Pattern routing grief

[Brian Holcombe]

Afternoon gents. I'm doing to pattern routing for chair parts and running into a bit of trouble here and there. I'm getting catches where I have not expected them and I can't quite understand it. I'd appreciate any insight.

The arrows show the direction I have been feeding when successful, but what confuses me is why the inside curve wants to be routed against the grain. I don't recall it having such preference last time I performed this operation (which was with walnut and ash) but for some reason it seems to prefer it here.

The catches have been completely unnerving and so I want to better understand what I'm doing here to prevent any kind of injury.


https://brianholcombewoodworker.com/wp-content/uploads/2018/07/eHBk7gQpu3SRtuxmdPYw-2373266503-1532637445575.jpg

[andy bessette]

Prior to routing, trim as close as possible to the line. Then pattern route only about 1/4" deep. Finish with full length bearing follower.

[Tim Bueler]

Since I see a router table in the picture I assume you're using that and not a hand held router. Judging by your arrows it looks like you're feeding into the grain, on both inside and outside curves, which does lead to catching, tearout, etc. Try flipping your set up over and feed your work piece into the bit in a counter-clockwise rotation all the way around. If my brain is working the way I hope:confused: that will put you feeding with the grain, so no grabbing. If I'm upside down I'm sure someone will correct me. The point I'm trying to make is you'll have better results feeding with the grain.

[Jon Grider]

What Tim said.

[johnny means]

Looks like you're climb cutting that inside curve. So your cutter is biting in and trying to pull the piece in.

[Brian Holcombe]

Andy, I trimmed very close, within 1/16"


Since I see a router table in the picture I assume you're using that and not a hand held router. Judging by your arrows it looks like you're feeding into the grain, on both inside and outside curves, which does lead to catching, tearout, etc. Try flipping your set up over and feed your work piece into the bit in a counter-clockwise rotation all the way around. If my brain is working the way I hope:confused: that will put you feeding with the grain, so no grabbing. If I'm upside down I'm sure someone will correct me. The point I'm trying to make is you'll have better results feeding with the grain.

Tim, what you're describing is exactly what I was doing when the bit caught, both times feeding into the grain. That's my reason for this post is that I can't quite understand why it worked successfully feeding against the grain.

[Brian Holcombe]

I know to avoid climb cutting, that's not my question. The arrows note the successful attempt, not the times when It grabbed. That is why I'm wondering what the problem is, as they're often breaking the rules of cutting with the grain and yet the bit cut nicely in those directions and did not when I was doing as I should be doing.

I should be going the opposite direction of those arrows on the inside curve, and yet when I did so it grabbed terribly.

[Mel Fulks]

A shaper with steel knives would be better. The raggedy saw cut edges of the material make tear out worse. Try using sandpaper to quickly remove those square rough corners before the trimming. It can keep the sweater from unraveling.

[Mark Hennebury]

390417Flip your wood and pattern over.

[Brian Holcombe]

Given some after-hours contemplation and another attempt this morning, I figured out what I was doing wrong.

I'm a bit of a chicken when it comes to pattern routing so I had been taking small bites, then getting out of the cut, backing up and taking more. I was thinking that making short cuts rather than one long continuous cut would allow me to regroup at the end of each cut but it was instead making it so the bit had a chance to grab as I re-entered the cut.

So, to those following my folly, don't take this stupid approach. :D

[Tim Bueler]

390417Flip your wood and pattern over.

Marks picture is what I was trying to describe.

[Brian Holcombe]

I'm certainly understanding what you guys are saying. I have a feeling that the short-cuts approach was what was causing the issues, rather than direction of the cut.

I had the same problem on the back side, but I think it has more to do with the pattern on that side of the arm. The pattern doesn't have a lead-in and I think that is also causing issues, so I'm working on that now also.

Appreciate the insights.

[Brian Holcombe]

On the backside of this arm, I was getting a grab at the outside corner. I'm thinking this was due to the lack of a lead-in, so I set the tool fence to limit depth of cut and that seems to have cured the issue. This is what I'm talking about:

https://brianholcombewoodworker.com/wp-content/uploads/2018/07/bHN5CpCJQeul8FPiB2wrKA-1424748922-1532698786859.jpg

[Ken Fitzgerald]

Given some after-hours contemplation and another attempt this morning, I figured out what I was doing wrong.

I'm a bit of a chicken when it comes to pattern routing so I had been taking small bites, then getting out of the cut, backing up and taking more. I was thinking that making short cuts rather than one long continuous cut would allow me to regroup at the end of each cut but it was instead making it so the bit had a chance to grab as I re-entered the cut.

So, to those following my folly, don't take this stupid approach. :D

No offense Brian but you don't have the patent on using stupid approaches.


By the way, while pattern routing I turned off my plunge router, flipped the router over releasing the depth lock as I flipped it. I looked across the shop at my telephone where I'd received a phone call just a minute earlier joyfully announcing the successful surgery of a dear family member. I pushed the router down another 1/4" while looking at the phone. My wrist happen to be over the bit which hadn't quite stopped yet. My wife was at lunch at the elementary school from which she's retired. Luckily for me neighbors were at home and took me to the ER. 14 stiches later things were better. Eventually the minor nerve damage resolved itself and the numbness in the area between my thumb and the palm of my hand went away. No sir. You don't have the patent on stupidity. :o

[John M. Smith]

Whiteside makes an excellent bit fir doing this. Pricey, but I've gone any way towards the grain with no catching or tear out.

[Jim Morgan]

A starting pin makes it easier to ease into a cut and avoid start-up grabbing.

[Warren Lake]

router table is mickey mouse way to do that. Id be using a shaper depending on the part and radius. More likely id flip your jig over and use a hand held router on top of the jig. There is no control on a router table. Put the router in your hands part clamped firmly and you can do whatever you want, climb float cut one way towards you then go back and trim the last likely next to nothing off. You will get clean cuts if you use a spiral bit, even a two flute using it with some feel and its about feel. You have no feel on a router table, when you have a router in your hand you have the feel of the tool and you move it as you want not how you have to move on a table.

[andy bessette]

router table is mickey mouse way to do that... There is no control on a router table... You have no feel on a router table...

Gotta disagree on this. And he doesn't need a shaper for this job.

The problem comes with trying to take off too much material in one pass.

[Brian Holcombe]

No offense Brian but you don't have the patent on using stupid approaches.


By the way, while pattern routing I turned off my plunge router, flipped the router over releasing the depth lock as I flipped it. I looked across the shop at my telephone where I'd received a phone call just a minute earlier joyfully announcing the successful surgery of a dear family member. I pushed the router down another 1/4" while looking at the phone. My wrist happen to be over the bit which hadn't quite stopped yet. My wife was at lunch at the elementary school from which she's retired. Luckily for me neighbors were at home and took me to the ER. 14 stiches later things were better. Eventually the minor nerve damage resolved itself and the numbness in the area between my thumb and the palm of my hand went away. No sir. You don't have the patent on stupidity. :o

Very sorry to hear about that Ken. Ouch!


Whiteside makes an excellent bit fir doing this. Pricey, but I've gone any way towards the grain with no catching or tear out.

I've been wanting one, but the height of cut is too short for this process. The overall height at this point is 1.625" and I think the tallest 'ultimate' bit is still considerably shorter than that.


A starting pin makes it easier to ease into a cut and avoid start-up grabbing.

I spoke with Mark Hennebury earlier today and he mentioned using one of those as well, I'm going to fabricate or purchase one for the next round of this.


router table is mickey mouse way to do that. Id be using a shaper depending on the part and radius. More likely id flip your jig over and use a hand held router on top of the jig. There is no control on a router table. Put the router in your hands part clamped firmly and you can do whatever you want, climb float cut one way towards you then go back and trim the last likely next to nothing off. You will get clean cuts if you use a spiral bit, even a two flute using it with some feel and its about feel. You have no feel on a router table, when you have a router in your hand you have the feel of the tool and you move it as you want not how you have to move on a table.


Gotta disagree on this. And he doesn't need a shaper for this job.

The problem comes with trying to take off too much material in one pass.

I cut the material to 1/16" overhang, but even that was too much where I was trying to start on a change in direction. Using the fence as a lead in really helped a lot and I will be doing the pin method next go-round.

https://brianholcombewoodworker.com/wp-content/uploads/2018/07/fullsizeoutput_7ac.jpeg

The next batch of this work, for this project has a directional change in the center of the curve.

[Warren Lake]

Never said he needed a shaper but large head diameters work better that way than a router bit. Hand held opens the router up a better level because you can move in directions you cant do on a table.

1/16 is too much overhang as well. When you hand held you can tolerate more overhang and have less problems than the table, but you also still dull the bits quicker. My usual runs were 50 -80 parts at a time in different woods and shapes. I worked at getting more life out of bits or testing different changes to make the process better different bits and and. Ive done 12-15,000 parts over the years I have some experience with it.

[Mel Fulks]

It is possible to try to remove too much wood at once, but many times obstinate grain will tear out even with a small cut.
A slight rounding of the sharp splintery edge does help. On small shaper runs of carefully prepared S4S ,I have even set up the shaper with a small round over and climb cut as prep for the profile run. The highest feed speed can be used for
that ,so it doesn't take much time and asures all the pieces will be perfect. But some prefer to just keep dressing more wood.

[Brian Holcombe]

Never said he needed a shaper but large head diameters work better that way than a router bit. Hand held opens the router up a better level because you can move in directions you cant do on a table.

1/16 is too much overhang as well. When you hand held you can tolerate more overhang and have less problems than the table, but you also still dull the bits quicker. My usual runs were 50 -80 parts at a time in different woods and shapes. I worked at getting more life out of bits or testing different changes to make the process better different bits and and. Ive done 12-15,000 parts over the years I have some experience with it.

Warren, my issue with the hand held is that I'm not sure how to do the work holding with a part like this. What's your approach on this?

[Warren Lake]

I didnt study your template but build it or its fine as it is so you can work upside down. Skip the ball bearing bits they limit you though they do firm up a bit that might have some whip in it because it rests on the template. I made all my templates out of 3/4 baltic birch. Looking you have a base and clamps and a template to work to, Turn your base into the template and clamp to that. You might need two for that part not sure I could always work it out to work from one template. Another important thing is whatever material overhangs the more consistent it is then you get less blow out, for instance i have customized bits that cut .020 oversize. if you cut a part to size and your whole overhang is .020 you will get more clean parts when you cut to size. Always make some extra parts.

[Ken Fitzgerald]

Brian, I think the idea of using a guide pin on your table will work well too. There was a Canadian produced router show featuring a father and son routing. They often used a template with clamps on a router table and a pin to start the cut. If you have a bandsaw, I would cut within 1/8" of the line, clamp it to your template, use the pin and go for it. Try it on a couple of pieces of scrap just to become comfortable with the new procedure. I often do that with a router when trying new procedures.

[Brian Holcombe]

Thank you both! Appreciate the insights.

[Jim Morgan]

Here is my starting pin. It's a socket head screw with the appropriate thread for the little hole to the right of the insert and a couple of nylon bushings cut to fit the the exposed thread when the screw is bottomed out (the hole is not very deep). I went crazy and splurged on a stainless steel screw, so the whole thing cost me $3.
390461

[Brian Holcombe]

Thanks James, I’ll make something about like that.

[andy bessette]

...my issue with the hand held is that I'm not sure how to do the work holding with a part like this. What's your approach on this?

One method is to attach the template to the workpiece using double-sided tape. Then use a top-bearing follower bit* to create a shallow "ledge" the precise shape of the template. The pattern can then be removed and the ledge used to finish the part on the router table.

*Looks like this. Template is made thick enough so that only a shallow cut in the workpiece is necessary.
https://www.amazon.com/Yonico-14169q-Mortising-Router-2-Inch/dp/B00KZM0XYQ/ref=pd_lpo_vtph_469_lp_img_3?_encoding=UTF8&psc=1&refRID=FS2RSK4MV70RSB3VTWVT&dpID=41WMHbiT9qL&preST=_SX300_QL70_&dpSrc=detail

[Patrick Walsh]

As Andy suggested and in the case of a hand held router double sided tape is your friend.

Brian I have many time experienced exactly what you are when making furniture feet for box cabinets.

I gave up on the router table and started using a hand held router. I still have yet to tackle pattern shaping on the shaper being the same exact experiences you are having with a router table. Maybe someday I will gain the confidence and knowledge. Till then I’ll keep my finger “and arms” and do what I’m doing.

Looks like you got a order for those chairs?!

[Brian Holcombe]

Ah, that’s an interesting way to do it. Thanks Andy!

Patrick, I can very much appreciate your experiences, as much as I’d like to use a shaper for this, so far the idea of learning with something that has 5-10hp and much bigger tooling is not appealing to me either. Even though I understand it to be a better approach.

Filling an order for the chairs, yes very excited about that. Piled a few more on to drop off at various showrooms.

[glenn bradley]

I do a lot of template routing and use various jigs similar in function to what you are using.

390483

Things I've learned along the way; as always YMMV:


Use the largest diameter bit that will follow the concave path (tightest curve).
Always route downhill

A top/bottom bearing bit makes this easy.
Even with templates double-stick taped to odd shapes.


390484 . 390485



Have plenty of template bearing surface before and after the cut when possible.

This allows the template to engage the guide bearing before and after the cut.
This replaces the guide pin function and results in smooth begin/end results.



Having an array of large diameter, tall cutting height, top/bottom bearing bits is not for everyone. It looks like you may be through the tough part. If I were doing much more of this I would look at investing in a Whiteside 2715 if the cutting height of 1-1/2" is sufficient for a single pass cut. For taller cuts I do them in two passes using the template as the guide for a batch of first cuts and the first cuts as the guide for the second cuts.

[Brian Holcombe]

I have another round if this work coming up, so I may pick up an ultimate bit for it. Very much appreciate your comments. Ive been digesting all of this information, this thread has been a great help.

[Tim Bueler]

Brian you need to flip your pattern and workpiece over. As is you are feeding into the grain, not with it. The way you're showing in the picture it's not IF it will grab, it's WHEN. Flip your setup over but still feed in the direction you are in the picture, counter-clockwise (which direction is CCW on a digital clock???:rolleyes:) all the way around.

Also, not sure what diameter shank is on the bit you're using but you will get better results if it's a 1/2" shank...less deflection and vibration. And/or try a larger diameter bit. I have a Freud with 1/2" shank and 3/4" cutting diameter that is head and shoulders above a bit with 1/4" shank and 1/2" cutting diameter.

Shapers work great for what you're doing but there is learning curve, not everyone has a shaper in their arsenal and often not even in the budget.