New 1/8" cutting bit causing serious overheating problem

[DickB]

I've cut dozens of these gears in the past, and never had a problem like this until today. The project board is 1/4" Baltic birch on a 1/2" sled. The cuts are made in one pass. I've run the same project with the same material and sled a dozen times. I did switch to Designer 2, and also used a brand-new bit that I just got from LHR. The new bit is seriously overheating to the point of starting a fire. I had smouldering sawdust in my dust collection system. Scary.
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Since I changed both software (machine code) and bits, I compared predicted cut time for the project with both Designer 1 and Designer 2, and they were identical, so I don't think the feed rate has changed. However, comparing the new bit (right) to the old (left), the spiral flutes are tighter on the new bit. I believe sawdust is not being ejected from the cut as well with the new bit. This causes overheating to the point of heavy charring and near fire. This is not a fluke; it happened twice. Like I said, nothing like this has happened before, same project, same wood.

63483

I am making another run with the old bit. Of course I will be keeping a close eye on this.

[CarverJerry]

Think maybe the rpm's for the tool has changed? Don't know how to check the speed with out using a tack or a special instrument for rpms. Looks like it cut ok at first but then loaded up or something. Keep us posted on what you find out. Thanks

[CNC Carver]

That looks bad. Glad there was no major fire trouble.

[lawrence]

Glad you are all right... scary indeed

Was there any damage to your machine?

Lawrence

[DickB]

No damage to my machine, but my dust pickup which is half wood was charred.

I just finished a rerun of the project with my old bit with no incident (top left). Still using Designer 2 software and firmware. Don't know about the RPMs. Comparing the two results, the new bit does seem to load up the cut more, but it's not a dramatic difference. It is clearly running hotter. I wonder if I could get temperature readings with my non-contact thermometer? Not anxious to use that new bit again though.

63485

I have to conclude it is the bit. I would like to know the reason for the bit change. I would also like to know how I can get replacements identical to my old one before it gets completely dulled or broken. As it stands, the new style are no good for this.

[brdad]

Any chance the bit and/or holder are not 100% straight?

[DickB]

Any chance the bit and/or holder are not 100% straight?Two different new bits, same results.

[lawrence]

Two different new bits, same results.

Do you think the bits are damaged/prematurely dulled now from excessive heat?

Lawrence

[DickB]

Don't know. They definitely got blackened, but feel sharp as I rub my thumb over them. I may get brave tomorrow and try to get temperature readings.

[JoeinWestMich]

I would like to hear from the Carvewright staff to find out if they changed suppliers. Like most manufacturers, I would assume they are always on the lookout for suppliers who will provide them with parts and bits at a lower cost. They supply the specs and then the suppliers bid on the RFPs. Could be a new supplier. I am sure LHR will do their very best to get to the bottom of this for us. And they cant begin to check things out until they know there could be a problem. Hope this gets resolved for you very soon.

[aokweld101]

I was told to check the sharpness of a bit was to take the edge and rub it on your fingernail and if it shaved a layer from your fingernail then it is sharp.

[DickB]

Well, there can be no question about bit sharpness BEFORE the burning. The first bit had been used only a couple of hours before the first failure. I used a brand new, never been used bit on the second try which resulted in the second failure. The bits were factory sharp. My old bit which worked with no problem has countless hours on it and can't be all that sharp.

The difference in bits is the tightness of the spirals. The new bits have tighter spirals. I would think that would be part of the specs, not just a supplier change, but I would like to avoid guessing and welcome input from LHR. I have a third new bit in the box that is going to stay there.

I posted this to alert other users to the problem, let LHR know, and solicit input from other users. I request other users to count the number of spirals on your 1/8" cutting bit and compare to my new ones (refer to the photo). If you have the same bit, have you had any issues or noticed any difference?

Edit: To be clear what I mean, I count 5 spirals down the old bit and 7 down the new one.

[Digitalwoodshop]

WOW... My first thought was a BAD Mechanical.... As we saw this with BAD QC's in the OLD days where I blamed the latest version of Designer and was WRONG.... See the picture and the one on the Right I was BLAMING had BB Marks in the Bit holder.... From a BAD QC and a Mechanical FLOPPING AROUND of the bit.... MY BAD.... A BAD QC....

So since 2 new bits give BAD Results and 1 Old Bit gives GOOD Results.... (Good Job by the way) WE have something to work with...

It is possible that in the Bit Manufacturing Process... A Error was made... OR... Is the Sleeve 100% Centered.... DO you have a Dial Indicator to measure RUN OUT with the Bit INSTALLED in the MACHINE?..... THAT would be my next check...

AL

[DickB]

I ran a test mpc this morning, just the gear tooth cutout of a 32-tooth gear. Same piece of Baltic birch plywood, same mpc (Designer 2) first the old then the new bit. I measured bit temperature with a handheld IR thermometer at about 4-5" distance (cover switches temporarily bypassed). It has an aiming LED; the hottest temps were with the LED on the bit at about 1/2" above the board's surface. The old bit ran at about 105 - 110 degrees fahrenheit. It took cutting about 4-5 teeth to get to that temperature, then did not get hotter for the remainder of the cutout. The new bit got to 145 after a few teeth, then 160, then 170. At the eighth tooth I read 182 and I stopped the test.

I would like to get some comment from LHR on this topic. If time to investigate is needed, I understand. But as I said earlier, the three new bits that I just bought are not usable by me at least for this project. I need to have a source of usable bits.

Would other users please count the number of flutes down one side of your 1/8" cutting bit and let me know if you have one like the new ones I have? Old bit, 5 edges, new bit, 7. Is anyone having similar issues with the new style bit?

[RMarkey]

Give our support staff a call so you can return the bit to us.

[gapdev]

Most of mine have 5 edges down the side, including the 2 new ones I bought over the 4th of July. 1 bit that came out of a QC adapter is slightly longer and has 6 edges (has been used to cut without problems).

Kenny

[DickB]

Thanks. Just got off the phone, I can return the bits, but that doesn't really solve my problem. Next step per the tech is kick this upstairs next week, so I will wait till then.

[lynnfrwd]

Sorry. I'm not back until Monday.

[farmer]

I just received a new 1/8 bit today for my CT spindle and it is the same as my old one 5 spirals down the side 4 flukes.

[DickB]

Wanna trade?;)

[mrtaz]

I have been having the same problem. I've told LHR that they need to give us the control of which way the cutter is turning. the problem is we have this 1/8" bit that
sticks out the holder 1-1/2" and climb cutting, I can't get them to understand that we shouldn't be cutting that way due to all the vibration which in returns causes fiction
and heat. what I've done is made my own holder, so now all I have to do is go to MSC and buy an 1/8" end mill for $15.00 rather than paying $40.00 dollars and having
it last for one or two projects. I wish somebody at LHR would understand "NOT TO CLIMB CUT".

[Digitalwoodshop]

I have been having the same problem. I've told LHR that they need to give us the control of which way the cutter is turning. the problem is we have this 1/8" bit that
sticks out the holder 1-1/2" and climb cutting, I can't get them to understand that we shouldn't be cutting that way due to all the vibration which in returns causes fiction
and heat. what I've done is made my own holder, so now all I have to do is go to MSC and buy an 1/8" end mill for $15.00 rather than paying $40.00 dollars and having
it last for one or two projects. I wish somebody at LHR would understand "NOT TO CLIMB CUT".

I am having trouble understanding what you say is wrong? I understand Climb Cut to be the direction the bit is moving along the length of the board. If you did a rectangle then one side would be a climb cut and the other not... Since the Bit is Computer Controlled and held in position with servos with a appropriate feed rate... The bit would never really have an opportunity to run away along the grain of the board.

So then it comes down to properly setting up the cut in Designer taking into consideration the Wood Density where you would be more Conservative with OAK and MAPLE than you would be with soft pine. Since we don't yet have a Feed Rate control we DO have a Multi Pass Cut and can select HOW MUCH to cut in each pass. Effectively the same as Feed Rate since a slow full depth cut or many faster shallow cuts is effectively the same.....

This is a Hobby Grade Machine and it runs on Roller Bearings.... 8 for all the Axis.... And with that many bearing surfaces you must be conservative with the cuts. Then we have Rubber Y and Z Drive Belts. And lastly, the most important part... The Z Truck... A Carve Tite or Rock Chuck is best.... We have all seen the burnt Cutting Bits from the days when WE used our WORN OUT QC longer than we should have. The Burnt Bits were Directly Related to the Bit flopping around inside the cut... The side pressure causing heat....

Bits only lasting a project or two... That is a MECHANICAL PROBLEM... I have been using the same cutting bit for over a YEAR.... No burnt, NO snapping... I maintain my machine and I am in tune to what it is doing... I have posted before.. I rip off a section of the sand paper belt at the brass roller as I do many 6 inch wide sign and handle boards and it causes the belt to wear and become tapered on one side causing the drift... IF I was not in tune with the machine watching the drift... IT could cause a Broken BIT

A Carve Tite and Rock have bee show to be Superior in holding the bit in place and stable. Are you using a QC?

Anyone who is seeing burnt bits needs to take a close look at the mechanical of the machine...

1. Y Gear Box... The 2 inner bearings... IF worn can let the bit "Hunt" back and fourth even though the servo is holding it tight to position... Think of it as using a Softball BAT but keep your hands LOOSE.... Same theory...

2. Loose Servo Motors....

3. Loose Roller Rail Bearings....

4. Worn out rubber Drive Belt as in the Y Belt...

So tell me again how a shorter bit from someone else is better.... Besides price? Just be sure you stay away from the Roto ZIP bits... They BEND since they are not solid carbide and will destroy your machine when they bend...

This topic was worthy of a NEW Post.... A picture of your Bit Setup from MSC would be NICE and also a picture of Burnt Bits.

AL

I blamed the new Designer Change for the Burnt Bits... I was WRONG.... You can SEE the BB Marks in the bit Holder... I failed to see them and understand the REAL PROBLEM.... You can look at the picture dates and find the old posts where I was WRONG...

[mrtaz]

Believe me, your preaching to the choir.
all I want to do is tell the machine what direction to move when doing a cut out. I'm going to try a left hand end mill and see if that doesn't make me happy.
I'll try to get some pictures of my collet and I even made my own Flex shaft Pivot Assembly out of D2 that's another story in itself.

[DickB]

The problem that I am having is bit related. My old bit works fine. My new bits have a tighter spiral and run significantly hotter, to the point of starting a fire. There is no difference in direction of cut between the two - or difference in material, project, feed rate, roller bearings, you name it. The only difference is in the bits.

Frankly, I do not understand why direction matters when doing a cutout. If truly milling an amount of material less than the diameter of the bit, I understand it would make a difference. But when cutting ,the entire diameter of the bit is pushed through the material - I don't see how moving left to right versus right to left would make a difference.

[DickB]

I finally got around to trying some different bits. At bergerud's suggestion I picked up a Freud 1/8" spiral upcut router bit, $21.97 at Rockler, and put it in my ER11 chuck. It cut nicely and measure temperatures were in the 120-130 degree F range, same as the old cutting bit. I will be using this for cutting 1/4" Baltic birch going forward.

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[bergerud]

And how does it feel to know it will never break? That is a big one for me.

[unitedcases]

What kind of bit then for 1/2 material? And 3/4? That ones does look perfect though for 1/4 inch.

[bergerud]

I have a 1/8", two flute carbide with 1/2" LOC (see picture) and a similar 3/16" with 3/4" LOC. (I also have 1/8" and 3/16" with straight shanks with varying LOC up to 1". )

[unitedcases]

Freud as well? For both?

[bergerud]

The 1/8" in the picture is Freud and I think the 3/16" is also. I cannot remember for sure.

[Digitalwoodshop]

Is the Software still throwing a fit when the 1/8th inch bit is not set to the CT bit length? Just curious...?

My next bit purchase I will seriously look at this..

Thanks,

AL

Still using 1.184... and happy with it... works... don't need to fix it... :)

[DickB]

I tried a very long bit and this short one - no issues. The firmware is the latest from Designer 2, although I used Designer 1.187 for the project.

I think the key to this application is that the bit has only two flutes and the spiral is not tight. It does a good job of ejecting most of the sawdust. I have not found a router bit like this in 3/4" cut length, but mscdirect has 2- and 3-flute 1/8" end mills in lengths up to 1" that I may give a try. I occasionally get a little burning on rounded corners such as gear teeth when cutting 1/2" or 3/4" hardwood like oak with the old Carvewright 1/8" cutting bit.

Of course the ER11 chuck is a great tool to allow the use of these other bits - a wide variety is available and the cost can be significantly less.

[DickB]

The Freud router bit is fine for 1/4" and 1/2" stock, but I've got to come up with something to cut 3/4" stock. I just ran this with the new bit, and you can see it burned all the cut edges. The old bit never burned like this.

65584

[tierman]

Dick, I have found that if I am going to cut out a piece of 3/4" mat'l, I need to make sure that all of the sawdust is blown out of the previous cut path otherwise it is going to burn or possibly shift and even worse, break the bit. I do have dust collection but it does not get it out of the deep cut. My cuts depths are never more than .125 per path. This is why I use my CW very little to cut parts out. I have found that I can save myself time and money by making a router fixture for my router table. I know what you are cutting is quite complex but that's just my input.

[DickB]

The sawdust seems to be the issue, or at least a contributing factor. The new bit has tighter flutes and ejects little sawdust - most of it seems to get packed in behind the bit. On the third cut pass the sawdust itself also got bunt. My dust collection is also not powerful enough to suck the sawdust out - maybe Dan's dust shoe would do the job. I don't like to blow sawdust around in the machine, but as an experiment maybe I should rig up a compressed air nozzle on the spindle and see if I can blow the sawdust out to see if that makes a difference. Otherwise the bit is my focus. The Freud bit has only two flutes with more empty space and loose spiral, and comparing cuts in 1/4" material it ejected more sawdust. I am going to get some two- and three-flute end mills on order and give them a shot.

I haven't used my 3/16" cutting bit in a while, but it also has more open space and a looser spiral. I don't recall having any burning issues with it. For many projects the larger diameter is not an issue, but for clock gears and the like it is. Plus, when I'm working on projects for the Pattern Depot I prefer to stay away from the specialty bits and use only the two "standard" bits whenever possible.

I'm surprised others have not reported this problem - I can't be the only one. I'm concerned for unsuspecting customers of my clock patterns having issues and possibly starting a fire.

[Digitalwoodshop]

I know everyone is focusing on a "Bit Thing" and I even have my input above...

Do me a favor... Replace the Y Gearbox Bearings and try it again with the same setup.... I am starting to believe that a sloppy Y motion due to bad 685ZZ Bearings could be the cause of this... I know it is frustrating.... That Black Bit I had could have started a fire on me too...

AL

[DickB]

I appreciate the input, but recall that I measured bit temperatures back-to-back. The old bit (and new Freud) topped out at 130 degrees F, while the new Carvewright bit hit 180 and was still rising before I stopped the test. The bit has got to be a heavily-contributing factor.

[Rob Mulgrew]

I didn't get to read this whole thread yet but I recently bought a brand new 1/8 cutting bit from LHR and the very first project I used it on filled the whole shop with smoke and turned the bit black.
Them I tried another project and put the old bit I got on eBay for only $20 and it worked fine. I only cut 3/4 pine at a .25 pass depth so there is definitely a problem with the bits.

[DickB]

It would help if you could compare the two bits and describe any differences. I would like to know more about the eBay bit.

If I am measuring and calculating correctly, my old bit has a helix angle of about 20 degrees while my new bits that are giving me trouble are about 30. It seems that 30 is quite common in the industry. I checked with a couple of suppliers and could find bits of 30, 40, and more, but nothing less than 30 in 1/8" diameter and 3/4" or 1" length of cut. I was able to find 30 degree bits with only two flutes, which I am going to try. The Freud bit has only two flutes (I haven't measured it's helix angle).

65622

[DickB]

New 2-flute bits arrived today. Same project, same machine, same wood - in fact, the adjacent piece of the same board! - no burning. (I did have a depth of cut issue unrelated to the quality of cut which I have solved). This bit ejects considerably more sawdust from the cut path. In the bits photo is my old bit at left, new Carvewright bit, and Kennametal 2-flute bit at right. Most of the discoloration on the new Carvewright bit came from running this same project and board. Notice how bright and shiney the 2-flute is after the same project run.

I also measured the 2-flute while machining the same gear as before, and this bit ran coolest of any - one spike at 121 degrees F but typically 95-105 degrees.

65697 65698

[DickB]

I just received some new 1/8" cutting bits from LHR. The new bit is on the left, an old bit center, and one that I got prior to this latest one on the right. The helix angle appears to be even less on the newest bit than the old bit. I ran my gear test project and the new bit performed well. It ran at about 100-110 degrees F with one spike to 119. Clean cut and no burning. Back in business.

66266

[Rob Mulgrew]

I also had called LHR about the new 1/8th cutting bit design and they sent me a new bit after nearly setting my shop on fire. The new bit they sent me cuts beautiful with no problems. There seems to be a major design flaw on that other bit. I was only cutting a simple shape out of pine @ .25 per pass and it nearly started a fire the very first time I used it. I would say but I don't know how to measure the helix angle and not sure about the difference in flutes either...All I know is the bit I just got cuts just like it should and the one I got a couple months ago got way hot and could of started a fire.

[DickB]

The new bits that I just received are 4 flute but the helix angle is smaller.

[chief2007]

Interesting enough to maybe for LHR to ask all the carvewright users to check the 1/8 cutting bits.

[dltccf]

I was just using the new 1/8 inch cutting bit I received back in late October of last year and it has a serious problem with burning the wood. Attached is a picture of it cutting a piece of Maple. Max cutting depth is set at .200. I see this conversation was from about that time frame. Was there a bad batch of bits?

dave

68859

[DickB]

If you look at the photos of bits I posted in post #41, LHR had changed helix angle on the bits, and that caused me problems. They have since switched to a helix angle that actually ran cooler than the original bits in my tests. I was provided with replacement bits that work well. I would contact them with your problem.

[dltccf]

If you look at the photos of bits I posted in post #41, LHR had changed helix angle on the bits, and that caused me problems. They have since switched to a helix angle that actually ran cooler than the original bits in my tests. I was provided with replacement bits that work well. I would contact them with your problem.

Thanks, DickB, I contacted LHR and they asked me to send a picture of the bit and the burned project and they would send a replacement.

dave

[swaggerstick]

Kudos to Dick B for a great job of troubleshooting. I am sure he solved a lot of problems for Carvers and Carvewright as well. Great job Dick.

[cestout]

I noticed that the new bit you just got has the groove running higher up the shaft. That would help on a deep cut. Where do I get an ER11 chuck?
Clint

[unitedcases]

EBay. Just do a search for er11.

[cestout]

Thanks, I will.
Clint

[DickB]

I know that this is an old thread, but this problem resurfaced for me today. Luckily I caught it. This is a 1/8" Carvewright cutting bit, first time using it. It is the same configuration helix angle as when I first had the problem. What I don't know is if this was a bit that I purchased years ago, or more recently. I thought I had gotten rid of all of the problematic bits by returning them to Carvewright at the time.

If you have purchased a 1/8" cutting bit from Carvewright recently, could you check the configuration? Just count the number of spirals - the problematic ones show 7 as you count top to bottom of the bit. 4 flutes. If I order more bits from Carvewright, I'd like to know what I'm getting. I don't want any more of these bits in my shop.

87352

[CarverJerry]

It's hard to see but almost looks like the secondary relief is higher than the primary cutting relief (the cutting edge) Meaning the 2nd relief area is rubbing behind the cutting edge. May be wrong but the guy who resharpens bits would be able to for sure tell you.

[Mugsowner]

It's hard to see but almost looks like the secondary relief is higher than the primary cutting relief (the cutting edge) Meaning the 2nd relief area is rubbing behind the cutting edge. May be wrong but the guy who resharpens bits would be able to for sure tell you.

Great eye or point to bring up at the least. most people would not even thinking that the cut on a bit would have this issue. That would definitely cause the affect that is seen here.

[CarverJerry]

Mugsowner, over my 40+ years in the machine shop and doing some of my tool grinding which included end mills, our bits are nothing but an end mill, one is tapered with a ball nose, one is a standard 1/8" 4 flute end mill. I can see where maybe during a batch of tools made the secondary relief got missed or just not ground enough, and that would cause issues. At least it's only in wood where I would have seen a lot bigger problem being used on metal. I forget the guys name who will resharpen our tools, but I'm willing to bet he would take a look at these and be able to tell you. I hope DickB can get this figured out so he can get his clock gears cut out. There are many of places on line where we can buy our tools from. Any questions I'll try to answer them, PM me as I don't always check our forum everyday.

[DickB]

Interesting theory, but I don't believe that it is the case. Here is a photo, using my PC microscope, of the offending bit:
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I see a nice curve away from the edge.

Let me recap the original problem, and the conclusion to which I came. The offending bit is a 4 flute Carvewright 1/8" cutting bit with a helix angle of about 28 degrees. Carvewright had changed the helix angle specification on this bit.
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Previously, the bits had a smaller helix angle:
87356

I note two characteristics of these bits. First, if you draw an imaginary line down the center of the bit and count cutting edges, the "bad" bit has about 7 edges, while the "good" bit has about 5. Second, the gap between flutes to eject sawdust is tighter on the "bad" bit.

Now, here is a Kennemetal bit that I used while Carvewright looked into the problem and subsequently changed specs again:
87357

Note that while the helix angle is greater, it is a 2 flute design. So, there are fewer cutting edges, and the opening to eject sawdust is less twisted and larger.

My conclusion is that the burning is a result of the number of flutes and helix angle. The offending bit left more sawdust in the slot which I am guessing can cause more friction. Likewise, it has more cutting edges which I also assume causes more friction.

The reason for my recent post was to simply find out what is the configuration or specs of the 1/8" cutting bits now being shipped by Carvewright, as I was unsure if my "bad" bit was new old stock in my personal inventory, or a new bit. So, I asked anyone who had purchased a bit recently to look and report. Still asking.

I have since reviewed my inventory, and I believe that the most recent bit that I have purchased is the one pictured with about a 22 degree helix angle. I am still curious to learn what others have in their personal inventory, and if possible when purchased.

(BTW I went back to the Kennemetal bit to rerun my project with no incident.)

[CarverJerry]

The difference in the helix angle is like threads on a bold, the coarser one 22° would pull the wood chips out better than the finer 28° one. The 2 flute one would do an even better job as they are made for roughing work and the 4 flute are more for finishing. Just more of my 2¢ worth.