Hey y'all.
I'm in between projects here at Chaos Central...
...and I decided I had a couple of minutes, and I could make a quick video...
...kind of a "Tips & Tricks" video.
I know that my lighting is bad, my audio is bad...
Please forgive the pitter-patter of rain on the roof of the shed.
But it's winter time here in Oregon, and that's just a fact of life.
I'll do the best I can.
A question I keep seeing come up over and over again...
...in some of the beginners Facebook groups...
...and in some of the other Facebook groups I'm a member of...
...has to do with how much of...
...a bit's shank should go into the collet of the spindle or router.
For some this may be simple, for others this may be a bit more complex...
So I figured I'd take a couple of minutes...
...we'll zoom in real close, and I'll show you what I'm talking about.
So I have a selection of bits here...
...and I'm going to walk you through some of these.
Here is a standard 1/4 inch downcut spiral bit...
...in my 1/4 inch collet.
Again, I can tell it's a downcut spiral...
...because the cutting edge is on the bottom of the spiral.
But if you look here...
...at how much of the shank I have in the collet...
You can see that the cutting edge is about 1/8 of an inch...
...away from going into the collet itself.
If I spin it around this way, we can see...
...how much of the shank is buried inside that collet.
That's going to give me firm mounting.
Again, we want to get as much of that shank into the collet as possible...
...without the cutting edge slipping up into the collet itself.
On these smaller bits...
...like what's in my 1/8 inch collet...
...that's not always possible.
Some of these bits have this plastic collar...
...while others don't.
If we look closer...
...if this will focus, that is...
...we can see that the cutting edge...
...is inside that little collar.
That's fine.
This collar is pressed on at the factory...
...and what we want to do is bury...
...all of the shank behind the collar into the collet.
If I flip it up, we can see that the shank doesn't go all the way up into the collet.
There's a bit of a recess.
But there's enough of the shank buried in the collet...
...to where it's really going to grip that shank.
Personally, I'd prefer a bit more shank in the collet...
...but I've been using these for a couple of years now...
...and I've never had one slip on me...
...or break, or anything like that.
Some folks will tell you that these collars...
...are pressed a specific distance from the tip of the bit...
...so that you don't have to reset Z zero after a bit change.
I disagree with that statement.
The only real evidence I have to support my disagreement is, if you look at this pack of bits...
...you can see that the amount of bit exposed past this collar varies.
They're not standardized at all.
So, just my opinion...
...I don't care if it's got a collar or not, I'm resetting my Z zero after I do a bit change.
It's just not worth messing around and hoping it's right.
So, that's a straight shank or spiral bit.
When you get into something like this v-bit, or this large straight mortising bit...
...which I use to surface my spoilboard...
...the situation is a little different.
Let's see if the camera will focus in on this...
If you look at where the shank...
...meets the orange cutter head...
...you'll see that there's a bit of a radius.
It's not a straight shank that ends flat against the underside of the cutter.
There are no 90° angles there.
They do that because a 90° angle there...
...could open up the possibility of stress fractures forming at that 90° angle.
And you don't want this cutter head breaking free of the shank...
...at somewhere between 10,000 and 20,000 RPM.
That would get real exciting, really fast.
So there's a bit of a radius here...
...is what I'm trying to say.
If you look at this big bit...
...it's very exaggerated, but you can certainly see that radius.
What we want to do...
...when we're using a bit like this...
[...come on out of there...]
...we want to bury as much of the shaft in the collet as we can get...
...but then back it out...
...about 1/8 inch...
...or 3 mm for those of you who insist on using the metric system...
...back it out of there so that the radius is not up here in the collet.
If the collet is tightened down on the radius instead of the shank...
...the jaws of the collet are grabbing the radius.
After running for just a few seconds...
...the bit is going to slip, because that radius is not enough of a surface to grip.
So on a bit where you have a...
...solid shank meeting a cutter head...
...slip the bit all the way in, then back it out...
...about 1/8 inch (3 mm.) Something in that range.
This becomes just slightly more complex if you use a touch plate...
...to set your Z zero...
...and, like me, you don't have a router or spindle that's grounded...
...and you have to use an alligator clip...
...to ground the bit, for use with the touch plate.
What I do is put that alligator clip on the bit shank...
...so it's nice and secure...
...put the bit in the collet, then slip it into the router...
...like so...
...then tighten the collet into the router.
Then I know that I have a good, solid connection with the alligator clip...
...and I know that there's enough of the bit shank buried in the collet.
Again, don't slip the bit all the way into the collet
That's a big mistake.
The collet just can't get a grip on the shank of the bit.
So remember to back it out about 1/8 inch, then you can tighten it up.
So that's basically it.
Without overstating it or being too repetitious...
...the thing to remember is to bury as much of the bit's shank into the collet as you can...
...without either snugging up on that radius...
...or putting a cutting edge up into the collet itself.
If you got anything out of this video...
...I do hope you'll give me a thumbs up.
If you have any questions or comments...
...feel free to leave them down in the comment section.
If you'd rather not leave a public comment, or you have a question on something else...
...head over to my website marklindsaycnc.com
...and click the Contact Us link.
But I do ask that you include a valid email address...
...and please double check it.
Lately, I've been getting quite a few messages through the Contact Us link...
...and there was a problem with the email address when I tried to reply.
If you've sent me a message and I haven't responded to you at all...
...please resend it. I've had several replies bounce back because the email address was not valid.
So if you'd like to follow along with some of the projects I'm doing on my Gatton CNC..
I do hope you'll subscribe to my channel.
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Like this one!
But whether you subscribe to my channel or not...
I'd like to thank you very much for watching.
Y'all take care.
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