All tools are not created equal

[ltlvt]

I've been trying to re bore a hole in my apron today. Kept trying to take .010 DOC and when I would start to bore it was trying to take .125 DOC. Finally, I realized the boring head was loose in the spindle bore. This was caused by a variance between the length of the threads on the draw bar and the threads inside the R-8 arbor. I solved the problem by machining a quick spacer to take up the slack and now itis cutting on target. I've been seeing the same thing with a set of R-8 collets that came with the mill and also bought a complete set of R-8 new collets and same problem. the spacer will take care of the problem on all of them, but it is damn sad that a precision tool is not standard. All R-8 should fit all draw bars etc. Some of the tools from China are M-12 thread but R-8 taper. I got the problem fixed but should not have to spend valuable time correcting problems of this kind. It is not just this mill or this draw bar PM 833-T states in the manual that some tools will require a spacer.

 

[benmychree]

You seem to be trading quality for price, they don't always equal each other.

 

[ltlvt]

You seem to be trading quality for price, they don't always equal each other.

High price does not always equal high quality. The issue I am describing is standardization not cost or quality. If every Hobbyist on this forum only used the highest price tools there would be many less hobbyists.

 

[MikeInOr]

The spacer goes between the top of the mill and the top of the draw bar? ...to effectively make the draw bar shorter? ...because the threads in the R8 boring head aren't long enough?

I have never heard of this but I am a novice so that doesn't mean anything. I will have to file this in the bottom drawer of my mind in hopes I might remember if I should come across a similar problem. Thanks for sharing!

It kind of sounds like something is out of spec like the length of the draw bar?

 

[T Bredehoft]

Ideal standardization is a dream, not a reality. Part of the charm of being a hobbyist is not knowing how well the next assembly will fit together. Professionals, (Tool & Die workers, Machinists, etc., know and understand that part of their job is modifying things to fit "their own" standard.)

Hope to be surprised that things fit, take pleasure in the ability to make them work together.

 

[cathead]

On several occasions, I have had to put new threads on my draw bar by welding on new threads on
the bottom end. It's not difficult but one needs to be sure the threads are perfectly in line with the draw bar.
I use a spacer as a wear surface. The horizontal attachment for my vertical Enco mill required a
significantly longer draw bar to function so I had to make one extended a few inches for that. Generally
one can feel when the R-8 seats in the mill head as the draw bar is tightened. I don't fret about
that sort of thing much and just do what works in each situation.

 

[Charles scozzari]

What condition is the draw bar in. Is the underside on the bar mushroomed or the threads pulled.

 

[ltlvt]

The spacer goes between the top of the mill and the top of the draw bar? ...to effectively make the draw bar shorter? ...because the threads in the R8 boring head aren't long enough?

I have never heard of this but I am a novice so that doesn't mean anything. I will have to file this in the bottom drawer of my mind in hopes I might remember if I should come across a similar problem. Thanks for sharing!

It kind of sounds like something is out of spec like the length of the draw bar?

I thought the same but doing the research I found that the length for the draw bar is correct. Just FYI when buying r-8 tools be aware that some of them are threaded Imperial and some are threaded Metric.

 

[RJSakowski]

The drawbar length will depend upon the design of the spindle assembly. I see no reason to expect that all drawbars would be the same standard length. OTOH, the depth of the threads in an R8 collet or other tool should all be the same or at least meet a given minimum.

 

[ltlvt]

The drawbar length will depend upon the design of the spindle assembly. I see no reason to expect that all draw bars would be the same standard length. OTOH, the depth of the threads in an R8 collet or other tool should all be the same or at least meet a given minimum.

I agree. Different mills can all have different length spindles and draw bars but the R-8 collets are an industry standard and should all have the same threads and thread depth. As well with R-8 tools. My Keyless chuck must also use a spacer