# Spiral vs straight



## wvubeerman (Feb 11, 2014)

Ok, so I have read more than I need to and still can't decide. I want to use a 1/4" bit right? to dado cut for my drawer bottoms to put the 1/4" plywood in them. Should I get a spiral or a straight bit for this job? I purchased a diablo bit from THD but have not opened it. I am a Amazon prime member and see that some bits I can get for a lot cheaper on there. Whitside seems to be the brand of choice on here, but I'm having some issues reading how they label them on Amazon to get the right bit. Spiral up or down is now the question I think. I am sorry that I probably sound like an idiot, but any tips on what bit I should buy to do this job would be great. 

I want to make sure that using a 1/4" dado cut is what I need to use to get my drawer bottoms of 1/4" plywood to fit in the groves. I am going to just have to start experimenting and stop over reading, but I'm pretty thorough when it comes to starting a new hobby and try to soak up information before I start the actual experimenting.


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## jw2170 (Jan 24, 2008)

Hi, since you will only be going in around 1/4", either will do.

I would not buy a special bit just for that job. if you have a straight bit, use the straight bit...

BTW, 1/4" ply is not always 1/4" thick.......


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## BrianS (Nov 7, 2004)

Hi Beer. Your 1/4" plywood is actually about 7/32". If you use a 1/4" bit, the fit will be a bit sloppy.. There are bits sold specifically for plywood that are the correct width. As for what bit, either straight or spiral will do the job.


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## Mike (Nov 22, 2004)

Beer, did you read the sticky thread at the top of this section? It explains the difference in bits. For plywood to fit the best you should use a bit sized for plywood and they are available as a set of the 3 most popular sizes for very reasonable prices. Whiteside would be my choice for this set.


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## michmags (Nov 25, 2011)

Check your plywood for thickness as already mentioned. Rockler has a good selection of "plywood" bits that are sized for the actual thicknesses of plywood. My recommendation would be the spiral downcut bit. The downcut will reduce tear-out and splintering on the inboard face of your drawer sides.


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## Quillman (Aug 16, 2010)

Neither.
A slotter is the more efficient tool here.
Using a 3/16" thick tool will let you tune the slot width to whatever.
More on the spiral: See no. 12


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## mailee (Nov 11, 2005)

I would use a straight bit on plywood as if you use an up cut spiral it will tend to tear out the upper grain of the timber. HTH.


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## thomas1389 (Jan 4, 2012)

Hello Mike: Question, where do I see the sticky thread you refer to in your answer to Beer? I don't pick up on what you're saying.
Thanks


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## Jakexp (Apr 26, 2013)

Up spirals, down spirals, top bearing, bottom bearing router bits are referenced as if the router bit is hanging in a router, ie shank pointing towards the sky.


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## Garyk (Dec 29, 2011)

The upcut will expel the sawdust upward but as stated will splinter the top ply. Downcut will not splinter the top ply but if a hole is deep enough will pack the hole with the dust. Use upcut if going completely thru the wood and stop the spin before reversing the plunge cut. As the guys said with a shallow depth either will work spiral or straight will work. IMO the spiral will stay sharper longer. I have the Whiteside plywood set and they give a perfect fit on the undersized (read foreign made) plywood. However true hardwood plywood should be 1/4 or 1/2 or 3/4 as advertised. Always measure it first. The guys at Whiteside are great at giving advice on the proper bit for a particular job.


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## Mike (Nov 22, 2004)

Sticky threads are at the top of each section of the forums.


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## thomas1389 (Jan 4, 2012)

Thanks, Mike. So if I wanted to post a thread on this subject I would open the threads, click "new thread" then submit my offering. Is that correct ? (not that I have anything to say)
I'm continuing to stumble upon vast amounts of information in this forum. I could spend all day reading.
Thanks again.


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## Mike (Nov 22, 2004)

Yes Thomas, that is how to start a new thread. The way threads become sticky threads is they have good information and lots of traffic. I review all the threads on the forums and when I find something that I think will benefit most members I make it a sticky thread.

Reading through these threads will provide many answers to commonly asked questions or provide insight into how others accomplish a task. As long as it is safe there is no wrong way to go about any particular project. A good example of this is making box joints. This can be done with a table saw or router, even by hand cutting with a saw. All the methods work although the best method in my opinion is using the Oak Park box joint jigs or one of the clones offered by various companies. Learning new methods and getting feedback from members is the forums at its best.


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