Pattern Bit Grabbing

[Paul H]

Hey Guy's,

I have a GMC 1250 Router mounted in the GMC table with a 50mm 1/2 in pattern following but in. I have jigsawed out some shelf brackets (pine) with a couple of curves in and the idea is to fix my template on and run them through the router.

The bit, however, wants to grab hold of the work and through it across the workshop/in my face!!:eek:

Not too keen on that idea.

Any ideas on why it is doing it? I am not shoving the work onto it, just gently feeding it on to the bit. I've lost two roughs already with the bit tearing huge chunks off. I might have to go back to the drum sander in the drill press otherwise.

Cheers
Paul H

[Wood Butcher]

Which direction are you feeding the timber? you should be feeding the timber against the direction of router bit. If you feed the timber with the rotation of the bit you could end up in serious trouble, ie timber being flung across the shed or worse into you!

[Paul H]

Hey Rowan,

Thanks mate, yes feeding against the direction of the bit. The strange thing is that I have done this before, a while back though. I have looked at the bit and it is clean and sharp. Haven't used it that much and not on any Jarrah yet.

Cheers
Paul H

[journeyman Mick]

Paul,
what Rowan said, plus you may need to have the job against a starting pin.

Mick

[martrix]

Most likely, it's the change of direction in the grain when the curve's change from concave to convex, and vice-versa......I really need to draw a picture to explain it better, but it's time for bed.

Best and safest option, is to have your bandsawn piece with template, fixed down, and to use the router hand-held. That way, you can back-cut the area's where the grain is running against the cutter direction(ie; want's to rip out chip's).....sorry if I have confused you.......hopefully someone else can explain betterer than moi! night........

[Termite]

To solve the against the grain problem get hold of one of the pattern bits with a bearing at each end, all you do is turn the job over so you are cutting with the grain all the time.

[Paul H]

Comrades,

Figured out the problem apart from the fact it's a GMC, or perhaps because of it. I was doing some rounding over, and I normally put my spanner on the table over the hole to set the height of the bit. the shoulder not quite touching the spanner.

I noticed that even with this it still cut a bit of a shoulder on the wood.

It's because the bit is tilting to the right!

I set it with the spanner on the right side of the bit, and as the wood passes over the left side the shoulder get's cut. When I put my 2" long Pattern bit in the machine and put my square along side there is a gap at the bottom (on the right hand side) of around a half a mm.

I put in a quality bearing, but that has not corrected it. I know need to figure out how to shim it, or where the error is coming in.

Bugger.

Cheers
Paul H