At one time drill bits had 1 flute (spoon bit) and then some one said if they had 2 flutes and a twist they could cut a cleaner hole and faster ,same thing is true for the router bit..it just took a longer time to get them on the market place.. you could call it a shew angle on the router bit.

Note to say anything about mill ends 2,3,4,6, flutes, cleaner cuts with less speed,...speed = heat...and a shorter life for the tool..

========

 

The spiral bits will cut cleaner and quicker. There are upward spirals, downward spirals and a combination of the two called compression bits. You may want to consider all three.
The upward spiral, when handheld, will likely cause some tearing of the wood on the top edge of the cut. So if a clean top edge is required then a downward spiral bit would be the better choice. But since the downward bit will be pushing chips downward into the trench, you would probably need some vacumn assistance for chip clearance. The opposite is true if using the router in a table.
The compression bit has flutes running towards the centre of the bit. They give clean edges on both top an bottom and are ideal for cutting laminated sheets. You will be limited in the thickness of material however. I have one compression bit, it allows me to cut material up to about 19mm, I think. Which is ideal for whiteboard (melamine coated chipboard) but not much else.
These bits are usually more expensive than straight cutters but since I bought mine I haven't used anything else. Worth it if you can afford them.

 

Let's see now, Spiral vs. Straight bits. Spirals always win with me, they give a much cleaner and smoother cut than that of the straights. Atleast with my experience that is.

 

Up spiral in the table and down spiral hand held for plunge routing in my experience are far superior to the common or garden straight cutter for both chip clearance and clean cut.

 

The only thing I've found with routing smaller, less than 1/4", dados with upspirals in soft pine is that they tend to wind the wood fibers in long strands instead of chipping. Noticed it mostly doing box bottom dados so I switched to slot cutters or straight bits for that. Spirals are pretty much my go to for everything else, especially anything involving a plunge.

 

Especially in confined spaces, when template routing (even when routing vertically), straights tend to pack debris in the corners preventing the guide from reaching the corners. I'm slowly replacing my old straights with spirals and going back to mortising bits for plowing.

I'd got into the habit of using plunge straights for template/plowing, (fewer bit changes) but I probably spent as much or more time with extra sanding.

 

Ever since I started a fire in my shopvac (go ahead and laugh!), I broke down and switched to spiral. The cost is now comparable to straight bits - maybe because they are becoming more popular.

 

Hi Gav,

Technically, it works both ways. Depends on the material, ie., ply vs solid wood.

 

Hi Peter,
I got them from schachermayer(.hr). Although they in turn had to order them and it took about 10 days. Today I made up for the cost of those by finding a set of carbide tip bits at the flea market. They are razor sharp, brand new and unbranded. 6 bits (straight and profiles) set me back 100 kuna (about us$20). Thats less than the price I would have to pay for one bosch bit in the hardware store here.

 

Hi Gav

I can see I'm going to have to come over there !
I wonder where the guy in the flea market sourced them. There are plenty of people sourcing stuff directly from China. Pevec certainly were and were trucking the stuff down from Rotterdam and Hamburg on their own trucks. If we could find someone with established Chinese relationships that could be persuaded to add router bits to their range we might get somewhere. I've been in contact with some Chinese suppliers but, although their minimums were quite low, I've no distribution mechanism to get rid of the surplus and no particular desire to start one. At the time, we were much too busy in the office. The flea market guy must be dealing with someone who is importing them from a router bit supplier. Getting hold of whoever that is and persuading them to widen their range could be useful.

Cheers

Peter

 

He just had the one boxed set of bits and I neglected to ask him where he got them. The other stuff he had was just a few odd tools and bits and bobs so I don't think he got them from a supplier. In fact, maybe he got them from someone who worked at pevec. I hear a lot of that was going on in the last days. If he's there next week, I'll ask.
Someone posted a link to chinese router bit supplier on this site a while back and they had the best size range of spiral bits I'd seen. We're not the only ones in this country wanting them at a decent price. I've read a few Croatian forums about woodworking and guitar making, and there seem to be quite a few people frustrated about the poor selection and high price available here.
Perhaps I'll make a few posts and see if there is any interest.

 

Hi Gav

Any Istrians on the Croatian forums? Not speaking much Croatian, I've never tried them.

You could be right about ex Pevec people. They probably took them when they weren't paid.

 

Sorry to hijack the topic, but it's pretty much the same thing. I am planning on building a bookcase for my first ever project. If I am going to use dadoes for the shelves, what type of bit should I use? A spiral bit or a straight bit?

 

Hi Joshua

I suggest using the bits below, made just for dado slots..

for plywood

4 pc 1/2" SH Dado Plywood Straight Router Bit Set - eBay (item 140362910691 end time Dec-25-09 18:51:51 PST)


for real wood

MLCS dado router bits

====

 

Hi Josh

As the dados are shallow, I don't think it would make much difference but others may disagree. A down spiral could leave a cleaner finish depending on what wood you are using.

Cheers

Peter

 

Thanks for the response. Perhaps since this is my first project, I should just start with a straight bit and learn. Then on down the line try out the spiral bits. I saw that they were helpful with mortises, but didn't know if I would be able to see much benefit from them now.

 

What makes a bit specific for use with plywood?

 

Hi Gav

It's not so much specific to plywood as matching the real thickness of plywood for dados. What is sold as 3/4", 1/2", 3/8" and 1/4" thick plywood is often not literally that. Some of it is the nearest metric size and some seems to just be undersized. Consequently, someone cutting a 3/4" dado with a regular 3/4" cutter finds the matching plywood is a loose fit. Several cutter manufacturers offer sets approximating to what the real world thicknesses of plywood are. Holbren had a great deal on some earlier in the year that were mis marked and they knocked out for pennies to get rid of them.

HTH

Peter

 

Gavin,

Measure your plywood.. What we have here in the US is always undersized. Out 3/4" is actually 23/32" or slightly under, so companies make plywood dado bits (calling them plywood bits) that are also undersized. That's why 23/32" is common but 21/32" isn't.

 

Thanks, that clears that up.
I'l have to check the ply next time I get some.

 

Now I am tempted to get some spiral bits.

 

Hi Mike,

I think that once you try a spiral, you won't want to use anything but spirals.

 

Hi, Mike.

Maybe this will help. You've probably seen a fluted reamer, which is used to
enlarge a hole with great precision, in tiny increments. When you use one,
all the waste material gets compacted into the flutes, and if you imagine this
hand-operated tool being spun at 20,000 rpm, you can relate this to a router
bit in a slot or dado. The straight bit does not eject the waste except by
a scattering process, but the spiral bit conducts the waste from the cutting
zone, thereby not causing binding and plugging in the cut. The result is a
cooler bit, and a clean shear line. The good quality bits of made of solid
carbide, which should last an extremely long time for the average user.

They cost more, they do a particularily accurate milling action, and are made
by several honorable brand names. I like Freud and Bosch.

Regards,
Art

 

Trend bits cost a fortune. I may get a set of the MLCS bits.

 

Rutlands do some Tornado 3 Pce Up Cut Set (TR31) - Buy online from Rutlands.co.uk
I've been waiting to see whether they come down in price but no joy so far !

Cheers

Peter