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Spiral Router Bits - what sizes?

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Forum topic by WorksInTheory posted 05-29-2018 09:55 PM 1231 views 0 times favorited 20 replies Add to Favorites Watch
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WorksInTheory

177 posts in 2022 days


05-29-2018 09:55 PM

Hi – think I will make the jump to spiral router bits, atleast for mortising. Everything I search on talks about downcut vs upcut vs compression but none talk about what sizes to get first in a set. I am thinking I need 3 diff sizes but not sure which ones are the ones to get. Will get upcut and will use in table and handheld. Not sure what are the 3 diameters and lengths to get. Should I get the longest possible for a given diameter for versatility?


20 replies so far

View Bill White's profile

Bill White

5210 posts in 4380 days


#1 posted 05-29-2018 10:03 PM

1/4”, 3/8”, 1/2”, and be sure to get those that will plunge cut. I don’t have carbide due to their rather brittle nature (and expense).

-- [email protected]

View pintodeluxe's profile

pintodeluxe

5951 posts in 3233 days


#2 posted 05-29-2018 10:08 PM

I have found 1/4” spiral bits to be extremely valuable in the shop. Don’t mess with the HSS variety, go for the solid carbide.

I get the Whiteside in their standard length. I think they’re around 3” long overall.

Good luck with it.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View LesB's profile

LesB

2126 posts in 3863 days


#3 posted 05-29-2018 11:22 PM

I think carbide is the only way to go for router bits.
Spiral bits are no exception. One difference in down vs up cut is the affect on the edge of the recess you are making. The down cut will make a clean edge to the cut while the up cut may (depending on the wood) tear out some wood around the edge.. Next. Up cut brings the waste material out of a recess like a mortise where as down cut does the opposite. If I had one choice it would be up cut unless I needed a really clean edge. On Mortises the edge of the recess is usually covered so up cut is not a problem.
If you are limited in funds I would start with the 1/4” because with a template guide for the mortise you can always make multiple passes; of course for deeper mortises you will need to make multiple depth passes too. If you can affortd the cost then get a 1/4, 3/8, and 1/2 in a quality carbide like Whiteside. As with most tools buying inexpensive or low quality will not lead to happiness.

p.s. I even have a couple of 1/8” spiral bits for making template guided inlays.

-- Les B, Oregon

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WorksInTheory

177 posts in 2022 days


#4 posted 05-29-2018 11:40 PM

Okay if I can afford it 1/4, 3/8 and 1/2 or maybe 1/4 and 3/8 might cover it. Get the longest possible?

Also has moving from flute to spiral like a game changing experience?

View jonah's profile

jonah

2075 posts in 3718 days


#5 posted 05-29-2018 11:54 PM

I find I use 3/8” the most, since that’s the mortise size used most for 4/4 stock. If I could only pick one, it would be 3/8”. Second would be 1/2”.

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WorksInTheory

177 posts in 2022 days


#6 posted 05-30-2018 12:33 AM

I was going to buy them from Infinity but strangely they only have 1/4 and 1/2.
What’s the best bang for the buck spiral bits?

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jonah

2075 posts in 3718 days


#7 posted 05-30-2018 01:45 PM

Freud and Whiteside are premium bits with the price to match. There are a few less expensive ones. I have a Yonico bit that is perfectly fine. I haven’t had it long and have only used it twice, but it seems fine so far.

Solid carbide bits are going to be relatively pricey any way you slice it, but the Yonico was like $35 where the Whiteside bits were $60 or more for the same size.

View Lazyman's profile

Lazyman

3543 posts in 1807 days


#8 posted 05-30-2018 01:55 PM

As was mentioned above, an upcut bit can cause a little tearout in some cases so when cutting mortises, it can be helpful to start as if you are going to cut it out by hand by scoring with a knife or marking gauge and then using a chisel to cut the long sides at least. If you are going to square the moritise after using the router, you might as well do the entire mortise perimeter before you start.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View Andre's profile

Andre

2672 posts in 2225 days


#9 posted 05-30-2018 02:57 PM



I have found 1/4” spiral bits to be extremely valuable in the shop. Don t mess with the HSS variety, go for the solid carbide.

I get the Whiteside in their standard length. I think they re around 3” long overall.

Good luck with it.

- pintodeluxe

Just had a Freud carbide 1/4” break in half, first time it has ever happened. Was on my 1.5 hp Grizzly shaper
cutting some white oak only about 1’4” deep , funny thing was it happened at the end of the last cut, lifted board off and bit was snapped? Have looked at the Whiteside but the cost has kept me with the Freud.

-- Lifting one end of the plank.

View splintergroup's profile

splintergroup

2728 posts in 1642 days


#10 posted 05-31-2018 01:54 PM

I’ve used/use a number of spiral bits for morticing (and I also had a 1/4” carbide bit snap).

1/4, 3/8, and 1/2 are by far my most used.

Carbide is the cats meow for cutter life, but only get bits with cutter length as long as the deepest mortice you plan to cut. Long cutters are weaker.

Lately I’ve been using three flute HSS mill bits for my 1/8 – 1/4 cuts. Only a few bucks each and they produce a very clean cut. I haven’t worn one out yet! (cuts with these bits usually are no more then 1/4” deep).

View WorksInTheory's profile

WorksInTheory

177 posts in 2022 days


#11 posted 05-31-2018 06:57 PM

What is the rule for mortise and tenon length? I know width is like 1/3 rule right.

View splintergroup's profile

splintergroup

2728 posts in 1642 days


#12 posted 06-01-2018 01:37 PM

Length depends…

Typically I’ll try for at least double the tenon thickness, more if the joint needs optimum strength. The other consideration is the mortice. Its integrity should not be compromised by a large (deep) mortice. For example, I would limit a table leg mortice to no more then 1/2 the leg thickness when the mortice is within a few inches of an end. Mortices away from the end of leg can go completely through.

Tenons can be the full thickness of the part, but a shoulder helps with racking strength and alignment. Tenons thinner then say 1/4” don’t have much strength for something like a table but are plenty for a cabinet door.

Lots of variables!

View Holbren's profile

Holbren

23 posts in 1423 days


#13 posted 06-01-2018 06:00 PM

Be careful when buying solid carbide spirals, the cutting diameter often matches the shank diameter because they start from a rod of carbide. You can get 3/8” diameter with a 1/2” shank just need to make sure you don’t order the 3/8” shank by accident unless you can accommodate then you will save some money.

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WorksInTheory

177 posts in 2022 days


#14 posted 07-18-2018 07:30 PM

Okay sorry life got busy and I have been away for a while. Back for air.

Picking up where we left off – settled on 1/4” and 1/2” upcut. Don’t want to deal with 3/8” shank and can cover that with the other 2. Finally getting it from Infinity – chance to try out something from them. Will deal w/ downcut later but in the meantime can use some of the methods suggested such as scoring.

Question: 1/4” will pick up a 1” cutting length should cover it. But on 1/2” what should I be considering – choices 1 5/8” vs 2 1/8” cutting length or 3 1/2” overall length vs 4”. I will be using likely in a Bosch 1617 handheld or Triton 3.25hp in table.

View Andybb's profile

Andybb

1932 posts in 1023 days


#15 posted 07-18-2018 09:14 PM

No issue using the Bosch or a any 3.5hp monster for any of those bits. Just make sure you have the collets for the bit size.

-- Andy - Seattle USA

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