# Coaxial Indicator - First Job



## epanzella (Apr 7, 2022)

I had a friend come to me with an emergency job. He had to put a thumb on an excavator because a job was being held up. He had his fab guy torch off a mount off an old junk machine but discovered the bosses were bored for a 1.5" pin but the new thumb used a 1.75" pin. He brought it to me to get bored out. This was pushing the limits of my HF round column mill but I am his last resort. The part was too big to bore both bosses from the same setup so I had to bore one hole and then flip the whole setup around and bore the other one.  I was nervous about getting the new enlarged bores to line up with each other. The bosses had been ground on and welded on so there was no surface to indicate off of. I figured the angle plate would take care of the X direction but the Y was flopping in the breeze. I finally tried taking a straight boring bar, stuck it thru both bosses against the Y direction and held it with a bungee cord. Then I indicated it vertically until the holes were in in alignment. Next I took my shiny new coax indicator out of the box and stuck in a collet. I love that thing. Once I figured out what probe to use I had had the needle barely trembling in about a minute. Best $80 I ever spent. I bored the two holes from separate setups and said my prayers. There was no way to test the alignment until the job was all done. The pin went in like it was sliding into a jar of honey. Murphy must have called in sick!


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## Martin W (Apr 7, 2022)

Nice job!
Cheers


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## C-Bag (Apr 7, 2022)

I’ve used my clone coax several times and it has never let me down. I don’t even run the machine like I’ve seen Mr. Pete do, just spin by hand and it works great. My learning curve included realizing there was a plastic ring clipped on that limited travel. Once I got that sorted life was good. I also paid $80 and worth every penny.


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## DavidR8 (Apr 7, 2022)

Fantastic work.


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## ErichKeane (Apr 7, 2022)

I love my coax indicator! It is so useful for just about every project.  I ended up breaking the glass on mine today though, dropped it out of the collet and it dropped onto the floor.  Not the first (and probably not its last time falling to the ground


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## JimDawson (Apr 8, 2022)

Nice setup


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## epanzella (Apr 8, 2022)

Just a follow up. My friend sent me a cupla pix of the part welded in place on the excavator boom and the thumb installed onto the boom. All that's missing is the hydraulic cylinder that connects the thumb to the new pin.


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## C-Bag (Apr 8, 2022)

Good job. More proof that the operator is more important than the machine. I've done some crazy stuff on my mill/drill and it has never been the problem if there was one. It was always either dull tooling or dull operator, not the mill.


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## Janderso (Apr 9, 2022)

ErichKeane said:


> I love my coax indicator! It is so useful for just about every project.  I ended up breaking the glass on mine today though, dropped it out of the collet and it dropped onto the floor.  Not the first (and probably not its last time falling to the ground


I have the same problem. You need three hands when removing them. I now place a bucket with a towel so the coax drops nice and easy. (When possible)


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## brino (Apr 12, 2022)

epanzella said:


> Murphy must have called in sick!



By the sounds of this it was not luck that got you thru, but knowledge and planning.
Well done!

Brian


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## gard (May 28, 2022)

Nice job, I have never used a coax indicator, is it better or faster than a edge finder along with X-Y DRO? Sound like yet another item to add to the wish list.
I am guessing when you indicated in the second side you just added a 1/8 shim between the boring bar and already bored hole?


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## epanzella (May 28, 2022)

gard said:


> Nice job, I have never used a coax indicator, is it better or faster than a edge finder along with X-Y DRO? Sound like yet another item to add to the wish list.
> I am guessing when you indicated in the second side you just added a 1/8 shim between the boring bar and already bored hole?


The coax indicator is a 100X faster than an edge finder, at least for me. In a bored hole the edge finder is affected by the radius of the hole which is not unsurmountable but is another place to inject error. As the coax indicator is spinning just fiddle with X&Y feeds until the needle stay on zero. It just takes a minute or two. Good call on your part but I didn't use a shim with the boring bar setup. (that pesky radius again) On the first hole I just used the bungee to hold the bar against both holes. When I bored the first hole I left 1.25" untouched at the bottom of the bore to keep the boring bar vertical  when doing the second setup.  When I bored the second hole I was also able to reach deep enough to remove the 1.25" left in the first bore. I would have been nice to bore the entirety of both holes from one side but I just couldn't reach deep enough.


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## C-Bag (May 28, 2022)

The thing the coax has over all other indicators is the dial always faces forward. Edge finders etc you often have to look around them to read them, not the coax.


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## Winegrower (May 28, 2022)

The coaxial indicator is a beautiful invention…Mr. Coax outdid himself.   The main setup issue I have is that there is a kind of cone of effectiveness, bigger downward, and sometimes for bigger diameter holes the stock tips don’t work, because they are too short.   So I’ve had to make up several rods and bend them to fit each application.  Anybody ever solve this more elegantly?   If so, I would like to pirate your solution.


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## gard (May 30, 2022)

So can the coax indicator also be used as an edge finder on a straight surface or traming in a vise? Would that be with the motor off?
How about traming a mill head to a table? Or is it used mostly to find hole centers? You can probably guess I have seen them in catalogs but never in person.


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## C-Bag (May 30, 2022)

gard said:


> So can the coax indicator also be used as an edge finder on a straight surface or traming in a vise? Would that be with the motor off?
> How about traming a mill head to a table? Or is it used mostly to find hole centers? You can probably guess I have seen them in catalogs but never in person.


I’ve never even thought about using my coax for edge finding or tramming a vise but I it could be used like that. I don’t use the motor when I use my coax I just spin by hand because the pulley on my mill drill is easy to grab. The only thing is it doesn’t read in .0005, only .001 so it’s not as sensitive as my test indicator. It doesn’t seem suited for doing mill head tram as it’s not made for reading at horizontal like a DTI on an arm is. Something to think about though.


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## epanzella (May 30, 2022)

gard said:


> So can the coax indicator also be used as an edge finder on a straight surface or traming in a vise? Would that be with the motor off?
> How about traming a mill head to a table? Or is it used mostly to find hole centers? You can probably guess I have seen them in catalogs but never in person.


Some of the old salts on here may be able to come up with a way to use a coax ind. to edge find a straight surface but I'm gonna go with "NO". You'd have to lock the quill and lock the indicator as well basically turning it into a DI or DTI which is what you should have been using in the first place. As far as tramming, you have to remember that what you read on the COAX dial is not an absolute reading but just a relative reading with respect to the other parts of the circle. What shows as .001" on the dial could actually be more or less depending on the length of the arm you're using. Even if you determine you're out of tram you still don't know how much you need to shim.  The COAX indicator is an awesome tool when used for it's intended purpose.


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## solo (Yesterday at 1:32 PM)

Where are you buy these for 80.00? I've dreamed of having one, but to costly.


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## ErichKeane (Yesterday at 1:42 PM)

solo said:


> Where are you buy these for 80.00? I've dreamed of having one, but to costly.


The Shars one is $86 on Amazon: https://www.amazon.com/SHARS-Co-Axi...=coaxial+indicator&qid=1673548863&sr=8-3&th=1

HFS is the same: https://www.amazon.com/HFS-Coaxial-...5d-baed-4c5053c92e38&pd_rd_i=B0149F2BOO&psc=1

This no name one is sub-$80: https://www.amazon.com/Coaxial-Cent...mzn1.fos.18ed3cb5-28d5-4975-8bc7-93deae8f9840


The cheap ones seem to work well enough!  I've had an HFS one and a Shars one and am happy with it.


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## ttabbal (Yesterday at 2:49 PM)

Just curious.. For those of us with DRO, I've used it a couple of times to center X in a bore, then go to X0 and center Y, all with an edge finder. It seems to work well for the basic stuff I've done it on. I can then put a pin in the collet and it moves through the bore well. I compared it to a DTI on an arm and was within .002", which is plenty for those projects. Perhaps not as fast as a coax. And if I use a tenths indicator I can get it really close, but I don't often need that level of accuracy. I feel like I have to be missing something with these.


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## matthewsx (Yesterday at 3:43 PM)

Oh boy, I have a job that needs this tool. Now I have to order one. Good to hear the Shars will do the job....

John


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## ErichKeane (Yesterday at 3:45 PM)

ttabbal said:


> Just curious.. For those of us with DRO, I've used it a couple of times to center X in a bore, then go to X0 and center Y, all with an edge finder. It seems to work well for the basic stuff I've done it on. I can then put a pin in the collet and it moves through the bore well. I compared it to a DTI on an arm and was within .002", which is plenty for those projects. Perhaps not as fast as a coax. And if I use a tenths indicator I can get it really close, but I don't often need that level of accuracy. I feel like I have to be missing something with these.


I have a DRO and have used that before, and typically do unless i have a good use for the coax-indicator.  I suspect they are within reason of the same accuracy?  DRO is perhaps a little faster, but the coax indicator is more fun  It also works in situations where the edge-finder in the DRO wouldn't work.   Cases like, "centering on a shoulder behind some threads", or a hole where the edge-finder won't reach.

Though, I guess you could use a wiggler-tip for both of those, so *shrug*.


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## Charles scozzari (Yesterday at 4:03 PM)

matthewsx said:


> Oh boy, I have a job that needs this tool. Now I have to order one. Good to hear the Shars will do the job....
> 
> John


It's a gotta have tool.


matthewsx said:


> Oh boy, I have a job that needs this tool. Now I have to order one. Good to hear the Shars will do the job....
> 
> John


Makes life a lot easier not to mention on the money.


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## C-Bag (Yesterday at 6:34 PM)

I have a DRO, TI, DI, and still needed the coax. For me it’s so quick and easy, almost as fast as an edge finder. I think I got mine from LMS on sale. I know it wasn’t over $80 and worth every penny for those special setups.


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## Provincial (Yesterday at 6:39 PM)

I found a import model at the Restore for $1.00.  It only had one arm, and the rod (handle) was missing.  The needle didn't move, either.  

I took it home and while watching TV I dismantled it enough to see the gear train inside.  After loosening the screws holding the gear train, and fiddling with things, the gears freed up and it works like new, with full travel.

I'm not concerned about accuracy of travel, since for centering I'm only interested in the amount of deflection.  It does seem to be pretty accurate in terms of measuring travel, but I haven't bothered to check it.


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## Larry$ (Yesterday at 7:28 PM)

I've got an import version. I stripped a screw in the part that holds the moving tip. Made a new part with more threads and it has worked well for several years. It came with an assortment of tips. I put the rotational stop arm in and something to act as a stop so I can use one hand on X  and the other on Y table adjustments. Run the spindle at slow speed. Very quick to center. Zero the DRO. How accurate? I don't know. Close enough for most work. By moving the spindle up & down while it is running you can tell if the hole is tilted. Even tell by how much and which way by the difference in DRO readings. Shift between ABS & INC. Use the DRO Z-axis and a quick bit of trig for a pretty good answer. If it matters then you can shim the part or use jack screws.


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## ErichKeane (Yesterday at 7:31 PM)

Larry$ said:


> I've got an import version. I stripped a screw in the part that holds the moving tip. Made a new part with more threads and it has worked well for several years. It came with an assortment of tips. I put the rotational stop arm in and something to act as a stop so I can use one hand on X  and the other on Y table adjustments. Run the spindle at slow speed. Very quick to center. Zero the DRO. How accurate? I don't know. Close enough for most work. By moving the spindle up & down while it is running you can tell if the hole is tilted. Even tell by how much and which way by the difference in DRO readings. Shift between ABS & INC. Use the DRO Z-axis and a quick bit of trig for a pretty good answer. If it matters then you can shim the part or use jack screws.


I use an old-style mag base with the solid straight-up arm for my 'stop', and it works perfect  Otherwise, I have the same experience as you.


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## epanzella (Yesterday at 8:01 PM)

I was pretty high off the table so I used a hunk of 3/8 x 16 all-thread and the t-nuts from my clamping set as a stop for the Co-ax indicator. (post #1)


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