1st pass "clear" itself from the material?

[LarryG]

It takes at least 3 passes, without any setting changes, for the bit to not cut again. Does that make sense?

Not exactly. If I'm following correctly, it sounds like you're not cutting all the way to the bearing, which is a potentially dangerous situation because the workpiece is not being properly supported by either the bearing or the fence. This means the bit could suddenly dig in deeper, possibly causing you to lose control of the workpiece.

[rcp612]

Not exactly. If I'm following correctly, it sounds like you're not cutting all the way to the bearing, which is a potentially dangerous situation because the workpiece is not being properly supported by either the bearing or the fence. This means the bit could suddenly dig in deeper, possibly causing you to lose control of the workpiece.

I'm up to the bearing but, it seems as though the bit isn't cutting to its total depth? I've checked and re-checked all settings to be sure nothing is moving to create this situation to no avail.

[rnelson0]

Just curious, if you take a narrow piece, maybe 6", and put a horizontal featherboard in, do you get the same results? Also, do you have a vertical featherboard on in the infeed and outfeed? If you only have one vertical and no horizontal (which is probably difficult if you're making large panels), I could see slight pivots as you move it forward.

Also, is your router table actually flat? A slight warp would provide a fulcrum point that could cause it to dip up or down at the wrong time.

[rcp612]

Apparently missing my question

OK, now I'm convinced that I didn't ask the right question.
Suppose you set up your router table with:
Panel cutting bit (horizontal)
2 featherboards (1 on infeed side, 1 on outfeed side, both vertical)
1 featherboard horizontally mounted in a miter slot
Then you:
Adjust the fence so it aligns with the pilot bearing
Adjust the depth of cut (example 3/16")
Adjust all 3 featherboards for enough pressure to keep the wood aligned and tight to the table and fence
Set the router speed (in this case 13,500 rpm)
Then:
Using push blocks rout the piece of wood.
Now my question:
If after clearing the end of the fence,(in other words, done) you rout that same piece of wood without having changed anything previously set, should the bit actually still touch that piece of wood??
I have checked over and over that nothing moved and it hasn't but, following the above example, 3 times through and the bit finally does not touch the wood, and it measures out to be right where it should be.

[mschrank]

Unless the bit is taking more than just a very slight skim on the second or third pass, I'd say it's not that unusual. I can't explain why this happens, but I know that I've often made a second or third pass and found the blade/bit to take just a hair more. Even happens on the table saw.

My theory (hairbrained, perhaps), is that the wood gets compressed just a bit during the cut, then springs back out a bit.

Now, if you are seeing sawdust and really getting some cutting action on those subsequent passes, then something else is definately going on.

[jonmulzer]

It will happen, easily. When the bit is rotating and you push your wood through it the bit pushes the wood away from the fence just a little. That causes you to not cut as much as you are wanting to. Just like a dado cut on the tablesaw does. You have to hold down on the wood there to make sure you depth is correct and consistent. Featherboards usually help out quite a bit, but you may have to put quite a bit of pressure on them.

[LarryG]

I agree with Mike and Jon. If you push the workpiece through a second or third time and all you hear is a very light buzz, that's entirely normal. Is that what's happening? Or are you saying it's taking a fairly significant bite on these subsequent passes?

[JimD]

If I understand you I think you are trying to take too big a cut. With appropriately light cuts, you can get a little more off with a repeat pass but not much. Maybe a tiny bit with a third but maybe nothing. If I try a full cut, or something approaching a full cut, the router screams and the wood rises some and I have to cut again anyway.

I have a lift on my current table so I set the fence to take the fully cut but drop the bit down and raise it with subsequent passes. The other strategy which I have used is to raise the bit to full height but position the fence so the bit only takes a partial cut into the wood - the wood is riding on the fence but away from the bearing of the bit.

I have done arched panels and solid oak panels but not arched panels in oak. You will need to be very careful working freehand to not try and remove too much wood. A starter pin for your router table would be a good idea.

Jim