Replies

1. 
   Midnight | Mar 05, 2005 09:48pm | #1

   Doug..

   Pat's your man to give a more qualified answer than I can, but it sounds to me like your taking an excessivly heavy cut per pass. Personally I try to keep the depth of cut well below 3mm / pass irrespective of the bit size. Granted it takes longer, but I prefer that to carbide shrappnel...

   Mike Wallace

   Stay safe....Have fun

1. 
   DougSmith | Mar 10, 2005 05:22am | #9

   Mike,

   I certainly thought that two flutes were better than one, but that impression has kept me from trying many single flute bits. Thanks for answering.

   Doug Smith

2. 
   Tao | Mar 06, 2005 12:03am | #2

   First, use single-flute router bits.  They cut faster and with less pressure than double flute.  You also might want to consider solid carbide spiral bits; they do a good job of getting the chips out of the cut. You may just have crummy bits.  If you are buying from a big box store, try buying from a shop that caters to the trade.  Bosch and Amana bits hold up great for me; I've had a lot of trouble with some of the others.

   Check your router's collet.  Look at the bits after using.  If there is a small bright ring around the shank of your bit, the collet is worn and needs to be replaced.  Clean the collet thoroughly.

   I have often used 1/4" bits to cut 3/4" deep mortises in cabinet doors in a single pass, with very little problem, so it's not impossible.  Vibration kills router bits, so make sure router and workpiece hare held firmly enough not to let them chatter.

   Feed speed should be fast enough that the bit doesn't burn, and slow enough to allow clean cutting.  It's hard to describe without being able to show you, but when you push too hard, the bit gets kind of "grabby".  As best I recall, a 1 1/2 inch long mortise takes about three seconds to cut ONce the bit has already been plunged into the wood.

   Michael R

    

3. 
   Pondfish | Mar 06, 2005 01:14am | #3

   You didn't mention your shank size; if a 1/4" bit on a 1/2" shank, you risk breaking bits where the shank was cut down to 1/4" size.  This is a natural stress point and placing too much pressure on the bit can cause it to fail.

   I know this isn't the problem you encountered, but it is one to watch for. 

   With your bits breaking, take less of a cut and don't feed as fast.  Also ensure that the bit is not getting clogged.  Routing dados or slots often leads to clogging, as the chips have no path to escape the slot.

   Good luck.  I use primarily bits from Ridge Carbide, and haven't had one fail yet.  I have had CMT and Grizzly bits fail...

   Paul

    

4. 
   highfigh | Mar 06, 2005 01:22am | #4

   If you use solid carbide bits and you don't want the edge to be rough, spiral down cut is what you need. They clear out the waste really well, cut down into the face and are very good at cutting without breaking, unless the feed rate is excessively fast. If you were using a straight, two flute bit, there's a lot more resistance to the wood moving.

   "I cut this piece four times and it's still too short."
5. 
   douglas2cats | Mar 06, 2005 02:50am | #5

   Somewhere years ago I read that you shouldn't try to make a deeper cut than the diameter of the bit. The only time I've ever broken bits has been when I've tried to go beyond that. I've gotten away with deeper cuts on 1/2" shank bits, but Il try not to exceed that rule of thumb too much. Takes longer to get holes to the right depth, but it's cheaper than replacing bits.

   If you build it - he will come.

1. 
   Tao | Mar 06, 2005 07:28pm | #7

   Somewhere years ago I read that you shouldn't try to make a deeper cut than the diameter of the bit.

   Simply not true.

   If that were the case. manufacturers wouldn't make cutting edges much longer than the bit diameter because they would have too many customer service problems, and there wouldn't be any market among knowledgeable users because of breakage problems.

   I've used 1/4" bits for routing out 3/4" deep face frame mortises in one pass for years, and have been in several cabinet shops that used the same technique, although M&T joints on face frames have fallen out of favor in the past few years.  If bit breakage were a problem, old school cabinet makers would have been finding another way to cut face frame mortises, and you can bet they weren't taking the time for multiple passes.

   Based on my experience, the problem is, in order of likelihood: Double flute bits, bad or dull bits, bad or dirty collet, excessive vibration due to bad bearings or poor technique, excesssive feed rate.

   I agree with the earlier observation about 1/2" bits with necked-down shanks being prone to breakage.  I use 1/2" bits as much as possible because they seem to run smoother and vibrate less, but with 1/4" straight bits I use 1/4" shank, solid carbide because that has proven most economical in the long run.

   Michael R

    

1. 
   DougSmith | Mar 10, 2005 05:41am | #12

   Michael,

   I appreciate your response. I do not think I was feeding excessively fast; I don't think my Ryobi has bad bearings as it is little used; there WAS serious vibration because of the depth of cut; my collet (1/4 ID inch sleeve closing down a 1/2 collet) is clean and unscored. So this points to your first and most likely cause: double fluted bits. I thought two flutes were better than one. If this is not so, I will try a single flute bit next time. I will also try a down spiral solid carbide bit.

   Thanks,

   Doug Smith

1. 
   Tao | Mar 10, 2005 08:19am | #14

   there WAS serious vibration because of the depth of cut; my collet (1/4 ID inch sleeve closing down a 1/2 collet) is clean and unscored.

   There's a real good place to look for the source of your problem.  Your router shouldn't vibrate any more on a deep cut than on a shallow one.  If you are overloading the router, it should just slow down with no appreciable increase in vibration.  The vibration is either from collet or bearing, and given the age of your router I would suspect the collet first.  There is the remote possibility of a bent shaft, but that is unlikely.  Try getting a proper 1/4" collet and see what happens.

   I don't mean to bust your chops, but in my experience Ryobi is petty much at the bottom of the quality ladder, maybe one rung above Harbor Freight.  Quality problems with collets would be no surprise, since it is such a critical item.

   Michael R.

2. 
   DougSmith | Mar 10, 2005 05:30am | #10

   Douglas,

   Thanks for answering. After writing this question, I tried routing in shallow passes, 1/8 inch per pass. This worked well and produced a neat clean cut. Then when I changed set up to rout a long shallow slot, the bit broke. I must have stressed it even though I was routing shallow passes.

    

6. 
   nikkiwood | Mar 06, 2005 09:44am | #6

   I agree with the other comments: you're taking too much in a pass, and your feed rate is probably too fast. Maybe the bit is not properly seated in the collet.

   But IMHO, you are also using cheap bits (MLCS). These things may be ok for light duty or sometime use, but I think you wouldn't have the breaking problem with a bit from the higher end of the spectrum -- Bosch, Amana, Whiteside, CMT, et al.

   Don't get me wrong, I think cheap bits have a place in anyone's router bit arsenal -- but usually where they are not likely to be used frequently beyond the project at hand.

1. 
   DougSmith | Mar 10, 2005 05:31am | #11

   Nikki,

   I thought MLCS was economical but I did not think they were of lower quality. This is news to me. I will definitely try a higher quality bit. I appreciate your advice.

   Doug Smith

1. 
   nikkiwood | Mar 10, 2005 06:18am | #13

   The longer you hang around here, the better you will see that quality is a slippery concept in the tool biz. There is virtually no hard data on quality and reliability, so in the end it is all pretty much a matter of an individual's personal perception. There are some who would argue passionately that MLCS is a "quality" line of bits priced at a reasonable level. And I suppose it is, if they are satisfied with the products. But for my part, I think it is reasonable to conclude that if a bit is priced at half the price as another in the marketplace, then it is a lower"quality" bit. All of which is to say, you get what you pay for.............. most of the time.

2. 
   MatthewSchenker | Mar 10, 2005 04:51pm | #16

   nikkiwood,
   I have to respond to your comment about MLCS bits -- they are NOT "cheap bits." You may be getting them mixed up with something else. I've used all varieties of MLCS bits and have been extremely happy with them.You listed a few router bits that you consider higher end: Bosch, Amana, Whiteside, and CMT. No doubt, Whiteside is certainly high end, but I'm not so sure about Bosch, and Amana and CMT are no better than MLCS. I know, because I have tried them all!But if you don't believe me, check out the Fine Woodworking review of 17 brands of router bits, in issue #137, July/August 1999, page 84. MLCS came out in the top five, in a virtual tie with Amana and CMT. There's a reduced version of the article online at http://www.taunton.com/finewoodworking/pages/w00045.aspOne thing about the top five bits, it appears that Oldham Viper is no longer available, since Home Depot has stopped selling them, and I have never been able to find a bit made by Liberty. This would elevate Amana/MLCS/CMT to a tie for third-best.Read the full version of the Fine Woodworking article. MLCS shows an even better performance when all factors are taken into consideration.

1. 
   nikkiwood | Mar 10, 2005 05:34pm | #17

   I remember the article well. While I laud FWW's effort to find some more objective means of testing router bit quality, I think one must be careful in drawing any sweeping conclusions based on their test results. Remember, they tested a single bit from each brand, and I think even Burkin would agree that imparting the same quality level (or lack of it) to all the other bits in the brand should be done with some caution. In the end, it still comes back to one's individual perception. Like I said earlier in this thread, quality in tools is often a slippery kind of thing. If someone finds a bit (or a tool) that works well for them, and they therefore regard it as a "high quality" item, I am not going to argue with them.

1. 
   MatthewSchenker | Mar 10, 2005 06:24pm | #19

   nikkiwood,
   Like you said, it's difficult to make general statements about quality. Really, I was only objecting to your statement that MLCS bits are cheap but CMT and Amana are quality. In my experience, all three are good quality.I really like MLCS bits. But I agree with you that Whiteside stands above the rest in terms of quality and longevity.Most hobbiests, or even semi-professionals, will be happy with Whiteside, MLCS, Amana, CMT, and Freud. Go with the one that has the bit you need, when you need it. I can run out and within an hour buy Freud and Whiteside bits at my local Woodcraft. MLCS is mail-order, and so I need to wait a few days to get them.

2. 
   DDay | Mar 10, 2005 05:35pm | #18

   The oldham bits I think are now porter cable bits.  PC and delta's parent company bought oldham and last summer that tool group was bought by dewalt's parent company, Black and Decker.  My guess is that the PC bits home depot sells now are oldham bits with the pc name and color.  Also, a rep for Freud posts here sometimes and he has said that some companies have their bits made for them by others, so bosch bits 5 years ago could have been made by oldham and now their made by mlcs, etc.  I don't trust any of the tool companies bits because you'll never know if they change manufacturers, so bosch bits, pc, etc are out.  I'll stay with whiteside, freud, mlcs and the like.

    

   In October 2002, Oldham was acquired by Pentair, Inc., the parent ofPorter-Cable, Delta, and DeVilbiss tools. Oldham now operates as theaccessories arm of Pentair. We continue to offer our great products andlook for new, innovative products to add to our line

1. 
   MatthewSchenker | Mar 10, 2005 06:27pm | #20

   DDay,
   I was wondering about this, since the Porter+Cable bits are in the same rack where the Oldham Viper bits used to be! But I was skeptical.The Oldham Viper bits were great, and I used several different ones. They were tough and lasted a long time.I'll have to try the Porter+Cable bits to see if they have maintained the Oldham Viper quality.Thanks for the information.

3. 
   lwj2 | Mar 11, 2005 03:34am | #24

   Matthew:Liberty router bits are made by Ridge Carbide Tools.Website: http://www.ridgecarbidetool.com/Regards,Leon Jester

7. 
   SgianDubh | Mar 06, 2005 08:03pm | #8

   "help needed with breaking router bits"

   Doug, you don't seem to need any help with that task, ha, ha.

   It's most likely you've acquired some lesser quality bits. I certainly hammer mine and expect them to survive, but perhaps I don't hammer them quite so hard as Michael (Woodwiz) describes. I let the tone and note of the router as well as the sound of the cutting action of the bit tell me if I'm working the router and the bit too hard.

   Michael is right to say that single flute bits will stand a more aggresive cut. So too will stagger tooth bits. The shear angle of the flutes, the number of flutes, and the intended purpose of a bits design do determine what can be torn out in one pass. Sometimes aggressive cutting ability comes at the price of a less refined finished surface, which may, or may not matter.  Bigger shanked cutters can be used more aggresively than small shanked. I'll work a 1/2" shanked cutter harder than I will an 8 mm or 1/4" shanked one. Slainte.

   RJFurniture

8. 
   MatthewSchenker | Mar 10, 2005 04:31pm | #15

   Doug,
   I have been using MLCS bits for some time now, and I have never had one break on me. In fact, I really like MLCS bits.

   It is possible you just got a lemon or two, but I see a bright red flag in your description of the cut.

   You are using a 1/4"-shank bit to cut a 1/2"-deep groove! That is way above the level you should be cutting in one pass with that bit. Even the 1/8"-deep pass is pushing it with a 1/4"-shank bit. I never cut more than 1/8" depth at a time, and that's with a 1/2"-shank bit.

   Keep in mind that no matter what the cut diameter, the shank bears the brunt of the cutting force. Also, keep in mind that the larger the bit, the greater the cut, because the total cut is a factor of the depth plus the diameter. For example, a 1/8"-deep cut with a 1/4"-diameter bit is less total surface area than a 1/8"-deep cut with a 1"-diameter bit. In either case, you're still dealing with the same shank diameter, which bears the stress of the cut. With spiral bits, you can get away with a little more.

   If you really need to hog out that much material at a time (and I don't recommend it), at least get a router that accepts 1/2"-shank bits.

   
   

   ---

   Edited 3/10/2005 8:53 am ET by Matthew Schenker

1. 
   Tao | Mar 10, 2005 06:46pm | #21

   You are using a 1/4"-shank bit to cut a 1/2"-deep groove! That is way above the level you should be cutting in one pass with that bit. Even the 1/8"-deep pass is pushing it with a 1/4"-shank bit. I never cut more than 1/8" depth at a time, and that's with a 1/2"-shank bit.

   Mathew, do you have an objective basis for that opinion? 

   How do you explain the fact that many commercial cabinet shops have used 1/4" router bits to cut full depth face frame mortises in a single pass since the 1960s, and the fact that I have been using the same practice for the same amount of time with never a problem? The 1/4" face frame mortises on the cabinets in my house (circa 1970) are just over 5/8" deep and you can bet they were cut in a single pass.  I haven't been in a single cabinet shop that used m&t face frames that would take the time for multiple passes. It's true that almost all of them have switched over to pocket screws, but that doesn't change the fact that the practice worked for years.  What has changed?

   How do you account for the fact that my Tyler drawer front machine used standard 1/4" bits to cut slots in drawer fronts 3/8" deep by 20" long in about four seconds, and that the 3/8 " diameter, 1/4" shank dovetail bits would cut a french dovetail slot 3/8" deep and 3/8" wide in about the same amount of time, turning out about 6 drawwer fronts a minute with never a bit broken in thousands of drawer fronts?

   How do you account for the fact that the cutting flutes on most 1/4" straight bits is usually just shy of 3/4", and even 1/8" bits have a flute length of about 1/2"?  Don't you think that the router bit manufacturers would shorten up the flutes if cuts needed to be restricted in depth?  What determines flute length"  It's not chip clearance -- you don't need a carbide edge for that, so why do manufacturers make the cutting edges so long if they are not to be used?

   What information do you have that overrides the experience of countless professional woodworkers?  Doesn't practicality overrule theory?

   Michael R

1. 
   AlanWS | Mar 10, 2005 07:11pm | #22

   Whatever the conclusion with regard to bit quality, I think it's safe to say that if there's vibration as you cut, something is wrong. The deeper you cut in one pass, the more sideways force you put on the bit. Some routers can handle a deep cut smoothly, but others may not have the collet, bearings, or mass to prevent excessive vibration with that cut, and the vibration can lead to damage of router, bit, workpiece, and/or you. If you are repeatedly breaking bits, even with shallow passes, that means the deep passes, while possibly contributing, must not be the whole problem. As this does not happen to most of us with MLCS bits, either you got an extraordinarily bad batch of bits, or there is a problem with router or technique. Could it be that your 1/4" adapter is very slightly out of alignment? Do 1/2" bits run more smoothly?

2. 
   MatthewSchenker | Mar 10, 2005 07:14pm | #23

   Woodwiz,
   I'm not claiming that I have the final word on this issue. In my experience, however, the cut feels uncomfortable and forced whenever I hog out more than 1/8" in a single pass. That's not to say that I haven't done this, on occasion, especially when I was new at woodworking. Of course, the type of cut being made is a factor. If you are routing an end profile, you can take a little more off at at time because the bit is not buried in wood chips. But if you're routing grooves or dadoes, I think taking 1/2"-deep cut in a single pass is a problem since you are collecting a huge amount of wood around the bit. Like I said, the spiral bits help with this issue, but still, taking 1/2" at a time is putting a lot of stress on any bit. If someone does 1/2" or even 1" at a time and feels comfortable with it, the more power to them! I for one will stick to my general rule of 1/8" at a time. If you're a hobbiest, what's the rush anyway?I generally will do things in two or even three extra steps if it feels smoother to do it that way. I think this is a good instinct to develop in woodworking.Just so you know, I use a 3.25 HP Porter+Cable router in my table, so it's not a question of power.

   Edited 3/10/2005 11:17 am ET by Matthew Schenker