[SCzEngrgGroup]

Seems that I will need a boring bar to machine my own motor mounts.

But once the mill is up and running w/ CNC, I'm guessing the boring bar will no longer be needed.

Am I correct?

or am I missing something?

Matt,

You'l probably still use the boring head (you'll need a boring bar also, to go IN the boring head...) from time to time, when you need a VERY precisely round hole.

Regards,
Ray L.

[cadmonkey]

Ditto on HimyKabibble's post - I've used my boring head several times since CNC'ing. It leaves a much better finish than an interpolated helical milled hole and is much more precise - bearing pockets, close fit matings, etc.

[project5k]

ok, this is gonna be bad, so go easy on me... i keep hearing the term boring bar, and boring head... can someone please explain to me exactly what this is, and how to use it? I'm guessing that its for "drilling" or boring a hole larger than you have drill bits for.

so that would mean that it cuts the entire diameter of the hole or pocket. Ok so then am i to understand that a fly cutter dosent cut in the middle, and only cuts on the set outter perimeter?

Pictures if at all possible, makes it much easer for me to understand

[ihavenofish]

ok, this is gonna be bad, so go easy on me... i keep hearing the term boring bar, and boring head... can someone please explain to me exactly what this is, and how to use it? I'm guessing that its for "drilling" or boring a hole larger than you have drill bits for.

so that would mean that it cuts the entire diameter of the hole or pocket. Ok so then am i to understand that a fly cutter dosent cut in the middle, and only cuts on the set outter perimeter?

Pictures if at all possible, makes it much easer for me to understand

a boring bar is in some ways similar in concept to a fly cutter. its a single point cutter (sometimes fixed, sometimes adjustable) that basically acts as a reverse lathe, spinning the tool and milling the final diameter of a hole.

it is not a replacement for a drill - it will not start a hole. it is only used to make a final pass to get a perfectly precise straight and round hole. the adjustable kind are good for doing arbitrary diameters without needing dozens of fixed diameters. like flycutters, you can often make your own from bar stock and lathe tooling fairly easily if you needed something special - or were just bored



heres a fixed set. note these are also used in lathe tailstocks.


a boring head can take those fixed bars and "slide" them like a flycutter to make very precise passes to a final hole diameter. it also allows you to use one tool to get many larger hole sizes.

[project5k]

ah ha! ok, so i'd still need to make my "starter hole" to the final depth, but then i can enlarge it to the outside diameter of my bearing or whatever and have it come out more precise than doing it with just the cnc and dealing with the backlash of changing directions on the x and y axis... ok, cool!

[caleb105]

So I have a question....

If I need to make a 15/16" hole for my ballnut holders, I would need to drill a hole that is about 13/16", then use the boring head and boring bar to finish them to final dia. right?

So what do I use to drill the initial hole? A 13/16" HSS drill bit? A drill mill?

Thanks!

-Caleb105-

[pete from TN]

I think what you might be meaning is that your ballnut mount hole needs to be machined. That is usually a boring and then a threading operation. You can buy a tap for that thread but I just did it on my lathe. Is that what you are asking. If not then yes a boring head will easily make a precise hole for the bearings or whatever as long as you are careful and remember to only move the adjustment of the boring head in one direction and keep the setscrews kinda snug to take out any backlash in the head. Then as you get closer to the final dimension make sure you take light passes and I usually go down with the head again after the cutting pass to make sure the spring in the toolbit is taken out and the cut is exactly what you dialed in. Once you have one of these very necessary tools you will understand what I am talking about.... good luck man...peace

[caleb105]

Pete,

Exactly.....I already bought the 15/16" x 16 tap....I just need to figure out how to make the hole.

-Caleb105-

[ihavenofish]

So I have a question....

If I need to make a 15/16" hole for my ballnut holders, I would need to drill a hole that is about 13/16", then use the boring head and boring bar to finish them to final dia. right?

So what do I use to drill the initial hole? A 13/16" HSS drill bit? A drill mill?

Thanks!

-Caleb105-

that would be the way to do it yes. drill the hole with a drill bit or an end mill or really anything else than can make the undersized hole. then bore it in one or more passes to final diametre.

if the machine has no play or backlash and the hole isnt deep, you can get away with circular interpolation. some benchtop machines can make circles happily to .001" roundness which is fine for many things. for bearing races and other things that need better precision and concentricity, the boring bar is much better. its also obviously better if the machine cant make an accurate circle or the hole is very deep and an end mill or drill bit would deflect too much resulting in tapered or skewed holes.

reaming is an alternative to boring especially for long precision holes, but it usually requires a fixed precisely sized tool which gets expensive if you need many diametres.

[escott76]

Pete,

Exactly.....I already bought the 15/16" x 16 tap....I just need to figure out how to make the hole.

-Caleb105-

Hole is .875", and you can use a silver and demming drill to do it in one shot if you have one. If you have access to a CNC mill, you can just as easily use that to circular interpolate the hole. Boring isn't needed here for precision, only if you have no other way to get the hole that big.
I used the S/D drill, and it was simple to tap at this size. If you bore a 15/16th hole, you won't get any threads.

[pete from TN]

That is what I figured... For me the way I do it usually is to measure the minor diameter of the bolt or thread that you intend to internally thread for and then bore to that number. Then the tap should go in without any problems. If you do not already have one, you might want to get a tap/drill chart. I got one from one of my tooling suppliers and it is plastic and mounts on the wall. It has basically every size of tap and it's corresponding drill size at a glance. I did however look at my tap drill chart and there is no listing for that tap size. I measured my ballnut that uses that size tap tho and I got .830" for a bore and then run the tap into it. Measure your ballnut at the inside of the thread diameter or the bottom of the grooves so to speak and bore to that size. Then your tap will make the threads from there. Otherwise call the guys you got that tap from and ask them the drill size... Good luck...peace

[caleb105]

Hole is .875", and you can use a silver and demming drill to do it in one shot if you have one.

Scott,

Thanks for the info!

Will this drill bit work then:

http://www.use-enco.com/CGI/INSRIT?P...PARTPG=INLMK32

-Caleb105-

[escott76]

Scott,

Thanks for the info!

Will this drill bit work then:

http://www.use-enco.com/CGI/INSRIT?P...PARTPG=INLMK32

-Caleb105-

Eric, Scott is my last name If you have a something to hold it sure, the shank is .875 on that. The reason I suggested the silver and demming is that they have a reduced shank, usually 1/2". S&D is a brand, but is commonly used to refer to the reduced shank style of drill.

[escott76]

That is what I figured... For me the way I do it usually is to measure the minor diameter of the bolt or thread that you intend to internally thread for and then bore to that number. Then the tap should go in without any problems. If you do not already have one, you might want to get a tap/drill chart. I got one from one of my tooling suppliers and it is plastic and mounts on the wall. It has basically every size of tap and it's corresponding drill size at a glance. I did however look at my tap drill chart and there is no listing for that tap size. I measured my ballnut that uses that size tap tho and I got .830" for a bore and then run the tap into it. Measure your ballnut at the inside of the thread diameter or the bottom of the grooves so to speak and bore to that size. Then your tap will make the threads from there. Otherwise call the guys you got that tap from and ask them the drill size... Good luck...peace

http://www.mcmaster.com/#2595a441/=v3baf
Recommended drill bit listed there. .875

[caleb105]

Eric,

Thanks for the info.

What about this one:

http://www.use-enco.com/CGI/INSRIT?P...PARTPG=INLMK32

ETA: I already got the tap, I just need the drill to make the hole.

-Caleb105-

[escott76]

Eric,

Thanks for the info.

What about this one:

http://www.use-enco.com/CGI/INSRIT?P...PARTPG=INLMK32

ETA: I already got the tap, I just need the drill to make the hole.

-Caleb105-

Much more like it. Low RPM and plenty of coolant.

[SSN Vet]

Piggy back question....

I'm selecting a boring bar set for use with my X3 mill....

could someone please comment on the merits of a threaded boring head on an R8 shank as shown in this link..
https://www.grizzly.com/products/G9322

opposed to boring head with an integral shank as illustrated here....
https://www.grizzly.com/products/H5679

Obviously, you can switch heads on the first.... but just how large of a boring head can be used given the power and rigidity of the X3 mill. Do you lose anything in the way of precision with the threaded head set up.

Also.... the diameter of the boring bars themselves is 1/2" on the first and 3/8" on the second. Is the X3 beefy enough to benefit form the rigidity of the 1/2" bars? Or are they just over kill.

Thanks in advance...

Matt

[SSN Vet]

and another Q....

is .0005" resolution test indicator sufficient for hobby work on an X3?

I'm shooting for an over all tolerance of .005" on my projects. But I realize that every +/- I introduce will stack up.

Here's my targets and plans so far....

1. shooting to get my X & Y back lash down to .005" or less.
2. will run back lash comp in Mach 3
3. planning on micro stepping w/ 1/8 or 1/10 resolution
4. will be using a Chinese angle lock vise with ~.003" runout over 5" for as much of my work holding as possible.

I don't want to add error in every set up with a course test indicator.

But don't want to polish the cannon ball when the rest of my equipment can't take advantage of it.

My goal is to match the quality level of my components to get an overall set up that will hold .005"

[SCzEngrgGroup]

and another Q....

is .0005" resolution test indicator sufficient for hobby work on an X3?

I'm shooting for an over all tolerance of .005" on my projects. But I realize that every +/- I introduce will stack up.

Here's my targets and plans so far....

1. shooting to get my X & Y back lash down to .005" or less.
2. will run back lash comp in Mach 3
3. planning on micro stepping w/ 1/8 or 1/10 resolution
4. will be using a Chinese angle lock vise with ~.003" runout over 5" for as much of my work holding as possible.

I don't want to add error in every set up with a course test indicator.

But don't want to polish the cannon ball when the rest of my equipment can't take advantage of it.

My goal is to match the quality level of my components to get an overall set up that will hold .005"

Matt,

Let me get this straight:

0.005" backlash
0.003" vise runout
probably +/-0.004"/foot lead error in your screws

And you're hoping for 0.005" overall accuracy? Consistently achieving 0.005" accuracy is not gonna happen.

I wouldn't be concerned about the resolution of the indicator. Buy a good (name brand) one, even if it's 0.001" graduations. They can easily be read to a few tenths, which is far better than you can really make use of.

Regards,
Ray L.

[SSN Vet]

which is far better than you can really make use of.

that is what I suspected... thanks for the reply....