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Tear-out ?

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Dog

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I use only softwood for making stuff, at present, and even though I put a backing piece on my routing jigs I get serious tear-out. Is this due to the bit, although quality and new, the speed of the router or something else or ?
 

johnelliott

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I'm sure I (and many others here) can help with this but we need more info. Can you describe more exactly what you are doing? A diagram would be great (I use MS Paint and save as a .jpg when I want to send a diagram)
Pine is more prone to ragged edges than hardwood, but the principles are the same for any wood. When I'm machining tenons using a sliding carriage, I use a fresh piece of backing (6mm birch ply) for every tenon, and make sure that the whole is firmly clamped up
John
 

Chris Knight

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Richard,

I am very surprised that a backing piece does not prevent tearout. A couple of thoughts are :-

1. Use hard wood backers - rather than softwood that may crush
2. Sharpen your bits with a diamond "card stone"
3. If your design permits a choice and you can do it safely, use climb cutting. Please double check before doing this!
4. Use packing tape (the clear plastic sort) to tape over the cut lines before routing.
5. Mark the cut lines with a knife before routing
 

Midnight

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Richard....
sorry to hear you're having trouble bud... I'd echo what waterhead said.. and add a suggestion to take finer cuts with each pass; no more than a couple of mill...
 

Dog

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Reading through your replies I can see where I've gone wrong on two points. I've used softwood as a backing instead of hardwood and attempted to make a 7mm cut in one go instead of a series of cuts. Simple little things that make all the difference! Thanks all for putting me on course to a better routing technique :)
 

Dewy

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One point to make is to cut across the end grain 1st as this is where most break out is likely to occur then finish along the grain. This way you minimise breakout when routing as you will be cutting the breakout away on the last cuts.
 

Dog

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Thanks Dewy.

Just wondering, is hardwood easier to route compared to softwood, do you get a 'cleaner' finish or does it just depend on how you use your router ?
 

Chris Knight

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Richard,

Well-behaved hardwoods (like the usual furniture species) cut much more cleanly than softwoods. With softwoods, razor sharp tools are needed to avoid crushing the fibres and leaving a ragged looking joint. This applies to routing too. In softwoods, it would be worth trying HSS bits rather than carbide, since the latter cannot be sharpened to as fine an edge as HSS. (For this reason, Woodrat only sell HSS bits).

I don't think working in softwoods is a great way to encourage beginners, sloppy joints that look rough are too easy to make, especially as a beginner has probably not yet mastered tool sharpening. A nice piece of cherry or walnut though more expensive, is liable to prove much less frustrating.
 

Alf

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waterhead37":31lfb1xy said:
With softwoods, razor sharp tools are needed to avoid crushing the fibres and leaving a ragged looking joint.
Which is why paring softwood endgrain with your newly honed plane iron or chisel is a better test than how many arm hairs it can remove. :D (Sorry, wandering off topic a bit there. How unlike me... :oops: )

Cheers, Alf
 

Dog

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Chris, were can I buy HSS bits for my 1/2" router ? I'll give that a try as I have a large amount of softwood to get through but at the moment no hardwood to experiment with, all that will change I'm sure.
 

johnelliott

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At the risk of repeating myself, it would help us to provide more info if you would provide more info about the routing jobs you are undertaking (routing softwood with a 1/2" router is a bit vague). You mentioned not trying to rout 7mm in one go. Some cuts I would go 10mm deep easily, more maybe, it just depends on the actual job being undertaken
John
 

Adam

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Dog":uwl8nzlb said:
Chris, were can I buy HSS bits for my 1/2" router ? I'll give that a try as I have a large amount of softwood to get through but at the moment no hardwood to experiment with, all that will change I'm sure.
You could try the woodrat site...http://www.woodrat.com

Adam
 

Chris Knight

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Richard,

I'm not sure who carries these things in a full line these days - if anyone. Trend did have them until a few years ago but appear now to have gone over fully to carbide. I think cheap carbide imports killed HSS in this usage.

Bosch do/did a few, as did/do Leigh (for their jig) you could also try asking Wealden. Depending what sizes you want, end mills and slot cutters are available in half, five sixteenth, three eighths and quarter inch shank sizes from places like Tilgear. These common sizes will usually fit a router collet or suitable adapter.

You won't find HSS router cutters in any but straight bits nowadays - or the dovetails available from Woodrat. HSS dovetail bits for milling machines will have the wrong angle/size for wood.

Their superior sharpness notwithstanding, if I were going into production mode, I would opt for carbide cutters as they will last far longer between sharpenings. I also favour the replaceable insert type of straight cutter (I use KWO but I see Trend do them now)and I find these both sharp and long lasting. Despite being - or rather because they are a single cutter, they clear the waste very quickly, avoiding damaging heat build up and they also make a super job of cutting clean mortices (better in my view than the spiral solid carbide type).
 

Dewy

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Last time I looked in B&Q they had some Bosch HSS bits.
B&D do HSS bits too often costing more than TC.
 

Dog

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I've had a look around for HSS bits, the size I require is 19mm straight and 9mm straight. Prior to asking this question I had already ordered and received a 1/4" solid carbide 9mm straight bit made by CMT via APTC. I've yet to try this bit but as far as I can see on the Trend website they advertise a 19mm straight bit 1/2" HSS for £30 plus vat depending on where you buy it from. At present I'm using a TCT 19mm straight bit 1/2" again from CMT but have not tried this bit with hardwood backing on my jig which might make all the difference to the tear out problem. The cut at 7mm deep x 19mm wide has been smooth but tear out has been the problem.

To answer your questions John, I'm routing 7mm x 19mm across the grain on a piece of pine 50mm x 50mm x 265mm, 25mm down on two sides at the top, 45mm up on two sides from the bottom of this piece of timber. Then I'm routing the same piece with the grain up the centre on two sides with the 9mm bit, through the bottom 7mm x 19mm route and into but not beyond the upper 7mm x 19mm route. That's about as confusing as I can put it so I'll get a picture up asap and you'll see what I am trying to explain and why I haven't tried to explain before :wink:
 

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