Greetings from an inveterate lurker. Hope some of you will weigh in on a topic discussed before – maybe I’ll pick up something I’ve missed.
The situation: routing to a 1/4″ MDF template, 3/4″ cherry material, 2 different radiuses (radii?), each of which involved end grain. The larger radius was convex, the smaller, concave. The tools were a PC 1.5 HP router in a D handle base and a fairly new Freud top bearing flush cut bit – 2 flutes and 1/4 shank.
Having had tearout problems a while back on a similar project in red oak, I had done some reading here, and was prepped with new techniques to eliminate same. The workpieces (4) were jigsawn to close to the cut line, the template mounted on the workpiece w/ 2bl sided tape. I began by nibbling at the fatter cuts with careful climb cuts, and when quite close to the template, finished each cut against bit rotation.
The results were very discouraging. Only one of the four pieces came out clean. Two of the others had nasty tearout on the steepest part of the endgrain cut. The fourth was worst of all. While nibbling my way close to the template, the bit caught and pulled a huge crack down the grain – perhaps 6″. Instead of moving quickly and efficiently on to the next phase, it’s now repair and mitigation…..sigh.
So what gives?
Replies
RD,
Possible causes are:
* still taking too big a bite - 1/16" or 1.5mm is about right for the amount sticking out beyond the template as anymore risks slowing the bit and then spelking.
* router bit rotating too slowly - check you haven't accidentally turned the speed down on the router.
* router bits not sharp enough - give them a few swipes on the flat sides with a 1200 grit diamond mini-hone.
I'm not sure what you mean about the climb cuts (can be dangerous, especially with no fence, eg around curves).
With oak and other splintery stuff I usually do "dab" cuts along the sections likely to break out (determined by looking at the grain direction relative to the cutting direction). "Dab" means pushing the work straight into and out of the bit, leaving around 1 - 2 cm of wood remaining between the dabs, to be routed off as normal.
The dabs mean that any potential splinter is quite short. The more likely a splinter will occur, the closer should be the dab cuts.
Lataxe
I use my routers all the time. My favorite tool. However, I find that woods like Jatoba, Purpleheart,Hickory will do that if you are not really careful. And even when you are really careful.
Just a thought/suggestion? Are you using anti-kickback design bits? They limit the depth that they cut and can really help.
You mentioned 'top bearing flush cut bit'. Do you have a set of different diameter bearings you can use? Takes more time, but you can change bearings and 'sneak up' on the depth you are cutting.
But then again, I almost always use my router tables and rarely cut by hand. I get better results using a table. Much more control over what I am doing.
Expensive, but when I use a straight bit, I find that a top bearing combination spiral works the best overall. Now, if they only had spiral bits with profiles!
Just me though.
Use a Spiral solid carbide bit. Preferably 1/2" dia. for straight sides. If you are doing a shaped profile, find a bit that has as much shear angle as possible.
Work Safe, Count to 10 when your done for the day !!
Bruce S.
End grain routing is usually met with some adversity; lots of fiber ends to whack compared to only a few strands down grain.
Eliminate or greatly reduce end grain tearout: Use 1/2" shanked tools with cutting diameter = 3/4" or more. & in a plunger taking 5-10% of the thickness/pass.
Routs from time to time.
It sounds like the problem is where you were cutting "against" the grain. The ideal is to cut along the grain whenever possible so the bit cannot pull away the material. This can be accomplished by attaching the template to the other side of the piece and routing the tricky parts or you can use a top and bottom bearing bit like this to avoid having to relocate the template:
View Image
Freud America, Inc.
Take it from one who has frequently routed cherry using a template that you MUST climb route any area where the standard direction be into the downhill grain. Just don't even think about routing the regular direction. Many wood are the same way.
Hey guys.
Thanks for all the replies. Some comfirm thoughts I've had while chewing over the problem, some debunk similar thoughts.
Lataxe: the router in question is a single speed, so the speed was as fast as it could go.....but at only 1.5 HP, the workpiece might well have slowed it down below optimum RPM. I was actually thinking that maybe I should have brought in my variable speed 2.25 HP and slowed the speed......guess that was poor thinking. I also like the idea of "dapping", although I think that's essentially what I was doing (perhaps a tad too aggressively?) when the big blowout occurred.
Routerman: I like the idea of incremental plunging, together, I presume with all other cautions employed. I was also thinking perhaps bigger would be better. Thanks for the input.
Charles: No aspersions cast upon Freud here. I've liked the router bits, provided one uses them appropriately. I have also found that so long as one purchases the industrial line (saw blades), they too provide excellent service. The bit pictured could be a real time saver, as well as an aid toward eliminating alignment error when switching templates to the other side of the workpiece.
Don't mean to ignore other posters - can't refer back to the thread from here - but the other thing that all made clear is that one can't be too careful, slow, incremental, etc. in situations like this. And that perhaps a spiral bit in a guide with a modified template might be a better approach, although I'm not immediately coming up with a simple means of shrinking down a radius so as to compensate for the guide's increased diameter......
Perhaps things will go better next time.....was it Einstein who defined insanity as expecting different results when one repeats a procedure?
So I am just me.. I only slow down the router for BIG bits.. As in over one inch in diameter. I could be wrong...
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