Another Stupid Question

[jspangler]

All right, I know I should know this, but I don't.

 

 

I am trying to enlarge a single hole in a piece of .25 aluminum from 2.5, to 2.625. How do I set it up to be sure that it's centered? What does "sweeping" it mean?

 

Help.

[Allan]

Well you could sweep the shop with a broom

 

To center a hole on a machine tool I would use a test indicator. I would call this dialing it in.

 

Allan

[BernieT]

quote:

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How do I set it up to be sure that it's centered?

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Clamp the partdown, move the spindle to approx center over the hole. Put a test indicator in the spindle (mag base is OK) and 'sweep' the indicator around the inside of the hole, moving X & Y until indicator needle doesn't move. Now set X & Y to '0'. In Mastercam, draw a 2.625 circle on 0,0, and write your toolpath.

 

BerTau

 

[ 06-20-2002, 12:10 AM: Message edited by: BerTau ]

[Guest CNC Apps Guy 1]

John,

 

You're doing fine. Last year at this time you barely had a CNC and now you're prgramming and getting it done quite well from what I understand.

 

Don't be so hard on yourself.

 

[McRae]

This is one other techniques that I learned from a hatchet machinist. He claimed that he could out perfrom me picking up holes. His trick was to use a .500" dowel pin and a magic marker. Touch in X +/- and then Y +/- and average the coordinates to get to the center of the hole. He claimed this is an aerospace technique. Well he scrapped the first part and we used Allan's method from then on in.

[Scott Bond]

Good Morning

 

quote:

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He claimed that he could out perfrom me picking up holes.

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When I worked with Jay, he bosted the same thing.

 

Hi John, I have some stuff for you.See you soon.

 

[ 06-20-2002, 10:22 AM: Message edited by: Scott Bond ]

[chris m]

My 2

 

If you are new to sweeping a bore for center, it can be a bit of a workout to get in the ballpark; if possible it might be easier to edge find something on the part or set up a stop and dial over to where you think the hole should be, then stick on the indicator and make fine adjustments from there...

 

or...

 

I have also used the method Andrew describes and feel it is fairly accurate to eyeball an edge finder into the center of the hole, edge find the left and right "sides" of the hole, and split the difference to find the center; repeat for y axis and you're there.

 

I know its a hack, but it can be pretty accurate and will at least get you close enough so that your indicator isn't bottoming when you start off sweeping.

 

C

 

[ 06-20-2002, 10:30 AM: Message edited by: chris m ]

[Keith Graydon]

To continue......

 

Bring the stylus of the TEST indicator to a point just ABOVE the bore. Set the stylus so it is less than the bore diameter, by eye. Sweep it around to X and then adjust table by about ~ 1/2 the difference between the to sides. continue in Y. Now you close enough to be be within range of the test indicator.

Continue as described in the above posts.

 

and REMEMBER, NEVER NEVER NEVER turn on the spindle with the indicator in it. hehe

 

my.02

KLG

[cadcam]

quote:

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When I worked with Jay, he bosted the same thing.

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Are you ready again.I'll go to my tool box right now and whip out my coaxle indacator and have the hole in about a min or less.

[Keith Graydon]

Jay i got of them too! kinda long 'tho

 

KLG

[cadcam]

Kinda long to work with.

I had it down real fast and vary easy to use.

Used to keep in a holdr next to the machine.

I have a long tip and a shot tip.

You know this talk just does not sound right.

 

[ 06-20-2002, 11:13 AM: Message edited by: cadcam ]

[Keith Graydon]

Hehe funny Jay.

 

Here Look, here's a picture

'

'

'

'

 

[ 06-20-2002, 12:59 PM: Message edited by: Keith Graydon ]

[Jack K]

My renishaw probe will do the trick in seconds.....way to go!

 

jk

[n_tydingco]

My coaxial indicator has seen limited duty on the VMC's. Unless I am sweeping a hole larger than 1.5", I just use our test indicator mounted in the holder; eyeball the center; adjust the x-axis; then move the y-axis til it matches the x-axis readings. Remember -- you only need 3 points to find the center of a circle.

 

[Matthew]

For the majority of picking up I have to do, I use an edge finder, find the two edges in x, split the difference, then find two edges in y and split the difference. If it is really fussy, I throw an indicator in afterwards and make fine adjustments, but I find the edge finder is usually accurate to .0005" max, sometimes it is bang on.

[jspangler]

HI

Wow, thanks for all the responses. i guess I had posted too late last night, after everyone had gone home, cause I gave up after about an hour of checking the board, and figured it out. What I did was set up my dial indicator on its stand in the spindle, and swept it around the circle until it was pretty close. then I lowered the Z, and touched it off while spinning the spindle ( Scott says NO). It took me FOREVER to figure out that I only had to adjust HALF the distance on the indicator to get it centered, but I FINALLY got it. It tried to use my edge finder but the damn battery was dead.

Anyway, I cut the part and it came out Swwweeeeet.

I left work about 10pm, all proud of myself, and wrecked my car on the way home. Ever wonder what's inside of those big yellow trash cans you see when there's construction on the freeway???

 

 

Thanks Again

 

John

 

PS

Solids are kickin' xxxx

[Hugh.Venables]

John, there was nothing wrong with asking the original question. It generated a lot of interesting discussion. The topic name you chose to give it wasn't very informative though, was it?

Hugh Venables.

[cadcam]

Now Keith Graydon do I have show a picture of my tool sense you showed us yours?

 

Sorry could not help my self.

 

but that is one of te nice tools I have in my box too...

 

Later jay

[n_tydingco]

Talk about going from one extreme to the other -- sounds like your car crash wasn't going to set back your shop success

 

"The only stupid question..."

[Scott Bond]

Good morning

 

quote:

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then I lowered the Z, and touched it off while spinning the spindle ( Scott says NO).

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I was saying no only because he had the spindle on, and I felt that it was a little risky for his indicator.

[iowajim62]

John,

Let me begin by saying AWESOME!!!

I just finished reading all the threads on this topic and was impressed by James's comment on your background of 1 yr ago just getting a machine and starting programming as well. I've been in machining for 21 yrs and have never heard of anyone coming up in the trade so fast except for Team Ferret. Anyway enough rambling from me.

Once again I just want to repeat James comment

(Don't be so hard on yourself.) I know people who have been in the trade 30 yrs and don't know half of what you have already Mastercammed!!!

Jim

[jspangler]

Hi

Thanks for the encouragement.

I do feel that I've learned ALOT in the past year, but there is so much stuff that I still have NO CONCEPT on how to do. People like James Meyette, and Scott Bond come here and make it look easy.

If I can find time I am going to take the NTMA classes that James teaches. For now I just read everything I can here on the forum, and keep going throught the In-House tutorials, and Scholars books.

One thing that makes my life a little easier, is that all the parts I make right now are for my products, and if I say thats how they are SUPPOSED to look and fit, well then that's it. As long as I don't break anything in the process.

 

Thanks

 

John

 

" What do you get when it doesn't turn out the way you thought it would?

 

Experience."

 

Scott Bond

[Kenneth Potter]

Sweeping a hole is NOT Rocket Science!...Gheeeh

 

Eye in the indicator to center visualy weres the tip during a sweep looks concentric to the hole.

 

Sweep X.... X zero Deg to X 180 Deg ...Take note of the differnce & jog X axis to half of that difference.

 

Sweep Y......Y 270Deg to 90 Deg....Repeat the same steps as X

 

Take some time to practice .....you can get it down to 60 seconds.