# spiral vs. straight bits



## newby (Feb 24, 2011)

Hey folks, I am about ready for the Oak Park box jig, Will I get better results from spiral over straight bits for my cuts? My set now a 1/2" shank mlcs set. Thanks to everyone for their in-put about the O.P. jig Mike


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## Mike (Nov 22, 2004)

Mike, for the best results with your jig I suggest using a solid carbide spiral up cut bit. This bit will cut cleaner and last much longer. To understand the "Why?" think of using a knife to cut a tomato. When you simply push the sharp edge against the tomato it will make a cut but the tomato will slightly deform. Now try slicing by drawing the edge across the tomato; it will cut cleanly and not deform the tomato. Router bits work much the same way. As the bit spins the spiral is slicing for a cleaner cut with less chance of "fuzzing" or tear out. Another advantage is the up cut spiral bit will pull the saw dust and chips away from the work piece like a drill bit. Bit manufacturers realized this and made an improvement to straight bits by setting the carbide insert at an angle length wise. You can prove this by making a pass in wood with each of the bits. While all three styles will make the cut a straight bit will pack the dust tightly in the slot behind the bit, the angled bit will remove part of the dust and a spiral bit will remove most of it.

This brings up another common question: What is the difference between an up cut spiral bit and a down cut? Which should I use when routing free hand or table mounted? The answer is it depends on what material you are using. It does not matter if you are above the table (free hand) or table mounted.
An up cut spiral bit pulls the dust away from the material towards the router. This is best for solid materials.
A down cut spiral bit pushes the dust into the cut to prevent tear out with veneers or plywood.
A compression spiral bit is for edge routing an entire edge with laminated materials like plywood and the cutting action squeezes them together to prevent tear out or separation.


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## dougop (Jul 2, 2010)

If you can find the right size, a spiral bit is almost always a better choice ! The shearing action of the " angled " edge will greatly reduce tearout on most cuts/materials, load on your machine is more even, and slightly less power is required due to a more even load. At lower rpm's, the feeding of work is smoother as well, especially with larger diameter cutters. I find cutters from other types of work than just woodworking, and the spiral cutters' results are well worth the increase in tooling costs.


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## cdouglas1942 (Oct 15, 2007)

Spirals cut marked easier than straights in my experience. I have the Oak Park Box Jigs and like them alot. You will find the key item in their use is the space between the bit and the fence. It will need to be snugger on the spacer bar than you expect. I did my first set with the spacer bar just "kissing" the bit as it went by and the box joints had to be hammered together. A few taps of the fine adjustment tool to tighten things up solved the fitment problems...and as Bob says, "Isn't it nice when it fits".


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## SEJ (Jun 22, 2011)

WOW! Didn't know this forum existed. (But, I don't spend time surfing the net) I replaced mt tinker toy table saw with a real one a couple of years ago (Grizzly 2HP contractor style), and all of a sudden things got pretty easy. (Nothing like a good fence!) So I have been spending more time playing with wood these days, and buying more tools.
This is going to be informative and FUN!
Scott


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## woodmanz (Oct 31, 2011)

*oak park jig*

first want to say great forum. second can the op jig mount to any table I read it was made for there table. Waiting for an answer before I buy. thanks the woodmanz


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## jw2170 (Jan 24, 2008)

woodmanz said:


> first want to say great forum. second can the op jig mount to any table I read it was made for there table. Waiting for an answer before I buy. thanks the woodmanz


Hi David
The OP jigs are designed for easy mounting to the OP table, but they can be mounted on other tables.

I and others have used them on other brand tables before I purchased an OP table.


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## bobj3 (Jan 17, 2006)

Hi

See the link below and take a hard look at the bottom part of the web page to see how to it mount to your table with out drilling any holes, (see videos) (OP type ) if they are to short for your table, mount it to some 1/4" thick MDF and then clamp it to your table..

Fast Joint Precision Joinery System

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woodmanz said:


> first want to say great forum. second can the op jig mount to any table I read it was made for there table. Waiting for an answer before I buy. thanks the woodmanz


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## fixrite (Apr 5, 2011)

thanks that has answered a few of my own questions


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## Quillman (Aug 16, 2010)

"Will I get better results from spiral "

See no.12 for some precautuionary background.


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## tdale (Feb 18, 2012)

Seems like it's difficult to find spiral bits with a 2" cutting height....


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## JimInWoodstock (Mar 12, 2012)

*2 inch flute 1/2 inch spiral bit*

There are 2 inch long bits at endmilldiscount.com


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## CW1 (Mar 20, 2012)

JimInWoodstock has a good point. Do not buy these things in a woodworking store. Go to a metal working store and buy two flute solid carbide endmills. That is what the "manufacturers" do then they double the price, call them router bits and sell them to the unsuspecting wood worker. I do wood as a hobby. I do metal for a living (or did. Recently retired).


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## JimInWoodstock (Mar 12, 2012)

Here is the URL

Very nice 1/2 in 2 inch long solid carbide cutter as well as others

End Mill Discount - Carbide End Mills


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## LMT Onsrud (Onsrud) (Jan 9, 2012)

*2" Cutting Edge Length on bits...*



tdale said:


> Seems like it's difficult to find spiral bits with a 2" cutting height....


Good evening,

Which material are you cutting...there are several available but it does really make a difference as to the material being cut so you can chose the correct bit...


Fred


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## rwl7532 (Sep 8, 2011)

Looking for spiral upcut bits. Will HSS be a waste money or an good opportunity to save cash?

MLCS's latest mailer (page 31) has an HSS set of 7 for $49.95 with free shipping!!


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## Mike (Nov 22, 2004)

Opinions vary on this Ralph. The HS bits work well but have a much shorter life span. Carbide stays sharp a lot longer but is also more brittle. If you are working mostly with soft wood like pine you get real value for your money with the HSS since you can buy a couple for less than the cost of carbide. I opted to go with the carbide since my first HSS bit burned up on the very first job; once they turn blue they are scrap.


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## bobj3 (Jan 17, 2006)

Hi

As you know I'm a big fan of the MLCS bits BUT they are not always a good deal the HSS bits you want to back up from, 7 bits for 50.oo sounds to good to be true and like they say if it sounds to good to be true it is most of the time..

You want to get the most out of your buck as you can I would suggest you take a hard look at the link below Fred will ship the items to you via.UPS for free and his spial bits are the best I found..I only 3 so far but I'm going to buy more of them.

I will say it's hard to find the bits(s) you want because you need to read the full page ( Onsrud ) to find out what size they are but it's worth the time to do so.

Just a note if you want the HSS ones take a look at HF ones but they don't list all the sizes..but they are cheaper on the HF site and they look the same as the MLCS ones but I'm 100% sure because I don't buy HSS router bits .

69-083 Onsrud Double Edge Solid Carbide Chipbreaker Finisher Router Bit | eBay

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rwl7532 said:


> Looking for spiral upcut bits. Will HSS be a waste money or an good opportunity to save cash?
> 
> MLCS's latest mailer (page 31) has an HSS set of 7 for $49.95 with free shipping!!


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## rwl7532 (Sep 8, 2011)

Mike said:


> I opted to go with the carbide since my first HSS bit burned up on the very first job; once they turn blue they are scrap.


Would reducing the speed of the router have extended its life?
Was your HSS bit a spiral?

*** breaking news/conclusion ***
I just figured out something. MLCS has reviews for all its spiral bits EXCEPT for the HSS ones.
I think that tells the entire story.


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## CW1 (Mar 20, 2012)

Mike said:


> HSS bit burned up on the very first job; once they turn blue they are scrap.


This is not true. Carbon steel will lose it's temper at a heat where it turns blue. High speed steel will not lose it's temper even if gotten red hot. Once it cools, it will be as hard as ever. The hotter it gets though, the softer it gets (while hot) so it is best to keep it as cool as possible for maximum cutter life but turning blue will not hurt it. That is the reason that it is called high speed steel. When it was invented, it enabled speeds far higher than the carbon steel tools then in use simply because of it's heat resistance. The metal working industry still makes extensive use of HSS due to its advantages over carbide though, for the sake of brevity, I will not go into that. 30 years ago, all router bits were HSS.


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## CW1 (Mar 20, 2012)

rwl7532 said:


> Would reducing the speed of the router have extended its life?
> 
> Yes, reducing speed will allow the bit to stay cooler thus increasing cutter life. Be aware though, that a full diameter cut is many times harder on a bit than an edge cut. For your application, I would recommend carbide. Leave the HSS for edge cuts.


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## Mike (Nov 22, 2004)

Ralph, yes... the HSS bit was a spiral. Wood generates a lot more heat on a bit than cutting metal since you can use coolant in that application. The 1/2" spiral bit I used to install a mounting plate turned blue and dulled on the first use. Sure, it will still cut but it is now sloppy and produces a lot of tear out. I keep it around for hack work. Having worked at a high tech scrap facility I used to recycle Gaylord boxes full of ruined HSS cutters and taps in preparing heats to produce new metal. Now all my bits are either solid or carbide tipped.


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## rwl7532 (Sep 8, 2011)

rwl7532 said:


> Would reducing the speed of the router have extended its life?
> Was your HSS bit a spiral?
> 
> *** breaking news/conclusion ***
> ...


So not the entire story.
I got an email from MLCS. They state that the HSS spiral bits are a recent addition so there have not been any reviews. 

I have received my 3/8" carbide spiral from them but haven't had a chance to try it out.


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## mikem88 (Dec 14, 2012)

Thanks that was the way I was leaning. Any comments on the number of flutes?


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## boxxmaker (Apr 28, 2013)

Hi folks,I,m new here and just found this post,and now have this system on the way,heck I fifured for what leigh sells them for,a $169.00 seemed like a good deal,plus the reviews here were really good,I'v been doing woodworking for many yrs,but never really had success with making dove tails in the past,but thought,what the heck,I'll give it another shot.


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## Dmeadows (Jun 28, 2011)

bobj3 said:


> Hi
> 
> As you know I'm a big fan of the MLCS bits BUT they are not always a good deal the HSS bits you want to back up from, 7 bits for 50.oo sounds to good to be true and like they say if it sounds to good to be true it is most of the time..
> 
> ...


7 bits for $50.00 is too good to be true, but Onsrud sells a 2 pack for $10.00( which if my math is correct is 10 bits for $50.00!) is a good deal? Hmm... can't follow that logic!


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## bobj3 (Jan 17, 2006)

How about a link ? to the 2 pack.

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Dmeadows said:


> 7 bits for $50.00 is too good to be true, but Onsrud sells a 2 pack for $10.00( which if my math is correct is 10 bits for $50.00!) is a good deal? Hmm... can't follow that logic!


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## Dmeadows (Jun 28, 2011)

bobj3 said:


> How about a link ? to the 2 pack.
> 
> ====


Sure...

40 044 Onsrud 1 2" High Speed Steel Single Edge Downcut Router Bit 2 Pack | eBay


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## bobj3 (Jan 17, 2006)

Thanks for the link......if you like using drill bits for router jobs...(HSS) 

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Dmeadows said:


> Sure...
> 
> 40 044 Onsrud 1 2" High Speed Steel Single Edge Downcut Router Bit 2 Pack | eBay


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## hankh (Jun 25, 2013)

*Why buy a straight bit?*

Thanks for all of the info. 
Mike - you make a great case for buying a spiral bit rather than a straight bit. So why do people buy straight bits?


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## jschaben (Jun 21, 2009)

hankh said:


> Thanks for all of the info.
> Mike - you make a great case for buying a spiral bit rather than a straight bit. So why do people buy straight bits?


Hi Hank - Well, spirals tend to be on the expensive side and all bits eventually wear out. I have a fairly good inventory of spiral bits but on jobs where a straight bit will work and a spiral isn't really necessary I will use that. Simply because the replacement is more economical.


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## chessnut2 (Sep 15, 2011)

Jim..........I followed the link. I'm not seeing the shank size on the various bits in the chart.Thanks.


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## Peter Harrison45 (Aug 26, 2013)

Hi Guys and dolls, i was wondering whats the difference between a Spiral up cut bit and a spiral down cut bit in terms of usage? which bit do you use for certain jobs?


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## Mike (Nov 22, 2004)

Hi Pete, you will find the answer in post #2 of this thread.


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## Peter Harrison45 (Aug 26, 2013)

Thanks mike


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## jdowney (Oct 9, 2010)

Has anyone opinions on the spiral flush trim bits? Given the cost, its no surprise to have never met someone who's tried one 

I do one fairly crazy operation in a router table that requires a tall flush trim bit -- flush trimming 6/4 or 8/4 walnut endgrain. Currently I use a 3 flute straight bit and it works fine about 90% of the time. The other 10% tends to be enough to keep me away from that operation for at least a week.

I've had spirals get out of control just often enough to guess that this would be a spectacularly bad application for one  But that's just a gut feeling, so I figured I'd ask if anyone had tried something similar.


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## TangoDown3727 (Oct 13, 2013)

I recently saw a three piece set (1/4, 3/8 and 1/2") of upcut spiral bits at Harbor Freight for like $12-$14 (can't remember exactly but definitely under 20 bucks). They really didn't look too bad; I was half tempted to give them a spin but I waited. They were HSS instead of Carbide. Any thoughts on this or has anyone used any? I know you get what you pay for but are they worth trying? Opinions welcome!


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## Dmeadows (Jun 28, 2011)

TangoDown3727 said:


> I recently saw a three piece set (1/4, 3/8 and 1/2") of upcut spiral bits at Harbor Freight for like $12-$14 (can't remember exactly but definitely under 20 bucks). They really didn't look too bad; I was half tempted to give them a spin but I waited. They were HSS instead of Carbide. Any thoughts on this or has anyone used any? I know you get what you pay for but are they worth trying? Opinions welcome!


Although I use a lot of HF stuff, I won't waste money on their router bits, Have a number of older HSS router bits... wouldn't waste money on more of those, either. Fortunately I didn't buy them, my dad did.

That said, HSS will take a sharper edge than carbide It just doesn't hold the edge nearly as long. For certain applications they do have an advantage over carbide, but IMHO not for general routing. YMMV.


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## Mike (Nov 22, 2004)

Dave, I agree with Duane on this. I will not use HF bits.


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## Badger2 (Nov 11, 2014)

That makes interesting reading, from someone just entering the mystical world of routing.
I am about to make a router insert for a Kreg plate. The table is 7/8" thick with Formica top and I would therefore ask if I should be using a compression bit or downcut? Intension is to cut straight through the top and use Kreg levelers on each corner of the plate. With the timber template stuck on (as photo) if that was 1/4" thick, what depth bit would be needed please.
Malcolm


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## Cherryville Chuck (Sep 28, 2010)

I usually aim for a perfect fit without levelers and I'm not familiar with the levelers on that plate but if I were doing it my way I would turn the router upside down and put a piece of the wood on top of the router with the insert plate and adjust the bit until it was almost flush then make the first cut and test the fit. Then make additional cuts as necessary.


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## Badger2 (Nov 11, 2014)

With a Formica to to the table, that method may cause a lot of tarout on the surface. I am going in from the top, by cutting the corners with a Foreste bit, then jigsaw almost to the edge and finish with the router, hopefully wth a clean edge to the Formica.

With the levelers, the table is cut right through and corner sections fotted with mounting scrrews to level the plate. https://www.kregtool.com/store/c41/...precision-router-table-insert-plate-levelers/

Malcolm


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## Cherryville Chuck (Sep 28, 2010)

Those levelers would certainly make for an easier installation. Just about worth the $25 Canadian it would cost me. I've cut countertop laminate with several different bits and as long as it is glued firmly to the substrate and you use a carbide bit you shouldn't have tearout.


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