[twyns]

I have just replaced a Bosch Colt with a new larger 1.25 hp Bosch GKF125CE on my CNC machine. After an approximate 10 minute run with the new router, the collet and bit were very hot. Too hot to touch for about 2 minutes. I never had this issue with the Colt. Is this a sign of future problems to come, does the router need some run time to "loosen up" or should I stop using it??

 

[difalkner]

Welcome to the forum! Add your first name to your profile to clear the N/a in the side panel and so we'll know what to call you.

We do like photos so show us your shop, tools, projects, etc. whenever you're ready. What sort of woodworking are you planning or doing with your CNC?

First question would be what are your feeds/speeds/depth of cut? Heat is a good indicator you're going too slow. Our CNC has a 3kW water cooled spindle and I cut fairly aggressively. After 10 minutes of what I would call heavy cutting the chips are very warm and so is the work piece near the cut, but the bit and collet can easily be touched as soon as the cut is over and the bit stops spinning.

David

 

[twyns]

Hi David, thanks for the reply. I'll be very honest with you. I've been making these same items for 5 years and have always went with the data computed at setup. I've never changed any settings other than pass depths and stepovers. Never had a problem. That is what stopped me today, when I went to change to a different bit and felt the extreme heat.

 

[difalkner]

Got any photos of your setup, Tom? What are your feeds/speeds and in what material are you cutting?

David

 

[Cherryville Chuck]

The only things I can think of that would cause the problem are some slippage between the bit and collet (any signs of that on the bit shank?), a dull bit, too slow a feed like David said, or a bad bearing on the router (but you should be able to hear that). If it's the bottom bearing then running it for several minutes without doing any routing should still cause it to get hot.

 

[sreilly]

I was going to suggest checking/changing the bit but Charles has that covered. If you're concerned it might be the router, which I doubt but could be checked, the motor would likely be heating up and that could be checked by checking the amp draw while running under a load. Best guess is the bit but it's a guess.

 

[roxanne562001]

Welcome to the forum

 

[Herb Stoops]

Welcome to the forum. Does the motor get hot too, or just the bit?
Herb

 

[Stick486]

you running the bit in reverse...

 

[Herb Stoops]

you running the bit in reverse...

How do you do that? I wanna try that! Do you plug it in upside down?
HErb

 

[Stick486]

https://www.holbren.com/left-hand-rotation-straight-router-bits/

 

[Herb Stoops]

thanks Stick, that is probably the problem, I didn't know that cnc's ran both directins.
HErb

 

[JFPNCM]

Definitely good information. I wonder how many customers have used those bits in with their standard router bits without thinking about it.

 

[Cherryville Chuck]

The old Sears bits where the bit screwed onto a separate shank could be put on backwards. You can put slot cutters on backwards too. VOE on that one. It's amazing how much smoke they make that way.

 

[ger21]

Was the wood burning, or the bit black from burning? If not, it's very unlikely that the bit is generating enough heat to make the collet too hot to touch.

My guess is that this is due to friction from the seals on the bearings. This should go away with use. Can you spin the shaft freely with your fingers, or does it feel tight?

 

[twyns]

Wow, I'm a new member and am amazed at all the feedback on my question. I took the weekend off and just now seeing all of your replies. I ran a test this morning and don't know why I didn't think to do it sooner. I ran the router plugged in with no bit installed and bypassing the CNC. I let it go for about 5 minutes............hot collet. So I believe it is a bearing problem as suggested. Hopefully, it will eventually loosen up or I'll be missing some fingerprints soon. Thanks again for all the suggestions.