Spiral Router Cutters - Uppercut or Below the Belt?

[wizer]

I've got a couple of Wealdens Spiral Upcut bits. I've used them for a few things and I must admit I've never been terribly impressed by them. I hear and read a lot about them but I still seem to get as much burning and chip out as with straight cutting bits, if not more. Should I have bought downcut bits?

For example, here's a few operations:

Routing small hinge recesses on jewellery boxes, on the Router Table.
Routing 15mm grooves in hardwood using a template collar, Hand Held.
Routing 4mm grooves for box tops and bottoms, on the RT
Routing Mortices hand held with a fence.

Would these all use the same type of bit?

 

[Chems]

Uppercut is right, removes the chips out the hole. Downcut is for things like laminate where you want to avoid chip out of the face side. But downcut is considered better for things where you will see the rebate or dado you are making, like your hinges, but you'll need to go even slower with a downcut to give it time to get ride of the waste.

Good extraction helps with burning, specially on a router table were the bits can get trapped an go round an round. But burning can often be caused by going to slow with the speed set to high.

 

[wizer]

I've just seen that Wealden don't do spiral bits bigger than half inch anyway. So that kinda solves that problem. I will use a straight bit for the grooves.

I used a 6.5mm spiral upcut bit to cut the hinge recess on the jewellery box today. It very nearly was a disaster because of chip out. I managed to save it, but it's not ideal. The bit may have been a too big. Doug Stowe recommends a 3/16" bit, which I think is about 4.5mm ? Wealden do a hinge recess bit, but it must be for door hinges as it starts at about 10mm.

I didn't have any extraction today but I also didn't have any burning issues. I'll need to use the big triton with extraction when I cut the grooves on the stool.

 

[woodbloke]

I use a conventional router bit for mortises and have never had a problem...spiral bits though are supposed to be better, but I've not tried one - Rob

 

[Harbo]

I use carbide spiral upcutters on my WoodRat for mortising with no problems at all.

Rod

 

[cutting solutions]

Solid Carbide bits are best used at high spindle and feed speeds. and are really for CNC machines.
Titman may be along shortly but from their catalogue:
max rpm 14,000 to 24,000 depending on diameter
feed speeds 10-20 metres/min

8-14 mm cutters with feed speed 8 metres/min should have spindle speed of nearly 16,000 rpm

Larger cutters are available

Maybe you are not using the right tool for the job.
Doug

 

[wizer]

Maybe you are not using the right tool for the job.
Doug

I suspected that Doug, so what would be the right bit(s) for the jobs listed?

 

[cutting solutions]

Will come back to that shortly....Andy pandy time

 

[Chems]

The dom has an upcut bit installed. Works nicely too.

 

[cutting solutions]

I suspected that Doug, so what would be the right bit(s) for the jobs listed?

I really dont think you would get a better finish than with a good quality sharp TCT 2 flute router.

many people use their routers over a period of time on different materials and dont realise the cutters gone blunt and needs sharpening.
Could that be the case with the spirals?

I will check the shallow hinge operation in the morning when I have a catalogue to hand.

 

[wizer]

Yes, it could be. It's not been used all that much, but it has been used on MDF and Ply. I will order a new one, which I needed anyway and I'm not going to bother with spirals for the time being. Perhaps I'll get one if I'm doing some large mortising jobs or something.

cheers

 

[leverb01507]

I think that straight cutters (two flute) are just as good as up cut bits as long as you keep them well touched up with a small diamond file, especially if your using an extractor to lift the waste.
The only spiral cutter i would use is a down cut bit for use on veneered sheet materials as the help keep the face clean and free from lifting/splitting.
But thats just me maybe other people find that an upcut bit really does make a difference to the quality of the finish.