# Knee or Quill



## Submachine (Jun 20, 2019)

Looking for opinions on whether to buy knee or quill.  The following article argues for quill which is opposite of what I have been told.  Please assume either is an option on the machine I am buying.

Opinions and why?



			Z on the Quill or knee


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## ThinWoodsman (Jun 20, 2019)

That article seems to assume that if you have a knee mill, you are moving the knee when boring. In Bridgeport-style knee mills, the knee is generally used to set the height of the part, then the quill is used for boring. I suppose if you have a knee and don't have a quill (maybe a horizontal mill with a vertical spindle adapter) then this article might apply.


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## bob308 (Jun 20, 2019)

if you are drilling and boring a lot of holes  then a quill mill will work just fine. but if you are milling parts to different thicknesses on the same part from experience a knee mill is the best


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## Winegrower (Jun 20, 2019)

Get a Bridgeport, do whichever makes sense for the specific operation.


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## Submachine (Jun 20, 2019)

bob308 said:


> if you are drilling and boring a lot of holes  then a quill mill will work just fine. but if you are milling parts to different thicknesses on the same part from experience a knee mill is the best



I am a beginner.  If a quill presents itself should I wait for knee mill?  I cannot  specify what I am going to do, because I don’t know yet.


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## RJSakowski (Jun 20, 2019)

I gathered that the article was asking whether the z axis should be assigned to the knee or the quill in a CNC conversion.  In addition to the points made, I would be concerned about the the ability to make rapid moves with the knee.  That's a lot of mass to move.  My preference would be to assign the z axis to the quill and ideally assign the fourth axis to the knee.


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## T Bredehoft (Jun 20, 2019)

After 30 plus years in the trade, if I had a choice, I'd have a machine with both a knee and a quill. They each have their uses. Imagine trying to tap with the knee!


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## RJSakowski (Jun 20, 2019)

Submachine said:


> I am a beginner.  If a quill presents itself should I wait for knee mill?  I cannot  specify what I am going to do, because I don’t know yet.


One consideration is the larger mass and greater rigidity of a knee mill.  Some of the square column bench mills approach the rigidity but don't quite make it.  Along with increased rigidity and mass, there is usually a larger motor all of which lend themselves to take heavier cuts.  Many of the feeds and speed recommendations simply do not apply to the more wimpy mills.

Much depends on your anticipated use.  While you don't know what you will want to do, you should have a fairly good grasp on your interests. If they trend toward smaller projects, a bench mill may suit your needs well.  There are many fine examples on this forum of work done on a relatively small bench mill.


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## Bob Korves (Jun 20, 2019)

I prefer (and have) a mill with both knee and quill.  Very handy setup, and I would find myself missing either right away if one or the other was gone.

Edit: When I first read this post this morning, the link you had up was about CNC machines, not something I have or am into, so I did not reply at that time.  If you are going to be doing purely CNC work, then your preferences will be different, and need to be addressed from that viewpoint.


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## matthewsx (Jun 20, 2019)

Get the biggest machine you can fit in your shop. If you’re looking there are tons of threads on here regarding what type of machine to buy. However, it’s hard to argue that more capability is worse than less.

Of course, if a smoking deal comes your way grab it up. 

John


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## JimDawson (Jun 20, 2019)

That article is addressing knee vs. quill for a CNC conversion.  Elrod makes quill CNC Z axis conversion kits for BP type machines.  One of the few quill axis systems that can be reasonably switched between manual and CNC operation.  Some CNC conversion systems use the knee for the Z axis, this would not be my first choice for a CNC Z axis.

For a manual machine none of this applies.  A manual knee or bed mill will still have a quill in all cases.


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## Submachine (Jun 20, 2019)

sorry about the CNC article, I am not asking about CNC.

This is what I have learned.
The reason to go with a knee machine is rigidity and better for part positioning.
Quill only machine for size and weight.


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## JimDawson (Jun 20, 2019)

Submachine said:


> sorry about the CNC article, I am not asking about CNC.
> 
> This is what I have learned.
> The reason to go with a knee machine is rigidity and better for part positioning.
> Quill only machine for size and weight.



A knee or bed mill of similar size will produce the same part within limitations.  Normally a knee mill also has a turret head & ram system that allows the head to be moved into positions that would normally not be possible on a bed mill.  There are variations on this.

A BP type vertical turret mill is probably the most flexible system as far as being able to make parts that have odd and compound angles.  A bed mill of similar weight should be a bit more rigid than a knee mill. 

In general the heavier the machine the more rigid it is.

I think you may be confusing the quill with the head that moves vertically.  The quill is mounted in the head and moves up & down like a drill press, the head is independently adjustable vertically on a bed mill, and takes the place of the knee.  It needs to be said that the larger CNC bed mills have no quill but have a large head travel that provides the Z axis.

All of the bed bench mills that I know of do have a quill, and the head adjusts vertically to provide vertical clearance like a knee.  Normally the maximum quill travel is 4 or 5 inches, where the head may be able to move 12 inches or more.


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## Mitch Alsup (Jun 20, 2019)

Are there any knee mills that do not also have a quill?


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## JimDawson (Jun 20, 2019)

Mitch Alsup said:


> Are there any knee mills that do not also have a quill?



Not that I have ever seen.


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## MikeInOr (Jun 20, 2019)

I think it was stated above that a horizontal mill with a vertical head will likely have a knee without having a quill.  Most of the common vertical knee mills I have seen are basically of the Bridgeport type design that have a knee and a quill.  My 8 x 30 mill is a smaller mill with both a knee and quill... I really appreciate the flexibility of having both.

When milling a part I try to keep the quill extension as short as possible for maximum rigidity, especially with larger cutters.  For boring a hole I want a quill.  A knee mill with a quill gives me a lot of flexibility.  Raising the knee is usually a lot quicker and easier than lowering the head on a mill without a knee... at least with the 1 non-knee vertical mill I used.

#1 - What do you want to do with your new mill?

#2 - Are you looking for a manual mill or a CNC mill?


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## Bob Korves (Jun 20, 2019)

Mitch Alsup said:


> Are there any knee mills that do not also have a quill?


Yes.


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## Mitch Alsup (Jun 20, 2019)

MikeInOr said:


> I think it was stated above that a horizontal mill with a vertical head will likely have a knee without having a quill.



So something like a K&T will not have a quill--gotcha.


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## C-Bag (Jun 20, 2019)

I'm not sure Deckel or the vert head on the Hispano Suiza I saw did either.


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## dirty tools (Jun 21, 2019)

When I have to do boring the depth governs which I use
I use the knee on deep lengths ( over 5”)
And the quill on short length ( ( up to 5”)
Although my quill will go to 6” I don’t like using the maximum my machine can handle ( room for error).


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## MrWhoopee (Jun 21, 2019)

If your budget and shop are big enough, get a Bridgeport or a copy thereof. There are no other machines as versatile. That's why they became so dominant and so frequently copied.


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