Thread: Spiral or straight cut bits for the I-Box jig?

I've never used an I-Box but assume you're exclusively cutting in to end grain. If that's the case an upcut bit would be the best choice IMO, I can't see any advantage in using a downcut bit.

If you are getting the tearout on the entry face of the piece I would say it is the quality or sharpness of the bit causing it. When using the Gifkins jig you only use straight bits and no tearout on the front face. These are quality bits supplied with the jig.
When I use my homemade Finger Joint jig, I use a spiral upcut bit but it wasn't a <$100 bit and I don't get tearout.
I think you will always get tearout with ply especially the cheaper stuff.

Aaah yes, with the router inverted in the table an uncut bit does become a downcut and vice versa. I did wonder how people go on with the Gifkins and other similar jigs as there is never mention of tear-out so the quality of the bit probably has a lot to do with performance. Similar to comparing a Toyota to a Trabant I would imagine. I shall check out the "Carbitool" offerings next time I venture into town.
Thanks for the advice.

Correct me if I'm wrong Hilly but I always thought that upcut and downcut was in reference to the piece being cut. Upcut draws material out of the cut but also runs the risk of tearout at the edges. Downcut prevents tearout beautifully but does compromise removal of material.

Oh, and I've given up on the Big Green shed bits Hilly. Carbitool or CMT and just get the one bit you really need. slowly you will end up with a small but usable collection, better than a whole suite of unsatisfactory ones.

Originally Posted by Bendigo Bob

Correct me if I'm wrong Hilly but I always thought that upcut and downcut was in reference to the piece being cut. Upcut draws material out of the cut but also runs the risk of tearout at the edges. Downcut prevents tearout beautifully but does compromise removal of material.

Yeah, I realise this but in my defence and to use my late Mother's excuse "but I'm old!" and I was looking at something that's upside down. And when the instructions tor the I-Box jig said to have the red knob on the left hand side of the router table......Looking from which end? Fortunately it only takes a few minutes to turn the thing around.
And yes, I have almost given up on that big green shed, except for a few things where they are cheaper than the smaller blue sheds.

"Age related" That's what my doc says every time I go in with a complaint. 70 next year so it's sneaking up on me.

One thing I did find with router bits is the HUUUGE difference in cut quality even with the same profile bit. I had one of those 'sets' from the box store and was making stuff for a local artist group out of ply (just table top criss-cross easels.)

Was having terrible trouble with tear-out on a 1/4 inch round-over bit. Went and bought a Carbitool one from Tools Unlimited here in Bendigo and WOW, could even smoothly cut up into the grain and leave it smooth.

To look at the two bits you could not see any quality difference at all, but you really knew it in use.

Found the same with straight cut dado bits. My Triton bit is several levels better than the cheap ones

Yes Bob, I think this is a good excuse to go to town and buy something not related to gardening or flood damage restoration. I think I saw some Carbitool bits at Total Tools so I might just go and see what's available. One good bit probably costs about as much as a whole set from the Green Shed but works a whole lot better!

Bunnings used to stock Diablo bits which I always found to be acceptable but they seem to have dropped them a year or so ago so I won't buy the bits they stock now either.

Yes, they were reasonable (which is probably why Bunnings got rid of them) but I ventured into Total Tools and grabbed a Carbitool bit to see how it works. I might even get chance to try it out if the weather keeps me indoors instead of doing garden stuff.

Originally Posted by Old Hilly

Yes, they were reasonable (which is probably why Bunnings got rid of them) but I ventured into Total Tools and grabbed a Carbitool bit to see how it works. I might even get chance to try it out if the weather keeps me indoors instead of doing garden stuff.

I had to buy a really long 1/2" straight cut bit (95mm total, 50.8mm cut) for the mortises on my current workbench build and ended up with a Carbitool bit which has been excellent.

Well, initial observations indicate a vast improvement. If I get really addicted to making boxes I might just try a spiral upcut bit but I will wait and see what happens with something other than Meranti.

Another option for buying quality bits is here. They have a limited range but the price is good.

Originally Posted by Old Hilly

Yes, they were reasonable (which is probably why Bunnings got rid of them) but I ventured into Total Tools and grabbed a Carbitool bit to see how it works. I might even get chance to try it out if the weather keeps me indoors instead of doing garden stuff.

Ha, I now dearly wish I DIDN"T have a garden.