LumberJocks

My fault or normal attrition???

  • Advertise with us

« back to Joinery forum

Forum topic by cracknpop posted 09-11-2021 07:40 PM 468 views 0 times favorited 12 replies Add to Favorites Watch
View cracknpop's profile

cracknpop

521 posts in 3596 days


09-11-2021 07:40 PM

Topic tags/keywords: dovetail bit dovetail jig router bit

I’ve used the Dovetail Wiz for several years on several projects. Usually clamp board/jig and use router by hand. Today I left router in my table and moved jig/board.
SIGH!!!!! Top of router bit broke off half way through second board of hickory.
Should I NOT use jig on router table?
Or was this likely Just wear and tear?

I was careful in moving jig so it stayed flat on table and moving slowly. It was balanced well and did not tip at all.
Now to see how quick I can get one shipped in so I can finish.

-- Rick - I know I am not perfect, but I will keep pressing on toward the goal of becoming all I am called to be.


12 replies so far

View tvrgeek's profile

tvrgeek

2292 posts in 2896 days


#1 posted 09-11-2021 07:58 PM

I have used my fast joint jig on a table many times. Maybe you got too aggressive? Maybe bit was fatigued from some previous operation? Sat down hard or something.

View JAAune's profile

JAAune

2038 posts in 3564 days


#2 posted 09-11-2021 08:23 PM

The load may have been too much for that bit going through hickory or maybe the bit was defective or dull. It’s hard to say for sure.

Router bits break when they are overheated which happens if the bit is too dull or the feed-rate is too slow. But if you feed too fast while taking too much material bits will break from the excessive force being applied. Getting the right feed rate is a balancing act since going faster is better until it isn’t.

Knowing the sound of a good cut helps a lot. Screeching means the bit is moving too slow and rubbing instead of cutting. Growling and chipping means the bit is being forced too fast.

-- See my work at http://altaredesign.com

View CaptainKlutz's profile

CaptainKlutz

4906 posts in 2741 days


#3 posted 09-11-2021 09:21 PM

‘Stuff’ happens?

+1 could be anything. Dull bit, feed rate, previous accident, etc.

IMHO – Hickory was created by Devil. :)

Sharp tooling is critical with Hickory, as end grain can be unpredictable. The fibrous bundles can stick together and chip out in large chunks; even when you do everything perfect. If one of these chunks gets wedged in the cut, the bit breaks. DAMHIK

Best Luck.

-- If it wasn't for bad luck, I wouldn't have no luck at all, Doom, despair, agony on me… - Albert King - Born Under a Bad Sign released 1967

View LesB's profile

LesB

3100 posts in 4690 days


#4 posted 09-11-2021 09:47 PM

Hickory is very hard on bits. One way to reduce the load is to remove the center of the cut with a straight bit or cut it out on the table saw first. Then remove the rest with the dovetail bit. I have also seen some people cut most of the wood away with a band saw and then make a finish cut with the router bit. Of course that involves more time marking the cut first.

-- Les B, Oregon

View Dark_Lightning's profile

Dark_Lightning

4850 posts in 4356 days


#5 posted 09-12-2021 03:04 AM



The load may have been too much for that bit going through hickory or maybe the bit was defective or dull. It s hard to say for sure.

Router bits break when they are overheated which happens if the bit is too dull or the feed-rate is too slow. But if you feed too fast while taking too much material bits will break from the excessive force being applied. Getting the right feed rate is a balancing act since going faster is better until it isn t.

Knowing the sound of a good cut helps a lot. Screeching means the bit is moving too slow and rubbing instead of cutting. Growling and chipping means the bit is being forced too fast.

- JAAune

I’m going to need education on how a slow feed rate results in excessive heat. That’s pretty counterintuitive, to me.

-- Steven.......Random Orbital Nailer

View robscastle's profile

robscastle

8279 posts in 3451 days


#6 posted 09-12-2021 04:07 AM

Yep had that happen shock is the culprit i think, your going OK then…cracknpop!

I have a blog somewhere I will see if I can find it for you and attach it. All very odd to me I thought too!

-- Regards Rob

View JAAune's profile

JAAune

2038 posts in 3564 days


#7 posted 09-12-2021 05:26 AM


I m going to need education on how a slow feed rate results in excessive heat. That s pretty counterintuitive, to me.

- Dark_Lightning

Various CNC manuals will give more information on this but I’ll provide a quick, informal explanation. The bit basically produces the same amount of friction and heat with every rotation while in contact with the wood. Doesn’t matter if the shaving is .001” or .010”. What does matter is that the heat is distributed over a longer distance, larger shavings carry more heat out of the kerf, the bit does more work for the same amount of wear, and the bit stays cooler so the carbide holds up longer.

Worst case scenario happens when the bit is trying to take a .001” shaving but is too dull and starts deflecting. That’s when you get chatter (awful sound) because the bit bends until there’s enough force to take a bigger bite out of the wood.

The same principle applies to any kind of routing, drilling, etc. It’s just a lot easier to control and observe this on a CNC router.

Of course it’s dangerous to try hogging material at high feedrates by hand or at a router table which is why shallower passes are often needed. LesB suggested removing excess material with a straight cutter and that is probably going to be necessary for the OP’s operation due to the density of hickory.

-- See my work at http://altaredesign.com

View robscastle's profile

robscastle

8279 posts in 3451 days


#8 posted 09-12-2021 06:10 AM

Found it read and weep

https://www.lumberjocks.com/reviews/6170

the comments are possibly of benefit

-- Regards Rob

View therealSteveN's profile

therealSteveN

8900 posts in 1821 days


#9 posted 09-12-2021 06:10 AM

If that is a 1/4” shank I have had a number of 1/4” shanks shear off over the years. Heat, stress, whatever they don’t work very hard. Now if it was a 1/2” shank, I’ve never had one of them snap off.

-- Think safe, be safe

View Dark_Lightning's profile

Dark_Lightning

4850 posts in 4356 days


#10 posted 09-12-2021 09:09 PM


I m going to need education on how a slow feed rate results in excessive heat. That s pretty counterintuitive, to me.

- Dark_Lightning

Various CNC manuals will give more information on this but I ll provide a quick, informal explanation. The bit basically produces the same amount of friction and heat with every rotation while in contact with the wood. Doesn t matter if the shaving is .001” or .010”. What does matter is that the heat is distributed over a longer distance, larger shavings carry more heat out of the kerf, the bit does more work for the same amount of wear, and the bit stays cooler so the carbide holds up longer.

Worst case scenario happens when the bit is trying to take a .001” shaving but is too dull and starts deflecting. That s when you get chatter (awful sound) because the bit bends until there s enough force to take a bigger bite out of the wood.

The same principle applies to any kind of routing, drilling, etc. It s just a lot easier to control and observe this on a CNC router.

Of course it s dangerous to try hogging material at high feedrates by hand or at a router table which is why shallower passes are often needed. LesB suggested removing excess material with a straight cutter and that is probably going to be necessary for the OP s operation due to the density of hickory.

- JAAune


Thanks for the education! I learned to calculate surface feet per minute in metal shop about 55 years ago, but no wood CNC in those days, afaik. I’ve had metal things made via CNC, but the programmers took care of that detail. Of course, they have a steady stream of lubrication coolant spraying onto the parts. I wouldn’t try that with wood!

-- Steven.......Random Orbital Nailer

View cracknpop's profile

cracknpop

521 posts in 3596 days


#11 posted 09-17-2021 03:06 PM

I’m going to blame it on using a dull router but on a really hard wood (hickory).
New Whiteside bit cut like a champ!!

-- Rick - I know I am not perfect, but I will keep pressing on toward the goal of becoming all I am called to be.

View cracknpop's profile

cracknpop

521 posts in 3596 days


#12 posted 09-17-2021 10:22 PM



...dull router but on a really hard wood (hickory).

Was supposed to read …”dull router BIT on a really hard wood”...

-- Rick - I know I am not perfect, but I will keep pressing on toward the goal of becoming all I am called to be.

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com