Author Topic: Bit pulling out arggg!  (Read 999 times)

Offline chuckeroo

  • CNC Jedi
  • *****
  • Posts: 584
    • View Profile
Bit pulling out arggg!
« on: April 26, 2022, 22:36:55 pm »
Well i think that I might be pushing on it pretty hard. using a 3/8 bit and cutting a depth of .25  and 4 step over .Feed rate 280. Yes it's pulling the bit out. Question is can I use an E R style collet on a Porter Cable 7518 router and if so are there advantages on holding the bit in place without this pulling out that is occurring. Also can you reccommend where i could purchase these items. Thanks for any and all help on this matter!!

Online lloydsp

  • CNC Jedi
  • *****
  • Posts: 8774
    • View Profile
Re: Bit pulling out arggg!
« Reply #1 on: April 26, 2022, 23:36:56 pm »
Huh?  I'm confused, Chuck!

How is the bit 'pulling out of the chuck', if it's been properly tightened?  I've never had that happen, in five decades of routing and milling operations.  Pulling out?  Really?

Lloyd

"Pyro for Fun and Profit for More Than Fifty Years"

Offline chuckeroo

  • CNC Jedi
  • *****
  • Posts: 584
    • View Profile
Re: Bit pulling out arggg!
« Reply #2 on: April 27, 2022, 00:14:11 am »
Yea LLoyd the darn bit is pulling out. I have done some some reading since posting and what i have read indicates that the E R Collets have superior bit retention as they put it. This info comes from Precise Bits.  Anyway if this is true this will be the way that I go. Basically I was looking for input that has gone thru this problem and if this solved their problem before I pull the trigger on yet another purchase. Hmmm maybe I should start with cleaning what I now have before making a purchase. Maybe the collets have a glaze or varnish that develops from heat. yea I'm guessing. Thanks for the response and have a good day! Oh yes as far as tightening goes it is white knuckle tight. I thought i was going to break the wrench well maybe not.
« Last Edit: April 27, 2022, 00:18:22 am by chuckeroo »

Offline EddyCurrent

  • CNC Jedi
  • *****
  • Posts: 5137
  • Made in England
    • View Profile
Re: Bit pulling out arggg!
« Reply #3 on: April 27, 2022, 08:33:35 am »
1. High frequency vibration of the tool is the main cause of that, maybe too much stick-out
2. dirt in the collet slots
3. oil or dirt on the tool shank or collet
4. wrong size collet (e.g. metric instead of inch)
5. worn collet or locking nut.
6. it's not good to overtighten the collet

Filmed in Supermarionation

Offline Tool-n-Around

  • Storm Trooper
  • ***
  • Posts: 193
    • View Profile
Re: Bit pulling out arggg!
« Reply #4 on: April 27, 2022, 14:09:55 pm »
4. wrong size collet (e.g. metric instead of inch)

+1

Almost always caused by a bit advertised as inch that is actually nearest metric size.

I presume the shank on the bit is 1/2" and you are using a PC collet not an aftermarket 3/8" PC colllet. If not, where did you get the collet? A lot of aftermarket collets for PC Routers are total junk. Especially the ones sourced on eBay and Amazon.

Best,
Kelly

Online lloydsp

  • CNC Jedi
  • *****
  • Posts: 8774
    • View Profile
Re: Bit pulling out arggg!
« Reply #5 on: April 27, 2022, 14:59:06 pm »
Another hint is to 'mic' the tool shank, and make sure it's really the diameter they said it is.  As Kelly mentioned, some are 'metric equivalents', and might not work in a collet that doesn't have perfectly-parallel closure.

I only buy cutters from known-good sources in the USA (like McMaster-Carr, and a few others), because they've never let me down.

Lloyd
"Pyro for Fun and Profit for More Than Fifty Years"

Offline Garyhlucas

  • CNC Jedi
  • *****
  • Posts: 1446
    • View Profile
Re: Bit pulling out arggg!
« Reply #6 on: April 27, 2022, 22:44:22 pm »
Precise Bits collets for routers are very good.
Gary H. Lucas

Have you read my blog?
 http://a-little-business.blogspot.com/

Offline chuckeroo

  • CNC Jedi
  • *****
  • Posts: 584
    • View Profile
Re: Bit pulling out arggg!
« Reply #7 on: April 29, 2022, 14:43:10 pm »
Thanks for all the input. i think I'll go with precise bits.

Offline chuckeroo

  • CNC Jedi
  • *****
  • Posts: 584
    • View Profile
Re: Bit pulling out arggg!
« Reply #8 on: July 21, 2022, 10:24:14 am »
I failed to mention that the collet i am using is a Muscle chuck and most of the bits I use are Amana from Toolstoday. Is anybody else using the Musclechuck collet and are you having good results. Thanks for any input!!

Offline Bob La Londe

  • CNC Jedi
  • *****
  • Posts: 4322
  • ^ 8.5 pounds on my own hand poured bait.
    • View Profile
    • CNC Molds N Stuff
Re: Bit pulling out arggg!
« Reply #9 on: July 21, 2022, 15:13:56 pm »
Usually chatter causes pull out.

Sometimes just changing your feed rate or your RPM a little bit to get out of that harmonic range can reduce or eliminate the problem.  Once I have an operation that works perfectly I usually save it as a style in my style library. 

Of course all the issues that people have mentioned about tool holding can be a factor.

One of my machines uses a quick change to holding system that uses the same collet for every tool. That's the Tormach TTS.  I have seen pull out occur when using a large tool pushing the horsepower of the machine. It could be the chatter from pushing it that hard but most likely it's just because the spring stack and the air cylinder are only capable of generating a very limited amount of force to pull the collet into the spindle.  I imagine if your hand tightening your collets around your tools that is not the issue for you unless as some have suggested you're using Miss size tools or Miss sized collets.
Getting started on CNC?  In or passing through my area?
If I have the time I'll be glad to show you a little in my shop. 

Some Stuff I Make with CamBam
http://www.CNCMOLDS.com

Offline chuckeroo

  • CNC Jedi
  • *****
  • Posts: 584
    • View Profile
Re: Bit pulling out arggg!
« Reply #10 on: July 22, 2022, 11:59:39 am »
I gave a close look yesterday and cleaned the collet and bits also.Checked for run out on the Musclechuck and found that it was misaligned so I corrected that. It's amazing what the results are. Problem solved. I do like the quick change setup and would recommend it. Thanks for all of the input from everyone. Ran it all day long with no problems!