Template Routing - End Grain Tearout

[Elroy Skimms]

I'm new to template routing, so I'm sure I am making some rookie mistakes. I'm having some issues with tearout when routing around the end grain. I'm currently using a 2-flute straight bit. I've got a couple of 3-flute bits ordered, one up-shear/upcut and one down-shear/downcut. I'm hoping that will do the trick but I thought I'd ask the pros here for any additional tips. Here are the bits I've ordered, I'm using a Triton TRA-001 3 1/4 HP: Amana 45475.

I can get most of the way around the piece, but inevitably there is one part where no matter how slow I move, the bit grabs and thinks go south. I've got it trimmed down to less than 1/16" off the curve with the bandsaw but that doesn't seem to be enough to stop this. I've got the speed dialed down to approx. 11,000 RPM, anything lower and the bit doesn't actually remove any material. I've looked at the Big Daddy bit that Marc mentions from William Ng's school, but the diameter is too large for some of the smaller radii that I am cutting. Any suggestions?

-E

 

[wdwerker]

Sometimes you need top and bottom bearings , or 2 routers set up then you can flip the part over and come from the other direction .

Climb cutting is another tactic but it does involve some risk.

[Ronn W]

Since the band saw does not leave a real smooth cut, try smoothing the surface with and paper or a rasp, so the bit does not catch on the rough surface left by the band saw.  Also, I tend to run faster rpms on end grain but not so fast as to burn the wood.  I would interested to hear other opinions.  Wdwerker posted while I was typing this - I like his thought.

[Brendon_t]

You linked to straight bit,  are the up cut/ down cut straight or spiral bits? If straight, I would definitely consider getting a spiral. 

It looks like your taking quite a depth, in one pass.  can you not take it a 1/2" at a time? 

Removing a 16th in end grain shouldn't be too bad. I would personally not be dialing the speed down. . I'd be jumping up.  More shears/second hopefully less chance to grab and break out.  Not sure what you mean by it not removing material below 11k rpm..  it's still going to cut

[galturner]

I agree with wdwerker..you must learn to read your grain directions, and attack the process from the proper direction.  I would also change the bits  as you have done, and get the router speed up and take smaller bites.

[wnaziri]

I have not used this particular bit but I have read that it is the bomb when it comes to tricky situations like yours:

https://wnwoodworkingschool.com/shop/big-daddy-pattern-bit/

The is bit is rather pricey but may be worth it if it works.  I am getting the bit for my collection.

[wtnhighlander]

I think Brendon hit on one problem. It appears that although you are cutting into the wood

only a sixteenth, you seem to be using the full length of the bit. Take smaller bites.

[Eric.]

Steve nailed it right out of the gate...switch directions.  Even with the best spiral bit I would never try going 100% against the grain like that, especially on such a tight radius.  Perhaps if you were routing a large circle or gentle curve, but there's almost no way to successfully round a tight corner like that without catching and tearing out chunks.  Go halfway around one direction with a pattern bit, stopping in the middle of the end grain, then flip the piece and use a flush trim bit in the other direction to complete the pattern.

[wdwerker]

Another trick I just remembered is to score the pattern line w a marking knife or Xacto , route as far as you dare then grind off the last bit on an osselating belt sander ( like the Ridgid )

[gee-dub]

Long ago a traveling wise man gave me these words of wisdom "always route downhill".  You can reverse your feed direction via a top/bottom bearing bit.  You can also route all the downhill profiles you can, place the template on the opposite side of your material and route the remaining now-downhill profiles.

Re-positioning your template is made easier by adding stops that reference off the blank.  This is true whether you use double stick tape to apply the template directly or clamp the template and parts in a jig.

 

[wdwerker]

Any time I have a difficult part to pattern route I make a couple of spare blanks or if the wood is in limited supply make a blank out of some sort of scrap.

Use a starting pin if you have to freehand route. It gives you something to brace against. 

Your problem is somewhat common and there are many ways to approach it. All the suggestions offered here have some validity. Try whatever you have the equipment & skill for. 

[Southwood]

Don't remember seeing it but watch the router speed as well. Spiral bit, flipping when you can and bit speed are you friend. 

[Elroy Skimms]

First, let me say thank you for all of the replies and advice. There are a lot of different suggestions so I will try and tackle them bit by bit (pun intended).

13 hours ago, wdwerker said:

Sometimes you need top and bottom bearings , or 2 routers set up then you can flip the part over and come from the other direction .

My stock on some of these parts is 2 1/8" thick. I can't find a bit with both top & bottom bearings that will work for this. The largest I could find is 2" but the diameter is 3/4", which won't fit my 1/2" radius curves. I could go back and redesign everything to make this work if I have to, but that's a rabbit hole I'd like to avoid jumping into unless it is absolutely necessary. I already have 2 bits, one top-bearing and one bottom-bearing, which allows me to flip everything as needed. It's tedious but it works.

 

13 hours ago, Ronn W said:

Since the band saw does not leave a real smooth cut, try smoothing the surface with and paper or a rasp, so the bit does not catch on the rough surface left by the band saw.  Also, I tend to run faster rpms on end grain but not so fast as to burn the wood.

11k RPM was the best I could do without burning the Cherry into charcoal on the inside curves. I did sand down my 2nd attempt after the band saw, before the router, and it worked well for the first pass. The 2nd pass, not so much.

 

13 hours ago, Brendon_t said:

You linked to straight bit,  are the up cut/ down cut straight or spiral bits? If straight, I would definitely consider getting a spiral. 

It looks like your taking quite a depth, in one pass.  can you not take it a 1/2" at a time? 

Removing a 16th in end grain shouldn't be too bad. I would personally not be dialing the speed down. . I'd be jumping up.  More shears/second hopefully less chance to grab and break out.  Not sure what you mean by it not removing material below 11k rpm..  it's still going to cut

The straight bits linked have an angle to them for up/down cutting. They aren't true spiral bits though. Are you suggesting something like the Whiteside RFT5200?

 

3 hours ago, Eric. said:

Go halfway around one direction with a pattern bit, stopping in the middle of the end grain, then flip the piece and use a flush trim bit in the other direction to complete the pattern.

I was afraid you would say something like that. For the parts that are cut from 4/4 stock, this isn't a big deal. First pass. Flip. Second pass. Done. Easy peasy. However the larger items cut from 8/4 stock will be a nightmare. First pass (3/4" height). Flip. Second pass (3/4" height). Flip. Third pass (1 1/2" height). Flip. Fourth pass (1 1/2" height). Flip. Fifth pass ( 2 1/8" height). Flip. Sixth pass (2 1/8" height). Done. Not so easy peasy. I tried this method and screwed up my on my third pass (1 1/2" height). I failed to account for the change in grain direction after flipping it back. What was a downhill cut on the previous pass was now an uphill cut after the flip and I ripped out a couple of nice chunks of cherry from the center of the board. It was 100% operator error. Your advice appears sound. The problem is my ability to mentally keep track of which end of the grain is which direction and then remembering how many times I've flipped the board to know if the downhill is now uphill or if the uphill is back to being uphill again.

I'm going to step away from the router table for a bit and try again tomorrow. I will try and keep track of the changing directions on each flip, hopefully that will do the trick.

-E

[Brendon_t]

19 minutes ago, Elroy Skimms said:

 

The straight bits linked have an angle to them for up/down cutting. They aren't true spiral bits though. Are you suggesting something like the Whiteside RFT5200?

If I had it, that's the one I'd grab.  A real spiral. It's not a magic bullet that you can climb cut against the grain and be fine but it Def stacks the deck in your favor. 

 

[Eric.]

You could always pull out the rasps and spokeshave and do it old school! 

[Immortan D]

Just now, Eric. said:

You could always pull out the rasps and spokeshave and do it old school! 

That's funny coming from you LOL

 

[Larry Moore]

I have a Yonico 14135,pattern/ flush trim bit that is 2 1/2 inch cutting length

[Brendon_t]

8 hours ago, Immortan D said:

That's funny coming from you LOL

 

Hopefully not too funny. Have you seen the homies hand tool cabinet? If they aren't being used, it's a darn shame.

[Immortan D]

14 minutes ago, Brendon_t said:

Hopefully not too funny. Have you seem the hand tool cabinet? 

A woodworking masterpiece! 

 

[Eric.]

I always take the path of least resistance.  But I don't own any tools I don't use.

[wdwerker]

What about that Fuji sprayer ?

[Eric.]

1 hour ago, wdwerker said:

What about that Fuji sprayer ?

Okay, ya got me...I have a couple.  But it's a tool that I will use, I promise.

[Elroy Skimms]

This has been an educational weekend for me, and I mean that (mostly) in a good way. I was able to route some end grain without blowing out the stock, so long as I am careful about not cutting uphill with the grain (I also learned that UPHILL and CLIMB cutting are two completely different things). Hat tip to @Eric., @galturner, @wtnhighlander, and @gee-dub for that.

I did see the benefit of having a bit with both top and bottom bearings, will be ordering one of those today. It doesn't allow you to cut uphill with the grain, but it does make it much easier to flip the work piece without having to change bits out. Not having to swap bits will be a big time saver. Hat tip to @wdwerker and @Larry Moore.

Several of you mentioned spiral bits as well (@Brendon_t & @Southwood). I've already ordered 2 straight bits that are angled (up or down) which, according to the manufacturer and marketing materials, should do the trick. I have half a mind to order a spiral bit as well and do a side-by-side comparison. At the moment, I have plenty of spare material and I'm not under a time crunch (yet). I have a month to finish the project, so waiting a couple of days for shipping shouldn't be too bad. I'll do a little experiment and post the results here. For science!

-E

[Elroy Skimms]

The up & down shear Amana bits arrived and I was able to give them a test. First, I used a smaller bit which allowed me to try @Brendon_t's advice, taking a more shallow pass instead of a full 1" depth. This worked really well, even routing uphill on the end grain. I even tried to be a little reckless with it by starting a pass on the end grain, which is absolutely the worst thing I could do. Even with that, I barely had any tearout on the shallow pass. The shear angle on the cutter really left a much smoother end grain as well, compared to the straight cutter.

Because it's not a fair test trying both a shallow pass AND the shear cutter, I swapped to a 1" height shear cutter to see if it was the shallow pass or the shear cutter that worked so well. You can see the results in the picture.

Conclusion: Shear cutters really do leave a beautiful finish on the end grain, but they don't necessarily allow you to cut uphill through end grain. Shallow passes are a good idea though.

My spiral cutter is in the mail, it might be here tomorrow. I'll post those results too.

-E

[Brendon_t]

Glad you found something that works.  If it were me though, I'd leave good enough alone and leave the reckless to the people who easy sushi in Vegas. 

The router isn't somewhere I want to find the limits of what is safe. Every time the blade catches,  there is the possibility of damaging the board, the bit or you.