New shaper bit blowout

[Patrick LaFree]

Hi all,

Im hoping for some advice on a grizzly 3/4" rabbeting bit I bought for my shaper. Ive used it ~20 times and the blowout is getting worse and worse. Is this just a cheap bit or am I doing something wrong? Ive run it with a powerfeed, fence, and by hand and get the same affect.

The 3/4" bore on my shaper fits into a large collet. Its somewhat of a strange design to me and sometimes it feels loose. Maybe thats the problem? Anyone had a similar experience with a shaper like this?

Let me know your thoughts,

Patrick

[J.R. Rutter]

Climb cut will be better, but messier. Use the feeder.

Nothing should feel loose though...

[Mel Fulks]

If it's a single speed 8000 rpm machine ,I would say the cutter is too small for low rpm

[Peter Kelly]

Might also try a rebate cutterhead with scoring knives. CMT makes one with a 3/4" bore.

http://www.cmtutensili.com/media/files/471_279_fs_694.100.jpg

http://www.cmtutensili.com/show_items.asp?pars=HK~694.100~2~2~3

[David Kumm]

How many passes? Small diameter with no knickers needs almost router speed to get the tip velocity where you want it. As JR suggested, climb cut might be better. Does the spindle attach with a draw bar into the taper? Have you measured runout? I don't think that is the issue, but good to know. Dave

[Mark Bolton]

If you make a zero clearance face for your fence you may reduce the problem quite a bit

[Cary Falk]

What wood is that. I see similar things in red oak but this looks like maple. The bit may be dull. I would make a shallow scoring pass first and maybe make a couple or more passes. I agree with the zero clearance fence helping.

[Rod Sheridan]

Possible issues

- cutter speed too low

- cutter diameter too small

- no scoring cutters

-dull cutter

- difficult wood ( climb cut with feeder).

In other words, basically what everyone before me said............Regards, Rod.

[Patrick LaFree]

Thanks for all the advice. I make mostly poplar interior doors. Thats the material shown above.

I will try a new zero clearance fence. I suppose I have gotten lazy. I have been hesitant to climb cut because I do it mostly by hand as my power feeder isn't the best. I will see how it works though.

Thanks again!

[Jeff Heath]

Just to reiterate......please use the feeder of you're doing a climb cut. Stating this for the new guys that might not know better.

It gets ugly quickly when spears fly across the shop, and through a wall, at 200 mph. DAMHIKT.

[Rod Sheridan]

Just to reiterate......please use the feeder of you're doing a climb cut. Stating this for the new guys that might not know better.

It gets ugly quickly when spears fly across the shop, and through a wall, at 200 mph. DAMHIKT.

That's a word to the wise Jeff..............Rod.

[Joe Acquisto]

I have the same bit and not had a problem. I do use a zero clearance fence which I think is why I don't have a problem

[Jim Mackell]

Could one of you clarify what you mean by "climb cutting"? Are you referring to making multiple passes taking off a little more each time?

Thanks!

[Cary Falk]

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This should explain it.

[Jeff Heath]

You always want to feed the wood "into" the direction of the spinning cutter. Going opposite of that, with the rotation of the cutter, is a climb cut, and be interesting if precautions aren't taken.....to say the least.

[Rod Sheridan]

Cary provided a great illustration of conventional and climb cutting.

To climb cut you'll need a stock feeder...............Rod.

[Jim Mackell]

Thanks Cary. Not something I want to experiment with.

[J.R. Rutter]

Climb cutting is a piece of cake with a feeder for small cutters. It can get a little more exciting with larger cutters, but if you set the feeder up properly, still not a big deal. Biggest issue is the dust collection. It requires an extra collection point out along the fence where the chips get ejected...

[Mark Hennebury]

The biggest problem with climb cutting is that cutters are not designed for climb-cutting they are designed for up-cutting.
The tool geometry for up-cutting is a compromise to prevent the splintering that you had.
A small rake angle provides more forward push and less lift.
382293
A large rake angle cuts better as long as the grain direction is good, when the grain direction is bad it will lift the grain and splinter out.
So they make the rake angle small to counter that.
It doesn't cut so much as scrapes but it doesn't lift and splinter, so its a compromise.

382294

A high rake angle works best for climb cutting.
A high rake angle with chip limit design works the safest.
Climb cutting with up-cutting bits can be done and will often give better results if you are having problems up-cutting.
Climb cutting with an up-cutting bit is not ideal, it is like playing basketball with soccer cleats, you can get away with it if you have to. But the "blunt" angle will not cut very well but will grab more, and it can shoot the wood like a bullet if it is not properly controlled, that is why many have suggested to use a power feeder.

A bit designed for climb-cutting does not have to be a compromise like the up-cut bit as it has no concern for lifting the chips, and can therefore be a "sharper " angle as it is only concerned with cutting not lifting. A sharper angle will cut easily without the grabbing effect of an up-cut bit. One designed with a chip limiter would cut cleanly and will be easy to control feed. The climb cutting is cutting down into the wood so there is no splintering.
Unfortunately i don't know of any company that makes climb-cutting tooling.


382299

[Brian Holcombe]

I make these cuts with my router table occasionally, I don't have a bit with a knicker so what I do is simply score a line with my marking gauge. I set it very exacting and make certain that the cutter is cutting at the line so that the mark is removed by the cutter. Works well, especially in a spot where it absolutely must be crispy clean.

[Jim Andrew]

I have found that taking a full cut with my shaper making door rails splinters bad, so have taken to just jointing the splintered edge and running again which eliminates most of the splinters.

[Mel Fulks]

Jim, one good way to stop that tear off is to use a small roundover bit to climb cut those pieces before the "real " cut. "Keeps the sweater from unraveling". That round over can be done with the feeder on high speed. Try it

[Joe Calhoon]

We used braised tools like that to make square edge doors back in the 80s. A backup fence will help but not all the time depending on species. In the case of larger house size grooves we would cut on the shaper over depth then take a 1/16 off on the jointer or planer. Another method was to climb cut a 1/16 or so deep using a clamp on fence for quick setup and then do the final cut conventional. Both with a feeder of course. This method produces good results.

As JR mentions climb cutting makes a mess and is something we rarely do anymore for safety reasons.

We use adjustable groovers now with nickers and get clean cuts with one pass. We also have a custom made head that takes the whole edge, is adjustable for width and puts a 1mm radius round over where the panel goes in. This one makes a nice cut but not everyone likes the look of the rounded edge.

[Phillip Gregory]

If it's a single speed 8000 rpm machine ,I would say the cutter is too small for low rpm

That cutter is 2 5/8" in diameter, and would need to be spun at a minimum 10,000 rpm to attempt to cut well. 8000 rpm would be appropriate for a 4-5" cutter head.