# Quick Question:spiral bit, upcut or downcut?



## p3auul (Jan 3, 2012)

I need a bit for my table mounted router to cut some box joints and I need to know which I should use; up or down?
Thanx
Paul


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## Gene Howe (Jul 10, 2007)

Up cut will clear the waste from the cut.


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## bobj3 (Jan 17, 2006)

Hi Paul

You don't need to use a *spiral bit, upcut or downcut bit
I normal standard straight router bit will do the job just fine..

You are not plunging the bit in for box joints..save it for the jobs that you will need it for..

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p3auul said:


> I need a bit for my table mounted router to cut some box joints and I need to know which I should use; up or down?
> Thanx
> Paul


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## p3auul (Jan 3, 2012)

Well here was the problem. The bit I had was a no-namer on a card that I had for years, unopened. As you might be aware, I was using it in conjunction with the Incra Ultralite that I got recently. In order to cut box-joints you have to center the bit on the material that you are going to use. What they have you do is draw a centerline down the middle of the 3/4 board cut to the width of the 4 pieces of wood you willl use. You line the mark on the approximate center of the bit. You then bring the fence up and clamp it. You rout a 1/4 deep dado along the middle, switch it end for end and run it through again. This will give you a slot wider than 1/4 inch because you couldn't get exactly in the middle, so you place the bit back in the slot and and micro-adjust the fence till there is an equal amout of space on each side of the bit. But get this. I'm adjusting the fence a 1/1000 of an inch at a time trying to eyeball the center. If there is not such a word for oxymoron of a procedure, there needs to be. Although I'm not an engineer, I come from an engineering background and this isn't precise enough for me. On my router table, in the direction I'm cutting is a line on the table that goes right through the center line of the bit. I don't believe the cutters on the straight-sided bit I have are centered. When I place my marked board on the centerline on the table and move it up to the stationary bit, one cutter is wider than the other, even though I have moved the bit where the widest part is facing the wood. The spiral bit, by it's very nature will be even all around. It even has a slight peak at the center like a drill bit. If I center the cutter on the piece of wood and bring the fence up and clamp it, I should have it perfectly centered on the wood. This would eliminate the ambiguity with the Incra method of centering. 

The reason for being all this precise in the first place is that when I fit my joints together, One board is slightly higher the other other at right angles to it. Incra says in the manual that the reason is the board is not perfectly centered. I'll let y'all know how it comes out!


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## cagenuts (May 8, 2010)

You should have just bought the Ibox, no messing around with centre line.


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## neville9999 (Jul 22, 2010)

Paul up cut and down cut spiral bits were originally made for CNC Router use and the spiral was made to cut "up from the face side if the face side was down when the cut was done" and "down from the face side if the face side was to be up when the cut was done" This was done to give a more perfect finish on the face side. These cutters are over kill for home use and are also not normally needed for professional use, that is they are more expensive a cutter than you would normally need, they do cut very nicely and are worth the money, as a professional then I have a few of them and I try to just use them only when I need a better cutter but for normal router used then double fluted Tungsten Tipped Cutters that are made by a quality manufacturer will serve you very well. All cutters can be resharpened and spiral cutters can be also resharpened but they have to go back onto a machine similar to the one they were made on to do that spiral grind so general cutter sharpeners don't always have one and they send them off to someone who does, router cutters are sharpened on the inside so spiral cutters are no different, they just have to be given an exact spiral grind to get that front edge like new again. There are many things that we have to spend money on so don't get fooled into thinking that you need spiral cutters and just buy them if you have a real need. NGM


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## Gene Howe (Jul 10, 2007)

It may just be my perception but, spiral cutters seem to cut smoother (easier) than straight cutters. It is *not* just my perception that spiral cutters produce less tear out and leave a smoother cut surface. Both of which are important to me.


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## Phil P (Jul 25, 2010)

+1 on what Neville says



neville9999 said:


> These cutters are over kill for home use and are also not normally needed for professional use


Like you, Neville, I have only a few. Most of my cutters are either brazed 2-flute or for certain purposes (mainly tempate routing MDF in volume) I have some TC-RT. Spirals are only any use for straight edges. You can't get spiral profile cutters, can you?

Regards

Phil


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## al m (Dec 13, 2012)

Paul
Use a scap piece the same length as your actual work piece.Mark center as instructions.Take one cut,measure the width of the cut,with a caliper,then turn the piece and take the second cut.Measure the width of the cut again and subtract your first cut from that.Half the differance should be how far of center you are.


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## p3auul (Jan 3, 2012)

Thanks Al. now that makes sense and is precise which is what I wanted. It also avoids the problem I was having with trying to find the center of the router bit. With that method I can use any type straight bit. i am using a dial caliper already. I also think I have found the problem with my center line on the board. My bandsaw table was not square to the blade. I fixed that and waiting for some time to work!


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## al m (Dec 13, 2012)

Paul
I should have also noted to pay attention to what side of the slott the second cut removes material from(you could color the sides of the slot with marker pen to make it easier).You will then make your adjustment in the opposite direction.For instance,If your secund cut removes material on the side of the slot closest to your fence,you need to move away from the fence to find center.
Sorry,I can not comment on what cutter to use as I have only used straight two flute cutters.
Keep playing with that incra and do not lose faith in it or yourself,you will get there.


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## p3auul (Jan 3, 2012)

Well, that it! the spiral goes back to Lowe's tomorrow. When I made the centering cut down the center line the wood kicked back on me. Broke a hunk out of the wood and misaligned my fence! Now I have to start back over. This never happened with the other bit. It cut just as smooth as pie. I had removed the clamps and installed bolts. Now I'm back to the c-clamps. I had to re-square the fence so I had to remove the bolts. I think they will stay off. It will make it easier to realign in the future. Some one said i should have stuck with the iBox. No, no versatility there. box joints is all you get. The iBox was just a metal and mechanical version of the jigs woodworkers have made for years. Thinking about it, I think it is way overpriced. I can do much more with the Ultralite and adjusting it is really just part f the fun. Besides, I'm lucky to have all the experience of you guys to fall back on! I'm going to make a belated new year's prediction and say that we'll see a substantial decrease in the list price of the iBox by the end of 2014.


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## Mike (Nov 22, 2004)

Paul, please take the time to read the sticky threads in this section and you will know all you need to about spiral bits. I use mine all the time. Understanding how a bit cuts is key to getting good results.


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## neville9999 (Jul 22, 2010)

Phil P you are correct, if I did not make it clear then spiral cutters are normally for edge use, or they were made for cleaning up edges where you wanted to protect one side more than the other side so you would choose a spiral that favoured the up side or the down side depending on your work piece, I have only ever seen them as a straight cutter, that is I have not seen a shaped spiral cutter however there are sone very interesting milling type spiral that have a halk inch shaft and I think that they would run very well in a hand router, if you had the money to spare that is, this does not mean that they do not work well with other processes as they do, being made from superior tungsten then they cut very well, they stay sharp for a good long while, if money is not an object, that is that you are rolling in it and you have run out of things to spend it on then buy as many spiral cutters as you like, the thing is that for normal router use then they are not needed, I also use them for deep straight cutting, the reason is that they are damn strong cutters and take the load with ease, they don't seem to get that hot under load and I think that that does help them to keep that sweet edge, as a professional then I have half a dozen of them but I choose what I use them on as normal cutters that are made well and kept sharp, work very well. NGM


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## neville9999 (Jul 22, 2010)

p3auul said:


> Well, that it! the spiral goes back to Lowe's tomorrow. When I made the centering cut down the center line the wood kicked back on me. Broke a hunk out of the wood and misaligned my fence! Now I have to start back over. This never happened with the other bit. It cut just as smooth as pie. I had removed the clamps and installed bolts. Now I'm back to the c-clamps. I had to re-square the fence so I had to remove the bolts. I think they will stay off. It will make it easier to realign in the future. Some one said i should have stuck with the iBox. No, no versatility there. box joints is all you get. The iBox was just a metal and mechanical version of the jigs woodworkers have made for years. Thinking about it, I think it is way overpriced. I can do much more with the Ultralite and adjusting it is really just part f the fun. Besides, I'm lucky to have all the experience of you guys to fall back on! I'm going to make a belated new year's prediction and say that we'll see a substantial decrease in the list price of the iBox by the end of 2014.


I think that it is highly unlikely that this "kick back, broke a chunk out, issue" was due to the "Spiral Bit" they are outstanding router bits, this looks more like your workpiece slipped or the cut was too deep, using router bits is just physics and if the load is too high then something will have to give way. NGM


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## p3auul (Jan 3, 2012)

You maybe right Neville, I have noticed a raised rough place on the round insert in my router table that gives a little trouble with the spiral bit that I did not notice with the other bit or with ogee bits. When I push the 3/4 flat wood piece over the that spot I can feel it hesitate(the wood not the bit), but I push past it hold down the wood firmly and I haven't hat it repeat the the kick back. It might have been that I was just unprepared also since I hadn't had a kickback before. I don't have a rubbersoled push block and can't find one locally, so I wrapped some sandpaper around a 2x4 and use that as a non-slip block. seems to work alright. I haven't tried the spiral bit to cut the boxjoints yet. Thy will be up on edge, but secured to the right angle sled with a c-clamp so they should be alright or else all ****'s going to break loose!  

I haven't taken the spiral bit back yet and I may not but here's a question. I though the up spiral was supposed to carry the chips toward the router and away from the cut but when I pick up the wood after the cut, the slot is full of saw dust. Did they put a down spiral in the box by mistake? How can you tell?


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## bobj3 (Jan 17, 2006)

" How can you tell? " run your finger down the flute, keep in mind how the router will turn when you power it up..

The bits are tuning so fast it's hard for all the chips to come out and they will jam up in the slot just no way around it...the norm is they come off the stock and go around and around in the slot,if you use them on a edge the chips will come off easy and not gang up the norm..think of them like right hand and left hand drill bits that will help..

4.50 each from with free shipping
http://stores.ebay.com/LMT-Onsrud-Router-Bits-and-Blades?afsrc=1
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p3auul said:


> You maybe right Neville, I have noticed a raised rough place on the round insert in my router table that gives a little trouble with the spiral bit that I did not notice with the other bit or with ogee bits. When I push the 3/4 flat wood piece over the that spot I can feel it hesitate(the wood not the bit), but I push past it hold down the wood firmly and I haven't hat it repeat the the kick back. It might have been that I was just unprepared also since I hadn't had a kickback before. I don't have a rubbersoled push block and can't find one locally, so I wrapped some sandpaper around a 2x4 and use that as a non-slip block. seems to work alright. I haven't tried the spiral bit to cut the boxjoints yet. Thy will be up on edge, but secured to the right angle sled with a c-clamp so they should be alright or else all ****'s going to break loose!
> 
> I haven't taken the spiral bit back yet and I may not but here's a question. I though the up spiral was supposed to carry the chips toward the router and away from the cut but when I pick up the wood after the cut, the slot is full of saw dust. Did they put a down spiral in the box by mistake? How can you tell?


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## J. Leigh (Jul 15, 2012)

Gene Howe said:


> It may just be my perception but, spiral cutters seem to cut smoother (easier) than straight cutters. It is *not* just my perception that spiral cutters produce less tear out and leave a smoother cut surface. Both of which are important to me.


This is not perception but fact. The spiral flutes produce a shearing effect which leaves a much smother surface as well as reducing tear out.


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