Keeping wood from splintering

[HowardH]

I have to use a pattern bit on my router table on occasion to form a curve on a board using a particle board pattern I have made for this purpose.  It's attached to the actual board using double sided tape so it doesn't move.  I am using cypress and I am careful not to go too fast but invariably the wood will splinter a bit in spots and a chunk can fly off.  There is usually about a 1/8" between the actual board and the pattern that has to be removed.  Is that too much to expect to get a consistently clean edge?  I can usually fix it with some wood filler but I am wondering why it splinters in the first place.  I bought a Freud 3 bladed bit just for this purpose and it's razor sharp.  It can also happen using a round over bit as well but not nearly as much.  Is it a grain direction issue?  Would slowing down the bit help?  I'm using a PC 3.25 HP router in my table.

 

[PaulMarcel]

I assume you mean pattern routing as in the cutter is a bottom-bearing flush bit, no profile.  (oh i'm assuming the pattern is on the top of the stock)

Couple ideas:

- with figured or splintery wood, I bump route it to help out.  Basically bump the bit to the pattern and retract, move over an inch and do it again.  Afterwards, do your pass.

- Use a spiral bit. If your pattern is on top, get a bottom-bearing down-spiral bit.  The down-spiral will use your pattern as a backer leaving a much cleaner edge.  Well, if you have 1/8" between the pattern and stock, no, but switch to turner's tape and the gap will be reduced enough to make a difference.

- Better still, use a bearing-guided compression spiral.  Tip is up-spiral, rest is down spiral so the stock itself backs the cut.  Not the most mainstream bit though.

- Switch the bearing to one about 1/16" radius larger; run the pattern(s).  Switch back to the flush bit and run it again taking off so little.

Combining the above helps.  I used a spiral and bumping to pattern route a vanity top that had a lot of crazy grain (ribbon sapele) and places where you were routing against the grain.  Sure, took awhile, but a lot less time than redoing it.

 

[HowardH]

Great ideas, Mark.  I didn't know there was such a thing as a down spiral bearing pattern bit.  The Freud is a top bearing since it's mounted in a router table. I don't think I was clear tho in my explanation.  The pattern board and board to be trimmed is stuck together tight using the tape.  I band sawed down to an 1/8th" to the line and that's all that is left to be trimmed using the pattern bit. 

 

[PaulMarcel]

Ah, okay.  I read that to mean 1/8" between the pattern and stock so I thought you were using that foamy double-stick tape.  oops

Definitely Eagle America sells a bottom-bearing down-spiral bit. One is permanently chucked in my MFK-700.  On a router table, you'd therefore have the bearing on top so the pattern is on top.  I personally prefer that scheme since it limits the bit exposure, but I could see the other way having advantages.

I find that spirals have less grab, too.  For that reason, I've sometimes used a larger bearing and routed normally then switched to the flush bit and climb-cutted where the grain dictates.  But only do that if your are comfortable.

 

[HowardH]

Is this what you are referring to?  And, yes, the pattern and bearing is on top.

 

[PaulMarcel]

Yup, that would be it   Say hi to the cute operator for me

 

[HowardH]

Will do!

 

[nickao]

It happens because of the grain directional change as said. You need to flip the piece over 1/2 way through the cut, but you can't easily becasue of the profile. And changing bits would be a huge pain. So get one of these and just raise and lower the bit, bearing to bearing:

Watch the video on this page and get one of their Katana bits:

http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/katana_bits3.htm#katana_flushtrim_video_anchor

Hope this helps.

 

[Ken Nagrod]

Nick,

I like that.  Now a question about the bit below that.  It seems to accomplish what the MFK700's 1 1/2 deg. base does, but what's the square bearing benefit?

 

[nickao]

Well, the square bearing does not spin and the theory is it will not pick up the adhesive or gunk and dirt that tends to build up in a spinning bearing, especially when trimming laminate tops, etc. That is at least one reason for them anyway. 

 

[Tim Sproul]

I have to use a pattern bit on my router table on occasion to form a curve on a board using a particle board pattern I have made for this purpose.  It's attached to the actual board using double sided tape so it doesn't move.  I am using cypress and I am careful not to go too fast but invariably the wood will splinter a bit in spots and a chunk can fly off.  There is usually about a 1/8" between the actual board and the pattern that has to be removed.  Is that too much to expect to get a consistently clean edge?  I can usually fix it with some wood filler but I am wondering why it splinters in the first place.  I bought a Freud 3 bladed bit just for this purpose and it's razor sharp.  It can also happen using a round over bit as well but not nearly as much.  Is it a grain direction issue?   Would slowing down the bit help?  I'm using a PC 3.25 HP router in my table.

I run into this problem, especially when bull nosing curved edges.  My solution is to use multiple bearings, going from oversized and  then to final size - how many bearings depends on the wood.  The final pass or passes is done climb cutting to prevent chipping out.  Trying to rout in multiple directions is also a solution but in my experience, a dicier proposition.  It is really easy to rout just a tad too far before switching directions.

For climb cutting on a table, make sure your work is hefty.  Lightweight/small stuff is more difficult to control.

 

[HowardH]

cutting small stuff on my router table scares the hell outta me.  [scared]  I use my OF1400 for the small stuff.  No possible way of my fingers getting close to the bit. 

 

[nickao]

A sled or jig of some kind should be used to hold the work piece, so your hands do not go anywhere close to the bit. Little piece are a hassle doing by hand as well because you need to find a way to secure them. The time it takes to secure those small pieces can be used to make a hold device for small pieces to be used on the router table, so really it is a wash. It is operation dependent and/or preference on which way to go, hand or table. Obviously, your preference it hand routing.  I like using the table as much as I can.

Fear is not good around tools, respect is.  

 

[bonesbr549]

I'm coming late to this conversation, but have dealt with this type activity before.  On question is are you going in smal increments or hogging off large amounts.  I'd go very slow and take many passes.  Secondly, a picture would help better diagnose the problem.  Since I can't see it I'll  assum your pattern is on the bottom and your using a pattern bit with bottom berriing (as it protrudes through the table).  dpending on the provile i.e. an ogee I'll sometimes score the final profile location to break those fibers and avoid the issue.  Second, do you have a good sharp bit that's clean.  If it's got a lot of pitch built up or you've used it forever without lapping and honing it, that could cause the issue and finally is it a good bit.  I try to stick with quality bits they cost more, but you get what you pay for.  I prefer whiteside  or cmt or sommerfield bits or eagle america.  Finally if you still have issues, you could climb cut the final profile which I do anyway to get that final perfect finish. 

 

[Jesse Cloud]

Hey Howard,
Good advice above.  I'll add my 2 cents worth...

Cypress loves to splinter, its not just you.

I think the grain issue is the root of the problem.  When I'm doing a curve, I will mark on the pattern which direction the cut should be going to stay with the grain.  It will change a few times over the shape of the curve.  Either use the two bearing bit or change from a top bearing to a bottom bearing bit.

I hate doing this kind of work on a router table, mainly because you can't see what's going on and the table never seems big enough to move the piece the way you want to.  I like to use the rockler bench cookies and an OF1400.

1/8 is a lot to take off.  Definitely use multiple passes or bandsaw closer.  A trick for trimming with the bandsaw is to draw the real line and then a second line just a hair further out.  Cut between the two lines.  Easier than trying to stay somewhere near a single line.

 

[venk67]

Jesse,

Am relatively new to forum and wanted to ask you if you ever found it necessary to clamp your work piece with template to your MFT table, with the benchcookies sandwiched between?

I have a project using a template, which will be on top of my 1/2 inch plywood ,and wanted to know if i use my 1400 router whether i will need to clamp the workpiece and bench cookies to the table?

thanks

Venk